Studies in Environmental Science 1
ATMOSPHERIC POLLUTION 1978 Proceedings of the 13th International Colloquium, UNESCO Building, Paris, France, April 25-28,1978 Organised by the Institut National de Recherche Chimique AppliquCe, Vert-le-Petit, France
edited by
MICHEL M. BENARIE Ddpartement Pollution des A tmosph&res, Institut National de Recherche Chimique Appliqude, Vert-le-Petit,France
ELSEVIER SCIENTIFIC PUBLISHING COMPANY AMSTERDAM-XFORD-NEW
YORK 1978
ELSEVIER SCIENTIFIC PUBLISHING COMPANY 335 Jan van Galenstraat P.O. Box 211, 1000 AE Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER NORTH-HOLLAND INC. 52,Vanderbilt Avenue New York, N.Y. 10017
I n t e r n a t i o n a l Colloquium on P o l l u t e d Atmospheres, l 3 t ’7, P a r i s , Prance, 1978. AtDospheric p o l l u t i o n , 1978. ( S t u d i e s i n environmenral s c i e n c e ; 1) Bibliography: p. 1. Air--Pollution--Congresses. I. Denarie, Ilic’iel Pa. 11. T i t l e . 111. S e r i e s .
~~881.1561978
ISBN 0-444-41~91-9
628.5’3
78-3 666
ISBN: 0-444-41691-9 (Vol. 1). ISBN: 0-444-41696-X (Series) Elsevier Scientific Publishing Company, 1978 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system o r transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Scientific Publishing Company, P.O. Box 330, 1000 AH Amsterdam, The Netherlands 0
Printed in The Netherlands
V
PREFACE
This volume contains a s e l e c t i o n o f t h e eighty papers presented a t the 13th International Colloquium on Atmospheric Pollution held i n P a r i s , UNESCO Building, from the 2 5 t h t o the 28th of April, 1978. Organized every second year, o u r Colloquium has the s p e c i f i c i t y o f covering a wide area in the f i e l d of a i r p o l l u t i o n . Some important symposia, meetings or conferences (on sulphur compounds, ozone, aerosol physics, e t c . ) gather the special i s t s of a more or l e s s r e s t r i c t e d branch of d i s c i p l i n e . Our purpose, however, i s t o mingle highly specialized people of several s u b - f i e l d s , in order t o be as i n t e r d i s c i p l i n a r y as possible. The r e s u l t i n g volume i s heterogeneous because i t was meant thisway,We intend t o show "what i s on" in a i r pollution in t h i s part of the world. The number o f papers published could have been much l a r g e r b u t f o r the r e s t r i c t i o n of p r i n t i n g space and presentation time. The programme committee had a very d i f f i c u l t j o b of s e l e c t i n g a reasonable number of papers from the a b s t r a c t s submitted. Looking a t t h i s "what i s on ?", we note a c l e a r o r i e n t a t i o n towards engineering applications. This does not mean t h a t t h e o r e t i c a l , basic research-oriented papers are lacking. I t only means t h a t instead o f asking purely i n t e l l e c t u a l questions such as "why" o r "how" (why o r how a phenomenon occurs - - basic understanding), most papers imply the question "what should be done t o obtain t h i s r e s u l t , t h a t e f f e c t , control or e l s e " . The papers a r e more on the "how-to-do'' s i d e because the general o r i e n t a t i o n of science i s accomplishment-oriented in the l a t e seventies. One of the main f a c t o r s t h a t influence the number of people engaged i n any f i e l d of research (besides fashion, i n e r t i a , e t c . ) i s financial endowment and positively not the "significance" (whatever the meaning given t o t h i s word) of t h e subject. The main sponsors - S t a t e Agencies, i n d u s t r i e s - nowadays prefer product (tangible or i n t a n g i b l e ) t o i n s i g h t , f o r g e t t i n g t h a t the two aspects a r e inseparably intertwined. Yesterday's pure i n s i g h t i s t o d a y ' s i n d u s t r i a l output. The subject matter o f t h e colloquium i s grouped in seven main subject headings with several subdivisions : 1.1 Survey methods 1 . 2 Survey r e s u l t s 2 . Methods o f measurement 2 . 1 Analytical methods in general
2 . 2 Measurements concerning the suspended matter 2.3 Methods f o r t h e measurement of gaseous p o l l u t a n t s 3.
Health e f f e c t s
VI
4.
Computations, m o d e l l i n g and s t a t i s t i c a l d i s p l a y o f t h e r e s u l t s
5.
T r a n s p o r t o f a i r p o l l u t a n t s and micrometeorolooy
6.
A i r chemistry
7.
Aerosol p h y s i c s
A p p r o x i m a t e l y h a l f o f t h e papers d e a l w i t h p a r t i c u l a t e m a t t e r : i t s s i z e d i s t r i b u t i o n , f o r m a t i o n , i n t e r a c t i o n s and measurement, w h i l e one s i x t h deal w i t h v a r i o u s aspects c o n c e r n i n g gaseous p o l l u t a n t s . One t h i r d o f t h e t o p i c s - as t r a n s p o r t phenomena, s t a t i s t i c s o r micrometeorology - a p p l y t o one o r t h e o t h e r class o f pollutants. Due t o t h e f a c t t h a t most r e s e a r c h i n a i r p o l l u t i o n i s m u l t i d i s c i p l i n a r y where means a r e concerned, and extends i n t o more t h a n one f i e l d a c c r e d i n g t o t h e r e s u l t s , some a r b i t r a r y judgement c o u l d n o t be a v o i d e d w h i l e d i v i d i n g t h e papers under t h e s u b j e c t headings. I n f a c t , except f o r l e g a l and economical aspects, t h e complete area o f a i r p o l l u t i o n i s covered. T h i s coverage i s d i f f e r e n t f r o m t h a t found i n handbooks and complenientary t o i t . Those f i e l d s where s o l i d e n g i n e e r i n g knowledge e x i s t s a l r e a d y , a r e n o t discussed; on t h e o t h e r hand, open t o p i c s , where r e s e a r c h and development r e s u l t e d i n a t u r m o i l o f a c t i v i t y , a r e r e p r e s e n t e d i n s e v e r a l papers. The a d j e c t i v e " i n t e r n a t i o n a l " i s j u s t i f i e d by t h e f a c t t h a t a p p r o x i m a t e l y h a l f o f t h e papers came f r o m France, w h i l e t h e o t h e r s were c o n t r i b u t i o n s f r o m
13 c o u n t r i e s o f f o u r c o n t i n e n t s . D u r i n g t h e Colloquium, t h e p r o b l e m s f language was s o l v e d by simultaneous t r a n s l a t i o n ; a t t h e moment o f p u b l i c a t i o n , we had t o choose between t h e use o f about t w e l v e o r i g i n a l languages o r o f a s i n g l e one. Any s c i e n t i s t wishes
-
and t h i s i s o u r d u t y
-
t o d i f f u s e h i s r e s u l t s among
t h e b r o a d e s t p o s s i b l e r e a d e r s h i p , s o as t o be understood by an i n t e r n a t i o n a l audience. T h i s c a t e g o r i c a l l y does n o t mean v a n i t y : t h e purpose o f a meeting and i t s subsequent p u b l i c a t i o n i s t o d i s c u s s means and c o n c l u s i o n s , and f i n d people and groups who a l l around t h e w o r l d pursue s i m i l a r endeavours. I n t h i s way, d u p l i c a t i o n i s avoided, money economized and i d e a s c r o s s - f e r t i l i z e d .
M i c h e l BENARIE
VII
ACKNOWLEDGMENTS The enormous a d m i n i s t r a t i v e work necessary f o r t h e o r g a n i z a t i o n
o f such a c o l l o q u i u m was t h i s t i m e a l s o e x p e r t l y executed by Mme Monique Thavard, t o whom t h a n k s a r e expressed h e r e w i t h .
Atmospheric Pollution 1978, Proceedingsof the 13th InternationalColloquium,Paris,France, April 25-28,1978,M.M.Benarie (Ed.), Studies in EnvironmentalScience,Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
3
SOME PRACTICAL EXPERIENCES WITH A SMALL AUTOMATIC S02-NETWORK J.G. KRETZSCHMAR, H. BULTYNCK and H. PEPERSTRAETE
Nuclear Energy Research Centre, SCK/CEN, Mol (Belgium)
ABSTRACT This paper deals with the maintenance and calibration aspects of a small automatic SO*-monitoring network in a region with some specific industrial S02sources. It is also shown what kind of information one can expect from such a network.
INTRODUCTION The region of Tessenderlo in the northern part of Belgium (Province of Limburg) is characterized by the presence of some important chemical plants. Partly due to some rather spectacular events in the early seventies, the Secretary of State for Regional Economy committed the Nuclear Energy Research Centre with the investigation of the air pollution situation in that region.
Based on
the results of an extensive mobile campaign in 1974 (ref. 1 ) some of the local industries had to change their emission characteristics.
In order t o follow
the further evolution, the Department of Public Health and Environment, in cooperation with the local authorities and the local chemical plants, decided in 1976 that three local monitoring stations for SO2 and one for vinylchloride,
ethylene and EDC had to become operational in 1977.
This paper deals with the
problems and the results of the three SO2 stations during the first nine months of their installation.
DESCRIPTION OF THE S02-NETWORK The exact position of the monitoring stations and the local sulphuric acid plants are indicated on Fig. 1 .
Each monitoring station has a Philips S02-
monitor (PW 9 7 5 5 ) with an analogue recorder and an integrating device giving half hour averages (counts/30 min.).
4
fl
I
KM
Fig. 1 . Pollution roses for the 95-percentiles of the recorded half-hourly SO 2: averages during the period March - November 1977. The centres of these pollution roses also indicate the positionsof the monitoring stations. With a periodicity of 1 2 h a calibration unit delivers zero-air and spangas, each for 30 minutes, in order to check the proper functioning of the monitor. In one of the monitoring stations ("Het Hof") windspeed and wind direction at a height of 18 m are continuously recorded.
5
MAINTENANCE AND CONTROL PROCEDURE Twice a week, on Monday and Friday, a "de visu" check is done by means of the analogue and digital outputs of the instruments. Zero and span fluctuations are of prime importance here.
During the same controls a couple of parallel S02-de-
terminations (30 min. averages) are done by means of the pararosaniline (TCM) method in each station. Portable sampling units are used for these determinations (ref. 4 ) . Every three months the S02-monitors return to the laboratory for calibration, servicing and recalibration on the SCK/CEN primary calibration unit (ref. 2 and 3).
The main purpose of this procedure is the determination of the actual cha-
racteristic equations giving the relation between the SO2 input of the monitors and their electric output (analogue in recorder units and digital in counts/30 min.).
At least five to six different S02-concentrations within the range of
the specific monitor are therefore realized by means of a primary calibration unit based on permeation tubes.
The portable sampling units for the TCM method
are checked at the same time on the central manifold of the calibration unit. As the monitors and the portable sampling units are calibrated under lab conditions against the same standard,based on the permeation technique, they should lead to comparable results under field conditions e.g. in the above mentioned routine controls in the monitoring stations. As such, those portable sampling units form a link between the performances of the monitors under lab and field conditions. SOME SPECIFIC RESULTS
During the first nine months of operation valid environmental S02-data were obtained during 79 Z, 91 % and 86 % of the time in the three stations respectively.
The loss of data was mainly due to the three monthly servicing and cali-
bration procedure.
One or two back-up monitors would reduce this time-out in a
drastic way. Cumulative frequency distributions (CFD) of the 30 min.-averages and the 24 h-averages were quite different for the three monitoring stations.
Those
CFD's seemed to be lognormal in the 60-percentile to 95-percentile range, but showed important deviations outside this range. Although the investigated region is only about 4 km2 large, important spatial fluctuations in the statistical parameters were observed (factors 2 to 4 ) . Median values were below 30 ug/m3, arithmetic averages dit not exceed 60 ug/m3 but the highest half hour levels reached 500 to 1000 pg/m3.
Those phenomena
are specific for regions with a limited number of industrial sources. Many different investigators tried to determine the relationship between corresponding statistical parameters for different averaging times.
6 It was noted here that the ratio between the 95-percentiles for tav and tav
=
= 30
min.
24 h ranged between 1 and 1.5, while the ratio for the maximum values
varied between 2 and 5. As expected this shows that for a given region those ratios are a function of the source-monitoring station configuration and the meteorological conditions during the period of measurements. More accurate information on the contribution of specific sources is obtained by analyzing the measured S02-concentrations (30 min.-values) as a function of the wind direction. As an example Fig. I gives the pollution roses for the 95percentiles of the half hour averages for the different wind directions. influence o f the S02-sources is obvious.
The
On the same figure a wind rose for the
same period and region shows how frequently the different directions occurred. Pollution roses in a specific monitoring station give information on the average levels and the percentiles (Fig. 1 ) when the wind is blowing from a given direction.
As far as there is only one source for a given direction, this source
will cause approximately the same levels under different wind directions in the corresponding points at the same distance from the source.
A s such, informa-
tion obtained in a specific point can be extrapolated over a region. Once the individual half hour S02-averages have been classified according to the mean wind direction during their determination, it is interesting to subdivide each wind direction class into wind speed classes and/or stability classes. For the wind directions giving the highest influence of the S02-sources upon the ambient levels (Fig. I)
it was noted that high wind speeds ( > 8 m/s at 18 m
height) under neutral atmospheric conditions are most unfavourable for monitoring stations close to the source, while windspeeds between 3 and 5 m/s under a slightly stable atmosphere give the highest levels for those directions whereby the monitoring station is further away from
a source. Low level releases
seem to play a major role in the first phenomenon, while high level releases are responsable for the second one. REFERENCES 1 J.G. Kretzschmar, H. Peperstraete and T. Rymen, Extern, V(1976) 147-178. 2 H. Bultynck, J. Kretzschmar, M. Loos and H. Pe erstraete, in M.M. Benarie (Ed.), Atmospheric Pollution, Proc. of the International Colloquium, Paris, May 5-7, 1976, Elsevier, Amsterdam, 1976, pp. 279-296. 3 H. Peperstraete, in Proceedings of the Fourth International Clean Air Congress, Tokyo, May 16-20, 1977. 4 J.G. Kretzschmar, Tribune du Cebedeau, 361 (1973) 498-503.
I
AtmosphericPollution 1978, Proceedings of the 13th International Colloquium,Paris, France, April 25-28,1978,M.M.Benarie (Ed.),Studies in EnvironmentalScience,Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
THE CEKTRALIZED SUPERVISION SYSTEM FOR ATMOSPHERIC POLLUTION IN THE REGlON OF FOS
- ETANG DE BERRE
G.E. SIMON AIRPOREP Martigues (France)
-
ABSTRACT
A system for checking atmospheric pollution has been installed Etang de Berre region by the Authorities with the in the F o s
-
participation of various Organizations, among which AIRFOBEP. The system consists of a central station in which a oomputer unit is located, and thirteen stations in which captors have been installed. The central station is connected to the capturing stations by means of Hertzian beams, and every fifteen minutes the computer aonsults them in order to get the results of the measurements and to stock them on a magnetic memory. The modular layout of the system easily allows increasing the number of stations and captors. As a matter of fact, the system is presently going to receive extensions and will act as a warning system
INTRODUCTION Etang As there is a high concentration of Industries in the F o s de Berre region, the French Government has decided to create a specific Organization for study and concerting, the IISecritariat
-
Permanent pour les Problemes de Pollution Industrielle" (SPPPI). The installation of a centralized system f o r supervision of the atmospheric pollution of the region was one of the first steps taken by this Organization. The system was financed by the Government, the region's manufacturers grouped within the "Association des Industriels de la RQgion de Fos l'Etang de Berre pour lVEtude et la Prevention de la Pollution" (AIRFOBEP) and equally by the Autonomous Port of Marseilles. Furthermore, the local communities have facilitated the implantation of the stations.
Its operation is handled by SPPPI and AIRFOBEP.
8
General. c i e s c r i p t i o t l of t h e Pos
__I
The sy:,tem sul,-strtt
irJrls,
c o n s i s t s of
it
- Etang
g r o u p Qf t h i r t e e n s t a t i o n s a n d
t.h.0
i n ~ h i c ht h o c a p t o r . ? a r e i n s t a l l e d . They a r e l i n k e d
b y F - i . t z i a r > h r a n i s wi t h th;. C e n t r a l . S t i l t i o n l o c a t e d a t M a r t i g u e s .
Gena.AraI f y ,
t h c s t a t i o n s a r e 1 . o c a t e d a t t h e v i c i n i t y of u r i i a n z o n e s .
F i r % t l y , t h e rystem g a t h e r s d a t a which a r e b e i n g analyzed i n o r d e r t o e s t a b l i s h a warning procedure. rrnchs.1,
Then, when t h i s h a s b e e n
t h r system w i 1 . l f u l f i l i t s second t a s k , hvhich i s t o g i v e
w a r n i n g i n c a s e of p o l l u t . . i o n . Tho i n d u s t r i e s w i l l t h e n h a v e t o
rcducc t h e i r s u l p h u r d i o x i d e emissions. D e s c r i p t i o n of t h e s y s t n m q s - s : t a t j a n s . , - s ~ s t - i n gs t a t i o n i n c l u d e s c a p t o r s , c e p t u r i n y i n t e r f a c e s , a rerno-tt. t r a n s m i s q i o n u r i i t ant1 a t r a n s c r i v e r .
-
Thc c b r p t o r s a r c for : mrosrii-iiig thfb c o n c c r l t r a t i o n o f a i r p o l l u t a n t s .
t h e f i r s t s p e c i f i c mcnsurement t o b e t a k e n ,
High a c i d i t y i s
as i t gives a global
intlication c j f thc pollution.
-
mea.surj.ng t h e m e t e o r o l o y i c a l f a c t o r s : wj.nd s p e e d a n d d i r e c t i o n ,
t e m p e r a t u r e , hygrometry,
p r e s s u r e et.c.
The cnptu.ring i n t e r f a c e s a d a p t t h e in f o r matio n d e l i v e r e d by t h e
c a p t o r s t o t h e remote t r a n s m i s s i o n u n i t ,
and d e t e c t f a i l u r e s i n
t h e power s u p p l y o f t h e s t a t i o n s . The r e m o t e t r a n s m i s s 3 o n nn3.t a s s u m e s t h e f u n c t i o n s of m n l . t i p l e x i n g and s e r i a l j z a t j on of t h e d . i g i t a l i n f o r m a t i o n f r o m t h e i n t e r f a c e s b e f o r e t r a n s m i t t i n g them t o t h e C e n t r a l S t a t i o n . The t r a n s c e i v e r
e n a b l e s c o n t a c t hy H e r t z i a n waves i n a l t e r n a t i v e
niode w i t h t h e C e n t r a l S t a t i o n .
T h i s e q u i p m e n t c a n be u s e d f o r
speach tra nsm i s s i o n . Central S t a t i o n -____-----__-_
of Martigues
The C e n t r a l S t a t i o n is e q u i p p e d w i t h a t r a n s c e i v e r ,
a remote
t r a n s m i s s i o n u n i t a n d a mini - c o m p u t e r w i t h i t s p e r i p h e r i c s . The t r a n s c e i v e r a n d t h e r e m o t e t r a n s m i s s i o n u n i t a r e a b o u t t h e same a s t h o s e i n s t a l l e d i n t h e s t a t i o n s .
However,
t h e f u n c t i o n s of
t h e reniotr t r a n s m i s s i o n u n i t i n t h e C e n t r a l S t a t i o n a r e t o decode the data received,
t o c h e c k them a n d t o t r a n s f e r them t o t h e m i n i -
computer. The p r i m a r y f u n c t i o n of o f the netivork.
t h e mini-computer
i s t o c o n t r o l t h e whole
For t h i s , i t s u c c e s s i v e l y q u e s t i o n s , w i t h a 1 5 - m i n u t e
9 periodicity,
a l l t h e s t a t i o n s of t h e system.
T h i s procedrlr-c. i s 1);lsnd
on t h e p r - i n c i p l e of e x c h a n g e s hy i n t e r r o g a t i o n / r e s p o n s e
: t h e coinw-
t e r e m i t s a code word c o n t a i n i n g t h e a ddress of one s t a t i o n t o a l l stations. answer.
Only t h e s t a t i o n which h a s r e c o g n i s e d i t s acicfYess w i l l .
Successively,
t h e computer
e m i t s t h e a d d r e s s o f path s t n t i.un
i n t h e grorip. The o b t a i n e d d a t a a r e c o n v e r t e d , cheched and t h e n s t o c k e d on mognetic r e c o r d s . The m i n i -coinprrter
can equa 11 y hand1 e v a r i o u s progI-itnirnr'"s.
The p e r i p h e r i c s c o n n e c t e d t o t h e niini-computer
c o n s i s t of a t e l e -
t y p e i n s . t a l l . a t i o n , a r e p r o d u c i n g u n i t f o r t h e m a g n e t i c r e c o r d s , a' f a s t - p r i n t i n g u n i t , a c a r d r e a d e r , a n e x t e r n a l c l o c k and a synoptic panel
o
The t e l e t y p e i n s t a l l a t i o n h a s a keyboard e n a b l i n g a dial.ogue w i t h t h e mini-computer parameters,
: c a l l i n g up of d a t a i s s u e s , m o d i f i c a t i o n of
i n v a l i d a t i o n of d a t a ,
t i o n , performance of c h e c k - t e s t s teletype installation,
p u t t i n g c a p t o r s i n o r o u t of o p e r a On t h e p r i n t i n g u n i t of
etc.
a l l incidents
(failures,
power c u t - o u t s
the etc.)
and i n t e r v e n t i o n s of t h e o p e r a t o r a r e i s s u e d .
On t h e m a g n e t i c r e c o r d i n g d i s c s , which have a t o t a l c a p a c i t y of 10 million octets,
t h e computing s y s t e m and t h e r e s u l t s of t h e ( l u n r t e r -
h o u r l y measurements a r e r e c o r d e d . The i s s u e s e n a b l e t o s u p p l y t h e measurement r e s u l t s , t h e h o u r l y a v e r a g e s a s w e l l a s t h e d a i l y a n d mont.hly a v e r a g e s , and a r e produced by t h e f a s t - p r i n t i n g
u n i t upon r e q u e s t .
The s u l p h u r d i o x i d e q u a n t i t i e s e m i t t e d by t h e f a c t o r i e s a r e i n t r o duced by t h e c a r d r e a d e r ,
which a l s o r e a d s t h e d a t a u s e d by t h e
s t u d y programmes The autonomous e x t e r i o r c l o c k s u p p l i e s t h e hour-time computer when i t s t a r t s up a g a i n a f t e r a power c u t . fact,
t o the m i n i -
A s a m a t t e r of
t h e s y s t e m h a s been d e v e l o p e d i n o r d e r t o o p e r a t e round t h e
c l o c k w i t h o u t hLman i n t e r v e n t i o n . A synoptic Panel r e p r e s e n t s
t h e r e g i o n and t h e l o c a t i o n o f e a c h
s t a t i o n f i g u r e s by t w o w a r n i n g l i g h t s ,
one o f which i n d i c a t i n g
whether t h e c a p t o r s a r e o p e r a t i n g or n o t , whether
and t h e o t h e r i n d i c a t i n g
t h e h i g h a c i d i t y d e g r e e measured d o e s o r d o e s n o t e x c e e d
a fixed l i m i t . M o d u l a r i t L o___-f t h e S y s tem --__-
The system h a s been d e v e l o p e d i n o r d e r t o e n a b l e :
-
easy a d d i t i o n of c a p t o r s d e t e c t i n g v a r i o u s p o l l u t a n t s
10
-
-
i n c r e a s e i n t h e number o f s t a t i o n s r e c e i v e d i n t r o d u c t i o n o f s u l p h u r d i o x i d e e m i s s i o n s from new f a c t o r i e s .
The f i l e s y s t e m has a c a p a c i t y f o r r e c e i v i n g d a t a from 1 2 0 c a p t o r s s p r e a d o v e r 32 a c t u a l s t a t i o n s and t h e e m i s s i o n s o f 3 0 f a c t o r i e s . F u t u r e e v o l u t i o n o f t h e System A d i s p l a y c o n s o l e w i l l be i n s t a l l e d a t t h e C e n t r a l S t a t i o n .
It
w i l l e n a b l e a f a s t check on t h e s p r e a d i n g of p o l l u t i o n . New r e m o t e t r a n s m i s s i o n equipment i s g o i n g t o r e p l a c e t h e e x i s t i n g material
i n the s t a t i o n s f i t t e d out with several captors.
They p a r -
t i c u l a r l y a l l o w t o c a l c u l a t e a mean wind d i r e c t i o n b e s i d e t h e a l r e a d y o b t d i n e d a v e r a g e wind v e l o c i t y . The number of s t a t i o n s i s g o i n g t o be i n c r e a s e d , u r i n g n i t r o g e n oxides, hydrocarbons, several stations. Furthermore,
t h e System o f t h e Fos
and c a p t o r s meas-
ozone, w i l l be i n s t a l l e d i n
-
Et,ing de B e r r e r e g i o n w i l l
be c o n n e c t e d t o t h e s y s t e m o f M a r s e i l l e s . warning_procedure. C r e a t i o n o f a----A v e r y i n t e n s i v e s t u d y h a s b e e n made i n o r d e r
procedure, t h e Fos
-
forecast.
if p o s s i b l e of p r e v i s i o n n l c h a r a c t e r .
t o c r e a t e a warning But t h e w e a t h e r i n
E t a n g de R e r r e r e g i o n i s v e r y v a r i a b l e and d i f f i c u l t t o T h i s i s due t o t h e i n f l u e n c e o f t h e s e a and t h e iiumerous
l a k e s and t h e v i c i n i t y o f t h e mountain r a n g e s and t h e Rhodanian corridor.
Because o f t h e s e c o n d i t i o n s , t h e i n v a s i o n s o f p o l l u t i o n
a r e g e n e r a l l y of s h o r t d u r a t i o n .
However,
i t h a s been p o s s i b l e t o
p u t a c e r t a i n number o f mechanisms i n t o e v i d e n c e which w i l l e n a b l e t o determine a procedure.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
11
MEASUREMENT OF PKYSICAL PARAMETERS ACCOMPANYING POLLUTANT FALLOUTS ON TRE SITE OF LACQ. STUDIES OF THE CORRELATIONS BETWEEN THE DIFFEREZT F'HENOMENA WITH A VIEW TO m D I C T I N G POLLUTION. D. LAURENT and R. PEYROUS
Facultk des Sciences de PAD (France)
ABSTRACT Measurements effected on the s i t e of LACQ, under d i f f e r e n t meteorological conditions, show a modification of the e l e c t r i c a l parameters of the atmosphere before and during f a l l - o u t s of polluting elements. Measurements of t h e E l e c t r i c Field permit the detection
of the SO2 ttcloudttabove the s t a t i o n while small ion measurements can a c t as an indicator
of the presence of SO2 a t ground level.
INTRODUCTION
Earlier measurements have indicated the probability of a relationship between atmospheric i o n concentrations and pollution, and these i n c i t e d us t o make an extensive Study, during 8 months, of t h e behaviour of atmospheric e l e c t r i c a l parameters on an i n d u s t r i a l location. Continuous recordings of the following elements w e r e effected : E l e c t r i c Field, Space Charge, p o s i t i v e and negative conductivities, and positive and negative i o n concentrations f o r both large and small ions.
MEXSUREMENT LOCATION.
The i n d u s t r i a l area of Lacq, i n the valley of the "Gave de Paul', is the site of a very s p e c i a l micro-climate of p a r t i c u l a r i n t e r e s t . A w e l l defined source of pollution
i s s i t u a t e d i n a rural s i t e . The measuring s t a t i o n is i n s t a l l e d t o the E a s t of the source of pollution w h i c h is the leeward side f o r the dominant winds.
APPARATUS.
The E l e c t r i c Field i s measured by means of a r a d i o a c t i v e antenna at the s t a t i o n and by a mobile measurer using a Field Mill i n s t a l l e d on a vehicle.
12 Two counters measure positive and negative large ion concentrations having mobilities
greater than 2.7 x 104 m 2 v-1.s-I. Two counters measure positive and negative small ion concentrations having mobilities
greater than 0.64 cm2 V'I S-I. The difference between negative and positive small ion concentrations gives the space charge. Two further counters, using the same geometry as the small ion counters, but a diffe-
rent wind speed, measure positive and negative conductivities. The above apparatuses were designed and constructed in our laboratory with a view to long term field measurements. To these were added :
- the measurement of NO, by chemiluminescent reaction (made by Biolafitte) - a counter of condensation nuclei (made by the "Commissariat h 1'Energie Atomique") Furthermore, the C.I.R.N.
(Laboratory for the study of pollution at Lacq) supplied
us with information regarding SO2 concentrations, measured by the conductimetric method and meteorological data taken at altitudes of 202 and 88 metres.
RESULTS.
The physical parameters are strongly effected by the fall-out of Pollutants.
Large ion concentrations are directly related to NO, concentrations when SO2 fallout occurs (at Lacq) and, also, to nuclei concentrations. The space charge indicates the periods during which SO2 fall-out occurs. In an unpol-
-
luted atmosphere, provided that the weather is not thundery, the space charge is positive (n+
- n- > 0 and n+/n-
I,25), but when SO2
fall-out occurs, the concentration in
-
small positive ions falls more rapidly than that of small negative ions, and the positive space charge falls and approaches zero (n+
- n-
-
0 and n+/n-
I).
Alm conductivities, though lower for both signs, remain approximately equal for each
polarity. This indicates an equal average mobility for positive and negative ions, and the normal weighting in favour of negative small ion mobilities has therefore disappeared. Our
studies have shown that SO2 fall-out is likely to occur when the Electric Field
is weakly positive ( C 50 V/m),
zero or negative.
Thus, the measurement of the Electric Field permits us to follow the changes in the concentration of an atmospheric pollutant, these chang;es being due, in large part, t o variations in the meteorological conditions. For example, with a negative Electric Field, the probability of SO2 fall-out exceeds 75
% while for a zero slightly positive Electric %.
Field, the probability of SO2 fall-out is about 50
13
Pm)
1.05
14
Fig. I.
18
16
G.M T
20
22
t
Recordings of e l e c t r i c a l and chemical parameters of the atmosphere. @ : large ions + and NO, : various n i t r i c oxydea F : earth’s el ect r i c f i el d SO : hourly sulfur dioxide averages n+2and n- : small ions + and
-
It would seem that the measurement of the E l e c t r i c Field permits tha localization of the ttcloud” of S02. With a Field Mill i n s t a l l e d on t h e roof of a vehicle, which c i r c l e s around the plant, the measurements indicate a strong inversion of the E l e c t r i c Field under the chimney plume w h i l s t , on e i t h e r s i d e of t h e plume, there is an increase i n t h e positive E l e c t r i c Field When compared with the r e s t of the area.
Let us now examine what happens when the meteorological Conditions a r e favourable for the occurence of f a l l - o u t (temperature inversion layer, fog conditions). An inversion
14 l a y e r usually occurs a t Lacq f o r North o r North-Easterly winds
: during t h i s period,
there is a considerable increase i n the concentratj.ons of large p o s i t i v e and negative ions, anl t h e positive E l e c t r i c Field takes on f a i r l y l a r g e values. The disappearance
of the inversion l a y e r corresponds with a veering of the wind t o West, and is accompanied by a sudden f a l l i n l a r g e ion concentrations, and a f a l l i n the value of the E l e c t r i c Field. The E l e c t r i c Field then turns negative accompanied by a fresh increase i n large ion concentrations, a d the space charge due t o small ions becomes eero. A t t h i s point, SO2 f a l l - o u t i s taking place.
With foF formation, w e note t h a t a f a l l i n conductivity starts 30 t o 60 minutes before the a r r i v a l of fog. When t h e fog i s formed, the conductivities remain approximately comt a n t a t about h a l f t h e i r previous value. Conductivities r i s e again when the fog i s about t o dissipate.
CONCLUSION
A t the present stage i n our studies, we can say t h a t the measurement of t h e E l e c t r i c Field permits us t o l o c a t e
t h e "cloud" of SO2 whilst t h e measurement of the space
charge due t o the small ions can be used as an i n d i c a t o r of SO2 f a l l - o u t . These two elect r i c a l parameters permit us t o predict a strong likelihood of SO2 f a l l - o u t (negative E l e c t r i c Field) and t o determine i f SO2 has reached the ground (zero space charge). Furthermore, when f a l l - o u t occurs, i t is found t h a t t h e i n t e n s i t y of the negative E l e c t r i c Field v a r i e s with the concentration of t h e SO2 f a l l - o u t , and the E l e c t r i c Field can theref o r e serve as an i n d i c a t o r of t h e s e v e r i t y of SO2 fall-out. Since the a l t e r a t i o n i n small ion concentrations, produced by SO2 f a l l - o u t , b r i n g s about a r e l a t i v e increase i n negative ions with respect t o positive ions, we are led t o suppose t h a t the SO2 "cloud" i s necatively ionized.
An apparatus for the measurement of small i o n mobilities, which we intend t o construct, should allow us to study the mobility spectnun and t o determine t h e exact a c t i o n of different pollutants
(so2 : NO^).
REFEENCES
I J. Bricard, Physique des ABrosols, C.E.A. Report no R 4831, w l . I e t 2, 1977. 2 M. Dolezalek, On the Electro-Atmospheric Fog Effect, vol. 105, Pure and Applied Geophysics, 1973/IV, 907-909. 3 J.-Y. Paugham, Rdalisation d'une s t a t i o n semi-automatique de mesure des paramhtres Blectriques de l1stmosphkre e t de l a teneur de l'air en noyaux d'Aitken, These Jkme cycle, Universitd de Rennes (1977). 4 M.F. Tammet, The Aspiration Hethod f o r t h e Determination of t h e Atmospheric Ion Spectra, I s r a e l Program f o r S c i e n t i f i c Translation, Jerusalem (1970).
17
Atmospheric Pollution 1978,Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
METEOROLOGICAL EPISODES I N C R E A S I N G A I R POLLUTION I N BELGIUM
F. DE WIEST L a b o r a t o i r e de T o x i c o l o g i e de 1 'Environnement, U n i v e r s i t e de Liege, Belgium
D u r i n g t h e course o f a r e c e n t s u r v e y i n Belgium, we observed s e v e r a l i n t e r e s t i n g cases o f a i r p o l l u t i o n i n c r e a s e due t o t h e atmospheric c o n d i t i o n s .
I n a general
way we can say t h a t t h e s e s o - c a l l e d episodes 1) a r e a s s o c i a t e d
w i t h c o l d c o n t i n e n t a l a n t i c y c l o n i c a i r masses f r o m t h e North-East; 2 ) a r e charact e r i z e d by m e t e o r o l o g i c a l parameters
-
l o w w i n d speed ( < 2 m s - l ) and v e r y pronounced
d i r e c t i o n n a l s t a b i l i t y o f t h e a i r masses, n e g a t i v e a i r temperatures near t h e ground, v e r y s t r o n g and v e r y p e r s i s t e n t t e m p e r a t u r e i n v e r s i o n s ( + 2" t o t 5OC/100 m) a t l e v e l s below 500 m
-
which f a v o u r t h e a c c u m u l a t i o n o f t h e gaseous and p a r t i c u l a t e
p o l l u t a n t s . These f a c t o r s must be encountered a t t h e same t i m e i n o r d e r t o induce p o l l u t i o n i n c r e a s e ; 3) a r e observed d u r i n g t h e c o l d e s t months o f t h e y e a r (January, February, November, December); 4 ) can p e r s i s t 2 t o 5 c o n s e c u t i v e days; 5) have a maximum annual o c c u r r e n c e f r e q u e n c y o f t h e o r d e r o f 5%; 6 ) g i v e r i s e t o mean p o l l u t i o n l e v e l s about 3
-
3.5 t i m e s h i g h e r t h a n t h o s e u s u a l l y observed w i t h w e l l - v e n t i l a t e d
m a r i t i m e s winds f r o m S.W. I t i s i m p o r t a n t t o n o t e t h a t a l l N.E.
winds a r e n o t s y s t e m a t i c a l l y l i n k e d w i t h
more p o l l u t i o n because, as we s a i d b e f o r e , t h e dynamic c h a r a c t e r i s t i c s o f t h e l o w e s t atmosphere p l a y a d e t e r m i n i n g r o l e .
To i l l u s t r a t e t h e s e f a c t s we s h a l l c o n s i d e r two c o n c r e t e cases o f such episodes. The f i r s t f r o m 10 t o 14 November 1975 was observed d u r i n g an a i r p o l l u t i o n survey cond u c t e d a t T i l l e u r i n t h e Meuse V a l l e y ( i n d u s t r i a l area o f L i e g e ) . The second from 2 t o 5 February 1976 was s t u d i e d d u r i n g measurements made i n an urban area (Mons,
1700 inh/km2). From 10 t o 14 November 1975 an a n t i c y c l o n e , i n i t i a l l y l o c a t e d on Scandinavia, p r o g r e s s i v e l y moved eastword towards t h e S o v i e t Union g i v i n g r i s e t o N.E.
continental
winds c h a r a c t e r i z e d by a v e r y s t r o n g s t a b i l i t y o f t h e a i r n e a r t h e ground. F o r example, on 11 November between 00.00 H and 12.00 H t h e d e t e r m i n i n g atmospheric parameters were: -1 = 0.3111s , t = -0.15"C, s t r o n g i n v e r s i o n - t 2.4°C/100 m - f r o m 0 t'o 150 m.
3
D u r i n g t h i s p e r i o d e , we measured h i g h h o u r l y mean c o n c e n t r a t i o n s : SO2 1060 pg/m , 2 NO 200 ppb, CO 15 ppm. The c o r r e s p o n d i n g mean l e v e l s were r e s p e c t i v e l y 629 ug/m , 144 ppb and 12.5 ppm. The comparison o f t h e observed c o n c e n t r a t i o n s o f s u l f u r d i o x i d e w i t h t h e norms o r i n d i c a t i v e recommanded v a l u e s (IRV) i n f o r c e ( i n 1971) i n t h e main
18 i n d u s t r i a l c o u n t r i e s shows t h a t i n t h e presence o f such atmospheric c o n d i t i o n s i t i s n o t p o s s i b l e t o r e s p e c t t h e r u l e s e n f o r c e d i n Japan, S o v i e t Union, Czecho-
S l o v a k i a , F i n l a n d , Sweden, Germany and I t a l y . F o r example t h e a l e r t l i m i t o f
3 568 vg/m ( a t O'C) f o r 3 c o n s e c u t i v e hours i n f o r c e i n Japan was exceeded 2 t i m e s . 3 On 11 November t h e mean d a i l y SO c o n c e n t r a t i o n was 495 ug/m t h i s i s much h i g h e r t h a n t h e l i m i t v a l u e o f 250 pg/m5 imposed by t h e Swedish I R V f o r 24 h o u r s . From 10 t o 11 November t h e mean c o n c e n t r a t i o n o f SO2
-
410 ~ g m -- ~n e a r l y reached
t h e l i m i t i n f o r c e i n Japan f o r 48 c o n s e c u t i v e h o u r s . S i m i l a r o b s e r v a t i o n s were a l s o made between 12 and 14 November. TABLE 1 M e t e o r o l o g i c a l e p i s o d e f r o m 10 t o 14 November 1975 : mean c o n c e n t r a t i o n s o f SO2 NO and CO a t T i l l e u r and c o r r e s p o n d i n g atmospheric parameters.
Mean C o n c e n t r a t i o n s Oate November
CO
NO
SO2
Hours
(vg/m3) ( P P ~ )(ppm)
M e t e o r o l o g i c a l parameters t Gradient u (m/s) (OC) ( O C / ~ Om) O
13.00to15.00
400 214 488
172
75 233
8.1 6.2 14.7
0.15 0.50 0.30
t2.2 t4.9 +0.9
t1.6 -0.4 t3.3
11
00.00to12.00
14.00to16.00
629 139
144 39
12.5 4.7
0.35 3.10
-0.15 +7.3
t4.8 -0.65
13
20.00to23.00
539
106
12.8
0.50
-2.7
t3.2
14
00.00to10.00
368 533
77
12.3
174
16.1
0.30 0.45 0.40
-3.6 +0.5 -0.8
t3.3 t4.2 t5.0
10
08.00to12.00
17.00to24.00
13.00to24.00 16.00to23 .OO
-
The d a t a summarized i n t a b l e 1 show
-
t h a t d u r i n g t h e course o f a m e t e o r o l o g i c a l
e p i s o d e 1 ) any changes o f t h e atmospheric parameters d i r e c t l y i n f l u e n c e t h e c o n c e n t r a t i o n s o f t h e p o l l u t a n t s ; 2) t h e h i g h e s t c o n c e n t r a t i o n s a r e observed when the determining f a c t o r s
-
u << lms-l;
f
< O"C,
s t r o n g temperature i n v e r s i o n s
-
a r e encountered a t t h e same t i m e . These f a c t s a r e c l e a r l y e v i d e n t f r o m t h e comparison o f t h e mean c o n c e n t r a t i o n s o f SO2,
NO and CO measured on 11 November r e s p e c t i v e l y f r o m 00.00 H t o 12.00 H and
f r o m 14.00 t o 16.00 H. F o r t h e whole p e r i o d e f r o m 10 t o 14 November t h e mean c o n c e n t r a t i o n s o f SO2 and NO were 418 pg/m
3
and 114 ppb which a r e r e s p e c t i v e l y 2.8 and 5.4 h i g h e r t h a n t h o s e
measured a t t h e same p l a c e i n t h e presence o f w e l l - v e n t i l a t e d and u n s t a b l e m a r i t i m e winds f r o m S.W. From 28 January t o 5 F e b r u a r y 1976 a h i g h p r e s s u r e a r e a moving between
19
Scandinavia and t h e Soviet Union gave r i s e t o cold continental a i r masses from t h e N.E. Despite t h i s meteorological evolution, t h e mean concentrations of benzo(a) 3 3 pyrene (57 ng/m ) , of SO2 (83i~g/m ) and of NO ( 2 1 p p b ) in t h e a i r did not change s i g n i f i c a t i v e l y from 28 t o 30 January. The advection s t r u c t u r e of continental a i r masses observed during these days - turbulent winds with peaks above 15 m/s marked l a t e r a l v a r i a b i l i t y ( a. & 30-45') - explain why, despite N.E. winds, the polluting l e v e l s did not increase. On t h e o t h e r hand from 2 t o 5 February the N.E. a i r masses were characterized by low wind speeds, by the persistance of the mean wind d i r e c t i o n f o r 2 t o 3 days, by very weak horizontal wind direction f l u c t u a t i o n s (ae 2 15") and by very s t a b l e and strong subsidence inversions which lower t h e mixing height below 500 m . Simultaneously the mean level of pollution increased markedly i n comparison with previous days : 182 ng/m 3 f o r benzo(a)pyrene, 3 251 ug/m f o r SO2 and 74 ppb f o r NO. The r a t i o s of the average concentrations respectively measured from 2 t o 4 February and from 28 t o 30 January a r e highly s i m i l a r - BaP 3.19, SO2 3.02, NO 3.52 - and compare favourly with the increasino f a c t o r s observed a t T i l l e u r from 10 t o 14 November 1975. What can we conclude on the basis of the above observations ? In t h e presence of some p a r t i c u l a r meteorological conditions - N.E. winds s t r o n g l y s t a b i l i z e d under the influence of an anticyclonic area - the concentrations of the primary p o l l u t a n t s i n t h e ambient a i r exceed in Belgium most of the l i m i t values imposed by t h e a i r pollution l e g i s l a t i o n s i n force in t h e i n d u s t r i a l c o u n t r i e s . T h u s i n p r a c t i c e these l e g i s l a t i o n s a r e proper t o s a t i s f y t h e j u r i s t s b u t n o t t h e hygienists. The only way t o respect these a i r q u a l i t y r u l e s in highly populated and i n d u s t r i a l areas will be a b e t t e r control efficacious legislation conditions.
-
-
and therefore an
of the emission r a t e s in connection with the atmospheric
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
21
ATMOSPHERIC POLLUTION SURVEY NETWORK I N THE STREETS OF P A R I S
J . VAREILLE L a b o r a t o i r e C e n t r a l de l a P r e f e c t u r e de P o l i c e , P A R I S - (FRANCE)
ABSTRACT Urban networks, a c c o r d i n g t o t h e i r use, a r e e i t h e r survey, o r r e a l t i m e warning networks. The P a r i s survey network i s h e r e w i t h d e s c r i b e d . The choices made by t h e L.C.P.P. a r e a n a l y z e d .
INTRODUCTION
In France, t h e f o l l o w i n g c a t e g o r i e s o f survey networks a r e d i s t i n g u i s h e d : E_n*onmental
p o l l u t i o n warning o r o b s e r v a t i o n network
Measurements a r e b e i n g made f a r from sources. I n d u s t r i a l and domestic sources a r e herewith not distinguished. Warning network Warning networks a r e implemented i n areas w i t h i n t e n s i v e i n d u s t r i a l a c t i v i t y ,
(ROUEN-
LE HAVRE)or i n a g r i c u l t u r a l areas (BORDEAUX) .Real t i m e t r e a t m e n t o f d a t a a l l o w s t o a n t i c i p a t e t h e p o l l u t i o n i n c i d e n t s . Under adverse m e t e o r o l o g i c a l c o n d i t i o n then, t h e author i t i e s w i l l t a k e a l l necessary s t e p s t o p r e v e n t them.
A delayed d a t a p r o c e s s i n g a l l o w s t o f o l l o w l o n g term t r e n d s and t o check t h e e f f i c i e n c y of p r e v i o u s a c t i o n s . O b s e r v a t i o n network The p r o c e s s i n g o f s u r v e y d a t a i s delayed so i t d o e s n ' t a l l o w t h e implementation o f emergency a c t i o n s . However
, as
i n t h e p r e v i o u s case, t h e a u t h o r i t i e s when made aware
o f t h e g e n e r a l e v o l u t i o n , can make l o n g t e r m d e c i s i o n s . ( t h i s t y p e o f network i s under t h e c o n t r o l o f " L a b o r a t o i r e d'HygiPne de l a V i l l e de PARIS"). Neighbourhood p o l l u t i o n o b s e r v a t i o n network
I t i s used t o f o l l o w t h e e v o l u t i o n o f s p e c i f i c nuisances o f s p e c i f i c sources. The o b j e c t i v e i s n o t t o o b t a i n t h e average l e v e l o f p o l l u t i o n b u t t o observe t h e maximal r i s k b y measurements a t s e l e c t e d p l a c e s . We s h a l l d i s c u s s t h e p o l l u t i o n c o n t r o l networks i n urban areas d e s c r i b i n g , as an example, t h a t o p e r a t e d by t h e L.C.P.P. PARIS.
in
22
PRELIMINARY STUDIES Test Pollutant As i t was imposs ble t o measure a l l the p o l l u t a n t s , we had t o choose a reference pollutant which wou d be s p e c i f i c t o t h e observed source and allow a proper estimate of the emission ( r e f . 1 - 2 ) . Carbon monoxide was chosen because i t i s s p e c i f i c of emissions a t ground level. i t i s a b u n d a n t i n the automotive exhaust, i t s i n t r i n s i c t o x i c i t y , moreover, i t i s e a s i l y measured by non d i s p c r s i v e infared spectrometry (N.D.I.R.) The so-called "317 POINTS" method I n 1960, a systematic study was c a r r i e d o u t a t 317 points within grid-squares r e s u l t i n g from t h e subdivision of t h e area. Concerned about the maximum r i s k s , high t r a f f i c density points were s e l e c t e d . A t each p o i n t , every month, four samples were collected in bags and l a t e r analysed a t the laboratory. I n s p i t e of i t s i n s u f f i c i e n c i e s , t h i s technique allows t o draw a pollution map,
which wasused as a basic reference t o e s t a b l i s h the network. PRESENTATION OF THE NETWORK
As e a r l y a s 1971, thanks t o the financial a s s i s t a n c e of automotive and petroleum i n d u s t r i e s , the L . C . P . P . s e t u p 11 devices f o r the determination of carbon monoxide a n d 5 devices f o r t h e sampling of p a r t i c u l a t e lead on t h e PARIS s t r e e t s .
During t h e following y e a r , t h i s network was supplemented with the i n s t a l l a t i o n of 3 devices measuring carbon monoxide in the o u t s k i r t s (one in each d i s t r i c t adjoining PARIS). (The s i t e s a r e described in r e f . 3 ) . A t each s t a t i o n the determiniiig of carbon monoxide i s done by a system of i n t e g r a t i o n (pneumatic or e l e c t r o n i c ) which d i r e c t l y y i e l d s t h e hourly average concentration. The p a r t i c u l a t e lead i s collected on m i l l i p o r e f i l t e r s (diameter 47 mm and poros i t y 0.4511). The flow r a t e approximates t h a t of the human breathing i . e . 600 1 . h - l .
Collection of the f i l t e r s takes place every Monday, Wednesday and Friday. Analysis i s made a t the laboratory by t h e atomic absorption method which replaced the colorimet r i c method with dithizon. EXPLOITATION METHOD Every y e a r , the r e s u l t s of t h e network, a f t e r being s t a t i s t i c a l l y processed, a r e
published in a note printed by t h e L . C . P . P . "Etudes de pollutions atmospheriques 1 PARIS e t dans l e s departements p@riph@riques". The attempts made t o e s t a b l i s h some c o r r e l a t i o n between t h e concentrations of carbon monoxide on t h e one hand a n d t h e number of c a r s or t h e concentration in p a r t i c u l a t e lead on the other hand have p a r t i a l l y f a i l e d . I n f a c t , f o r each s i t e and period,one obtains a l i n e a r equation with s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t ,
23
b u t as soon as one o f t h e parameters e.g.
space o r t i m e a r e changed a d i f f e r e n t
e q u a t i o n i s b e i n g o b t a i n e d . The reason o f t h i s semi-disappointment r e s t s i n t h e f a c t t h a t we d i d n o t know how t o t a k e some i m p o r t a r i t f a c t o r s i n t o account such as topography o f t h e area, m e t e o r o l o g i c a l i n f o r m a t i o n and s o on
...
On b a s i s o f t h e s e d a t a we t r i e d t o v e r i f y L a r s e n ' s h y p o t h e s i s ( r e f . 4 ) o f
lognormalcy. The c u m u l a t i v e f r e q u e n c i e s o f t h e CO-concentrations f o l l o w e d r a t h e r a normal, t h a n a lognormal d i s t r i b u t i o n . TABLE 1 E v o l u t i o n o f t h e annual h o u r l y average v a l u e expressed i n ~ m ~ . mf o- r~ t h e most r e p r e s e n t a t i v e s i t e s ( f o r a same s t a t i o n and f o r two c o n s e c u t i v e y e a r s , t h e d i f f e rence between t h e average was proved s i g n i f i c a n t by S t u d e n t ' s t e s t a t t h e 0.05 level o f significance). Stations
Place Mazas Place V i c t o r Basch Quai V o l t a i r e Place S a i n t - A u g u s t i n Avenue des Champs Elysees
Years 1972
1973
1974
1975
16.1 22.2 13.0 10.6 12.7
12.8 20.8 13.3 14.7 19.7
12.5 16.9 10.1 15.6 13.1
11.1 13.5 8.4 6.2 8.5
The d i m i n u t i o n o f t h e c o n c e n t r a t i o n s o f carbon monoxide observed i n 1975 can be a t t r i b u t e d t o d i f f e r e n t f a c t o r s such as some improvement t o t r a f f i c f l o w and t o t h e enforcement o f t h e r e g u l a t i o n c o n c e r n i n g t h e r e d u c t i o n o f CO i n t h e exhaust. However, d u r i n g 1976, t h i s tendency was i n v e r s e d f o r c e r t a i n s i t e s and t h e survey r e s u l t s o b t a i n e d i n 1977 w i l l p r e s e n t a g r e a t i n t e r e s t f r o m t h i s p o i n t o f view. Concerning t h e c o n c e n t r a t i o n s f o r p a r t i c u l a t e l e a d t h e o n l y i m p o r t a n t f a c t i s an s e n s i b l e i n c r e a s e n o t i c e d p l a c e V i c t o r Basch a t t h e end o f 1976 and which i s s t i l l going on i n 1977. ( 4 . 1 t o 10.5 ~ g . r n - ~ ) . CONCLUSION From o u r own experience, we a r e a b l e t o draw s e v e r a l u s e f u l i n s t r u c t i o n s f o r t h e c o n c e p t i o n and u t i l i s a t i o n o f a survey network o f urban roadways. A p r e l i m i n a r y s t u d y can be r e a l i s e d on t h e b a s i s o f r e p a r t i t i o n o f t h e t r a f f i c i n t h r e e zones
Zone w i t h a t r a f f i c f l o w
"home t o work t y p e "
Zone w i t h a t r a f f i c f l o w
"urban a c t i v i t y t y p e "
Zone w i t h a t r a f f i c f l o w
"mixed t y p e " .
Each zone c a t e g o r y w i l l be surveyed by one o r s e v e r a l s t a t i o n s a c c o r d i n g t o i t s importance.
24
The topography o f t h e areas and t h e i n f o r m a t i o n s o b t a i n e d about t h e t r a f f i c w i l l a l l o w us t o chose t h e s i t e c h a r a c t e r i z e d as " h i g h r i s k " . W i t h o u t q u e s t i o n i n g t h e a c t u a l i n t e r e s t o f CO measurements, i t c o u l d be necessary t o determine s i m u l t a n e o u s l y f o r each zone and f o r one s i t e : N i t r o g e n o x i d e s and p a r t i c u l a t e l e a d on account o f t h e i r own t o x i c i t y N i t r o g e n o x i d e s , hydrocarbons and ozone c o n s i d e r e d as p r e c u r s o r s f o r t h e o x i d a n t photochemical smog The knowledge o f t h e average spead o f t h e v e h i c l e s w i l l improve t h e p r e d i c t i v e f i t o f t h e computations.
Whatever t h e t e c h n i c a l o r a d m i n i s t r a t i v e d i f f i c u l t i e s are, t h e sampling p o i n t must be r e p r e s e n t a t i v e so i t w i l l be s i t u a t e d between 1.50 and 1.80 f r o m t h e ground. On t h i s p o i n t o u r c o n c e p t i o n i s d i f f e r e n t f r o m t h e one which p r e v a i l s i n USA where t h e y a r e s i t u a t e d between 5 an 15 m. I n s p i t e o f t h e important progress r e a l i z e d w i t h teletransmission, p e r i o d i c i n s p e c t i o n s and a c c u r a t e c a l i b r a t i o n s executed by a q u a l i f i e d s t a f f a r e necessary i n o r d e r t o o b t a i n meaningful r e s u l t s . Owing t o t h e i r c o n d i t i o n s o f work which a r e f a r f r o m b e i n g i d e a l , t h e a n a l y s e r s can g i v e wrong r e s u l t s consequently t o t h e d r i f t i n t h e i r o u t p u t s i g n a l . T h i s d r i f t u s u a l l y bound t o t h e f l u c t u a t i o n o f t h e temperature o u t s i d e , may p r e s e n t a c e r t a i n p e r i o d i c i t y i n t i m e and so m i g h t be unobserved w i t h o u t c o n t i n u o u s g r a p h i c r e c o r d i n g . F o r t h i s reason and f o r a g r e a t e r f l e x i b i l i t y i n t h e t r e a t m e n t , t h e L.C.P.P. adopted a new system f o r c o l l e c t i n g data.The analog o u t p u t i s r e g i s t e r e d c o n t i nuously i n t h e s t a t i o n and i s computed by means o f a "scanner" connected t o a computer. T h i s system w i l l a l l o w t o t e s t i n t e g r a t i o n on d i f f e r e n t l a p s e s o f t i m e and w i l l a l l o w t o t a k e i n t o account t h e d r i f t s which have been observed. REFERENCES
1 H. 14 2 H. 3 L. 4 R.
Moureu, P. Chovin, L. T r u f f e r t , 3. Lebbe, Revue de l a P o l l u t i o n Atmospherique (1962). Moureu, Proceedings o f t h e Royal S o c i e t y o f Medecine, 10 (1974) 1015-1020. T r u f f e r t , M. F a v a r t , M. Garein, Ann. F a l s . Exp. Chim., 70 (1977 419-431. Larsen, J . A i r P o l l u t i o n C o n t r o l A s s o c i a t i o n , 20 (1970)214-225.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
25
CONTADlINATION OF ROADSIDE SOILS AND PLANTS NEAR HIGHWAY TRAFFIC WITH CD, NI, PB AND ZN IN ALEXANDRIA DISTRICT, EGYPT'
I. H. ELSOKKARYf E 0 S o i l Dept., Agric. Univ. of Norway, 14 3 2 , As-NLII,
Norway
A BSTHAC T
Contamination of r o a d s i d e s o i l s and v e g e t a b l e s : cabbage and p a r s l e y , by Cd, N i , Pb and Zn have been i n v e s t i g a t e d a l o n g Alexandria-Cairo Agric. highway, Egypt. High l e v e l s of m e t a l s a r e found i n s o i l s and p l a n t s . Amounts of m e t a l s i n s o i l s a r e p o s i t i v e l y r e l a t e d t o t r a f f i c d e n s i t y and n e g a t i v e l y r e l a t e d t o b o t h d i s t a n c e from r o a d s i d e and d e p t h i n s o i l p r o f i l e . DTPAe x t r a c t a b l e m e t a l s a r e g e n e r a l l y h i g h but c o n s t i t u t e d l i t t l e p o r t i o n s o f t h e t o t a l s o i l c o n t e n t . P l a n t s sampled n e a r r o a d s c o n t a i n e d h i g h l e v e l s of m e t a l s t h a n t h e normal. Significant amounts of m e t a l s a r e c o a t e d on p l a n t s u r f a c e s t h a t c a n b e e a s i l y removed by water-washing. INTRODUCTION Contamination of r o a d s i d e s o i l s and p l a n t s by heavy m e t a l s a l o n g h e a v i l y t r a f f i c highways have been r e c e n t l y r e p o r t e d (Ref. 1,2,3 and 5 ) . While g r e a t d e a l o f l i t e r a t u r e s a r e a v a i l a b l e i n Western Europe, USA and Canada c o n c e r n i n g t h i s s o u r c e o f contamination, d a t a d e a l i n g w i t h s u b j e c t i n Egypt a r e u n a v a i l a b l e and s c a r c e . T h i s work a t t e m p t s t o i n v e s t i g a t e t h e l e v e l s of Cd, N i , Pb and Z n i n s o i l s and v e g e t a b l e c r o p s a l o n g Alexandria-Cairo A g r i c u l t u r a l highway i n Alexandria d i s t r i c t a s a f u n c t i o n o f t r a f f i c d e n s i t y , d i s t a n c e from r o a d s i d e and d e p t h i n s o i l p r o f i l e .
f T h i s wogk h a s been c a r r i e d o u t i n S o i l Dept., Agric. Ugiv. of Norway, As-NLH, under t h e s u p e r v i s i o n o f P r o f . D r . J. Lag and f i n a n c i a l l y s u p p o r t e d by t h e Norwegian Agency f o r I n t e r n a t i o n a l Development (NOKAD). **Post-Doctoral NORAD-Fellow, and Assis. P r o f . o f S o i l Sci., F a c u l t y o f Agric., Alexandria Univ., Egypt.
26
LUTERIALS AND METHODS The area selected is situated in the eastern south part of Alexandria City. The dominant climate during the growth of the tested plants has an average 200 mm rainfall, 65-70% relative humidity and temperature of 9 - 2 6 O C (November-March 1976). Most of the area is cultivated into vegetable crops which considered the main source for the city. The investigated soils (Table 1) are lacustrine deposits of lake Mariut. Samples of soils and their corresponding plants leaves are collected from two fields side by two traveled roads directed to the main Alexandria-Cairo Agric. highway. The tested plants are cabbage (Brassica oleracea var. capitata) and parsley (Petroselinum hortense). Samples of plant leaves are divided into unwashed and waterrwashed portions. Two-g soil are digested in conc. HNO3- HC104 acids-mixture and amount of metal obtained is defined as the total (Ref. 8). DTPA reagent is used f o r extracting the available metal. Metal content of plant is obtained by digesting two-g-plant material in conc. HNO3- HC104 acids-mixture. Varian Techtron AA-6 atomic absorption spectrophotometer is used for measuring Cd, Ni, Pb and Zn (Ref. 8). Table 1 Some characteristics of the investigated soils. Plant Crop pH Soi 1 7.8 Cabbage Parsley 7.8
Texture S.Cl.L. S.L.
Tot.COS- 0.U. % % 10.8 3.8 6.8 2.5
NaHC03 Traffic Density P,ppm carlday 10 58300 8 46600
Table 2 Average values of Cd, Ni, Pb and Zn, ppm, in some normal Egyptian soils and vegetables. Nat erial
Cd
Total content Ni Pb Zn
DTPA-extractable Cd Ni Pb zn
21
RESULTS AND D I A C U S S I O N The r e s u l t s i n T a b l e 3 showed s i g n i f i c a n t t e n d e n c i e s f o r t o t a l s o i l N i , Pb and Zn t o i n c r e a s e w i t h t r a f f i c d e n s i t y except Cd. A g r a d u a l d e c r e a s e i n s o i l m e t a l c o n t e n t i s found w i t h i n c r e a s -
i n g d i s t a n c e from r o a d s i d e . T o t a l m e t a l o r t h e s u r f a c e s o i l l a y e r (0-10 cm) a t 40 m from r o a d s i d e accounted on t h e average f o r about 50, 75, 70 and 75 p e r c e n t Cd, N i , Pb and Zn of t h a t a t 5 m. T h i s r e v e a l e d t h a t a marked e f f e c t of t m f f i c on t h e l e v e l s of m e t a l s could. be achieved a l c n g d i s t a n c e more thzn 40 m. The r e l a t i v e l y higher accumulation of nietels i n t h e s u r face s o i l l a y e r than the subsurface is referred t o the limited downward movement of m e t a l s i n s o i l s . T h i s i s due t o t h e conv e r s i o n of t h e f r e s h l y p r e c i p i t a t e d p a r t i c u l a t e s t o i n s o l u b l e m a t r i x (Ref. 4 and 6). The p r e s e n c e of h i g h e r l e v e l s o f m e t a l s i n t h e s u b s o i l samples (20-30 cm) t h a n t h e normal ( T a b l e 2 ) i s due t o t h e long-term e f f e c t o f h e a v i l y t r a f f i c a c t i v i t y upon the area. The amounts of UTPA-extractable m e t a l s a r e r e l a t i v e l y h i g h e r t h a n t h e normal e s p e c i a l l y i n t h e s u r f a c e s o i l samples a t s i t e s c l o s e t o r o a d s ( T a b l e s 2 and 3 ) . T h i s f r a c t i o n c o n s t i t u t e d on t h e a v e r a g e about 1 0 , 20, 6 and 8 p e r c e n t o f t h e t o t a l Cd, N i , Pb and Zn, r e s p e c t i v e l y , The s o i l s can be considered a permanent and r i c h s o u r c e f o r s u p p l y i n g p l a n t r o o t s w i t h m e t a l s , Higher l e v e l s of m e t a l s a r e accumulated i n t h e p l a n t s grown i n s o i l s c l o s e t o r o a d s i d e t h a n t h e normal l e v e l s ( T a b l e s 2 and 3 ) . The washed p l a n t s c o n t a i n e d lower amounts o f m e t a l s t h a n t h e unwashed. The d a t a i n d i c a t e d t h e t s i g n i f i c a n t amounts o f m e t a l s a r e c o a t e d on l e a v e s s u r f a c e s a s p a r t i c u l a t e s e a s i l y removed by washing ( R e f , 2 , 5 and 7 ) . I t i s c l e a r t h a t cons i d e r a b l e c o n t a m i n a t i o n of p l a n t s by Pb and Zn and t o some e x t e n t by Cd and N i h a s o c c u r r e d i n t h i s a r e a . REFERENCES 1 J.V. Lagerwerff and A.W. Specht, Environ.&i.Technol., 4 (1970) 583-586. 2 J.V. Lagerwerff, S o i l S c i . , 111 (1971) 129-133. 3 L.H. Motto, R.H. Daines, D.M. Chilko and C. X o t t o , Environ. S c i . Technol. 4(1970) 213-237. 4 M. S c h n i t z e r , I n t . Cong. S o i l S c i . Trans. 9 t h ( A d e l a i d e , Aust.) 1 (1968) 635-644. 5 d.A. Schuck and J.K. Locke, Environ.Sci.Technol., 4 (1970) 324-330 6 M. S i n g e r and L. Hanson. S o i l Sci. SOC. h e r . Proc. 33 (1969) 152-153.
28
7 8
N.1. Ward, R.D. Reeves and R.H. Brooks. Environ. P o l l u t . , (1975 I 243-251 A. 0 i e n and K. Gjerdingen, Acta. Agric. Scand. 27 (1977) 67-70.
9
Table 3 Cd, N i , Pb and Z n c o n t e n t , ppm, i n s o i l s and p l a n t crops. Plant Crop
Meter P l a n t Content Metal from Road U.W.
Cabbage
Cd
Ni
Pb
zn
Parsley
Cd
5
10 20 40
5
10 20 40
5
18.5
5
14.5 9.5 62.4 60.0 50.0 42.2
10 20 40 10 20 40
5
10 20
40
Ni
Pb
Zn
0.95 0.85 C.60 0.35 4.1 3.8 3.0 2.1
17.5
0.95 0.90 0.70 0.40
10 20 40
5
6.0 5.0 4.0 2.6
5
32.0
0.40 0.40 0.30 0.25 2.0 2.0 1.6 1.6 9.1 8.6 8.5 7.9 38.2 36.5 34.5 33.9
0.35 0.35 0.35 0.35
10 20 40
30.4 27.2 22.2
5
73.5 72.0 64.5 56.0
48.0 48.0 46.4 46.6
10-20
10
w.
2.6 2.6 2.3 2.3 12.6 12.6 12.1 12.4
10 20 40
Eetal i n s o i l s a t different depths (cm) 20-30
Tot. DTPA
Tot. DTPA
Tot. DTPA
1.00 1.00 0.85 0.50
0.90 0.90 0.80 0.50
0.60 0.60 0.60 0.50
0.10 0.10 0.09 0.05
0.08 0.08 0.08 0.06
56.0 50.0 46.0 40.0
2.8 2.2 2.1 2.0
44.0 42.0 41.0 40.0
2.1 2.1 2.1 2.1
39.0 39.5 38.0 38.0
282.0 220.5 210.0 195.0 498.0 495.0 410.5 380.0
43.5 42.0 42.0 38.5 61.0 58.0 58.0 54.0
189.5 180.0 170.0 170.0 395.0 390.5 380.0 360.5
34.5 34.0 34.0 32.0 51.0 50.0 50.0 50.0
160.5 160.7 148.0 135.0 360.0 320.0 300.0 300.0
1.15 0.10
1.10 0.90 0.60
0.10 0.09 0.08
1.00 0.08 0.90 0.08 0.80 0.07 0.60 0.07
2.0 2.0 2.0 2.0 28.0 27.0 26.0 26.0
0.05 0.05 0.01 0.01
2.0 2.0 1.9 1.9 31.0
31.0
30.0 30.0 48.0
45.5
44.0 44.0
0.60 0.04 0.60 0.04 0.50 0.02 0.50 0.02
1.9 40.0 1.9 38.0 35.5 1.8 35.0 1.9 95.0 27.0 94.0 27.2 83.0 26.5 77.0 26.0
50.0 45.5 40.0 36.0 170.0 160.5 135.0 116.0
2.5 2.2 2.2 2.0 30.5 30.0 29.0 29.0
42.5 41.0 38.0 37.0 145.0 145.0 135.5 100.0
375.5 370.0 300.0 265.0
44.5 44.0 40.0 40.0
301.5 40.0 185.5 300.0 40.5 170.0 250.0 38.0 160.0 230.0 38.0 135.0
39.5 39.0 39.0 38.5
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
29
FIVE, YEARS OF RECORDING THE ATMOSPHERIC FALL-OUT 1N THE INDUSTRIAL R L G I O N OF LIEGE,
W. DUHAMEAU and R. NOiL Institut Xational des Industries Extractives ( I M I E X ) , Lisge (Belgique)
SUblWRY
Since 1 9 7 2 , I N I E X has been maintaining a continuous record of' atmospheric fallout by means of deposit gauges. This network has showed up the high level of dust deposition in those zones where the primary-sector industries raw materials
-
-
those producing
are located. In many cases, significant local fall-out of toxic
elements such as cadmium, lead, mercury and fluorine have been observed. Specific local studies carried out in greater depth are maintained in these areas of dangerous pollution.
INTRODUCTION The establishment of a network of permanent stations for recording atmospheric fall-out in the Lisge region was justified by the presence of industries which emit large quantities of dust - ferrous and non-ferrous metal industries, cementworks, quarries and lime-kilns. A small number of localized measurements showed the significant amount of fallout; in 1972, I N I E X set up a permanent network of continuously-operating stations, comprising some 110 deposit gauges distributed over
44 communes of the Meuse
industrial basin. Tkisfirst permanent network measured only the mass of the fall-out over a period of three years. From 1975 on, at the request of the Ministry of Public Health, the control was extended to the totality of the industrial regions Of Southern Belgium. In addition, the new programme includes - as well as establishing the fall-out mass
-
the quantitative determination of certain marker or toxic
substances i n the deposited dust. This paper presents the results of the first five years of recording atmospheric fall-out in the industrial region around Lisge.
30 METHODOLOGY
Over a four-week p e r i o d , t h e atmospheric f a l l - o u t i s c o l l e c t e d i n a f l a s k which s u p p o r t s a f u n n e l o f p r e c i s e dimensions. G e n e r a l l y , t h e f a l l - o u t
gauge i s p l a c e d
on a f l a t , l e v e l r o o f . A t t h e end of t h e exposure p e r i o d , t h e pH o f t h e water c o l l e c t e d i s determined and t h e f u n n e l washed w i t h d i s t i l l e d w a t e r . The f o l l o w i n g d e t e r m i n a t i o n s a r e c a r r i e d o u t on t h e gauge c o n t e n t s :
i ) mass of t h e i n s o l u b l e and s o l u b l e m a t t e r ;
i t ) mass of t h e c a t i o n s o f i r o n , chromium, z i n c , l e a d , cadmium, calcium and mercury i n t h e i n s o l u b l e m a t t e r
Ti;)
mass o f t h e f l u o r i d e s , n i t r a t e s matter
.
These r e s u l t s a r e e x p r e s s e d as mg/m
2
phosphates and s u l p h a t e s i n t h e s o l u b l e Jay.
INTERPRETATION OF THE RESULTS F i g u r e 1 d e p i c t s t h e average l e v e l o f t o t a l f a l l - o u t
(insoluble matter +
s o l u b l e m a t t e r ) over t h e e n t i r e network a r e a d u r i n g t h e y e a r s 1972-1976. I n t h e most remote rural areas i n t h e i n d u s t r i a l b a s i n , t h e r a t e o f f a l l - o u t 2 i s o f t h e o r d e r of 180 mg/m .day. A s w a s t o be e x p e c t e d , t h e a r e a s o f h e a v i e s t f a l l - o u t
a r e n e a r t h e s t e e l indus-
t r y s i t e s , t h e c e n t r a l s t a t i o n s t o t h i s a r e a b e i n g t h o s e a t S e r a i n g and OugrCe, n e a r e s t t o t h e steel-making complex. A t t h e s e p o i n t s , t h e f a l l - o u t r a t e s measured
2
are o f t h e o r d e r of some 3000 mg/m .day, i . e . more t h a n 15 t i m e s t h e r a t e o f a supposedly “ c l e a n “ s i t e . I t i s however i n t e r e s t i n g t o p o i n t o u t t h a t , i n t h e v i c i n i t y o f a new s t e e l w o r k s s i t u a t e d a t V i v e g n i s , n o r t h - e a s t fall-out
2
r a t e o f 250 mg/m .day i s r e c o r d e d
-
o f LiSge, an average
an e x c e p t i o n a l l y l o w l e v e l f o r a
steelworks s i t e . I n t h e r e g i o n s a f f e c t e d by t h e d i s c h a r g e s from t h e cement-works
(Lixhe and
2
H a c c o u r t ) , t h e a v e r a g e r a t e l i e s between 700 and 800 mg/m .day, while t h e s i t e s i n f l u e n c e d by t h e l i m e - k i l n s ,
t h e q u a r r i e s , and t h e non-ferrous m e t a l p l a n t s 2 ( E n g i s ) e x h i b i t average f a l l - o u t r a t e s o f 400 t o 600 m g / m .day.
For t h e b u i l t - u p a r e a o f L i s g e , i n t h e south-western s e c t o r which i s a f f e c t e d by t h e d i s c h a r g e s from t h e i r o n i n d u s t r y t h e r a t e s r e c o r d e d a r e s i t u a t e d around 2 500 mg/m .day. I n t h e c e n t r e o f t h e town t h e p o l l u t i o n r a t e i s between 250 and
350 mg. F i n a l l y , t h e heavy f a l l - o u t works and t h e cement-works,
2
r a t e s are r e s t r i c t e d t o t h e v i c i n i t y o f t h e s t e e l -
and about 90 ’$ o f t h e s i t e s s u p e r v i s e d show f a l l - o u t
masses l e s s t h a n 400 mg/m .day. However, t h e d e t e r m i n a t i o n o f t h e mass o f t h e f a l l - o u t
g i v e s o n l y an o v e r a l l
i d e a of t h e i n d u s t r i a l d i s c h a r g e s . A b e t t e r i d e a o f t h e s c a l e of t h e p o l l u t i o n
31
Fig.
2
1 . Map of t h e a v e r a g e d u s t f a l l r a t e (mg/m .day) over t h e L i s g e i n d u s t r i a l
r e g i o n : 1972-1976. o f a r e g i o n i s o b t a i n e d by s t u d y i n g t h e c o n t e n t o f c e r t a i n elements p r e s e n t i n the dust deposited. The a n a l y s i s o f t h e n i t r a t e , phosphate and s u l p h a t e c o n t e n t v a l u e s o f t h e water c o l l e c t e d d i d n o t a l l o w of i d e n t i f y i n g s p e c i f i c s o u r c e s of emission. On t h e o t h e r hand, t h e d e t e r m i n a t i o n o f t h e f l u o r i d e s c l e a r l y demonstrates t h e predominant i n f l u e n c e of c e r t a i n i n d u s t r i a l s e c t o r s , p a r t i c u l a r l y t h e chemic a l and s t e e l i n d u s t r y .
In t h e Meuse b a s i n , where t h e background f l u o r i n e f a l l - o u t a v e r a g e s 2 0.70 mg/m .day, two d i s t i n c t zones o f heavy p o l l u t i o n can be d i s t i n g u i s h e d : i ) t h e Engis r e g i o n , where one o f t h e s t a t i o n s 1 km t o t h e ENE o f a superphosphate f a c t o r y e x h i b i t s an a v e r a g e d e p o s i t i o n r a t e of 2.75 mgF/m 2 .day; i i ) t h e steel-working area, where t h e S e r a i n g s t a t i o n s a l s o r e c o r d v a l u e s o f 2 some 2.5 mgF/m .day.
The composition of t h e i n s o l u b l e m a t t e r i n t h e f a l l - o u t
i s o b v i o u s l y governed
by t h e t y p e s of i n d u s t r y l o c a t e d i n t h e v i c i n i t y .
To p r o v i d e an i d e a o f t h e s c a l e o f f a l l - o u t i n t h e r e g i o n i n q u e s t i o n , ye g i v e below t h e composition o f t h e d u s t c o l l e c t e d i n one s t a t i o n i n t h e Belgian Ardennes, c l a s s i f i e d as a "white s t a t i o n " :
32 2 MembachStation - f a l l - o u t background i n mg/m .day Total
Fe
Zn
Pb
0.10
0.05
Ca
Cr
Cd
F
Hg
fall-out 110
2.3
0.3
6 , 4 ~ 1 0 - ~O . ~ X I O - ~ O . ~ X I O - ~ 0,16
I n t h e v i c i n i t y of t h e i r o n i n d u s t r y , t h e i n s o l u b l e f a l l - o u t
30 % o f i r o n and
4%
c o n t a i n s almost
o f calcium; t h e r e i s a l s o an i n c r e a s e i n t h e f a l l - o u t
2
of
chromium and cadmium, which a t S e r a i n g may a t t a i n 0 . 2 8 and 0.01 mg/m .day respectively. I n t h e a r e a s n e a r t h e cement works, t h e calcium on a v e r a g e a c c o u n t s f o r 18
%
o f t h e i n s o l u b l e m a t t e r ; h e r e t o o t h e r e i s a n i n c r e a s e i n t h e mass of cadmium, 2 which l i e s around 0.01 mg/m .day. One p a r t i c u l a r s i t e i n t h e L i s g e i n d u s t r i a l b a s i n h a s two z i n c p l a n t s and an a r t i f i c i a l f e r t i l i z e r f a c t o r y . Here t h e r e occur t h e h e a v i e s t r a t e s o f f a l l - o u t o f z i n c , l e a d , cadmium, mercury and f l u o r i d e s . The mass o f t h e i n s o l u b l e cadmium and z i n c d e p o s i t e d over an a r e a o f roughly 37 sq.km exceeds 0,005 and 2 mg/m2.day r e s p e c t i v e l y . The amounts o f t h e s e elements c o l l e c t e d i n c r e a s e t h e n e a r e r t h e s t a t i o n s a r e t o t h e d i s c h a r g e s o u r c e s , and r e a c h
2 0.26 mg/m2.day o f Cd and 30 mg/m .day o f Zn; f o r t h e cadmium t h i s i s 50 t i m e s t h e v a l u e observed on t h e edge o f t h e zone. I n s i d e t h i s zone, an i n n e r r e g i o n some 5 sq.km a c r o s s c e n t r e d on Engis r e c e i v e s t h e h e a v i e s t d e p o s i t s o f z i n c , cadmium, l e a d , mercury and f l u o r i d e s . A t t h e c e n t r e o f t h i s i n n e r r e g i o n , t h e a n n u a l f a l l - o u t r a t e p e r h e c t a r e i s a p p r o x i m a t e l y : z i n c , 110 kg; l e a d , 10 kg; cadmium,
1 kg; mercury, 20 g ; f l u o r i n e , 13 kg.
A s f a r as t h e urban and suburban zones a r e concerned, t h e average l e a d r a t e -
which i s v i r t u a l l y c o n s t a n t - is 0.20 mg/m2.day,
and a p p e a r s t o be l i n k e d w i t h
car traffic. To sum up, t h e e s t a b l i s h m e n t o f a permanent network t o r e c o r d f a l l - o u t
has,
f i r s t l y , made it p o s s i b l e t o l o c a t e t h e heavy d e p o s i t i o n zones; s e c o n d l y , t o determine t h e amounts o f c e r t a i n t o x i c e l e m e n t s such as cadmium and l e a d contained in the fall-out.
I n p a r t i c u l a r , t h i s i n v e s t i g a t i o n showed t h a t cadmium
i s one o f t h e most d i s t u r b i n g elements i n t h e L i s g e r e g i o n , where i t s maximum l e v e l i s almost 650 t i m e s i t s background l e v e l . On t h e b a s i s o f t h e s c a l e o f f a l l - o u t
and o f t h e t o x i c n a t u r e o f some o f t h e
components t h e r e o f , t h e i n v e s t i g a t i o n w i l l be c o n t i n u e d by means o f more i n t e n s i v e c o n t r o l of t h e "dangerous"zones. These zones w i l . 1 be s y s t e m a t i c a l l y d i v i d e d i n t o s q u a r e s , and t h e r e c o r d i n g frequency i n c r e a s e d , i n o r d e r t o i d e n t i f y any e m i s s i o n peaks which may occur a n d , above a l l , t o p i n p o i n t t h e p r i n c i p a l sources of p o l l u t i o n .
Atmospheric Pollution 1978, Proceedings of the 13th InternationalColloquium,Paris,France, April 25-28,1978,M.M.Benarie (Ed.),Studies in Enuironmental Science, Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
33
STUDY OF A LIGHT POLLUTION IN MARINE ATMOSPHERE A. FENOUX, A . MOUDEN Laboratoire de Physique des AProsols et de Radioactivite AtmosphPrique, Facult6 des Sciences (U.B.O.) - 29200 BREST, FRANCE. and
G.
MADELAINE
Laboratoire de Physique de 1'Atmosphere - C.E.A.-S.T.E.P.A.M., 92 - FONTENAY AUX ROSES, FRANCE.
ABSTRACT Measurements concerning pollution (dark smokes and acid pollution) have been taken in Brest during four years with the help of two S.F.8. Statistic treatment of the results show that, in gausso-logarithmic coordinates, the two distributions in cumulated frequencies (smokes and acid pollution) are log normal with an approximately similar
U about 1,9. By using a C.N.C. perfected by the C.E.A., the correla¶' tion between the results of the S.F.8 and the amount of condensation nuclei is quite
good. But such a correlation doesn't appear between the dark smokes concentration and the gravimetric determination of dust.
INTRODUCTION As part of the work carried out by the Regional APPA Committee in Brest we have used two devices of the S.F.8 type which allow us to measure simultaneously acid pollution and dark smokes. After a statistical analysis of four years results we have examined whether it was not possible to observe some correlations between the results from the S.F.8, the amount of condensation nuclei and the weight of atmospheric dust. RESULTS
A - Evolution of atmospheric pollution in Brest We have measured both the annual and seasonal mean concentration of acid pollution and dark smokes in the air in a lithtly polluted seabord area. The samples were taken over four consecutive years in Brest in two different sites which, according to the direction of the wind, are influenced by either the little polluted town or by the sea or again by a lightly industrialized area. For this, we have used two S.F.8 devices which can measure acid pollution and dark smokes simultaneously (ref.1)
34 a ) Annual mean
:
Fig.
1 shows o u r r e s u l t s .
I t i s t o be n o t i c e d t h a t
in Brest
d o m e s t i c p o l l u t i o n p r e v a i l s o v e r any o t h e r from o f p o l l u t i o n . b ) S e a s o n a l mean
:
(Summer - A p r i l t o September - Winter - October t o March - ) .
A comparison between s u m m e r and w i n t e r h a s been made ( t a b l e 1 ) c o n c e r n i n g t h e f o u r
y e a r s of measurements. The d i f f e r e n c e between summer and w i n t e r which i s s m a l l e r f o r d a r k smokes t h a n f o r h i g h a c i d i t y l e a d s u s t o t h e h y p o t h e s i s t h a t t h e r a t h e r c o n s i d e r a b l e c a r t r a f f i c , which v a r i e s v e r y l i t t l e w h a t e v e r 30
-AUD
t h e s e a s o n , p l a y s some r o l e . TABLE 1
POLLUTION
_--___ SMOKE
Acid p o l l u t i o n ug/m3
Dark smokes w/m3
Summer
15.3
14
Winter
27.6
22.3
1 .8
1.6
Winter
/ Summer
Fig. 1 B - Frequency c u r v e s
- Histogram of c o n c e n t r a t i o n
I t i s c o n v e n i e n t t o draw t h e non-cumulated
-3
by d i v i d i n g t h e l a t t e r i n t o 5 pg m
frequencies i n r e l a t i o n t o concentration
c l a s s e s . The c u r v e s r e s u l t i n g from o u r measure-
ments a r e d i f f e r e n t from a g a u s s d i s t r i b u t i o n ( F i g . 2 and F i g . 3 ) . They are b o t h d i s s i m i l a r from t h e l a t t e r f o r h i g h c o n c e n t r a t i o n . The two maxima a r e found i n t h e -3 10 - 15 L I ~m c l a s s and t h e y c o r r e s p o n d t o f r e q u e n c i e s which amount t o 24 % f o r b l a c k smokes and 2 2
T
%
f o r acid p o l l u t i o n over a
7
Fig. 2
Fig. 3
I n o r d e r t o s t u d y t h e c h a r a c t e r i s t i c s o f t h e two d i s t r i b u t i o n s w e draw t h e c u r v e s of cumulated f r e q u e n c i e s i n g a u s s o l o q a r i t h m i c c o o r d i n a t e s . I n t h e s e c o o r d i n a t e s t h e two d i s t r i b u t i o n s are l i n e a r ( F i g . 4 ) . Consequently t h e y are lognormal ( r e f . 2 ) .
35 Four p a r a m e t e r s can c h a r a c t e r i z e o u r d i s t r i b u t i o n s : g e o m e t r i c s t a n d a r d d e v i a t i o n and a r i t h m e t i c mean ( m ) . The c u r v e s on f i g . 2 and f i g . 3 look
a g , mode, median ( M )
l i k e a s l i g h t l y a s y m m e t r i c a l unimodal d i s t r i b u t i o n . I n t h i s c a s e ( r e f . 3) t h e r e l a t i o n between mode and mean i s :
mode = 3M - 2 m .
T a b l e 2 sums up t h e c h a r a c t e r i s t i c s of o u r two d i s t r i b u t i o n s
~
ACID
POLLUTION
.__ - - -.SMOKE
95.
TABLE
1
-.
2
Acid p o l l u t i o n
80-
I Dark
smokes
I
.. 0
w
c&z
LL
I
30..
( w m-3)
10-
10.5:
I
Mode a
.
13.3 I
10.7 I
1 .a7
4
1.91
CONCENTRATION ( p g / m 3)
IOCI
10
Fig. 4 I t is t o b e n o t i c e d t h a t t h e C
o
9
f o r t h e two d i s t r i b u t i o n s a r e a p p r o x i m a t e l y t h e same.
- C o r r e l a t i o n between n u c l e i , a c i d p o l l u t i o n and smokes S i m u l t e a n o u s l y w i t h t h e s e measurements w e have s t u d i e d t h e c o n d e n s a t i o n n u c l e i con-
c e n t r a t i o n of t h e a i r i n B r e s t w i t h t h e h e l p of a c o n d e n s a t i o n n u c l e i c o u n t e r whose t h r e s h o l d is about
wn ( r e f . 4 ) . From t h e c o n t i n u o u s measurements w e compute t h e
mean c o n c e n t r a t i o n o v e r 2 4 h o u r s p e r i o d s . The comparisons a r e made f o r November and 02
-ACID
05 POLLUTION
December 1977. F i g . 5 shows a v e r y good c o r r e l a t i o n between the concentrations i n nuclei, smokes and a c i d p o l l u t i o n p a r t i c u l a r l y a s f a r as maxima and minima are concerned.
Fig. 5
36 D
- Comparison between d u s t s and smokes Dark smokes a r e o n l y one p a r t o f t h e a t m o s p h e r i c p a r t i c l e s found i n t h e a i r . Con-
s e q u e n t l y it h a s been n e c e s s a r y t o compare t h e c o n c e n t r a t i o n o f d a r k smokes w i t h t h e g r a v i m e t r i c d e t e r m i n a t i o n o f t o t a l suspended p a r t i c l e s . F o r t h i s p u r p o s e we have u s e d n u c l e p o r e f i l t e r s 10
urn t h i c k ( p o r e d i a m e t e r 0.4 urn) ( r e f . 5). Our e x p e r i m e n t s show
t h a t t h e w e i g h t o f d u s t c o l l e c t e d d u r i n g one day i s on a n a v e r a g e o v e r 1 mg ( r e f . 6 ) . The measurements t a k e n w i t h a s e n s i t i v e b a l a n c e ( s e n s i t i v i t y lO-'g)
make i t p o s s i -
b l e t o weight t h e atmospheric p a r t i c l e s i n suspension i n t h e a i r w i t h accuracy f o r
, 1, -
24 h o u r s s a m p l e s . T a b l e 3 shows b o t h t h e a n n u a l and s e a s o n a l smoke-dust r a t i o s from t h e measurements t a k e n o v e r a p e r i o d o f one y e a r ( A p r i l 1975
-
March 1976). These
r e s u l t s c a n been compared w i t h t h o s e o b t a i n e d o v e r t h e same p e r i o d by o t h e r a u t h o r s ( r e f . 7 ) i n a p o l l u t e d s i d e i n London ( t a b l e 4). I t i s n o t i c e a b l e t h a t t h e r e s u l t s agree i n s p i t e of very d i f f e r e n t l e v e l s of p o l l u t i o n . TABLE 3
TABLE 4
Smoke
4
Our measurements have n o t e n a b l e d u s t o show t h e r e was a p e r f e c t c o r r e l a t i o n between smokes and d u s t s . I f i t i s p o s s i b l e t o n o t i c e a s i m i l a r i t y between t h e c u r v e s , no s t r i k i n g c o i n c i d e n c e a p p e a r s between maxima and minima ( r e f . 6). B a l l and Hume ( r e f . 7 ) have shown t h a t t h e agreement i s good e s p e c i a l l y i n w i n t e r and g e n e r a l l y when t h e r a t e of p o l l u t i o n i s h i g h t . CONCLUSION S t a r t i n g from r o u t i n e measurements o f a t m o s p h e r i c p o l l u t i o n i n B r e s t we have t r i e d t o o b t a i n some c o r r e l a t i o n s between t h e r e s u l t s on t h e S . F . 8
( d a r k smokes and a c i d
p o l l u t i o n ) and on t h e one hand t h e amount o f c o n d e n s a t i o n n u c l e i and on t h e o t h e r hand t h e t o t a l w e i g h t o f d u s t s . The c o r r e l a t i o n i s good w i t h t h e c o n d e n s a t i o n n u c l e i o n l y . I t f o l l o w s t h a t a c o n d e n s a t i o n n u c l e i c o u n t e r s h o u l d g i v e a good i n d i c a t i o n o f t h e
l e v e l of p o l l u t i o n i n a g i v e n s i t e . REFERENCES Norme F r a n q a i s e Homologu6e (AFNOR) 43005, J u l y (1967). P. Chovin and A . R o u s s e l , P h y s i c o c h i m i e e t p h y s i o p a t h o l o g i e d e s p o l l u a n t s atmospher i q u e s . Masson e t C i e , 1973. Yule and G. Udney, An i n t r o d u c t i o n t o t h e t h e o r y o f s t a t i s t i c . Londres Chas. G r i f f i n (1927). W. Haaf and R . J a e n i c k e , J . o f A e r o s o l S c i e n c e 8 , n " 6 (1977) 447-456. K . S p u r n y , J . P . Lodge, J r F r a n c k and D. S h e e s l e y , Env. S c . and Tech. 3, n 0 5 (1969)
453-464.
A . Renoux, A . Mouden, J . Y . B a r z i c , P o l l u t i o n Atmosph6rique 71 (1976) 241-244. D . J . B a l l and R . Hume, Atmospheric Environment, 1 1 (1977), 1065-1073.
Atmospheric Pollution 1978, Proceedingsof the 13th InternationalColloquium,Paris,France, April 25-28,1978, M.M.Benarie (Ed.), Studies in Enuironrnentul Science, Volume 1 0 Elsevier ScientificPublishing Company,Amsterdam - Printed in The Netherlands
37
TRACE ELEMENTS AND THEIR SIZE DISTRIBUTIONS IN ANKARA ATMOSPHERE DETERMINED BY THERMAL NEUTRON ACTIVATION ANALYSIS
5 . N . SOMER Ankara Nuclear Research and Training Center, Ankara (Turkey) G. Gundiiz Kimya Miihendisligi BBlumu, Orta Do&
Teknik Universitesi, Ankara (Turkey)
ABSTRACT In this research, atmospheric particulates have been studied for their trace element contents in Ankara atmosphere during fall and winter months (1976-1977). The observed trace elements were Na, K, Sc, Cr, Fe, Co, Zn, As, Se, Br, Rb, Sb, Cs, Ba, La, Ce, E u , Hf, Hg, and Th. Their concentrations and particle size distributions were determined. Their mass-median diameters, mass-size functions were estimated and enrichment factors of them with respect to both soil of Ankara and crustal abundances were calculated. Including fall and winter months, total particulates were found out to be maximum in January. The elements found in small particulates were toxic and highly enriched in Ankara atmosphere.
INTRODUCTION Ankara is one of the few cities which really suffers from air pollution in the world. In this research, the trace elements, constituting relatively small but important portion of polluted community air, were studied. The samples were collected by "modified Anderson sampler" (ref.1) which fractionates the particles in a series of s i x collection stages. The collected samples then, were irradiated at a thermal 2
neutron flux of loL3 /cm /see and analyzed using a gamma ray spectrometer with Ge(Li) detector coupled to a multi-channel analyzer. In calculations, comparative method of activation analysis was applied using standard samples (ref.2).
RESULTS AND DISCUSSION The amount of gross particulate material for September, October, November, December, 3 January, and February were 5039, 7903, 6855, 9192, 28362, and 6898 ng/m , respectively. As is seen from these values, gross particulates reached the maximum value in January. In this month, it was observed that the elements were highly concentrated in the
38 largest size particles (ref.3). The quantitative elemental analysis of atmospheric particulates f o r six months was given in Table 1. For almost all elements, the concentrations reached their maximum value early in winter, especially in November. February concentrations were well below the maximum values. This can be explained by the fact that the weather was quite above the normal February temperatures in 1977, so that less heating fuel was consumed in the city.
TABLE 1 Observed elemental concentration of atmospheric particulates for six months 3 Total concentration (ng/m ) Element
Sept(76)
Na
682
1206
1535
832
1463
611
K
693
344
759
3975
1482
2091
sc Cr Fe
0.612 16.6 3311
co
1.41
Zn
127.03
As
13.6
Se Br
1.157 89.97
Oct(76)
0.897 17.04 4755 2.552
Nov(76)
0.848 17.94 3781 2.839
Dec(76)
0.556 6.8
2925 2.005
Jan( 77)
0.576 14.47 24605 2.127
Feb(77)
0.796 14.48 3636 2.112
1309.17
309.80
1029.07
246.84
82.43
17.26
71.14
77.66
135.44
64.90
5.169
4.443
1.338 154.00
5.754 246.50
219.42
192.15
3.28 175.46
Rb
3.147
8.73
15.06
8.90
9.05
6.27
Sb
6.231
14.595
36.564
24.519
19.67
21.94
cs
0.788
0.966
0.949
0.965
0.945
0.563
Ba
84.70
59.05
157.73
78.70
146.10
128.53
La
2.80
3.13
3.06
2.13
2.08
3.95
38.47
53.17
Ce
4.01
5.44
5.61
3.36
Eu
0.038
0.067
0.186
0.050
0.086
0.073
Hf
0.268 -
0.108
0.345
0.172
0.216
0.281
0.457
0.209
0.139
0.151
0.122
0.586
0.964
0.010
0.400
0.060
1.081
Hg Th
Size distribution of twenty elements was studied for six months (ref.3). It was found out that Sc, Zn, and Hg showed maximum concentrations in October; Na, Cr, Co, Se, Br, Rb, Sb, Ba, E u , and Hf in November; K, and Cs in December] Fe and A s in January; and La, Ce, and Th in February. Among these elements Zn, Hg, Se, Br, Sb, and A s were concentrated in small particles while Sc, Th, Eu, Hf, Cr, C o , Fe, La, and
Ce in the larger ones. K, Cs, Na, Ba, and Rb appeared both in small and large
39 particles but mostly in larger ones. Mass-size function (MSF) of each element,defined as variation of its mass with particle size, was also estimated (ref.3), and it was observed that MSF was different for each element, but the shapes of the curves were very similar for each month. Mass-median diameter (MMD) of an element defined as the approximate average particle size of its 50% mass, was found out for each element i.e. Hg, Se, Br, As,
K, Zn, Sb, Cs, Na, Rb, Ba, La, Cr, Ce, E u , Fe, Co, Sc, Hf, and Th as 0.25, 0.46, 0.75, 0.8, 1.00, 1.2, 1.2, 1.3, 2.65, 3.0, 3.4, 3.5, 4.1, 4 . 1 , 4.2, 4.5, 4.5, 5.9, 7.0, and 9.0prespectively. So, it is seen that the elements Hg, Se, and As which are highly toxic have very small MMD,
that they can easily penetrate into lungs.
so
The enrichment factors (EF) of the elements were calculated all normalized to Fe=1.00 and with respect ta both soil of Ankara and crustal abundances (ref.3). It was observed that Zn, As, Se, Br, Sb, and Hg were highly enriched in Ankara atmosphere. Figure 1 shows the variation of EF as a function of particle size. As is seen from this figure, the smaller the size of the particle, the higher its EF. This could be generalized by the fact that, larger and/or heavier particles would settle down quickly under gravity and would have smaller EF. Smaller and/or lighter particles would have long residence times and would not settle down quickly. It was generally observed that toxic elements usually accumulate in small particulates, and the enrichments of these elements in the atmosphere are relatively higher than the others.
I
0.3
I
I
I 1 1 1 1 1 1
I
;
10 Enrichment factor
I l l l l l l-
I00
Fig. I. Variation of enrichment factor as a function of particle size
I
I
I
I
I l l 1
100
( Dec. 1976 )
40
An example of the distribution of elements in different stages of the modified Anderson sampler was shown in Table 2 .
TABLE 2 3 Size distributions of observed elements for November 1976 (concentrations in ng/m )
E 1ements Na
Stage 1
Stage 2
Stage 3
470
229
K
-
-
Stage 4
Stage 5
206
166
212
88
207
-
Stage 6 252 464
sc
0.519
0.136
0.077
0.058
0.010
0.048
Cr
8.28
2.65
1.64
1.95
0.78
2.64
2107
Fe
1.406
co
557 0 437
364 0.275
310 0.224
95
308
0.135
0.362
Zn
22.88
13.10
37.50
159.33
34.36
42.63
As
3.17
4.38
4.27
7.64
7.91
43.77
0.610
Se
0.075
0.335
26.95
25.06
Rb
5.23
3.33
Sb
4.709
2.525
cs
0.209
0.095
0.090
Br
0.545
0.769
3.420 131.23
16.63
25.50
2.63
1.67
0.56
4.979
6.739
7.715
10.436
0.121
0.089
0.345
21.13
1.64
Ba
46.46
30.89
27.27
18.24
12.23
22.64
Ce
2.91
0.73
0.47
0.54
0.21
0.75
La
1.10
0.53
0.48
0.47
0.25
0.23
Eu
0.065
0.032
0.031
0.023
0.019
0.016
Hf
0.162
0.037
0.050
0.056
0.025
0.015
Hg
0.002
0.013
0.008
0.017
0.023
0.146
Th
0.600
0.110
0.080
0.085
0.085
0.050
REFERENCES
1 R.E.
Lee, Cascade Impactor Network, Environ. Protection Agency, July 1972.
2 J.M. Ondov, W.H. Zoller, 1. Olmez, N.K. Aras, G.E. Gordon, L.A. Rancitelli, K.H. Abel, R.H. Filby, K.R. Shah, and R.C. Ragaini, Anal. Chem., 4 7 ( 1 9 7 5 ) 1 1 0 2 . 3 5.N. Somer, M.Sc. Thesis,Chem. Eng. Dept., Middle East Technical University,
Ankara, Turkey.
A tmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
CO3II’XRED TESTS O F !IJGlI A C J D I T Y AT ’ f l l E VICIXITY OF IXDUSTHI ,\I, FOS
G.E.
-
43
\X,\LTSERS C A R X l E D OUT O N TIiE S I T E lSSTALI,.\TIOSS OF T I E R E G 1 OX OF
ETAXG DE BERRE. SIMON and Air-Cornmi t t e e Xemhors o f ~lRF0R.k:l’.
AIRFOBEP
- Martigues
(France)
ABSTRACT I n F r a n c e , a t m o s p h e r i c p o l l u t i o n i s g l o b a l l y det.ermincd by h i g h a c i d i - t y . The Air-Committee
of AlRFOBEP wished t o know t h e p r e c i s i o n
of t h e measurements t a k e n on t h e s i t e by means of h i g h a c i d i t y captors.
F o r t h i s , two t o f o u r c a p t o r s have been p l a c e d s i d e by
s i d e r e s p e c t i v e l y on f o u r i n d u s t r i a l s i . t e s of t h e Fos Berre region.
-
Etany de
The use of s t a t i s t i c a l methods h a s e n a b l e d t o d e t e r m i n e
t h e t r u s t a b l e i n t e r v a l s of t h e measurements. The r e l i a b l e i n t e r v a l s improve i n r e l a t i v e v a l u e w i t h t h e i n c r e a s e
of t h e d u r a t i o n of t h e measurements,
and when t h e h i g h a c i d i t y v a l u e s
measured a r e becoming medium o r h i g h o Thus,
t h e o n - s i t e measurements
have s r r f f i . c . i e n t a c c i l r a c y when c a r r i e d o u t o v e r z i l o n g p e r i o d and when t h e y c o r r e s p o n d t o p e a k s i n p o l l u t i o n .
INTRODUCTION The main measurement i n e v a l u a t i n g a t m o s p h e r i c p o l l u t i o n i n France
i s t h e h i g h a c i d i t y measurement.
The t y p e o f a n a l y s e r
(or captor)
a g r e e d by t h e F r e n c h S t a n d a r d
( I ) captures acid pollutants
s u l p h u r d i o x i d e ) by b u b b l i n g ,
c a r r i e s o u t an o x i d i z i n g followed by
a neutralization a t pH =
(mainly
4.5
A s t h i s h i g h a c i d i t y measurement i s e x t r e m e l y d e l i c a t e and a s t h e
analysers are installed i n isolated stations,
i t seemed of i n t e r e s t
t o AIRFOREP ( “ A s s o c i a t i o n d e s I n d u s t r i e l s de l a RBgion de Fos 1 ’ E t a n g de B e r r e pour 1 ’ E t u d e e t l a P r e v e n t i o n d e l a P o l l u t i o n , ’ ) t o know t h e q u a l i t y of t h e i n f o r m a t i o n s u p p l i e d by them, b y d e t e r m i n i n g t h e r e l i a b l e i n t e r v a l of t h e measurements c a r r i e d o u t on t h e s i t e .
44
__ Coinparison
of t h e c . r p t o r s .
h a i n g the actual pol Lution
P
112 t h e r-t*.?ponser o f t h e 7-
bl
.&
bJ
P = alR1
P
z
n~fR2
n anni h
i n a z o n e o f tae.tsureinc
t w o captors p l a c e d
s i d e b y s.
, I r e r ~ s p e c t i v e l ythr- c a e f f i c i e n t a of re.;pons{
\ y s t , e i n r t r c s h i f t i n g of' t h e captor. hnohii, biit w e caii campars HI
.md
I?:!
rho e x a c t p o l l u t i i
and w e have
:
L72 = K t ( 1 + D
wi th K = r r l a t i i , n between r r ~ . p o n s e - c o e f f i c j c n t s D = s h i f t i n g between c a p t o r s Thc: l i n i c i r r e g r c s s i o n allows t o i n f e r K, D a n d a l s t c o e f f i c i e n t r and t h c t y p i c a l d i v e r g e n c e '.-eitieiit.i
-1
<,
of
the
I
ar-t>und t h e s t r a i g h t l i n e o f r e g r e s s i o n .
The v l w r n t i o r i consisted i n e s l d b l r s h i n g t h e l i n i a r the d L f f @ r r n t c a p t o r 3 tdheri two by two. [Ic'rtcids o f
I5
minutes,
6 0 minutes, t h r r e
This c c m p a r i ho1lt-s
and
01
r e g r i ' s s i o n s h a v e b e e n obt,t 1 ned. T h i s f i r s t p a r t of t h e s t u d y e n a b l e d t h e f o l l o w i n g
t o h e made :
-
-
t h e r e 1 s n o t a n y d i f f e r e n c e between t h e c a p t o r s t h e s y s t e n i a t i c s h i f t i n g c o e f f i c i e n t s D b e t w e e n cd g e n e r a l ~ yl o w :
3 t o 5 pg/m3
t h e r c o e f f i c i e n t s show t h a t t h e c o r r e l a t i o n bet1
i s always highly s i g n i f i c a n t the response-coefficients
K are generally sltuai
45 n.80 a,\cl 1 2 0 , which p r o v e s t h a t t h e c o n c o r d a n c e hetween t h e c a p t o r s i s s a t i s f y i ng.
- the
t l i s p e r s i o n o f t h e meiistlrcmenta i s h i g h .
Est
t i on of
ittla
t h e Reliablca J n t e r v i t l of a--measurement.
Thc, e ~ i t c t1 1 o l l r i t i o n P e + t i m a t e d from a reslionbe R o f a h i g h a c i d i t y c a p t o r c a n b e ~ r r l t t e na s
P = aR 'rke t y p i c a l d i v e r g e n c e
dp ( o r
the variance
6
2
is deduced from
t h e law of t h c c o m p o s i t i o n o f v a r i a n c e s :
whfaresa i s t h e t y p i c a l divergence of the c o e f f i c i e n t of response a ,
dR
i s Ltie t y p i c a l
d i v e r g e n c e o f t h e measurement.
By u s i n g t h e r e s u l t s s u p p l i e d by t h e l i n j a r r e g r e s s i o n s between c a p t o r s ( 2 ) ( 3 ) i t i s drmonstrated t h a t :
6'K
PJ
GG-w
qt 4
The t y p i c a l d i v e r g e n c e
6,
with K = / J . a2
qA=t y p i c a l
divergence of d i s p e r s i o n
deduced from t h e lid a r r e g r e s s i o n s
of the c o e f f i c i e n t s of response a i s
i n d e p e n d a n t o f t h e d u r a t i o n o f t h e t e s t s and e q u a l s 0.07. On the contrary,
t h e t y p i c a l d i v e r g e n c e G R o f t h e nieasurenients i s
a f u n c t i o n o f t h e d u r a t i o n o f t h e m e a s u r e s : i f t h e d u r a t i o n of t h e measurements i n c r e a s e s , t h e a c c u r a c y o f t h e measurements d e c r e a s e s . I n the following t a b l e ,
we have l i s t e d t h e r e l i a h l e i n t e r v d l s o f a
measurement c a r r i e d o u t on t h e s 3 t e f o r a 95 % r e l i a b i l i t y l e v e l o b t a i n e d from t h e t o t a l number of t e u t s f o r d i f f e r e n t p o l l u t i o n l e v e l s and m e a s u r i n g d u r a t i o n s : R e l i a b l e I n t e r v a l s a t l e v e l 95X :
26, ------_-____--________-____--
-----P o l l u t i o n Level in p d m 3
Duration
3 hours 1 day -~----__-------_----_-_-________________ 50 p / m 3 70 pg/m3 2 50 /uP;/~T f 42 pg/m3 2 2 7 , t ~ g / m 3 100 95 f 70 2 57 +, 37 300 2 1 3 5 'I 10.5 ,+ 90 It f 65 If
600
-
$1
11
-
15 minutes
2 170
------------
If
1 hour
-2 1 4 0
f 120
It
2 100
11
11
--___________--
For t h e low p o l l u t i o n v a l u e s , t h e e r r o r due t o t h e measurement is p r e p o n d e r a n t , w h e r e a s f o r v a l u e s s t a r t i n g a t 300 t o t h e c o e f f i c i e n t o f r e s p o n s e makes i t s e l f f e l t .
P g/m3
t h e e r r o r due
The u s e o f t h i s T a b l e i s v e r y i n t e r e s t i n g f o r a s u p e r v i s i o n system.
46
For i n s t a n c e if we o b t a i n 600/-~g/n13 d u r j n g t h r e e h o u r s on t h r e e c a p t o r s which a r e n e a r on t h e l o c a l s c a l e ,
i t will
be p o s s i b l e t o
e s t i m a t e t h e p r e c i s i o n o f t h e measurements b y means o f t h e r e s u l t s i n t h e Table.
As a matter
o f f a c t , we hove :
Which means t h a t f o r t h i s a c i d i t y l e v e l , t h e concordance o f t h r e e c a p t o r s i n working c o n d i t i o n l e n d s t o
it
r e l i a b l e r e s u l t and t o c o r r e c t
d e t e c t i o n o f a p o l l u t i o n peak. Remarks c o n c e r n i n g t h e measurements
_ _ _ _ I -
During t h e summer months,
i t was a p p a r e n t t h a t t h e h i g h a c i d i t y
measurements i n c r e a s e d when t h e e x t e r i o r t e m p e r a t u r e was h i g h , which f r e q u e n t l y happens i n t h e Fos E t a n g de B e r r e r e g i o n .
I n t h e most
u n f a v o u r a b l e c a s e s , t h e r e s u l t s o b t a i n e d would be i n c r e a s e d by 30 t o
4 0 pg/m3.
T h i s c o u l d mean t h a t t h e i n t e r i o r t e m p e r a t u r e r e g u l a t i o n
o f t h e c a p t o r s is i n s u f f i c i e n t i n v e r y h o t c o n d i t i o n s .
It was a l s o n o t e d t h a t p o l l u t i o n d u s t a o u l d be o b s e r v e d e s p e c j a l l y i n t h e morning between 9 and 1 2 h.
(from
6 to
1 2 i n summer).
The u s e
of a f l a m e - p h o t o m e t e r w i t h a v e r y s h o r t s a m p l i n g l i n e f o r m e a s u r i n g t h e s u l p h u r d i o x i d e d i d n o t show t h e p r e s e n c e o f t h e s e p e r i o d i c phenomena.
It is p o s s i b l e t h a t c o n d e n s a t i o n i n t h e s a m p l i n g l i n e
impounded t h e s u l p h u r d i o x i d e . Both a s s u m p t i o n s f o r e x p l a i n i n g t h e s e two a n o m a l i e s a r e g o i n g t o be checked.
-C--o-n c l u s i o n s The t e s t s o f h i g h a c i d i t y c a p t o r s which have b e e n c a r r i e d o u t duri.ng 8 months on f o u r i n d u s t r i a l s i t e s by AIRFOBEP have y i e l d e d some i n t e r e s t i n g p r a c t i c a l r e s u l t s . Under r e a l i s t i c o p e r a t i n g c o n d i t i o n s s i m i l a r t o t h e working cond i t i o n s of warning systems u s i n g h i g h - a c i d i t y c a p t o r s , i t has been p o s s i b l e t o make a n e s t i m a t i o n o f t h e r e l i a b l e i n t e r v a l s of
the
measurements t a k e n on t h e s i t e . N o t w i t h s t a n d i n g good m a i n t e n a n c e o f t h e c a p t o r s , t h e e s t i m a t e d r e l i a b l e i n t e r v a l s a r e r a t h e r high, nable accuracy,
and i n o r d e r t o o b t a i n a r e a s o -
it i s advisable t o take i n consideration only
measurements t a k e n d u r i n g a p e r i o d o f a t l e a s t one h o u r . Nevertheless,
t h e r e s u l t s of t h e c a p t o r s a r e v a l i d f o r d e t e r m i n i n g
t h e average p o l l u t i o n r e s u l t s over a long period o r f o r d e t e c t i n g p o l l u t i o n peaks.
47
References
I _ _ _
1 . French Norm NFX / t 3 O O g 2.
T h o m a s MTOWER ASS.
- Joiirrr6cs
\it- p o l 1 u t i on c o n t r o l
( 1 9 6 6 ) 16 p . 6 2 3
3. M A R T E N S , VIIIAL and LUCET Compared t e s t s of high . t c i d i t y n n a l y s n r s .
-
Pollution Atmo5ph6rique
-
3- 0
-
0
.\pr.il 0
. I
-
0 -0
-
-
0-
June 197;
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Enuironmental Science, Volume 1 0
49
Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
ELEMENTAL ANALYSIS AT SUB-PARTS-PER TRILLION CONCENTRATIONS BY SONRES
Jerry Gelbwachs, Chris Klein, and John Wessel Ivan A. Getting Laboratories, The Aerospace Corporation, El Segundo, California, (U.S.A.)
ABSTRACT A new method of detection has been developed for analysis of metallic atoms in the
gas phase. The method relies on Saturated Optical NonResonance Emission Spectroscopy (SONRES) t o provide efficient fluorescence analysis in an ambient pressure environment. The theoretical detection limit is approximately
atoms in the interaction volume
during a 1 second integration time, and a detection limit of much less than 160 atoms/ c m 3 has been demonstrated for sodium, corresponding t o detection of less than 0.2 atoms on time average. The method is almost independent of quenching process, therefore it is promising for high temperature ambient pressure applications. In this paper SONRES
is compared with conventional resonance fluorescence spectroscopy, with resonance ionization spectroscopy (RIS), and with atomic absorption spectroscopy. New results are presented for nickel detection.
INTRODUCTION In previous reports (refs. 1 and 2) we described an ultrasensitive elemental detection method based on laser excited Saturated Optical NonResonant Emission Spectroscopy (SONRES). A detection limit of 1 0 atoms per cubic centimeter was demonstrated for sodium This result was obtained using continuous in argon, representing detection of one-part in wave (cw) dye laser excitation a t 589.6 nm and it represented a large improvement with respect t o results obtained with pulsed laser excitation sources (ref. 1) which have small 3 duty cycles (ca. The signal recorded for sodium a t a concentration of 160 atoms/cm is shown in Fig. 1.
50
1
4
z v3 v3
w
1IT
z 0 v3
70
I
EXCITATION WAVELENGTH-
I
Fig. 1. Sodicy sigyal a t -25OC. The sodium concentration is 160 atoms/cm 3 and the detection volume is 10 cm , therefore the signal arises from a time average of 0.2 atoms. In this paper we report application of a frequency doubled cw tunable ultraviolet dye laser t o SONRES detection of trace metals. Preliminary data a re presented for nickel detection. In the SONRES method a laser is tuned t o an atomic transition to produce exciteds t a t e atoms. Collisions with ambient gases ar e exploited to promote transfer of excitation energy t o a
secd
excited s t at e of the atom which has a different energy than the first
excited state. Fluorescence from the second excited sta te is then monitored. Nonresonant detection is not limited by Rayleigh scattering from the ambient molecules or Mie scattering from the nonvolatilized particles. When excitation is provided a t saturation intensity, quenching by ambient molecules does not significantly reduce the fluorescence emission rate, and the SONRES signal is not degraded. In addition, the typical atom emits 108 photons per second a t t h e nonresonant wavelength under saturated conditions. Inasmuch as isctfopically emitted fluorescence photons can be converted t o photoelectron counts with an overall detection efficiency of l f 4 , it is theoretically possible to detect emission from an average of 104 atoms in the laser interaction volume with a one second integration time. This result follows from the ability t o reduce photomultiplier dark current noise to about one count per second. EXPERIMENTAL RESULTS Nickel was selected for study because its spectroscopic properties a re typical of
51 heavy metals of environmental and industrial importance. The excited states ape closely spaced and have an abundance of strong ultraviolet (uv) transitions suitable for nonresonance detection. An argon buffer gas was selected t o obtain a low saturation intensity. Nickel excitation a t 300.25 nm (33501 em-'+-- 205 em-', gf = 0.9) was obtained by frequency doubling output from a Rhodamine 6G tunable dye laser. Whereas uv conversion efficiencies of 1 per cent or more ar e routinely achieved with pulsed laser sources using angle phase matched KDP or ADP harmonic generation crystals, substantially poorer efficiency is obtained from low power cw sources. For example, cw powers of only 10 ,uW in an 8 GHz bandwidth a t 300.25 nm a r e obtained by focusing the output of a 0.5W c w dye laser into a 2.5 crn length KDP crystal cut and oriented for Type I1 phase matching. This power is sufficient for spectroscopic investigations, however it is inadequate for trace analysis applications. Typical optical saturation intensities a r e of the order 100W/cm 2 a t 1 atm pressure. Thus the 10 pW source must be focused t o an area of cross section cm 2 to achieve the desired intensity. This would restrict the method t o microprobe applications. Therefore effort has been concentrated on developing higher efficiency UV sources. Our approach is based on the work of Gabel and Hercher (Ref. 3) and of Frohlich, Stein, Schroder, and Welling (Ref. 4). The nonlinear crystal is placed inside the laser cavity where the circulating fundamental power is about 1 0 times the laser output power for Rhodamine dyes. The effective interaction length
in the nonlinear crystal is increased by using a 90' phase matched crystal which avoids walk-off problems (there is no divergence between second harmonic and fundamental beams). An ammonium dihydrogen arsenate crystal (ADA) thermostated a t 68OC was used for 90' phase matching. To maximize conversion in the intracavity configuration it is essential t o minimize fundamental losses. This has been accomplished by antireflection coating the additional intracavity optical surfaces on the lens and ADA crystal shown in Fig. 2.
PHOTON
ll
SPECTROMETER
r-8nm-l
Fig. 2. Frequency doubled cw dye laser and sample vaporization cell.
52 A concave mirror which reconverges the return beam is dielectric coated for 100 percent reflectivity a t 600 nm and transmits 90 per cent a t 300 nm. The total loss a t the fundamental frequency introduced by the new components was completely compensated by the
higher reflectivity of the output coupler and the intracavity fundamental power was measured t o be 10 watts with a linewidth of 5 GHz. Output of 1 m W at 300 nm was achieved under optimum conditions. The electric oven cell used for nickel vaporization consists ofahollow nickel plated rhenium cylinder of 3 c m length and 0.5 cm diameter that is electrically heated. Spectroscopic viewing ports of 0.2 c m diameter were cut on opposite sides of the central area of the tube walls t o permit spectroscopic viewing of the tube center. The port on the back side was cut t o avoid imaging blackbody emission from a hot emissive surface on the spectrometer slit. Holes were cut in the support electrodes to form an optically clear path down the axis of the cylinder for the excitation beam. The entire heater was enclosed in a stainless steel vacuum chamber which was provided with quartz excitation and viewing windows. Fluorescence was focused on the slit of a 3/4 meter spectrometer and was detected with a thermoelectrically-cooled blue-sensitive photomultiplier which had a dark count rate of 2-10 counts per second. In Fig. 3 the signal is displayed as a function of argon buffer gas pressure. Excitation was provided a t 300.25 nm (33501 205, gf = 0.9) and emission WES monitored from the directly excited upper s t at e a t 332.2 nm (335013410, gf = 0.11) and from upper statespopulated by energy transfer a t 338.06 (32982-3419, gf = 1 ) and 361.94 nm (31031 -+ 3410, gf = 1.5).
-
SONRES detection is optimized when the atoms in the upper level of the absorbing transition at 33501 cm-l ar e efficiently transferred to the upper level of the emitting transitions used for nonresonant fluorescence detection. The parameters responsible for energy transfer a r e the radiative lifetimes of excited states, the collisional transfer rates, and t h e quenching rates. The l at t er factor can be neglected when rare gas buffers are employed. The collisional transfer rate is a function of buffer gas pressure whereas the radiative lifetimes a r e not. Therefore, the optimum buffer gas pressure that maximizes the emission r a t e of nonresonant fluorescence photons may be experimentally determined by varying t h e buffer gas pressure while monitoring the nonresonant fluorescence emission. The analytical curve for the nonresonance transition obtained a t the optimum buffer gas pressure of 1 0 torr appears in Fig. 4. Nickel concentrations were estimated by measuring the temperature of the nickel heater element and determining the corresponding vapor pressure from published data (Ref. 6). These estimates were confirmed by measuring atomic absorption a t elevated temperatures. The signal-to-noise ratio approached 2 a t an atomic 6 3 The effective detection volume is defined by the concentration of 2 x 1 0 atoms/cm excited sample region that is imaged onto the spectrometer slit opening. In this experiment cm 3 Therefore at the reported detection limit, 40 atoms were in the laser it was 2 x
.
interaction volume.
.
53
JD!
-
STATE EXCITED BY LASER -
v)
-
I I 100 1000 PRESSURE ITorrl Fig. 3. Dependence of the SONRES signal for nickel on the ressure of argon buffer gas. The vaporization temperature was maintained at 1-3738K. ATOMS IN INTERACTION VOLUME
20
lo4 -
I
~ ~ 1 0 3 2x105 I
I
I
I
-
-
-
2 102-
-
loo -
-
A
2
cn
J
I
I
I
I
I
Fig. 4. The analytical curve of the SONRES signal versus nickel concentration obtained with an argon pressure of 10 tow.
54
COMPARISON OF DETECTION METHODS It is useful t o estimate detection limits obtained by various optical methods for similar analysis conditions. Conventional atomic absorption spectrometry can achieve detection
limits of about 1 08 atoms/cm 3 for the most favorable analytical transitions. Inability to measure changes in the transmitted probe beam smaller than 0.1 per cent sets this limit. When detection limits obtained by conventional atomic fluorescence are compared with results obtained by atomic absorption using similar atomization devices, it becomes apparent that the two methods have nearly identical detection limits. Even using pulsed dye laser excitation for atomic fluorescence, similar detection limits were obtained (Ref. 7, in those experiments th e duty cycle was In 1975 a spectacular advance was achieved for sodium detection in a vacuum en3 vironment. Hansch, Fairbank, and Schawlow (Ref. 8) reported detection limits of 100 atoms/cm using cw laser excited atomic fluorescence. Unfortunately this method is difficult t o extend t o higher pressure environments due t o spurious scattering of the excitation source a t the same wavelength as the measured fluorescence. Also the method makes poor use of the available atomic population in that only the portions of the Doppler profile in resonance with the very narrow line widths of individd cw laser modes are excited. Recently a method of atomic detection based on resonance two-photon ionization spectroscopy (RIS) was introduced (Ref. 9) and is claimed t o have single atom detection capability for cesium. This method avoids the problem of indirect scattering of the resonance excitation. However the selectivity is only marginally superior t o the single atomic resonance process. In addition it is extremely sensitive t o spurious ion formation, thereby precluding high temperature applications such as use in conjunction with an atomization device. For application to other elements RIS requires two laser sources. Major advantages of RIS include its t i m e resolution capability and the fact that current commercial pulsed laser sources a r e suitable for its implementation. The method operates a t ambient pressures, thereby assuring interaction with the entire Doppler profile. However it requires a buffer gas of high purity counter gas and the exclusion of electronegative species such as oxygen. The SONRES method provides the discrimination capability of double resonance and is therefore advantageous for most trace analysis applications. SONRES can be performed with a single laser source; however, for the ultimate detection capability, a moderately sophisticated cw frequency doubled dye laser is required. Continuous monitoring capability provided by cw excitation will be advantageous in many situations. Available spectroscopic data suggests that the method will be applicable t o more than 60 metallic elements. Therefore i t can be anticipated t h at SONRES will be valuable in numerous scientific and technological applications.
55
REFERENCES 1. J. A. Gelbwachs, C. F. Klein, a n d J. W. Wessel, Appl. Phys. Lett. 30 (1977) 489-491. 2. J. A. Gelbwachs, C. F. Klein, a n d J. E. Wessel, I.E.E.E. J. Quant. m e c t r o n i c s (in press). 3. C. Gabel a n d M. Hercher., IEEE J. Quantum Electronics QE-8 (1972) 850-851. 4. D. Frolich, L. Stein, H. W. Schroder, a n d H. Welling, A p p m y s . 11 (1976) 97-101. 6. R. E. Honig a n d D. A. Kramer, "Vapor Pressure Curves of t h e Elements:' RCA Laboratories, Princeton, NJ. 1969. 7. L. M. Fraser and J. D. Winefordner, Anal. Chem. 44 (1972) 1444-1451. 8. W. M. Fairbank, Jr., T. W. Hansch, a n d A. L. S c h a x o w , J. Opt. SOC.Am. 65, 177 (1975). 9. G. S. Hurst, M. H. Nayfeh, and J. P. Young, Appl. Phys. Lett. 30, 229 ( 1 9 m .
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
57
PARTICLL ELASTIC SCATTERING ANALYSIS USED FOR DETERMINATION OF C , N AND 0 I N SIZE FRACTIONATED URBAN AEROSOLS
K . KEMP Danish Air P o l l u t i o n L a b o r a t o r y , N a t i o n a l Agency o f E n v i r o n m e n t a l P r o t e c t i o n Blegdamsvej 1 7 , DK-2100 Copenhagen 0
INTRODUCTION
A number o f a n a l y t i c a l methods c a n b e u s e d f o r t h e d e t e r m i n a t i o n o f heavy elements i n aerosols.
One o f t h e s e i s P a r t i c l e - I n d u c e d X-ray Emission A n a l y s i s
(PIXE), which h a s been i n u s e f o r s e v e r a l y e a r s ( r e f . 1 ) .
However, t h e drawback
Lo a l l t h e s e methods i s t h a t e l e m e n t s s u c h a s c a r b o n , n i t r o g e n and oxygen c a n n o t be d e t e r m i n e d .
N e v e r t h e l e s s , a s t h e s e t h r e e e l e m e n t s made up a b o u t
u r b a n aerosol, s u c h d e t e r m i n a t i o n s are e s s e n t i a l .
1 of a normal
The o n l y method t h a t a t p r e s e n t
seems t o p r o v i d e r e a l i s t i c p o s s i b i l i t i e s o f d e t e r m i n i n g t h e s e e l e m e n t s i n a r e a s o n a b l e number o f s a m p l e s i s P a r t i c l e E l a s t i c S c a t t e r i n g A n a l y s i s (PESA). The PESA a n a l y s i s i s e a s i l y p e r f o r m e d t o g e t h e r w i t h a PIXE a n a l y s i s , b u t i t i s a problem t h a t t h e a e r o s o l s t o b e a n a l y s e d a r e u s u a l l y c o l l e c t e d on f i l t e r s o f o r g a n i c m a t e r i a l ( c o n t a i n i n g C and 0). T h i s r e p o r t c o n t a i n s a d e s c r i p t i o n of a p i l o t p r o j e c t f o r d e t e r m i n a t i o n of C ,
N and 0 i n d u s t c o l l e c t e d on N u c l e p o r e F i l t e r s by means of PESAusing 3MeV p r o t o n s . The s a m p l e s were c o l l e c t e d i n a p p r o x i m a t e l y 24 h o u r s p e r i o d s by u s i n g a sampler w i t h an i m p a c t o r s t a g e g i v i n g s a m p l e s i n two p a r t i c l e s i z e f r a c t i o n s .
METHOD I f a s a m p l e i s bombarded w i t h p r o t o n s ( o r o t h e r c h a r g e d p a r t i c l e s ) , p a r t i c l e s t h a t come c l o s e enough t o o n e of t h e a t o m i c n u d e iti t h e s a m p l e a r e s c a t t e r e d by t h e e l e c t r i c a l f i e l d from t h e n u c l e u s .
Energy w i l l b e t r a n s f e r r e d t o t h e
n u c l e u s t h r o u g h t h e s c a t t e r i n g a c c o r d i n g Lo t h e e l a s t i c s c a t t e r i n g l a w s o f c l a s s i c a l mechanics.
The l i g h t e r t h e n u c l e u s and t h e g r e a t e r t h e s c a t t e r i n g a n g l e
t h e more e n e r g y i s t r a n s f e r r e d .
T h a t i s , i f t h e e n e r g y of t h e s c a t t e r e d p a r t i c l e s
i s measured i n a c e r t a i n d i r e c t i o n , i t i s p o s s i b l e Lo d e t e r m i n e from which e l e m e n t ( i s o t o p e ) t h e y have been s c a t t e r e d .
A s a f i r s t a p p r o a c h t o t h e problem of d u s t on a n o r g a n i c f i l t e r , t h e p a r t i c l e s p e c t r u m from a b l a n k f i l t e r i s c o n s i d e r e d .
A t y p i c a l s p e c t r u m i s shown on f i g . 2 a .
The f i l t e r s are i r r a d i a t e d a s i n d i c a t e d on f i g . 1.
The w i d t h s o f t h e p e a k s a r e
d e t e r m i n e d by t h e e n e r g y l o s s i n t h e f i l t e r s d u e t o s m a l l a n g l e s c a t t e r i n g .
58 The p e a k s i n a s p e c t r u m from an e x p o s e d f i l t e r w i l l b e a l i t t l e b r o a d e r t h a n i n t h e blank spectrum corresponding t o t h e energy loss i n t h e d u s t :
dE i s t h e s t o p p i n g power f o r t h e incoming ( o u t g o i n g ) p a r t i c l e s i n t h e where dx i ( 0 ) d ~ s t , 0and ~ 0 a r e t h e a n g l e s between t h e f5lter normal a n d i n c o m i n g and o u t g o i n g p a r t i c l e d i r e c t i o n s ( c f . f i g . l ) , and t
is t h e thickness of t h e d u s t l a y e r . d S i n c e t h e e n e r g y l o s s i n t h e f i l t e r and d u s t r e s u l t i n g from s m a l l - a n g l e s c a t t e r -
i n g i s s m a l l compared t o t h e t o t a l p a r t i c l e e n e r g y , t h e s t o p p i n g powers may b e considered a s constants. I n o r d e r t o remove t h e m a j o r i t y of t h e b l a n k c o n t r i b u t i o n from t h e s p e c t r u m o f an e x p o s e d f i l t e r , a b l a n k s p e c t r u m c a n b e s u b t r a c t e d . s p e c t r u m i s shown on f i g . 2b.
A typical difference
The a r e a o f a peak from an e l e m e n t , i , p r e s e n t i n
t h e f i l t e r m a t e r i a l is p r o p o r t i o n a l t o : AiKaid
-
Sf
Sd
td
'
if
where aid is t h e amount p r e s e n t i n t h e d u s t , cif i s t h e c o n c e n t r a t i o n i n t h e f i l t e r o f t h e e l e m e n t i , and Sf is d e f i n e d i n t h e same way a s S d , b u t by u s i n g t h e s t o p p i n g powers i n t h e f i l t e r m a t e r i a l .
I n o r d e r t o f i n d t h e v a l u e o n e seeks,aid
i t i s n e c e s s a r y t o know t h e v a l u e of td. T h i s c a n i n p r i n c i p l e be found from t h e
eq.
w i d t h o f t h e low e n e r g y peak i n t h e d i f f e r e n c e s p e c t r u m by u s i n g
1, b u t i n
p r a c t i c e t h e v a r i a t i o n o f t h e f i l t e r t h i c k n e s s i s o f t h e same o r d e r of magnitude a s the dust layer.
Thus o n e must e i t h e r weigh t h e d u s t o r u s e a b l a n k s p e c t r u m
from t h e same s p o t a s i s l a t e r u s e d f o r a n a l y s i s o f t h e exposed f i l t e r . The amounts of e l e m e n t s n o t p r e s e n t i n t h e f i l t e r m a t e r i a l a r e s i m p l y p r o p o r t i o n a l t o t h e a r e a s of t h e c o r r e s p o n d i n g p e a k s i n t h e s p e c t r a .
The f a c t t h a t
t h e p e a k s from t h e d i f f e r e n t e l e m e n t s a r e r a t h e r narrow i n d i c a t e s t h a t t h e d u s t
i s c o l l e c t e d on t h e s u r f a c e of t h e f i l t e r s . MEASUREMENTS A e r o s o l s were c o l l e c t e d s i m u l t a n e o u s l y i n two s a m p l e r s .
One was a s i m p l e , h i g h -
volume s a m p l e r w i t h open s u c t i o n and a N u c l e p o r e f i l t e r ; t h e maximum d i a m e t e r of
pm. The o t h e r s a m p l e r c o n s i s t e d of pm m y l a r f o i l on t h e i m p a c t i o n s u r f a c e , f o l l o w e d by
t h e p a r t i c l e s c o l l e c t e d was a p p r o x i m a t e l y 80 an impactor s t a g e , with a 12
The m y l a r f o i l s were c o a t e d w i t h Apiezon L g r e a s e i n o r d e r
a Nuclepore f i l t e r .
t o a v o i d blow-off ( r e f . 2 ) . 2 . 2 and a p p r o x . 80 on t h e f i l t e r .
pn
The i m p a c t o r s t a g e c o l l e c t e d p a r t i c l e s of between
i n s i z e , w h i l e p a r t i c l e s s m a l l e r t h a n 2.2
Seven sets of 24-hour s a m p l e s were c o l l e c t e d i n September and
November 1 9 7 7 i n t h e c i t y o f Copenhagen. through each sampler i n 24 hours. diameter.
pm were c o l l e c t e d
A p p r o x i m a t e l y 20 m3 o f a i r were l e d
The e x p o s e d s p o t on t h e f i l t e r s was 3 5 mm i n
59
Dust
Fig. 1.
4 000
2000
2.o
2.5
Energy (MeV)
3.0
F i g . 2 . Proton s p e c t r a . a ) lower spectrum: Blank f i l t e r . b ) upper spectrum: D i f f e r e n c e between exposed and b l a n k f i l t e r .
60 A l l samples were analyzed by both PESA and PIXE.
Elements w i t h atomic numbers
g r e a t e r than or equal t o 14 ( S i ) were determined i n t h e PIXE a n a l y s i s . proton beam was u s e d f o r the PESA ed.
analysis.
A 3 MeV
2 One cm of the f i l t e r s was i r r a d i a t -
The a n a l y s i s of t h e f o i l s was r a t h e r a problem because t h e d u s t was c o l l e c t e d
i n narrow s t r i p s .
T h i s gave r i s e t o a smearing out of t h e peaks i n t h e p a r t i c l e
s p e c t r a , and a l s o some of t h e m a t e r i a l cracked o f f during handling.
The r e s u l t s
a r e subsequently disregarded, b u t t h e l a r g e p a r t i c l e f r a c t i o n may b e found from t h e d i f f e r e n c e between t h e r e s u l t s of t h e two f i l t e r analyses.
The weight of t h e t o t a l p a r t i c u l a t e on the f i l t e r s was found by weighing t h e f i l t e r s ( a f t e r proper c o n d i t i o n i n g ) before and a f t e r exposure. RESULTS
Ttic mrin bdlue and standard d e v i a t i o n of t h e sum of t h e r e s u l t s from each
f i l t e r i s found t o make u p 10328% of t h e t o t a l p a r t i c u l a t e . c e r t a i n t i e s a r e on an average approximately
15%.
The a n a l y t i c a l un-
Besides t h e elements d e t e r -
mined H, IJa, Mg, and A 1 a r e assumed t o be present i n not i n s i g n i f i c a n t amounts. On t h e b a s i s o f t h e r e s u l t s f o r t h e o t h e r elements, i t can be estimated t h a t H ,
Na, big, and A 1 c o n s t i t u t e on an average approximately 4% of t h e d u s t .
(Na, Mg
and A 1 could be determined from t h e PESA s p e c t r a , b u t t h e energy r e s o l u t i o n was not good enough t o give reasonable accuracy.
B e t t e r r e s u l t s could be obtained
by u s i n g higher proton e n e r g i e s ) .
Table I Comparison between t h e r e s u l t s from t h e f i l t e r s a f t e r t h e impactor s t a g e and t h e open f i l t e r s .
(Mean values from seven s e t s of f i l t e r s ) . Concentration
R e l a t i v e Conc. ( % of T P )
(ng/m3)
-
42.2pm
all
C
7500
21900
N
760
1370
0
4090
9060
42.2pm 63 5.0 27
Ratio small/all
all
56 3.4 25
MeantSD 0.4910.17 0.42+0. 14 0.4620.11
S
620
1150
4.3
3.4
0.5620.11
Ca
40
470
0.30
1.4
O.Ol~0.002
Fe
90
430
0.68
1.3
0.2120.04
290
610
2.4
2.3
16200
41000
Pb
TPx)
-
x ) TP= t o t a l p a r t i c u l a t e .
0.4820.06 0.4320.12
61
The d e t e c t i o n limits f o r C , N and 0 a r e found t o be approximately 2.5, 0.5 and 3 The measured values f o r C and 0 a r e well above t h e s e values, and t h e
0.5 pg/m
.
a n a l y t i c a l u n c e r t a i n t i e s a r c 10-20%. For N, some of t h e measured values one c l o s e t o be d e t e c t i o n l i m i t and t h e a n a l y t i c a l u n c e r t a i n t i e s f o r this element a r e s u b sequently somewhat g r e a t e r : 20-50%. Mean values f o r some of t h e r e s u l t s a r e found i n t a b l e 1.
The d e v i a t i o n s i n
t h e values f o r t h e concentrations a r e about 50% o r g r e a t e r , and s i n c e t h e r e s u l t s represent only 7 days, t h e values can only be used a s an i n d i c a t i o n of t h e order of magnitude of t h e concentrdtions t h a t can be found.
It can, tiowever, be cori-
cluded from t h e r a t i o between t h e small p a r t i c l e s and a l l p a r t i c l e s t h a t C , N and 0 a r e a t t a c h e d t o p a r t i c l e s of approximdtely the same s i z e s a s a r e , f o r example, S arid P b , i . e . ,
mainly t o t h e small p a r t i c l e s ( r e f . 1 ) . The o r i g i n of
these p a r t i c l e s i s mainly dnthropogenic.
T h i s may be a l i t t l e s u r p r i s i n g f o r 0 ,
b u t , a s can be seen from values f o r t h e t o t a l p a r t i c u l a t e , t h e majority of t h e
c o l l e c t e d a e r o s o l s a r e anthropogenic. REFERENCES
1. H. Flyger, F. Palmgren 3ensen and K. Kemp, Air P o l l u t i o n i n Copenhagen, p a r t i , Riss Report No 338, Riss Denmark, 1976. 2. 3 . 3 . Wesolowski e t a l . , i n T. Dzubay ( E d . ) , X-ray Fluorescence of
Environmental Samples, Ann Arbor Science, Ann Arbor, 1977, Clr. 9 , p. 121.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
63
APPLICATIOhS OF THE ATMOSPHERE ACOUSTIC SOUNDING TECHNIQUE TO SITING STUDIES C . CAPUT, D . GAUTHIER and R . HAULET Commissariat 1 1'Energie Atomique, I n s t i t u t de Protection e t de Sirret6 Nucleaire, Departement de Protection (France) ABSTRACT
A device f o r atmospheric acoustic detection i s described and a few examples a r e given of the application of t h e data obtained t o the thermal s t r u c t u r e of the lower atmosphere from 80 t o 1 0 0 0 M . _-__ 1. PHYSICAL PRINCIPLES OF SODAR (Sound Detection an Ranging) Theoretical considerations show t h a t a sound wave propagated in a f l u i d of unever temperature gives r i s e to a return echo. More p r e c i s e l y , only temperature variations a t a s c a l e of one-half of the wavelength of the transmitted signal provide a s u f f i c i e n t l y powerful echo. The frequency of the transmitted signal carrying t h e Sodar pulses i s 1 600 Hz, consequently disturbances in the scale of 10 cm generate a sound r e t u r n . 2 . SHORT DESCRIPTION OF THE SODAR (Sound Detection and Ranging) The Sodar i s s i m i l a r t o an electromagnetic radar b u t operates i n the sound spectral range. I t i s made of a parabolic antenna a l t e r n a t e l y receiver and t r a n s m i t t e r every 9 o r 18 sec. Whenever the Sodar sound wave meets a temperature gradient atmosphere l a y e r , the Sodar r e g i s t e r s an echo which gives 3 kinds of information : - the f i r s t one r e l a t e d t o echo energy i n d i c a t e s t h e temperature gradient i n t e n s i t i e s ; i t i s shown by a more o r l e s s dark zone on the recorder paper ; - t h e second one t o "echo s c a t t e r i n g " i n d i c a t e s the thickness of atmospheric thermal gradient ; - the l a s t one t o the speed of t h e acoustic wave indicates the a l t i t u d e of the a i r layer. The Sodar thus makes i t possible t o know and monitor the evolution of the v e r t i c a l thermal s t r u c t u r e of the atmosphere. The r e c e i v e r t r a n s m i t t e r apparatus must be completed by an acoustic enclosure in order both t o prevent disturbance t o the surroundingsand protect against interference.
64
3. USE OF SODAR FOR SITE STUDIES 3.1. Results obtained a t Gravelines This s i t e i s s i t u a t e d near the s e a , between Calais a n d Dunkerque. I n order t o
optimize t h e s i t i n g of sensors of a n a i r q u a l i t y monitoring network,atmospheric v e r t i c a l thermal s t r u c t u r e was investigated. The following were determined : - thickness of the s t a b l e atmospheric l a y e r a t ground level by nocturnal e a r t h wind : average = 290 m ; maximum = 600 m ; - thickness of t h e mixed ground l a y e r by daytime sea wind : average = 270 m ; maximum = 500 m ; - frequency of e a r t h and sea winds ;
an example of recording on august 25, 1976 shows the disappearance of night thermal inversion advert of a CQnveCtive exchange process.
I
c 600
1
I
I
I
I
I
'
I
4 I
I
Sodar r e c o r d i n g obtained o n t h e 25.08.76at Gravellnes
Strong inversion occurs a t the end of the night by very l i g h t wind. The SODAR recording shows t h a t t h e l a y e r i s then only 150 m t h i c k , however i t slowly increases u p t o 8 a.m. (250 m ) and then more quickly, while inversion i n t e n s i t y decreases progressivelyFrom 8 t o 10 a.m. t h e record indicates unevenness due t o wind speed and d i r e c t i o n f l u c t u a t i o n s a t various heights, whereas in the lower 100 m wind i s weak and inversion gradient s i g n i f i c a n t . Soon a f t e r 11 a.m. convection appears near t h e ground surface and inversion disappears. 3.2. Results obtained a t Larymna (Greece) The best height requirement f o r the stack o f a s t e e l m i l l s i t u a t e d i n an Aegean Sea creek was determined so t h a t smoke r e l e a s e would occur above t h e f i r s t uneven temperature gradient level during t h e strongwind periods prevailing in t h i s a r e a .
65
3.3. R e s u l t s o b t a i n e d a t Cordemais (Nantes, France) A remote sensing campaign was o r g a n i z e d by t h e CEC on an E l e c t r i c i t e de France s i t e near Nantes. The r e c o r d shows an example o f d e s t r u c t i o n o f n o c t u r n a l i n v e r s i o n and a d v e r t o f a c o n v e c t i o n p e r i o d a t about 10 a.m. ; q u i c k l y i n v a d i n g a l l t h e m o n i t o r e d area, i . e . 500 m, a t 12 f r o m 9.30 t o 11.45 a.m. and f r o m 1.15 t o 2 p.m. an a l t i t u d e echo v a r y i n g between 200 and o v e r 500 m was caused by t h e smoke w r e a t h f r o m t h e power s t a t i o n . A e r o s o l s and d u s t s i n t h e w r e a t h a c t e d as a m i r r o r f o r sound waves. T h i s example shows how Sodar can show m i c r o - m e t e o r o l o g i c a l 09 h
I
1 0h
11 h
1
I
12h I
.
1
I
I
'
1
I
'
phenomena r'rwrs
13 h
I
.
I
I
I
I
Sodar recordlng obtained o n t h e 10.09.77
at cordemals
4. CONCLUSIONS Sodar
supplies
v a l u a b l e i n f o r m a t i o n whenever one needs t o know t h e v e r t i c a l
thermal s t r u c t u r e o f t h e l o w e r atmospheric l a y e r s and m o n i t o r i t s e v o l u t i o n c o n t i n u o u s l y . For i n s t a n c e w i t h t h e c o l l e c t e d
data
, the
h e i g h t o f t h e atmospheric l a y e r
i n which atmospheric p o l l u t a n t s a r e d i l u t e d can be i n t r o d u c e d i n t o mathematical models. Furthermore, as i t m o n i t o r s t h e atmosphere between 80 and 1 000 m. Sodar p r o v i d e s a u s e f u l complement t o m e t e o r o l o g i c a l towers : f o r a small supplementary expense i t s h o u l d always accompany
any p r o j e c t f o r a m e t e o r o l o g i c a l tower.
Oneshould however n o t i c e t h a t i n t h e case o f f i n e a n a l y s i s o f t h e v e r t i c a l thermal s t r u c t u r e of t h e atmosphere, c o r r e c t i n t e r p r e t a t i o n o f t h e d a t a s u p p l i e d by Sodar can be a c h i e v e d o n l y by u s i n g a d d i t i o n a l d a t a s u p p l i e d by f r e e o r c a p t i v e sounding b a l l o o n s , m e t e o r o l o g i c a l towers, and so on. O n - l i n e computer p r o c e s s i n g of d a t a i s then advisable. The t e c h n i q u e o f atmospheric a c o u s t i c sounding i s l i k e l y t o become i n t h e near f u t u r e an e s s e n t i a l t o o l i n v a r i o u s f i e l d s such as meteorology, t r a n s p o r t , a g r i c u l t u r e o r p r e v e n t i o n o f atmospheric p o l l u t i o n .
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
3 . s3Im2T a,?;?
69
D. ULL.IIC;<
Icstitut fi.ir Iiasser-, Boden- .And Luftkygier,e des Bundes~esucdheitsamtes, Zerlin (Fed. Be2ublic of i3crmany) iNTEODU!:~Io!:
In s?itc of the advance2 state of the ChroEetographer's a r t , problems may arise
iii
the direct analysis of organic pollutants in the air because of the
relatively low concentrations of most of these pollutants in relation to the sensitivity of the analytical system used. The foll.oving article in its first pa-t gives a brief survey of the diffe-
rent sampling procedures, with particular regard to the cryogenic sampling which tozether with GC arinlysis provides a very powerful tool for the determinztion of volatile organic pollutants in arn!;ient air (ref.
I). In
-the s c -
cond part of the text, the applicability of the analytical systeai, includinz a simple CC sepnrntion and identification procedure, is discussed f o r two
innortant
cases:
the de%ermination of hydrocarbons emitted with vehicle ex-
haust g a s e s and the determinatioc of halogenated hydrocarbons in the air. AXALYSIS OF ORGAIJIC POLLUTANTS Following the traditional course of a chemical analysis, the analysis of volatile pollutants in the air includes three stages: sanpling, sample preparation and determination. Sampling As the concentration of most of the organic pollutants in ambient air
does not exceed the ppb-level, the direct sampling of the air using plastic bags or simple stainless steel or glass containers is only possible in those
cases where the detection system provides enough sensitivity. With direct sampling, l o s s e s of substances due to irreversible adsorption cannot be excluded, particularly when more polar compounds are to be sampled. On the other hand, this kind of sampling has the advantage of providing a bigger volume of sample thus giving the possibility of several analyses f o r control purposes. Since as a rule, the bag or container is filled rapidly with the air, the sampling time by this direct procedure is restricted for a l l intents
I
70 and p u r p o s e s t o one u o n e n t i n t i r , c . .'.nother p o s s i b i l i t y o f 3 f i l l e d :,iith approl;ri_ctte s o l i d m - t e r jal, t h e r e i ~ yc o l i c e n t r z t i n t ; t k e o
P
p o l l u t a n t s by a n a d s o r p t i o n process. O f the severa.1 -type:; o f s o a n e d , a c t i v a t e d c a r b o n 2nd Tcnax G C ,
r?
? o r o u s p o l y x c r , ?,re ,,!idel;r u::ec!
c o n c e n t r z t i v e smplin;;. A c t i v a t e d carberi is use& ?*t d e s c r i b e s by Z r o b and C r o b ( r c r c o l l e c t i o n o n l y f o r h y d r o c s r k o n s \:it)?s i x t r a p t h e C2 t o C6 h y d r o c a r b o n s as wc1.1, T e c a r t r i d g e i s h e l d a t -1 2OoC, t i , t i s t c : I p c r z i l i q u i d n i t r o g e n . The a i r i s :Ira exl>erii.ients c o n f i r m t h a t under p o s s i b l e for C2 hydrocarboils even a-t sx.ipl . I ,ien
I"
using c r y o <en ic sa x p 1-in,,
t h e c z r t r i d g e depends on the ex
a t -the n o u t h o f t h e c c . . r t r i d p c l a t i v e t u x i d i t y of 50 the cartridge.
)A, i t i s
I n o r d e r t o i n c r e a s e t h i s vo!~~~:ilc,'.:c use na,:n
a s rz d r y i n c a g e n t . :ic were a.l;le not a f f e c t the results. w h e n d e t be i n v e s t i g a t e d w h e t h e r or n o t t h i s h o l d s t i m e C O Y o t h e r o r g a n i c : > o l l u t a n i s ,
e .c. a l d e h y d e s , k e t o n e s o r p h e n o l s . ?'liere i s some e v i d e n c e -il..at t h o Titantit a t i v e d e t e r m i n a t i o n of a l c o h o l s i s n o t p o s s i b l e when usin,: A f t e r sar;pling,
t h e c a r t r i i . @ e i s ti:;!?tly
ambient t e x p e r a t u r c ,
..-nyloss
0 '
nagrier,i.uro. p e r -
3).
c h l o r a t e as d e s i c c a n t ( r e f .
c l o s e & . i t c a n t h e n b e r?.!r,cd
to
t r a n s p o r t e d e:id n t o y e d zt, l e a s t f o r ::cvcz-d d
subs~l;c..ncss.
S s q l e >repa::a'ii. o n
The p r c g a r a t i o n of
t:12
, l e f o r -t?.e n u b s c c u c i i t s
3
column. In -She c x e oC s!ircct
sncn!
Fnc vi.tI, :: i:ag
of t h e a . i r i s j.cjectec2 usinc a s y r i n c e
01% a
o r a con-!ra,incr,
x.n.1 i L u o t
* s a n p l i a g v a l l x ; i r j . i l l cr;ro,t?-
n i c zmiplin,-, t h e p o l l u t a n t s a r e - t i i e r n a l l y t l e s o r b e d . Tms, tl:o a g a i n c o o l e d down t o - l ? O ° C
vnlati 1e
cnrtridce is
and c o n n e c t e d w i t h t h e sli,-!itly n o d i f i e d i i i j e c -
t i o n p o s t of t h e z a s - c h r o n a t o c r a p h .
i i f t e r c o n n c c t i n c t t e other end. -to a - m c e
of c a r r i e r gas, t h e c a r t r i d g e i s h e a t e d t o 250°C i n n s t r e a m o f h o t Qir. Dur i n g t h i s o p e r a t i o n , t h e chron!atossaphic colun:? i s h e l d a t -90°C r e t a i n t h e p o l l u t a n t s a t t h e f r o n t of t h e c o l u n n .
i n o r d e r -to
71
APPLICBT IOITS
F i g u r e I nhoris t h e r e s u l t s o b t a i n e d vi-tli t h e t i f o colu;.m/-~!:o v3en analyoin?; an a i r chosen for (ref.
r?
.pie c o l l e c t e d a t
nore d e t a i l e d studjr
5 ) . The s i n i l e r i t y of
c o p i s e d easily as c a n t h e
3!'
:*':I-D
a: a tcc! --."
s i t e i n 3erli:2
,air p o l l u t i o n i?. a i x r : x
t h e gcttcr:i 31.
3
of' t h e t w o c!lx-oi~~~.to
i t l y d i f f e r e n t p c c i t i o n s c f eecl-: ool?i.i-tawt.
Although d l ccnpounds have been i d o n t i f i e d , only t h e p r i , i x i F ; L l p e e k s
CL'O
l a b e l e d for reasons of s p a c e . T a b l e 1 i n d i c a t e s t h e c o n c e n t r a t i o n rcnCes a:ld
t h e nean c o n c e n t r a t i o n s of t h e n c s t in2ort:i.n-i; hydrocarbons xeasuretl a t t h i s
The v a l u e s a r e r e p r e s e c t z t i v e for about 50 samples a t 1 5 ininutes eacl.1. A more conprehensi-re t a b l e w i t h valuer, for
s i t e betvcen J a n u a r y and J u l y 1:'77.
40 s u b s t a n c e s is t o be C u b l i s h e d ( r e f . 6 ) .
Fimre 2 shoirs t h e two c i i r o a a t o ! y n m resultin::
f r c r i tlic seprzxTztiono i i @ h -
t a n t s u s i n g one column e q ~ p with d two d e t e c t o r s , i . e . an 719 and a:? X D . Tlie ECD i s t h e more s e n s i t i v e d the tT.ro 2nd indicatez
mu
ti.&? hXlq-a~txl cor::!?ouXls.
TABLE 1 C o n c e n t r a t i o n s of s e l e c t e d hydrocarbons at a t r r e f f i c i n t e r s e c t i o r , i n B e r l i n IIydr o c a r b on ~
n-bu t a n e i-pentane n-pentane benzene toluene n-/p-xylene
Average c o n c g n t r a t i o n
(p d m J ) 29 .? 52 .G 47
.o
51 -7 1 0 2 .o 52 .e
Concentratipn ranye
( p;b ) )
12 -
56
- 110 10 - 35 16 - 99 1 6 - 169 2 5 - 34 12
72
12
F i g . 1 . C h r o m a t o p a n of a n a i r sample. Proceiiure wi-th tiro di€,'er.ent colmnnc. - Column 1 : 1 0 :5 O~r-101 + C I , :5~ cnrboirax 2 0 !i on C!~o:,io::or'c '(50 (100-720 n e s h ) , w i t h FID. - Colmin 3: 12 W-3 + 0,5 ;<'srbo::nx 2(J !i o n C'-.roi::osorb 750 (100-120 n e s h ) , w i t h P I D . 2 : n - b u t a n e ; 5: i - y e f i t m e ; 5: :i->enta.nc; 0 : benzene; 10: t o l u e n e ; 12: r?-/p-xxlene; 11: i.-:ioncne; 14: 1 ,?.e--b?iriethylbenzene.
-
::
Yig. 2 . Chronatogram o f an a i r s c n p l e . PI-ocedure i r i t h two d i f f e r c n t d c t e c -
-
Colunn: 1 0 72 Ov-101 + O,5 ;
REFElLEIJCES 1 D. Ullrich and B. S e i f e r t , 2 . Anal. Chem. ( i n p r e s s ) . 2 K. Grob und G. Grob, J. Chromatog. 62 (1971) 1 13. 3 E.II. B e r g e r t , V. Bet:: and 1). Pruggmayer, C h r o n a t o g s a p h i a 7 (1974) 115-121. 4 D. U l l r i c h and \J. Dulson, C h r o n a t o g r a p h i a 10 (1977) 537 - 541. 5 D. S c i f e r t and D. Ullrich, S t n u b Reinhalt. L u f t ( i n p r e s s ) . 6 E. Lahnann, 3. S e i f e r t and .!I Dulson, B u n d e s g e s u n d h e i t s b l . ( i n p r e s s ) .
-
-
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in EnvironmentalScience, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
ASSESSMENT B.T.
73
OF DIMETHYL-N-NITROSAMINF I N URBAN A I R
CHUONG, D. BODIN and 11. BENARIE
'
I n s t i t u t N a t i o n a l de Recherche Chimique A p p l i q u e e -91710 VERT-le-PETIT
(FRANCE)
ABSTRACT D i m e t h y l n i t r o s a m i n e (DMNA) was f o u n d i n 25% o f t h e a i r sampled i n P a r i s f r o m May t o December 1977. The r a n g e o f c o n c e n t r a t i o n was f r o m 0.2119 v i t y l i m i t o f 0.01pg
down t o t h e s e n s i t i -
I t seems t h a t by i m p r o v i n g s e n s i t i v i t y , more samples would
have shown t h e presence o f DMNA. H i g h e r homologues as d i e t h y l - , d i p r o p y l - , and d i b u t y l n i t r o s a m i n e were absent, so t h a t a p r e v i o u s l y d e s c r i b e d (Chuong and Benarie, 1976) method s p e c i f i c t o t h e n i t r o s o f u n c t i o n seems adequate f o r surveys. Meteorolog i c a l c o n d i t i o n s o f OMNAoccurrencepoint t o t h e p o s s i b i l i t y o f i t s f o r m a t i o n by n i t r o s a t i o n o f dimethylamine d u r i n g n i g h t - t i m e and r a p i d d e s t r u c t i o n by s u n l i g h t d u r i n g day-time. INTRODUCTION The presence o f v o l a t i l e N - n i t r o s a m i n e s i n t h e P a r i s a i r was observed r e c e n t l y by Chuong and B e n a r i e ( 1 9 7 6 ) . The d e t e c t i o n method t h a t has been used was f u n c t i o n s p e c i f i c and does n o t a l l o w w e i g h t d e t e r m i n a t i o n i n t h e presence o f more than a s i n g l e nitroso-compound.
I n o r d e r t o f u r t h e r b a s i c knowledge of urban a i r c h e m i s t r y , and i n
o r d e r t o s p e c i f y t h e l i m i t s o f a p p l i c a t i o n of t h e n o n - s p e c i f i c method, gas chromatography was used t o assess t h e chemical n a t u r e o f t h e n i t r o s a m i n e s e v e n t u a l l y p r e s e n t . MATERIALS AND METHODS
3
A i r was drawn a t t h e r a t e o f 10 Nm /24 h t h r o u g h g l a s s f r i t b u b b l e r c o n t a i n i n g
100 m l d i s t i l l e d w a t e r . E v a p o r a t i o n l o s s e s were a u t o m a t i c a l l y r e p l e n i s h e d , so t h a t t h e sampling c o u l d be extended t h r o u g h weeks, i f necessary. P r e l i m i n a r y experiments proved t h a t t h e sampling e f f i c i e n c y was v e r y near t o 100%. The aqueous s o l u t i o n was e x t r a c t e d w i t h d i e t h y l e t h e r and c o n c e n t r a t e d b y e v a p o r a t i o n a t room temperature t o 1 m l . The gas chromatograms were o b t a i n e d on a 6 - f t x 1 / 8 i n c h s t a i n l e s s s t e e l column packed w i t h Chromosorb 101 mesh s i z e 100/120; oven, i n j e c t i o n p o r t and d e t e c t o r 200°C; f l o w r a t e 25 m l N2/min. W i t h an a l k a l i f l a m e i o n i z a t i o n d e t e c t o r (AFID) and a c h a r t speed o f 2 mm/min, t h e chromatogram F i g u r e 1 has been o b t a i n e d
x To whom correspondence s h o u l d be addressed.
74
with the dimethyl-, diethyl-, dipropyl-, and dibutyl nitrosamine standards ( = DMNA, DENA, DPNA and D B N A ) . The detection limit in our setting was 0 . 5 ~ 9o f DMNA. The chromatogram o f an urban air sample is presented in Figure 2.
aJ vl
c 0 a ul
E L
0
c V
aJ
c
aJ U
50
LO
30
20
10
0
mi nut es
Fig.1 - Calibration chromatogram obtained with 1.5ug/ml dimethyl-(=peak 1); 5.2pg/ml diethyl-(=peak 2 ) ; 2.7pg/m1 dipropyl-(=peak 3) and 2.9ug/m1 dibutylnitrosamine (=peak 4". Injection volume: 5 111
30 20
10
minutes
Fig.2 - Chromatogram o f air sample Nr. 20 - 25 m3 air. DMNA concentration (peak 1): 0.1119 m-3.
0,
m
C
0
a m 0,
L
Fig.3 - Decomposition products o f dimethylamine: the peaks at 5 and 8.5min. Sample volume: 39 m3, dimethylamine conc. 0 . 0 5 ~ 9m-3.
0
L
0
c V
aJ 0,
Y 20
minutes
10
73
0
75
Under t h e s e o p e r a t i n g c o n d i t i o n s , dimethylamine (DMA) i s decomposed and y i e l d s two peaks a t 5 and 8.5 m i n which do n o t i n t e r f e r e w i t h n i t r o s a m i n e s ( F i g u r e 3 ) and a l l o w good i d e n t i f i c a t i o n o f DMA. RESULTS As d e s c r i b e d i n t h e p r e v i o u s s e c t i o n , a i r was c o n t i n u o u s l y sampled a t t h e Q u a i S t . B e r n a r d i n P a r i s ( U n i v e r s i t e P a r i s V I ) a t a h e i g h t o f 20 m f r o m s t r e e t l e v e l , f r o m May t o December 1977. a. T h i r t y - s i x h i g h volume samples were c o l l e c t e d , c o r r e s p o n d i n g t o 20 t o 50 m3 a i r d u r i n g two t o f i v e d a y s ' c o n t i n u o u s o p e r a t i o n . I t s
purpose was double : 1 - we
sought t o apprehend t h e presence o f n i t r o s a m i n e s a t as l o w a c o n c e n t r a t i o n as p o s s i b l e and 2
-
we wished t o o b t a i n enough sample m a t e r i a l f o r i d e n t i f i c a t i o n .
1. O n e - f o u r t h , i . e . n i n e o f t h e 36 l o n g - t e r m samples c o n t a i n e d measurable q u a n t i t i e s o f N - n i t r o s a m i n e s : t h e i r c o n c e n t r a i o n s f i g u r e i n Table 1.
TABLE 1 C o n c e n t r a t i o n o f d i m e t h y l n i t r o s a m i n e i n t h e a r o f P a r i s d u r i n g t h e y e a r 1977. Sampling on o t h e r days ( w i t h t h e e x c e p t i o n o f n o c t u r n a l sampling, see t e x t ) showed 2 DMNA-levels below t h e s e n s i b i l i t y l i m i t o f 10- pg m-3 May Date Concentration ug m-3
June
July
10-13
13-16
9-16
25-30
0.1
0.05
0.05
0.20
Nov
Dec
1- 5
14-17
Oct 25-31
1- 5
7-12
0.1
0.02
0.01
0.02
0.1
S o l a r r a d i a t i o n has been v e r y d e f i c i e n t i n June and J u l y , normal f o r t h e season i n August and September, and s t i l l normal b u t o b v i o u s l y d e c r e a s i n g i n autumn. N i t r o s a m i n e was absent i n August and September, and i t s occurrencemore f r e q u e n t on c l o u d y ( h u t n o t r a i n y ) days. T h i s seems t o c o n f i r m t h e l a b o r a t o r y r e a c t o r r e s u l t s o f Hanst e t a l . (1977) who f o u n d t h a t t h e h a l f - l i f e o f DMNA vapour under f u l l sun i s about 30 m i n . N i n e c o n c e n t r a t i o n p o i n t s a r e c e r t a i n l y t o o few t o make up a frequency d i s t r i bution. Nevertheless, w i t h a l l t h a t i s generallyknownabout t h e d i s t r i b u t i o n o f p o l l u t a n t c o n c e n t r a t i o n s , Table 1 suggests t h a t by improved s e n s i b i l i t y , DMNA c o u l d be d e t e c t e d i n a g r e a t e r percentage o f t h e samples. T h i s w i l l be o u r goal i n t h e near f u t u r e . A good f r e q u e n c y d i s t r i b u t i o n diagram would a l l o w t o f o r e s e e maximum c o n c e n t r a t i o n s and t o advance c o n t r o l . I t would a l s o improve s i g n i f i c a n t l y c o r r e l a t i o n w i t h m e t e o r o l o g i c a l f a c t o r s and p r e c u r s o r s .
76
2. The o b t a i n i n g o f l a r g e samples e n a b l i n g i d e n t i f i c a t i o n , was a t t a i n e d d u r i n g t h e p e r i o d o f June 25-30 f o r example, when a 10 pg sample c o u l d be c o l l e c t e d . With t h e b e f o r e mentioned s e n s i t i v i t y l i m i t o f 0.5 pg, t h e presence o f d i e t h y l - , d i p r o p y l - and d i b u t y l - n i t r o s a m i n e s c o u l d be excluded, p r o v i n g t h a t a t l e a s t 90% o f t h e n i t r o s a m i n e s i n t h e a i r o f P a r i s i s DF1NA. I n t h i s way, t h e p r e v i o u s l y d e s c r i b e d (Chuong and Benarie, 1 . c . ) n i t r o s o - f u n c t i o n s p e c i f i c r a p i d c o l o r i m e t r i c method can be used i n surveys c o n c e r n i n g h e a l t h e f f e c t s . b. D u r i n g September, October and November, s e v e r a l day ( 7 : O O t o 18:OO) and subsequent n i g h t (18:OO t o 7:OO n e x t day) samples were c o l l e c t e d . None o f t h e day samples and one o f t h e n i g h t samples (September 15/16; 0.2 l ~ gm-3 DMNA) showed t h e presence o f n i t r o s a m i n e s , t h u s c o n f i r m i n g a n o t h e r assumption o f Hanst e t a l .
vis t h a t n i t r o s a t i o n o f dimethylamine (DMA) vapour m i g h t t a k e p l a c e d u r i n g t h e n i g h t i n p o l l u t e d u r b a n atmospheres. (1.c.)
c . As a f u r t h e r t e s t o f t h e n i t r o u s a c i d - DMA r e a c t i o n , a t t e n t i o n was p a i d t o t h e d e t e c t i o n o f t h i s p r e c u r s o r d u r i n g t h e chromatography. A t s e v e r a l occasions ( e . g . August 24-29; October 1 3 ) DMA has been p o s i t i v e l y i d e n t i f i e d . d. F i n a l l y , a l i m i t e d number o f 24-hour
samples were analyzed i n view t o o b t a i n
more i n s i g h t i n t o t h e causes, i . e . t h e l i n k between p r e c u r s o r
-
DMA and meteorology.
While t h e s e r e s u l t s g e n e r a l l y do n o t c o n t r a d i c t t h e h y p o t h e s i s o f n i g h t - t i m e f o r m a t i o n o u t o f p r e c u r s o r and i t s d e s t r u c t i o n by s u n l i g h t , t h e y a r e n o t d e f i n i t i v e y e t . The number and span o f m e t e o r o l o g i c a l v a r i a b l e s i s such t h a t many more d a t a ( a t l e a s t a f u l l y e a r l y c y c l e ) have t o be c o l l e c t e d and dominant wind d i r e c t i o n t a k e n i n t o c o n s i d e r a t i o n b e f o r e any f i r m c o n c l u s i o n c o u l d be drawn f r o m t h e 24-hour sampling program. CONCLUSION D i m e t h y l n i t r o s a m i n e has been found and i t s c o n c e n t r a t i o n measured i n t h e a i r o f P a r i s . The d i e t h y l , d i p r o p y l and d i b u t y l homologues were n o t p r e s e n t i n t h e a i r samples. Dimethylamine as p o s s i b l e p r e c u r s o r was a l s o i d e n t i f i e d . The c o n d i t i o n s o f t h e o c c u r r e n c e o f d i m e t h y l n i t r o s a m i n e p o i n t t o t h e p o s s i b i l i t y o f dimethylamine r e a c t i o n w i t h n i t r o u s a c i d d u r i n g n i g h t - t i m e and t o i t s r a p i d d e s t r u c t i o n by s u n l i g h t . Due t o t h e s h o r t h a l f - l i f e o f n i t r o s a m i n e i n f u l l s u n l i g h t , i t s long-range t r a n s p o r t seems u n l i k e l y . REFERENCES Chuong B.T. e t B e n a r i e M. 1976 - Recherche d ' u n e methode pour l e dosage de l a N-Nitrosamine dans 1'atmosphPre. S c i . T o t . Env. 6, p.181-193. Hanst P.L., Spence J.W. and M i l l e r M. 1977 - Atmospheric Chemistry o f N - N i t r o s o Dimethylamine. Env. S c i . Techn. 11, 4, p.403-405.
Acknowledgement Support f o r t h i s r e s e a r c h w a s p r o v i d e d by t h e MinistBre de l a Culture e t de 1 'Environnement, C o n t r a c t N076-10. 7
Atmospheric Pollution 1978, Proceedingsof the 13th InternationalColloquium,Paris,France, April 25-28, 1978, M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
77
SULFUR DIOXIDE tEASU4EYENT IN YAIRINE ATNOSPHE9E AT CONCENTRATIONS LOWER THAN PPB B. BONSANG and B.C. NGUYEN Centre des Faibles IladioactivitSs, laboratoire mixte CNRS-CEA, 91 190 - Gif-sur-Yvette (France) ABSTRACT In order to measure the low concentrations of sulfur dioxide in remote areas, we adapted the West-Gaeke method. A marine origin for an oceanic background value of 0.1 palm3 has been established.
INTRODUCTION Sulfur dioxide is relatively slight reactive in the lower atmosphere. Its residence time in the marine atmosphere is long enough (12 hours ; ref.1) to allow its detection in the atmosphere. In highly polluted urban a r e a
s
,
SO2 concentrations are
relatively easy to measure. In the marine atmosphere where levels are lower than 1 pg/m3 (ref .2), the problem is of course more difficult and requires very drastic
precautions. Sulfur dioxide is not the only reactive trace gas in such an atmosphere but is present at the same order of concentration as NO,NO
0 H S , etc,... 2 ’ 3’ 2 Consequently, we have chosen the West-Gaeke method which is one of the most specific
techniques for SO2 measurements at low concentrations (ref.3). This method consists of two distinct steps : bubbling the air through IOcm3 of a sodium tetrachloromercurate solution (NaZHg Cl4) which leads to the formation of a stable complex disulfito-mercurate (Hg(S0 3 ) 2 )--; then spectrophotometrical analysis a t 560nm,after making a coloured pararosaniline methylsulfonic acid (11) complex. SMIPLING CONDITIONS Optimum flow rate 3 Because the low concentrations expected in the marine atmosphere (0.1 pg/m ) , the collected volume needs to be several m3 in order to obtain a sufficient accuracy in the results. The collection efficiency varies with the flow rate of air through the bubbling solution. A good efficiency of about 90% is obtained for flow rates up to 4 l/mn, this efficiency falls down to about 40% at 5 l/mn. The optimum flow rate is then 4 l/mn, and the collection time for marine concentrations less than 0.1 pg/m3 must be at least 12 hours. The evaporation of 10cm3 of the solution is very important for such a collection time and may represent 50% loss over 12 hours. The residence time of air in the
solutions consequently falls and the collection efficiency may reach 4 0 2 . A solution proposed by Benarie et al. (ref.4) consists of making an "isotonic"so1ution of glycerol. The efficiency of collection is good for flow rates as high as 10 l/mn, but the calibration is dependent on the concentration of glycerol. Toprevent any decrease in the final volume of the solution by evaporation, we have refined an electromagnetic device (ref.2) to regulate the level of solution in the bubbler by addition of bi-distilled water, thus maintaining the concentration of tetrachloromercurate constant by the same way. Field experimentation To keep out of our samples any contamination from ship effluents, the air inlet is always placed ahead the ship. An automatic system was used to prevent any contamination by cutting off systematically the power when the wind blows from astern in a sector of 180". Moreover, the comparison with sulfate concentrations exausted with levels 100 times higher than SO2 during fuel combustion provides us a supplementary method of control. Storage of samples Unfortunately, samples are not very stable at room temperature, previous experiments made by Lahman (ref.5) show a rapid decrease with time of the complex. Our experiments performed in laboratory with both spiked solutions of SO3' and atmospheric samples show (fig.1) that the best storage temperature is near 2'C.
The decrease in the concentration of disulfito mercuric complex is then
given by : R
=
0.939 t -0.0878 where t is the storage time in days and R the
efficiency of storage used in calculations.
%
40
2o
FIG. 1
Storage efficiency
i
\
It
\
\
(from lahmann 1969)
\
\
\
b
+2O0C
2
4
8
Y
one
week
16
32 t
one month
64
128
256
v
days
one year
FIG.2
,I' 0
.2
.4
.6
.El
LO l.2 1.4 pg ~ 0 , / 1 0 c r n ~
Fig.1 Stability of samples with time at various storage temperatures Fig.2 Calibration curve
79
ANALYSIS The analysis is made in laboratory with a "ZEISS PM Q 11" spectrophotometer. Calibration curve in fig.2 shows a good linearity up to 1.5pg of SO2 in IOcm3 of absorbing solution. The detection limit, for an acceptable accuracy of about 30% is ~ ~SO2 collected in the whole sample.Interferences with other of the order of 0 . 1 of
gaseous compounds have been studied particularly with nitric oxides. This interference may be ruled out by addition of sulfamic acid before analysis (ref.6). \je have checked that sulfides, as dimethylsulfide, do not interfer in the analysis at quantities of about 1 p g . Moreover a study of the stability of the mercuric complex (RSX),
(Hg C12),
shows no degradation, such as oxidation in solution, over a period of
several weeks. Interference with ozone is the main problem, since oxidation of SO3= in aqueous phase in presence of ozone is very rapid, the stability of the disulfito mercuric complex is high enough to preventany oxidation to sulfate. Other possibility is the interference during the spectrophotometric analysis by bleaching of pararosaline methylsulfonic acid. The time delay between sampling and analysis is long enough to lead to the destruction of ozone in solution with other reducing agents. CONCLUSION This technique is specificand sensitive enough to enable observation of the vari3 For several experimentations
ation of the SO2 oceanic values from 0.03 to 0.2pg/m
.
in the same oceanic areas, the reproductibility in our results confirms the occurence of a marine source of sulfur dioxide (ref.2). Correlation between SO2 and excess sulfate in marine aerosols supports this assumption (ref.7). REFERENCES Ba Cuong Nguyen, B.Bonsang, G. Lambert and J.L.Pasquier, Residence time of sulfur dioxide in the marine atmosphere, Pure and Appl. Geophys.123(1975)489-500. BaCuong Nguyen, B.Bonsang and G.Lambert, Atmospheric concentration of sulfur dioxide and sulfate aerosols over Antarctic, Subantarctic areas and oceans, Tellus, 26(1974)241-249. P.W. West and G.C. Caeke, Fixation of sulfur dioxide as disulfitomercurate (11) and subsequent colorimetric estimation, Anal. Chem.,28(1956) 1816-1819. M. Benarie, M. Callais, B.T. Chuong, B.Pontvianne, R.Simon and S. Zazartchenko, Mesure de la teneur en SO2 en zone faiblement polluse, Poll. Atmosph. 59(1973), 28 1-290. E. Lahmann, The stability of absorption solutions for sulfur dioxide determination by the West-Gaek method, Staub-Reinhalt. Luft, 29(1969)30-32. J.B. Pate, B.E. Ammons, G.A. Swanson, J . P . Lodge, Nitrite interference in spectrophotometric determination of atmospheric sulfur dioxide, Anal. Chem.,37(1965) 942-945. Ba Cuong Nguyen, B.Bonsang, A.Gaudry and G. Lambert, Oxidation processes of sulfur components in the marine atmosphere, IAGAIIAMAP Joint Assembly, Seattle August 1977, USA.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
A
83
NEW PERSONAL DUST SAKPLER, THE CIF
P. CCURBOPJ C e n t r e d ' E t u d e s e t Recherches d e s Charbcrlnages d e F r a n c e
ABSTRACT A f t e r r e c a l l i n g t h e main c h a r a c t e r i s t i c s o f t h e r o t a r y foam d u s t samplers
CPA and CFM 3, t h e paper d e s c r i b e s a new s e l f - c o n t a i n e d p e r s o n a l d u s t sampler i n t e n d e d for measurement of d u s t exposure a t t h e workplace i n t h e c o u r s e of a shift. The a p p a r a t u s i s based on t h e u s e of a new mode c f s e p a r a t i o n o f r e s p i r a b l e and non r e s p i r a b l e p a r t i c l e s , by a n n u l a r i m p a c t i o n w i t h i n a r o t a t i n g h o u s i n g c o n t a i n i n g a m i n i a t u r e f i l t e r made o f p o l y u r e t h a n e f o a n .
I t has s m a l l d i m e n s i o n s , a reduced weight and c a n be e a s i l y worn by a worker. I t s f l o w r a t e i s h i g h , more t h a n 10 l/mn ; i t i s i n s e n s i t i v e to j e r k s and can operate i n a l l positions.
INTRODUCTION The l e v e l of f i n e d u s t exposure a t t h e workplace i n t h e c o u r s e of a s h i f t i s u s u a l l y determined by t a k i n g samples of t h e p o l l u t e d atmosphere a t a f i x e d p o i n t . I n o r d e r t o o b t a i n a more r e p r e s e n t a t i v e sample of t h e d u s t e f f e c t i v e l y i n h a l e d , i n p a r t i c u l a r i n t h e c a s e o f a worker s t a n d i n g n e a r t o a s o u r c e of a i r b o r n e d u s t ,
or changing h i s p o s i t i o n d u r i n g h i s work, i t i s d e s i r a b l e t h a t samples a r e t a k e n c o n t i n u o u s l y , c l o s e t o t h e r e s p i r a t o r y t r a c t , by means of an a p p r o p r i a t e p e r s o n a l sampler.
A w e l l a d a p t e d , e a s i l y p o r t a b l e p e r s o n a l d u s t sampler should be s e l f - c o n t a i n e d , small i n s i z e and compact i n o r d e r t o be worn w i t h o u t d i s c o m f o r t . I t s flow r a t e must be h i g h enough t o e n s u r e c o l l e c t i o n t h r o u g h o u t a s h i f t of enough d u s t f o r weighing and a n a l y s i s . I t s h o u l d o p e r a t e s e l e c t i v e l y by s e p a r a t i n g t h e l a r g e s t p a r t i c l e s from t h e r e s p i r a b l e d u s t , and s h o u l d be c a p a b l e o f o p e r a t i n g i n any p o s i t i o n and b e i n s e n s i t i v e t o j o l t s .
84 WORK CARRIED GUT An i n v e s t i g a t i o n i n t o methods of d u s t c o l l e c t i o n w i t h a view t o d e s i g n i n g f u n c t i o n a l d u s t s a m p l e r s t o be employed a t t h e workplace o r f o r a i r p o l l u t i o n measurement, had r e s u l t e d i n t h e development, a few y e a r s ago a t t h e C e n t r e d ' E t u d e s e t Recherches d e s Charbonnages de F r a n c e (CERCHAR),
of r o t a r y f i l t e r s
made of p o l y u r e t h a n e foam. Two d u s t s a m p l e r s have been d e s i g n e d :
-
The CFA f o r air p o l l u t i o n measurement developed on b e h a l f of t h e C e n t r e
I n t e r p r o f e s s i o n e l d ' Etude d e l a P o l l u t i o n Atmosphkrique (CITEPA) and
-
The CPM
3 f o r sampling d u s t i n underground mines and i n t e n d e d t o be used
a t t h e workplace i n g e n e r a l . These two d u s t s a m p l e r s , of which a few hundred have been c o n s t r u c t e d s o f a r , make u s e of t h e same p o l y u r e t h a n e foam f i l t e r . The f i l t e r r o t a t i n g a t 5 GOO t/mn not only a s p i r a t e s the dust laden a i r but a l s o t r a p s the p a r t i c l e s . I n addition, t h e CFM 3 i s equipped w i t h a c y c l o n e p r e - s e p a r a t o r ,
which c o l l e c t s t h e b i g g e s t
p a r t i c l e s . T h i s a p p a r a t u s i s c u r r e n t l y employed i n t h e French c o a l mines f o r d u s t sampling i n a c c o r d a n c e w i t h t h e new r e g u l a t i o n s of December 1 5 , 1975.
TABLE 1 The main c h a r a c t e r i s t i c s of t h e CPA and CPM C PA Flow r a t e Time of i n d e p e n d e n t operation Particles collected Energy r e q u i r e m e n t Wei gh t Special feature
1.5
7 . 0 m3/h
m3/h
+
:
CPM 3
10 hours selective collection
10 d a y s all particles 0.5 W
0.550 kg
7 are as f o l l o w s
l e a d b a t t e r y ( 8 kg)
0.8 W 3 kg
( b a t t e r y included) intrinsically safe
A s shown i n t h e t a b l e a m a j o r a d v a n t a g e o f r o t a r y p o l y u r e t h a n e foam f i l t e r s i s t h e i r low e n e r g y r e q u i r e m e n t ( 0 . 5 and 0 . 8
W). F o r t h e same f l o w r a t e , i t i s
s e v e r a l t i m e s lower t h a n t h a t o f c o n v e n t i o n a l d e v i c e s i n which t h e c o l l e c t i n g element and t h e a s p i r a t i n g system o p e r a t e i n d e p e n d e n t l y . Consequently, f o r a g i v e n f l o w r a t e and p e r i o d of independent o p e r a t i o n , t h e b a t t e r y weight r e q u i r e d i s reduced. T h i s h a s l e d u s t o d e s i g n a m i n i a t u r e model i n t e n d e d for p e r s o n a l sampling, t h e CIP.
THE PERSONAL DUST SAMPLER, CIP The f i r s t p r o t o t y p e produced w a s equipped w i t h a s m a l l - s i z e d c y c l o n e p r e - s e p a r a t o r and a r o t a r y p o l y u r e t h a n e foam f i l t e r . Like any o t h e r p e r s o n a l sampler provided
85
with a cyclone pre-separator,
however, i t o p e r a t e d s a t i s f a c t o r i l y only when i n a
more o r l e s s v e r t i c a l p o s i t i o n . Now, i n many c a s e s , miners a t work o f t e n change t h e i r body p o s i t i o n , s o t h a t t h e sampler d e p a r t s from i t s v e r t i c a l p o s i t i o n . A s a r e s u l t t h e b i g g e s t p a r t i c l e s c o l l e c t e d by t h e cyclone become a g a i n suspended and mix w i t h t h e f i n e p a r t i c l e s c o l l e c t e d by t h e p o l y u r e t h a n e foam f i l t e r . S e l e c t i o n f a i l s . We have t h e n u n d e r t a k e n t o s t u d y a n o t h e r mode of s e l e c t i o n based on annular impaction within a r o t a t i n g housing.
F i g . P e r s o n a l d u s t sampler
. Type
CIP
The new d e s i g n i s r e p r e s e n t e d i n t h e f i g u r e . I t comprises :
-a -
c y l i n d r i c a l a i r i n l e t with a conical guide f o r the airstream,
a mobile assembly c o n s i s t i n g o f a r o t a r y cup c o n t a i n i n g a p o l y u r e t h a n e foam
d i s c , and a cup-shaped c o v e r h a v i n g a c e n t r a l and p e r i p h e r a l o r i f i c e ,
-
means f o r r o t a t i n g t h e mobile assembly (motor and power s u p p l y ) .
A s a r e s u l t o f t h e r o t a t i o n of t h e p o l y u r e t h a n e foam d i s c , t h e d u s t l a d e n a i r i s c h a n n e l l e d t h r o u g h t h e c e n t r a l c o n i c a l i n l e t , and assumes t h e shape of a n n u l a r a i r s t r e a m s t h a t c o l l i d e w i t h t h e bottom of t h e upper cup. Through t h e i m p a c t , t h e l a r g e s t p a r t i c l e s a r e stopped and under t h e c e n t r i f u g a l a c t i o n , t h e y a r e f o r c e d towards t h e cup s i d e - w a l l
; on t h e o t h e r hand t h e a i r c o n t a i n i n g t h e s m a l l e s t
p a r t i c l e s i s d e f l e c t e d towards t h e c e n t r a l o r i f i c e . The a i r goes through t h e p o l y u r e t h a n e foam d i s c where t h e f i n e p a r t i c l e s i n s u s p e n s i o n are t r a p p e d , and t h e dust-free a i r i s discharged outside.
86 Annular i m p a c t i o n i n s i d e a r o t a t i n g h o u s i n g i s c h a r a c t e r i z e d by t h e f a c t t h a t under t h e a c t i o n o f t h e c e n t r i f u g a l f o r c e t h e p a r t i c l e s c o l l e c t e d are n o t r e t a i n e d
a t t h e impact
p o i n t , b u t a r e f o r c e d towards t h e p e r i p h e r y . A s a r e s u l t t h e
p a r t i c l e s do n o t form a g g r e g a t e s as i n t h e c a s e o f c o n v e n t i o n a l i m p a c t i o n and t h e s e p a r a t i o n i s s t a b l e w i t h t i m e . The d e v i c e c a n o p e r a t e i n a n y p o s i t i o n . S i n c e t h e t r a p p e d p a r t i c l e s a r e f o r c e d a g a i n s t t h e i n t e r n a l s i d e w a l l of t h e h o u s i n g by c e n t r i f u g a t i o n , t h e system i s n o t s e n s i t i v e t o j e r k s . The p r o t o t y p e made h a s t h e f o l l o w i n g c h a r a c t e r i s t i c s :
-
length
-
diameter
44 mm
flow rate
10-15 l/mn
power r e q u i r e m e n t
0.1 t o 0.15
-
100 mm
w
d e t e r m i n a t i o n of t h e d u s t weight c o l l e c t e d by weighing t h e f i l t e r element
b e f o r e and a f t e r t a k i n g t h e sample. The d u s t c o l l e c t e d can be e a s i l y r e c o v e r e d f o r subsequent a n a l y s i s
-
power s o u r c e c o n s i s t i n g o f a small b a t t e r y w i t h a p e r i o d o f o p e r a t i o n of 10
h o u r s . On a c c o u n t o f t h e small s i z e o f t h e b a t t e r y r e q u i r e d and t h e low power r e q u i r e m e n t of t h e r o t a t i n g system, i t is planned t o d e s i g n a compact d e v i c e i n one p i e c e weighing 300-400 g r .
Atmospheric Pollution 1978,Proceedings of the 13th InternationalColloquium,Paris,France, April 25-28,1978,M.M.Benarie (Ed.),Studies in EnvironmentalScience,Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
87
A VARIABLE FREQUENCY ELECTROSTATIC MOBILITY ANALYZER
Y. HYUN and J.W. GENTRY Department of Chemical Engineering, University of Maryland College Park, Maryland (U.S.A.)
ABSTRACT An electrostatic mobility analyzer of the rod and cylinder configuration has been built and tested. rod.
A variable voltage (
D.C. square wave) is imposed on the
The charge distribution is determined by varying the frequency rather than
the net applied voltage.
The total particle concentration before and after the
precipitator is measured with a photometer. The instrument has been used to measure the charge distribution of latex aerosols.
The use of the instrument for determining the charge distribution of
polydisperse and non-spherical aerosols is discussed.
Numerical algorithms for
data inversion are presented.
INTRODUCTION In previously reported experiments, Megaw (refs. 1) described the construction of an electrical mobility analyzer using a D.C. electric field imposed between two parallel plates.
In subsequent work, considerable care has been taken to
insure laminar flow.
Recently (ref. 2 ) a series of experiments have been report-
ed for latex, sodium chloride, and parafine particles in the 1-2 1J.mrange. In these experiments the quantity of particles deposited as a function of their downstream distance is measured.
Specifically the number of charges ( 3 )
are given by 3 T Q D
J
x
=
H2Uo
2 E E X
where q is the gas viscosity, U
0
separation between plates, D
P
is the axial velocity, H is the distance of
is the diameter of the particle, E the applied
voltage, and X the distance downstream where the particles' deposition occurs. Presently there are two operational designs of mobility analyzers
-
one model
consisting of parallel plates (ref. 1) and the other consisting of concentric cylinders (ref. 3 ) .
The charge distribution can be determined either by measur-
ing the deposit along the axis (direct method) or by measuring the penetration before and after the analyzer.
88
1
P'
Figure 2 Flow Diagram of the Measurement Procedure
Figure 1 Schematic of the Mobility Analyzer
EXPERIMENTAL DESIGN A schematic of the mobility analyzer and supporting electronics is given in Figure 1. The outer shell of the precipitator (A) is gounded (K) and has a length of 76.5 cm and a 5.08 cm I.D.
The inner rod (A) is connected through a high volt-
age seal (D) to the voltage supply (E). The diameter of the rod is 0.32 cm and its effective length is 75 cm.
It is maintained in position with the spacer
(C).
A low frequency generator (HP Model 202A) (F) produces a signal which drives a power supply (El. The signal from the generator, appropriately scaled down, is recorded on the two pin charts (G) simultaneously with the penetration. Flow enters the analyzer at H and exits at I. In Figure 2 is a schematic of the flow systems.
In the series of experiments
reported here monodisperse latex particles were nebulized from a dilute aqueous solution in a Dautrebande generator neutralized (XI.
(Z).
The particles were dried (Y) and
[An option exists for bypassing the neutralizer].
The particle
than passes through the mobility analyzer (H) or a bypass (W) into the Phoenix Sinclair Photometer.
The signal from the instrument is continuously recorded on
a two pin strip recorder (G). The penetration is determined from the ratio of light scattered before and after the mobility analyzer.
This signal and the output from the power supply
which was proportional to the voltage on the inner rod were recorded simultaneously.
Controllable variables were the voltage, the frequency of the oscillation,
and the flow rate through the analyzer.
Since optimum conditions for the opera-
tion of the Dautrebande generator constrain the range of operating velocities to
89
:I
81-MODAL
D,=79p
UNI-MOOAL 0
1
2
3
4
5
FREQUENCY
6
7
8
9
1
I
0
01
(SEC-')
0 2 0 3 0 5 0 8 1
2
3
5
1
8 1
FREQUENCY ISEC 1
Figure 3 Penetration as a Function of Frequency for Uniform Flow
Figure 4 Penetration as a Function of Frequency (Experimental Data)
a narrow range, a dilution and venting manifold (not shown) were necessary to control of the flow rate through the mobility analyzer.
The signal generated by F
was in all cases a square wave D.C. signal which oscillated between positive and negative values. NUMERICAL SIMULATION Numerical simulation of the mobility analyzer can demonstrate limitations of instrumental design and indicate an economical experimental program.
It can indi-
cate the qualitative behavior expected for laminar or uniform flow as well as possible differences in the efficiency owing to changes in the polarity of the center rod when the charge distribution is assymetric. The basic idea
is to assume a charge distribution F(J) and a velocity profile
U(r), where J is the number of charges on the particle and r is the radial distance from the center of the rod.
For a given field strength E and frequency f
it is possible to determine a radius r (J) such that all particles with a posit2
ive charge J' will move to the wall of the outer cylinder in a time less than t where to is l/f and all particles between a radius r (J) and the outer diameter 0 1 of the center rod with a charge 0 - J will move to the center rod in a time less than to.
After a time interval to has passed, the polarity of the center rod
changes from positive to negative and the uncollected particles return to their original location. The collection efficiency for particles with J charges is then given by E(J,f) = 2
7T
I" r :
(J) U(r) dr/Q
(2)
90 where Q is the total flow rate.
The integral in equation (2) is the fraction of -1
flow in which all particles are collected within a time f
.
The overall efficiency is given by
It is this equation that is used to produce the simulations given in Figure 3. Three distrubutions were used for the simulation. These distributions were (1) symmetrical and unimodal, (2) symmetrical and bimodal, and (3) non-symmetrical and bimodal.
For all three cases the distributions were electrically neutral. The
first distribution is most commonly assumed, however data by LGffler and Muir support the bimodal distributions of forms (2) and (3). In addition to assuming three distributions, two flow fields
--
laminar and uniform flow
--
were assumed.
The simulations indicate the following results: (1) For symmetrical charge distributions the efficiency is independent of polarity for both laminar and uniform flow. (2) For a non-symmetrical charge distribution the efficiency changes with polarity for laminar flow, but does not change for uniform flow. ( 3 ) For a parallel plate mobility analyzer, the efficiency does not change with polarity as long as the flow field is symmetrical. ( 4 ) The efficiency falls off more rapidly with unimodal distributions than for bimodal distributions.
EXPERIMENTAL MEASUREMENTS A number of measurements have been made with three different sizes of latex particles and at different electrical field strengths. A typical result is given in Figure 4, where the efficiency is plotted as a function of frequency. The average potential field was volts/cm and the particle size was 0.79 um.
The difference observed with charges in polarity indicate a
non-symmetrical charge distribution and the relatively slow decrease of efficiency with frequency suggest a bimodal distribution. The solid curve in Figure 4 corresponds to the average efficiency. When the efficiency is plotted as a function of inverse frequency for different field strengths, the curves demonstrate (1) the efficiency decreases with frequency and that (2) at low frequencies the efficiency approaches a constant. This second point indicates that two time constraints are important
--
the residence
time in the analyzer as well as the inverse frequency. CONCLUSIONS A mobility analyzer using an oscillating square wave and a concentric cylinder design has been constructed. Preliminary measurements indicate that the charge distribution of latex aerosols are bimodal and asynrmetric. The flow appears to be laminar. REFERENCES 1. W.J. Megaw, J. Sci. Instr. Ser., 2 (1969) 1013-1016. 2. W. Muhr, F. Lgffler, Aerosole in Naturwissenschaft, Medizin, und Technik. Jahreskonyress GAF (1974). 3 . K.T. Whitby, W.E. Clark, Tellus, 8 (1966) 573-586.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium,Paris,France, April 25-28, 1978,M.M.Benarie (Ed.),Studies in Enuironrnentul Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
91
A CONDENSATION NUCLEI COUNTER WITH INHERENT SIZE RESOLUTION CAPABILITY
W. HOLUNDER, G. SCHUMA" and J. SCH8lRMA" Fraunhofer-Gesellschaft,
Institut fiir Aerobiologie, 5948 Schmallenberg (G.F.R.) and
Universitat Heidelberg, Institut fiir Umweltphysik, Im Neuenheimer Feld 366, 6900 Heidelberg (G.F.R.)
ABSTRACT To achieve size resolution with usual condensation nuclei counters (CNC's), a combination of a CNC and size discriminating devices like a diffusion battery or an electrostatic classifier is necessary. In the humidity gradient condensation nuclei counter (HGCNC) proposed here, the aerosol is dried before entering the CNC. The bottom of the expansion chamber is formed by a humidifier. Expansion takes place after a properly chosen time, which depends on the geometry of the expansion chamber. The humidity in the chamber is a function of the distance from the bottom and determines the maximum supersaturation during the expansion. Therefore the fraction of activated condensation nuclei and the droplet size to which they grow, decrease with increasing height above the humidifier. The condensation nuclei size spectrum can in principle be derived from the measured light extinction or scattering. Preliminary measurements show the feasibility of the proposed technique.
INTRODUCTION The determination of condensation nuclei size spectra is usually done with a CNC and a size discriminating instrument such as a diffusion battery or an electrostatic classifier (e.g. Rich [ l ] ;
Pollak et al. 121; Bricard et al. [ 3 ] ) .
All these techniques, however, suffer from the fact, that a sequence of measurements has to be performed. Since the spectrum is obtained from the differences of subsequent measurements, the results are not very reliable because there may have been changes in the aerosol and/or the CNC during the sequence of the measurements. For this repson, a method which allows the instantaneous measurement of the total spectrum would be preferable. In the proposed method, a single measurement gives all the information necessary to deduce the size spectrum.
92
MEASURING PRINCIPLE The scheme of the Humidity Gradient Condensation Nuclei Counter (HGCNC) is shown in Fig. 1 .
Humidity Gradient
Condensotion Nuclei
Counter
Gradientenkernzahler
Vacuum
pump
Valve
Bypass f l o w
NebenschluOstrom
Fig. 1 . Scheme of the Humidity Gradient Condensation Nuclei Counter (HGCNC)
In the beginning of the cycle, the valves I , 2 and 3 are opened, the rest is closed. The aerosol is dried in the column and passes the measuring cell with the humidifier. After flushing the measuring cell, valve 2 is closed, valves 1 and 3 switch to the bypass flow (which keeps the total flow constant during the entire cycle) and opening of valve 5 allows the vacuum pump to establish reduced pressure in the expansion volume. Then valve 5 is closed again and after an exactly determined delay time, the expansion valve 2 is opened. Condensation takes place on the nuclei. The amount of supersaturation and condensable vapor depends on the height above the humidifier. The measurement itself consists of a determination of heightdependent light extinction or scattering. The cycle ends with opening valve 4 ; now the pressures in the measuring cell and the expansion volume are equal to the outside pressure and the next cycle may begin.
THEORY OF OPERATION Since the problem of instationary vapor diffusion during instationary carrier gas flow is extremely complicated, only the qualitative situation is considered in the following simple model: A flat channel of width d is filled with partially moist air of the vapor partial pressure
93 po = p(h,t=O)
for h > 0
(initial value)
With the humidifier at the bottom',
diffusion occurs according to
(D = diffusion constant)
with the boundary values
ap ah
1
h=d
and
(rigid wall)
0
=
p(h=O,t)
=
p
(humidifier)
The solution for the relative humidity HR prior to the expansion obtained with Fourier's method is
with
Bn
4(po/pS-1)/(2n-1)lr
=
Several curves with the dimensionless time parameter 5 = (Dt)''*/d Fig. 2 as functions of h/d for po
=
are shown in
0.
Assuming adiabatic expansion, the temperature T2 after expansion can be calculated from the initial temperature T I and the expansion ratio p I / p 2 TI/T2 = (P,/P,) K
=
c /c
P
V
I-I/K.
ratio of specific heats
Since the saturation vapor pressure follows Clausius-Clapeyron's law, it can be described by (A-B/T)
p S ( T ) = 10
(3)
where A, B are empirical constants.
'Rayleigh-Benard-instability
conditions [ 4 ] .
does not occur with the chosen geometry and operating
94
Fig. 2. Vapor diffusion in a flat channel. HR: relative humidity; h/d: normalized height; 5 : dimensionless time parameter Kelvin's formula
gives the critical droplet radius r* for condensational growth as a function of the relative humidity after expansion H Exp. Here u is the surface tension, M the moleR cular weight of the vapor, pL the density o f the condensed vapor and R the gas constant. From ( Z ) ,
(3) and the wet adiabatic (which takes into account release of
latent heat of condensation), the amount of condensable vapor can be calculated. Assuming that the condensed liquid is equally shared by a known number of nuclei, the final droplet diameter x concentration n
=
can be calculated; a few examples for a given droplet Tr l o 4 cm-3 are shown in Fig. 3.
The concentration of activated nuclei nAkt is given by
f m
n
Ak t
=
f(r)dr
(5)
r=r*
where f(r) is the nuclei size distribution and r* can be evaluated from ( Z ) ,
(3)
and ( 4 ) . For brevity, only the case of extinction is considered. The transmission T of the optical path 1 is given by
95
1
-
2
49
n. = 1
0,s
P, = 760 Torr
.
~
~
~
4
1, = 300 K
0,7
.9
0
0,6 0,s
OA
8 -
02
.7
XTrbm) 1
0,l
100
10
1
Fig. 3 . Droplet sizes xTr for different expansion ratios p2 /p humidities H
and relative
R
T
=
2
exp[ - Q(rE) rE
Q
=
i~
(6
nAk t 11
Q(1,m,K.rE(nkt,HF))
is the ?fie efficiency factor, which depends on the
wavelength A, the real and imaginary refractive indices m and K and the droplet end radius rE, which in turn is a function of nAk t and HRExp. From (5) it can be seen, that nkt
=
nAkt (f(r),
HCXP).
Only in the case of an
infinitely rapid expansion H t X P is independent of f(r) and only a function of HR’ pl/p2 and T1. The problem now consists in the inversion of equation (6) in order to find the unknown nuclei size distribution in (5). Although it is a completely hopeless venture to attempt an analytical solution to this problem, one could study the numerical behavior of equation ( 6 ) . This has not yet been done, but it will be the next task with hopefully the result, that from real measuring values T the size distribution f(r) may be derived.
PRELIMINARY EXPERIMENTAL RESULTS In order to assess the feasibility of the experiments, test runs with NaCl aerosol: of different sizes were performed. Droplets from solutions of different salts concentrations c(g/ml) were produced in a spray generator. The remaining nuclei size depends in a unique way on the salt concentration [5]. Fig. 4 shows scattered light photographs of the laser beam illuminated droplet columns after expansion. The bars on the left and right ends of the pictures are given to allow comparison between
96
Fig. 4. Scattered light from the droplets illuminated by a vertical laser beam. top: c = 10-5 (g/ml); middle: c = 10-4 (g/ml); bottom: c = 10-3 (g/ml). c is the concentration of the solution dispersed; it corresponds to the particle size. The lower column extends over the total chamber height ( 3 cm). the height of the illuminated droplet column and the total height of the chamber. As can easily be seen from the pictures, there is a clear difference between the different nuclei sizes (salt concentrations). This means, that an instrument with reasonable performance can be built without great difficulties. At the present stage the experiments look promising and a theoretical investigation seems worthwile. REFERENCES 1 T.A. Rich, Atmospheric Environment, 4(1970)301 2 L.W. Pollak and A.L. Metnieks, Geofis. Pura Appl., 37(1957)183 3 J. Bricard, G. Madelaine, and M.L. Perrin, in Proc. 9th Int. Conf. on Atmospheric Aerosols, Condensation and Ice nuclei, Galway, Ireland, Sept. 21-27 1977 (in press) 4 S. Chandrasekhar, Hydrodynamic and Hydromagnetic Stability, Clarendow, London, 1961 5 W. Hollander, Dissertation, Heidelberg, 1978.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
97
INFLUENCE OF CKEMICAL STRUCTURF, OK THE S I Z I N G OF DROSOL PARTICLES H . STFUUBEL Vorderhindelang /Allgau,
( G . F.R. )
ABSTRACT S i z i n g of n o n s p h e r i c a l p a r t i c l e s i s d i f f i c u l t , as a l l t h e well-
known measurement methods imply a s p h e r i c a l shape. I n an e l e c t r i c a l c a p a c i t o r a e r o s o l p a r t i c l e s o f any f o r m can be hanged up f r e e l y , The aerodynamic d i a m e t e r i s determined by t h e e l e c t r i c a l v o l t a g e s con= n e c t e d w i t h t h e c a p a c i t o r . A f t e r t h i s t h e p a r t i c l e s w i l l be formed i n t o s p h e r e s , r e s t i n g i n t h e c a p a c i t o r , The s p h e r e s a r e e a s i l y e v a l u a b l e by o p t i c a l means o r otherwise. INTRODUCTION
Apparatus f o r p a r t i c l e s i z i n g a r e w e l l known.
a light scattering o r diffraction b mobility spectrometer c s e d i m e n t a t i o n , c e n t r i f u g e and impactor ( r e f s . 1-3) Deciding f o r a l l t h e above measurements i s only t h e knowledge of t h e mass m o f t h e p a r t i c l e , L i g h t s c a t t e r i n g methods, m o b i l i t y and s e d i = m e n t a t i o n a r e i n d i r e c t methods and need t h e knowledge of r e f r a c t i v e index n ( e v t l y , a b s o r p t i o n c o e f f i c i e n t ) and t h e s p e c i f i c weight However, t h e s e c o n s t a n t s a r e u s u a l unknown f o r t h e a e r o s o l s , Calcula= t i o n s w i t h approximate v a l u e s cause c o n s i d e r a b l e e r r o r s . I n a l l cases s p h e r i c a l shape o f t h e p a r t i c l e i s assumed, According t o t h e used method t h e r e w i l l be given an I1equivalent diameter!’ o r an ttaerodynamic d i a m e t e r ” , compared w i t h a sphere o f e q u a l mass m and of t h e same material.
.
METHOD AND RESULTS To g e t a simple r e l a t i o n between t h e aerodynamic diameter o f an i r r e g u l a r shaped p a r t i c l e and a sphere of equal mass m, t h e same m a t e r i a l and mass a r e used. I n a t h r e e p l a t e s c a p a c i t o r , described by t h e a u t h o r p r e v i o u s l y , t h e e l e c t r i c charged p a r t i c l e i s s t a b i l i z e d by t h e i n f l u e n c e o f d . c r and a.c, v o l t a g e s . Pig.1 ( r e f , 4 ) . F o r p a r = t i c l e s w i t h a diameter 7 3 0 p t h e r e l a t i o n U,/U,on the capacitor i s
98 100
80
0
La'='
60 50
a
LO
E
2
30
25 0.2
Fig. 1 Capacitor, feed with a.c. and d.~.
0.3
0.1
0.5
0.6
0.7
0.8
Fig. 2 Variation of aerodynamic resistance 0 paraffin flakes the same flakes melt as spheres
is independant of specific weightp , mass m and charge e. Geometry of the capacitor must be known (ref, 5). If a certain amount of the a.c. voltage is reached, the particle begins t o oscillate. These oscilla= tions are attenuated by the surrounding air. For spherical shape this attenuation is a minimum. For nonspherical shapes therefore the a.c. voltage for oscillating increases, dpending on the irregularity, (ref. 6). A higher a.c. voltage indicates immediately the "shapefactor", in relation to a sphere with the aerodynamic resistance factor 1.
.
Therefore, the measurement is composed of two measurements, the particle in its natural shape and melt as a sphere. The sphere can be formed by melting, by solution in the crystal-water, by solution in a solvent or by adsorption of fluids (particle as condensation nucleus), In each case the relation of U, (natural shape) / U,,, (spherical shape) indicates the aerodynamic resistance factor. Examples are given in Figs. 2 and 3 for paraffin, and in Fig. 4 for polystyrene-spheres (both solid, but with different quality of surfaces).
For all cases the d.c. voltage (irregular shape/spherical shape) must be constant during the research, indicating a constant mass m. No capture or loss of charges is provided and has not been observed during examination, The method described above yields a unilateral specific aerodynamic resistance, as the irregular shaped particle will ever adjust to the direction of maximal resistance. This applies to all investigations
99
(sedimentation, centrifuge, impactor, mobility spectrometer), However, if the bore in the middle plate of the capacitor is shaped as a slit (no circle), the particle oscillates in a rhombic figure instead of a straight line.(Fig. 5). Inclination of the slit against the horizontal (few degrees) causes the particle to glide (oscillating or not) along the slit axis, Therefore a combined measuring is attained: sedimentation in the axis and at the same time rhombic oscillation perpendicular to this axis, The result is a average specific resistance, which cannot be obtained by other methods of sedimentation.
Fig. 3 b sphere
Fig. 3 a flake
Fig. 4 a U,,,/U, = 0.36
Fig. 5 oscillations of a particle, a in circular bore b in slit MEASURING ACCUFACY
5a
Fig. 4 b U,/U,=
0.29
5b
this depends on the accuracy of voltmeters used for a.c. and d.c, on the validity of Stokes-equation: an ..cmplitudeof 0.2 mm of the
100
oscillating particle can be observed with naked eye, Using a.c. with 50 Hz the particle oscillates with 25 Bz. Therefore at an amplitude o f 0.2 mmthe maximal velocity will be 31.4 mm/s. This results for a particle with 30/wn diameter a Reynolds-number of 0.0385. The Stokesequation can be applied exactly, Changing of the mass m: by dihinishing a.c.voltage, the particle is held in the capacitor like in a cage and it is plenty of time for balancing the particle’s weight with d.c.voltage. With a space of 5 s and observing during this time a particle’s movement of 6 mm, variation o f mass would be detectable of 2 x By compensating the d,c. voltage in the relation 1:100, in the same time a massdifference of 2 x can be detected ( r e f . 8). CONCLUSIONS With a capacitor described above un&nown masses of nonspherical aerosol particles can be measured by changing their irregular shape in a spherical one, All materials can be principially converted in spheric shape either by melting or by solving or by adsorption of fluids, The appearing figures due to crystallisation and their aerodynamic factors depend on the chemical structure of these materials, RF FEREN CES
W,Stober, Colloquium Aerosolmesstechnik, Aachen Mart 4 (1975) I .Gallily, 4th Congress of the Association of Aerosol Research, Bad Soden/Ts. Nov. 3-6 ( 1976) W,Walkenhorst und W.Coenen, Staub-Reinhalt.Luft 37 ( 1977) 106-109 H.Straube1, Staub-Reinhalt.Luft 33 (1973) 174-177 H.Straube1, in !!Atmospheric Pollution” (Ed. M. Benarie) Proc,of the 12th Internat.Colloquium, Paris May 5-7 (1976), 471-476 Elsevier 1976
.
H Straube1, 5 Congress of the Association for Aerosol Research Karlsruhe, October 26-28 (1977) Staub-Reinhalt Luft,in Press I.N. T a n g et al, J.Aeroso1 Sci 8 (1977) 149 H. Straubel, Progress in Vacuum Microbalance Techniques (Ed. Eyraud and Escoubes), Heyden-London, Vol.3( 2975) 319
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
101
EXPERIMENTS O N P A R T I C L E DEPOSITION IN SAMPLING LINES iu'. GEIPEL
L e h r s t u h l f u r T h e r m i s c h e K r a f t a n l a g e n d e r TU Xiinchen
I I\] T RO DU C T I O N
The d u s t c o n t e n t o f f l u e g a s e s i s measured i n p a r t i a l f l o w s . The a e r o s o l i s drawn t o a f i l t e r t h r o u g h a s a m p l i n g t r a i n . The c o n c e n t r a t i o n i s c a l c u l a t e d by t h e c o l l e c t e d d u s t mass and t h e s u c k e d g a s volume. I n t h e s a m p l i n g l i n e a p a r t o f t h e d u s t may be d e p o s i t e d and s o a d v e r s l e y i n f l u e n c e s t h e m e a s u r e m e n t . T h i s e f f e c t depends on t h e geometry o f t h e t u b e and t h e p a r a m e t e r s o f t h e p a r t i c l e s and t h e two-phase f l o w . T h e r e a r e s e v e r a l i n v e s t i g a t i o n s on t h e d e p o s i t i o n o f p a r t i c l e s i n p i p e f l o w . Most o f t h e a u t h o r s t r i e d , however, t o p r e v e n t t h e r e - e n t r a i n m e n t o f p a r t i c l e s d e p o s i t e d . Because p a r t i c l e s r e - e n t r a i n i n r e a l t e s t s , i t was n o t s u p r e s s e d i n t h e s e e x p e r i m e n t s . Sampling t r a i n s were i n v e s t i g a t e d , which a r e u s e d i n f l u e g a s e s , t h a t means t u r b u l e n t f l o w w i t h p a r t i c l e s g r e a t e r t h a n 1 pm. The d e p o s i t e d mass i n t h e p i p e was m e a s u r e d b u t n o t t h e a l t e r a t i o n o f t h e p a r t i c l e size distribution. TIIEORETICAL DESCRIPTION O F THE PARTICLE DEPOSITION S t u d y i n g t h e volume e l e m e n t o f a p i p e t h e d e c r e a s e o f t h e p a r t i c l e concentration c of the gas-solid suspension i s described:
(L
pipe length; D
pipe diameter; w
gas v e l o c i t y )
The deposition v e l o c i t y k i s d e f i n e d by t h e q u o t i e n t o f t h e f l u x - o f deposited p a r t i c l e s t o the concentration: k = -
N F t c
(F
area; t
time; N
number o f p a r t i c l e s )
102
The amount o f t h e d e p o s i t i o n v e l o c i t y i s d e t e r m i n e d by t h e p a r t i c l e s , t h e p i p e f l o w , and t h e w a l l which a r e c o r r e l a t e d t o e a c h o t h e r . T h r e e i n f l u e n c e s may be d e s c r i b e d . F i r s t t h e p a r t i c l e s a r e t r a n s p o r t e d from t h e g a s f l o w t o t h e w a l l . Here t h e y a r e h e l d by a d h e s i v e f o r c e s . A l s o it i s p o s s i b l e t o r e - e n t r a i n s t i c k i n g p a r t i c l e s .
The r e s p o n d i n g
e q u i l i b r i u m causes t h e d e p o s i t i o n of i n t e r e s t . The t r a n s p o r t o f t h e p a r t i c l e s t o t h e w a l l i s done by g r a v i t a t i o n a l s e t t l i n g , eddy d i f f u s i o n , and e l e c t r o s t a t i c f o r c e s . The s e d i m e n t a t i o n i n t u r b u l e n t f l o w i s d e s c r i b e d by Fuchs 1 1 1
.
'The d e p o s i t i o n
v e l o c i t y k becomes:
(ws
s e t t l i n g velocity)
Many i n v e s t i g a t i o n s on eddy d i f f u s i o n d e p o s i t i o n r e l y on a work o f F r i e d l a n d e r 1 2 1 . H i s e x p e r i m e n t a l r e s u l t s a r e b e s t i n t e r p r e t e d by a n a n a l y s i s s i m i l i a r t o t h a t u s e d by von Karman f o r t h e r a t e o f t r a n s p o r t o f momentum and mass i n a t u r b u l e n t g a s s t r e a m . The c o e f f i c i e n t o f t h e mass t r a n s f e r k / w i s g i v e n f o r d i f f e r e n t v a l u e s o f a dimensionless stopping distance S x : c
The s t o p p i n g d i s t a n c e i s d e f i n e d :
(f
friction factor; p
mass ; dp
g a s d e n s i t y ; rl
p a r t i c l e diameter)
gas v i s c o s i t y ; m
P
particle
103
To e s t i m a t e t h e image f o r c e s b e t w e e n t h e p a r t i c l e s and t h e w a l l t h e l a w o f Coulomb may be u s e d . A c c o r d i n g t o Rumpf 131 t h e s e f o r c e s < 100 u m . D e p o s i t e d P p a r t i c l e s a r e h e l d t o t h e w a l l by van d e r Waals f o r c e s and l i q u i d
p l a y no r o l e on t h e a d h e s i o n o f p a r t i c l e s d
f i l m s . I f t h e r e a r e l i q u i d f i l m s between t h e p a r t i c l e s and t h e w a l l t h e c a p i l l a r y f o r c e s a r e h i g h e r t h a n van d e r Waals f o r c e s . P a r t i c l e s may b e r e - e n t r a i n e d by v i b r a t i o n s of t h e s a m p l i n g l i n e , r e b o u n d , a n d s h e a r s t r e s s e s o f t h e f l o w . The f o r c e s b e t w e e n t h e f l o w a n d t h e d e p o s i t e d p a r t i c l e s may b e e s t i m a t e d by d r a g f o r c e s a n d buayancy a c c o r d i n g t o measurements o f Rubin 1 5 1 . TEST PROCEDURE A p a r t i a l f l o w was i s o k i n e t i c l y drawn from t h e d u s t - a i r f l o w of t h e p i l o t p l a n t o f t h e I n s t i t u t e . The d u s t mass was c o l l e c t e d i n a glass-wad f i l t e r ( f i g . 1 ) . The g a s v e l o c i t y , t h e l e n g t h , and t h e diameter of t h e s t a i n l e s s s t e e l s a m p l i n g l i n e were v a r i e d . Each e x p e r i m e n t was s t a r -
- L-
t e d w i t h a "zero-measure-
Test pipe
Filter
ttt w m
ment" t o d e t e r m i n e t h e pump
d u s t mass mo.
In this
c a s e t h e f i l t e r was i n s t a l l e d i n t h e sampling l i n e adjacent t o the
Pilot Plant
Fig. 1 . Schematic arrangement of t h e equipment
t e s t f a c i l i t y . To measure the deposition, the pipe was f i t t e d . The d u s t mass s t i l l passing m
f was c o l l e c t e d i n t h e f i l t e r . From b o t h measurements t h e d e p o s t i o n r a t e A was c a l c u l a t e d : A =
"0
mO
mf
-
C
- l - T
(7) 0
The g a s v e l o c i t y i n t h e p i p e was m e a s u r e d w i t h an o r i f i c e . Q u a r t z , l i m e s t o n e , a n d f l y a s h were u s e d as t e s t d u s t s . A f t e r e a c h e x p e r i ment t h e s a m p l i n g l i n e was c l e a n e d c a r e f u l l y .
104
RESULTS In diagramm 2 the deposition in a horizontal pipe was plotted versus the gas velocity (Re = wD/v). The deposition of coarse particles differs appreciably from that of fine dusts. Increasing
1.04
I
Limestone
0
o
3pm 12pm
3 11 18
L= D=
0
10000
Re
20 000
-
Fig. 2. Deposition rate of the test dusts the gas velocity the deposition of big particles decreases. Fine particles show a distinct maximum deposition (Re w 8000). At low Reynolds numbers the forces of deposition by eddy diffusion prevail. The re-entrainment by the shear stresses of the flow sets in. Big parti1,o cles settle out. At high velocity settling is dis- horizontal turbed. In addition the particles sticking at the wall are re-entrained. A A fraction of coarse fly ash and one of fine limestone were sucked through a horizontal and Re a vertical sampling line (fig. 3). In the vertical Fig. 3 . Horizontal and vertical pipe there is no gravisampling line
105
1.0 '
L\:
d,=3,,m
D=6mm
,' ,.Go-'\, //
0.5A
/
-
-
L = 2,7m
y 1'5
'A
/
/'
\. \.
\.
b\ 7
it was not possible to investigate how the deposition of coarse particles varies with the diameter of the tube. Diagramm 4, however, shows experiments with a fine fraction. Following eq. ( 1 ) the deposition decreases if the
DISCUSSION OF RESULTS Finally these results are compared to the theories given first. Diagramm 5 shows measurements and calculations of the rate of deposition by sedimentation and eddy diffusion. The settled mass of big particles decreases with increasing gas velocity. Re-entrainment and rebound 1 7 1 make the measured values smaller than the ones calculated. At low gas velocities the deposition of fine particles is equal to the calculated value by eddy diffusion. Re-entrainment p r e vails if the gas velocity is increased to about Re = 9000 (D = 10 mm), and the deposition gets smaller. It is not possible to calculate this point. To estimate the adhesive and drag forces, which are responsible for re-entrainment, in practical sampling lines the para-
106
meters of t h e p a r t i c l e s a r e unknown. S i m i l a r v e l o c i t i e s a r e r e p o r t e d by Eddy diffusion Settling - Experiment
D = l O mm
\2
0'
10000
Re
20000
I
Chang 16 [ a n d Se hm e l 181 f o r t h e b e g i n n i n g o f reentrainment. Sampling t r a i n s should n o t b e t o s m a l l (Dw10 m m ) . To s a m p l e c o a r s e p a r t i c l e s avoid horizontal lines. The d e p o s i t e d mass i s
small i f t h e g a s v e l o c i t y w
F i g . 5 . Measured and c a l c u l a t e d Je P O s i t i o n
> 30
m/s.
Heating of the
l i n e prevents liquid films between t h e p a r t i c l e s and the w a l l of the pipe.
REFERENCES 1 N . A . F u c h s , The M e c h a n i c s o f A e r o s o l s , Pe rga m on P r e s s , O x f o r d 1Yo4, p.264 2 S.K. F r i e d l a n d e r , H . J . J o h n s t o n e , Ind.Engng.Chem.49(1957)1151-56 3 H . Rumpf, Chemie I n g . T e c i i n . , 4 6 ( 1 9 7 4 ) 1 - 1 0 4 El. S c h u b e r t , Chemie I n g . T e c h n . , 4 6 ( 1 9 7 4 ) 3 3 3 - 3 3 4 5 G . R u b i n , F . L o f f l e r , Chernie 1 n g . T e c h n . MS 3 7 3 - 7 6 ( 1 9 7 6 ) 6 [I. C h a n g , T . S m i t h , A m . I n d . H y g . A s s . J . , 33(1972)722-728 7 L . F . Forney, L.A. Spielman, J . C o l l o i d . I n t e r f . S c i . , 52(1975)468-478 8 G.A. Sehmel, Am.Ing.Ilyg.Ass.J., 31(1970)758-771
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmentof Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
107
MEASUREMENT OF COLLECTION EFFICIENCY OF AMOSITE FIBERS J . GENTRY*, K .
SPURNY, G. W E I S S , H . OPIELA
I n s t i t u t e f u r Aerobiologie, Grafschaft
,
Germany
*Department o f Chemical Engineering, University o f Maryland, College Park, U .S . A . ABSTRACT
The c o l l e c t i o n e f f i c i e n c y of amosite f i b e r s was measured f o r nuclepore f i l t e r s as a function of NPF pore s i z e and flow r a t e by four d i f f e r e n t measurement techniques
-
? -
a g r a v i m e t r i c determination based on t h e a c t i v i t y of "Fe,
a com-
p a r a t i v e f i b e r count using SEM, t h e use of a modified Royco with a v a r i a b l e flow r a t e , and a C l i m e t .
Comparisons of t h e four methods are made, and t h e i r appro-
p r i a t e n e s s i s discussed.
Measurements i n d i c a t e t h a t t h e e f f i c i e n c y i s a weak
function of flow r a t e . INTRODUCTION
Amosite i s a type of a s b e s t o s c h a r a c t e r i z e d by t h e following p r o p e r t i e s :
1.
The f i b e r s a r e s o l i d , rod-like with a comparatively uniform diameter.
[ref. 1 1 2.
The mineral amosite contains considerable Fe and can be e a s i l y l a b e l e d .
3.
C o r r e l a t i o n s of t h e aerodynamic diameter ( a s measured by a s p i r a l cen-
t r i f u g e ) show a p r o p o r t i o n a l i t y t o approximately t h e 1/6 power with respect t o the aspect r a t i o .
[ r e f . 21
Experimental measurements using amosite ( o r any non-spherical p a r t i c l e ) pose s e v e r a l unique d i f f i c u l t i e s .
More than one v a r i a b l e ( i . e . length and diameter)
a r e r e q u i r e d t o c h a r a c t e r i z e t h e f i b e r s , t h e degree of s c a t t e r e d l i g h t depends on t h e o r i e n t a t i o n as well a s t h e geometric p r o p e r t i e s of f i b e r s , t h e s i z e d i s t r i b u t i o n tends t o be more polydisperse than i s o m e t r i c p a r t i c l e s , and t h e f i b e r s a r e e a s i l y o r i e n t e d by v a r i a t i o n s i n t h e v e l o c i t y f i e l d .
[ r e f . 31
EXPERIMENTAL D E S I G N
The experimental apparatus can be subdivided i n t o t h r e e s e c t i o n s
- f i b e r gen-
e r a t i o n , agglomerate removal, and t h e measurement of t h e p e n e t r a t i o n .
The p r i n -
c i p l e o b j e c t i v e s of t h e design a r e t o generate a reproducible aerosol with a narrow s i z e d i s t r i b u t i o n of i n d i v i d u a l f i b e r s and a method of measuring and i n t e r p r e t i n g t h e p e n e t r a t i o n unambiguously. The f i b e r s w e r e generated from a ground, dry powder of amosite using a Spurny v i b r a t i n g bed g e n e r a t o r [ r e f . 4 1 .
Dry a i r p e r c o l a t e s through t h e bed of
*
powdered amosite which i s being shaken a t a constant frequency and amplitude. The c h a r a c t e r i s t i c s of t h e a e r o s o l l e a v i n g t h e generator can be c o n t r o l l e d by t h e flow r a t e through t h e bed and t h e frequency and amplitude o f t h e v i b r a t i o n s . Examination of t h e f i b e r s with an e l e c t r o n microscope show a narrow d i s t r i b u t i o n of diameter, a s l i g h t l y broader d i s t r i b u t i o n o f l e n g t h s , and a s t i l l broader d i s t r i b u t i o n of t h e c a l c u l a t e d aerodynamic diameter. The o b j e c t i v e of t h e a e r o s o l conditioning s e c t i o n between t h e f i l t e r and generator i s t o remove agglomerates (approximately 30% by weight) and t o minimize t h e e f f e c t of e l e c t r i c a l charge.
In each case t h e a e r o s o l stream leaving
the generator passed through an impaction s t a g e . ported,
In most of t h e experiments r e -
[ r e f . 51 e i t h e r an Andersen impactor o r a p r e f i l t e r
(8.0um) NPF was used.
The b e s t t e s t a e r o s o l was t h a t l e a v i n g t h e NPF p r e f i l t e r s t a g e which contained almost no agglomerates. well.
Unfortunately most of t h e long f i b e r s were removed a s
To minimize e l e c t r o s t a t i c e f f e c t s , t h e a e r o s o l was passed through a 8 5 K r
i o n i z a t i o n source.
For g r a v i m e t r i c measurements, t h i s s t a g e w a s by passed.
In
t h e s e measurements amosite l a b e l e d with 55Fe and 59Fe w a s used. The measurement procedure depended on whether g r a v i m e t r i c o r o p t i c a l methods a r e used. erator.
I n t h e g r a v i m e t r i c measurements, l a b e l e d amosite i s used i n t h e genThe t e s t f i l t e r s t a g e c o n s i s t s of two s t a g e s
-
t h e f i r s t with t h e t e s t
NPF and t h e second an a b s o l u t e f i l t e r c o n s i s t i n g of a 0.2um membrane f i l t e r with
a paper f i l t e r support.
The p e n e t r a t i o n was t h e a c t i v i t y of t h e backing f i l t e r s
divided by t h e a c t i v i t y measured from both s t a g e s .
The f i l t e r holders were de-
signed so t h a t t h e r e w a s no support s c r e e n . The o p t i c a l measurements were with e i t h e r a Royco (modified t o allow an i n creased flow r a t e ) o r a C l i m e t .
The b a s i c i d e a was t o pass a sample through t h e
o p t i c a l instrument which was drawn e i t h e r b e f o r e o r a f t e r t h e f i l t e r .
In these
experiments t h e a e r o s o l s were passed through t h e n e u t r a l i z a t i o n stage and no backing f i l t e r was used.
Provisions were made f o r a d d i t i o n a l d i l l u t i o n a i r when
higher flow r a t e s through t h e f i l t e r were necessary.
A s p e c i a l l y designed mani-
f o l d was incorporated i n t o t h e design so t h a t t h e sampling r a t e and t h e flow r a t e through t h e f i l t e r were independent. ELECTRON MICROSCOPY
For some samples, f i b e r s c o l l e c t e d on NPF were photographed using e l e c t r o n microscope (SEM)
.
The f i b e r s were then s i z e d and counted.
a scanning Approxi-
mately 100 f i b e r s w e r e used i n each sample. From e l e c t r o n microscopy it had been previously found t h a t t h e r e w a s l i t t l e
s i z e dependence of t h e d e p o s i t i o n p a t t e r n i n Andersen impactors and mostly agglomerates were deposited on t h e two s t a g e s .
Also, it was demonstrated t h a t
f i b e r s acquired a p r e f e r e n t i a l alignment f o r p e n e t r a t i n g NPF.
[ r e f . 51
A comparison of t h e f i b e r s passing through a NPF showed t h a t t h e average
length t o diameter r a t i o changed l i t t l e ( a decrease by approximately 20%) while t h e length and width decreased by over 5 0 % . The aerodynamic diameter decreases from approximately 2.0um t o 1.0Um.
The d i s t r i b u t i o n of diameters narrows a f t e r
passing through t h e f i l t e r . GRAVIMETRIC MEASUREMENTS
I n t h e gravimetric measurements, i r r a d i a t e d amosite was used i n t h e Spurny generator a s source m a t e r i a l f o r t h e a e r o s o l .
Previously reported measurements
[ r e f . 51 with a s e r i e s o f 6 NPF arranged i n a sequence of descending pore s i z e i n d i c a t e d t h a t f i b e r s were a b l e t o p e n e t r a t e pores with diameters l e s s than 15% of t h e f i b e r l e n g t h .
For t h i s experiment a t a low flow r a t e , t h e e f f i c i e n c y
ranged from 0 . 4 t o 0.75
(8um N P F ) .
No p r e f i l t e r was used.
More extensive measurements f o r
s i z e s of NPF over a wide range of flow r a t e s a r e r e p o r t e d i n f i g u r e 1.
For
each of t h e s e experiments a 8 u m NPF was used a s a p r e f i l t e r .
Approximate-
l y 75% of t h e mass of t h e f i b e r i n c l u d i n g most of t h e agglomerates and very long f i l t e r s were removed i n t h i s stage.
The t e s t a e r o s o l was almost
agglomerate-free and more uniform i n s i z e than the a e r o s o l l e a v i n g t h e gen-.
251
1
erator.
0
..
. I
2
3
12p
1 5
4
FLOW RATE (I/MIN)
Over a wide range of v e l o c i t i e s
(1-4 l i t e r s / m i n ) t h e r e was no apprec i a b l e change i n p e n e t r a t i o n with flow r a t e , and a s t e a d y i n c r e a s e i n penet r a t i o n with pore s i z e .
FIG. 1 Collection Efficiency A s a Function of Flow Rate and Pore Size
Penetration
ranged from 98% f o r l u m NPF t o 2 3 % f o r 1 2 u m .
These r e s u l t s suggest t h a t most
f i b e r s a r e c o l l e c t e d by i n t e r c e p t i o n . OPTICAL MEASUREMENTS
The primary d i f f i c u l t y i n o p t i c a l measurements i s t h a t t h e r e i s considerable ambiguity i n i n t e r p r e t i n g t h e p e n e t r a t i o n due t o t h e p o l y d i s p e r s i t y of t h e fibers.
I t was found t h a t meaningful measurements
[ r e f . 51 of t h e p e n e t r a t i o n
could be made, i f t h e flow r a t e through t h e instrument were increased.
This
was a t t r i b u t e d t o t h e f i b e r s a c q u i r i n g a p r e f e r e n t i a l o r i e n t a t i o n a t t h e higher flow r a t e s .
Several of t h e newer instruments (Royco and Climet) operate a t
s u f f i c i e n t flow r a t e s t h a t according t o preliminary d a t a , m e a n i n g f ~ ~ measurel ments can be obtained without a l t e r i n q t h e instrument flow r a t e .
(It is
necessary t o design a s p e c i a l manifold so t h a t t h e flow r a t e through t h e NPF can be v a r i e d independently of t h e instrument flow r a t e ) . Measurements i n d i c a t e t h a t t h e p e n e t r a t i o n i n c r e a s e s with decreasing o p t i c a l diameter.
For t h e most p a r t , t h e e f f i c i e n c y i s a weak function of flow r a t e ,
although t h e r e are some measurements a t high flow rates which suggest t h e f i b e r s acquire a p r e f e r e n t i a l o r i e n t a t i o n a s they approach t h e f i l t e r .
Measurements
with t h e Climet and f o u r f i l t e r s i z e s (3pm, 5pm, 8 ~ m ,12um) i n d i c a t e t h a t the p e n e t r a t i o n measured by g r a v i m e t r i c methods correspond t o an o p t i c a l diameter ranging from 0.9 t o 1 . 4 u m with a mean value o f 1 . 2 u m .
S c a t t e r was l e s s for t h e
3pm and 5.um NPF.
SUMMARY O p t i c a l measurements with Climet and a modified Royco a s w e l l as gravimetric measurements of the p e n e t r a t i o n o f amosite showed l i t t l e change with flow r a t e except a t very high flow r a t e s .
The g r a v i m e t r i c measurements corresponded t o
t h e o p t i c a l measurements with an o p t i c a l diameter of approximately 1 . 2 um. For reproducible experiments it was found necessary t o make o p t i c a l measurements a t f a i r l y high instrument flow r a t e s and t o p r e f i l t e r t h e t e s t a e r o s o l with a 8 Um NPF.
The dominant c o l l e c t i a n mechanism appeared t o be i n t e r c e p t i o n .
REFERENCES
1.
K. Spurny, e t . a l . , Atmospheric P o l l u t i o n , ed. M. Benarie (1976) 459-469
2.
W.
3.
J . Gentry, K . Spurny, Aerosole i n Naturwissenschaft, Medizin, and Technik, Jahreskongress, GAF (1976) 38-42
4.
K . Spurny, C . Boose, D. Hochrainer, Staub, 35 (1975) 4 4
5.
J . Gentry, K . Spurny, J . Colloid I n t e r f a c e S c i . ,
StBber, H. F l a c h s b a r t , D. Hochramer, S t a u b , 30(1970) 270
(1978), i n p r e s s
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science. Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
113
A I R POLLUTION AND CA.WOXYHAEMOGLOE1N IN MAN
J.R.
CLAUDE, J. I,EI,I,OUCH and M. THEVISNIN
Groupe d'Etude s u r 1 ' E p i d k n i o l o g i e d e l ' A t h k o s c l & o s e 2 7 , r u e Lacordaire
-
75015 PARIS
( GRF% )
FRANCE
ABSTRACT Smoking h a b i t s and exposure t o a i r p o l l u t i o n by car e x h a u s t s were i n v e s t i g a t e d
i n 1418 policemen, i n r e l a t i o n t o morning carboxyt1aemoe;lobin ( COHb ) l e v e l . COHb is v e r y r a i s e d i n smokers and remains h i p h e r t h a n i n nonsmokers even
after 8 t o 10 h o u r s o f tobacco a b s t i n e n c e . The exposure t o a i r carbon monoxide d o e s n o t i n c r e a s e COHb l e v e l i n nonsmokers, b u t might have a minor a c t i o n i n smokers. N e v e r t h e l e s s tobacco smoking is t h e main f a c t o r r e s p o n s i b l e f o r nonoccupational CO impregnation i n man.
INTRODUCTION E x p e r i m e n t a l r e s e a r c h ( ref. 1 ) and o b s e r v a t i o n i n man ( ref. 2 ) s u g g e s t t h a t Carbon Monoxide ( CO ) might p l a y a p a r t i n t h e c e n e s i s o r c o m p l i c a t i o n s o f c o r o n a r y h e a r t d i s e a s e ; t h a t c o u l d e x p l a i n why tobacco smoking i s a major r i s k f a c t o r f o r t h i s d i s e a s e , Moreover, it is now a d m i t t e d t h a t Carboxyhaemoglobin
( COHb ) l e v e l s as low as 2 t o 3 % c a n induce arterial w a l l l e s i o n s , provided t h e y are p e r s i s t e n t . I n p r e v i o u s work ( ref.
3 ) w e have shown t h a t i n smokers who i n h a l e , COHb
p e r s i s t e n l y reached s u c h l e v e l s , even a f t e r 8 t o 10 h o u r s o f tobacco a b s t i n e n c e . The scope o f t h e e p i d e m i o l o g i c a l i n v e s t i g a t i o n r e p o r t e d below i s t o s t u d y w e t h e r exposure t o urban a i r p o l l u t i o n c o u l d induce s i m i l a r phenomenon.
MATERIAL AND METHODS F r o m February 1975 t o December 1976, 1418 male government employees
( aged 18 t o 66 y e a r s ) o f t h e P r e f e c t u r e d e P o l i c e d e P a r i s , among them t r a f f i c policemen, were examined between 8h 30 t o 9 h 30 a t fasting.
After f i l l i n g o u t q u e s t i o n n a r i e s on tobacco consumption and h a b i t s , p o s s i b l e exposure t o a i r p o l l u t i o n f r o m t r a f f i c r e g u l a t i o n , home environment ( namely, h e a t i n g and v e n t i l a t i o n of room d u r i n g s l e e p i n g ), c h r o n i c b r o n c h i t i s ,
114 meteorological c o n d i t i o n s on EDTA.
... , a blood sample was obtained by veinous puncture
CO was measured by t h e i n f r a r e d non d i s p e r s i v e method o f BOUDENE e t
al. ( ref. 4 ) and haemoglobin by Coulter Counter S. COHb was c a l c u l a t e d f r o m t h e s e two parameters. On most blood samples, COHb was a l s o measured by t h e d i r e c t method o f COMMINS and LAWTHER ( r e f .
5 ), b u t t h i s method appeared t o be l e s s
r e p r o d u c i b l e and t o give more erroneous r e s u l t s f o r low values. So, t h e r e s u l t s presented below concern c a l c u l a t e d v a l u e s of COHb. RESULTS Tobacco smoking and COHb l e v e l Table I g i v e s t h e mean COHb l e v e l o f s e v e r a l groups o f s u b j e c t s , c l a s s i f i e d according t o t h e i r smoking s t a t u s . TABLE I Mean COHb l e v e l ( i n % ) according t o smoking h a b i t s Noninhalors
1. 65
Nonsmokers Exsmokers
Current smokers
Inhalors
d i d not smoke on day b e f o r e examination smoked on day before examin a t i o n , b u t n o t on day o f examination smoked b e f o r e examination
1. 66
1. 64
1.
51
1. 65
1.
91
2 . 78
3. 71
5. 33
The r e s u ~ ~ c l se a r l y show t h e very stm'u e f f e c t o f i n h a l a t i o n and t h e p e r s i s t e n c e o f a h i g h e r l w e l o f C O B after an abstinence period o f 8 t o 10 hours, as s i g n i f i c a n t i n n o n i i u d i n g smokers, as i n i n h a l o r s . I n o u r previous rork ( ref.
3 ) this
e f f e c t was observed only on i n h a l o r s . A i r p o l l u t i o n and COHb l e v e l
Table I1 compares f o r COHb l e v e l , s u b j e c t s who r e g u l a t e d street t r a f f i c on t h e day b e f o r e examination (
"
air pollution
"
exposed ) and s u b j e c t s who d i d not.
The groups defined i n t h e first three l i n e s o f Table I were r e u n i f i e d s i n c e t h e i r
COHb l e v e l s were similar. I t can be seen t h a t exposure t o a i r p o l l u t i o n does n o t induce s i g n i f i c a n t e l e v a t i o n COHb, except i n one group ( i n h a l i n g smokers who smoked on t h e day b e f o r e examination b u t n o t on t h e day o f examination ).
115 TABLE I1
Mean COHb l e v e l ( i n % ) according t o smoking h a b i t s and exposure t o urban a i r pollution
Nonsmokers
Current smokers
smoked on day b e f o r e examination, b u t not on day o f examination Non i n h a l o r s Inhalors smoked b e f o r e examination Non i n h a l o r s Inhalors
-
Non-exposed
Exposed
P
1. 64
1. 64
NS
1. a3
2.
56
05
-
2. 75
2.
99
NS
-
3. 74 5. 31
3. 31 5. 46
NS
NS
DISCUSSION From t h i s epidemiological i n v e s t i g a t i o n , it seems clear that:
lo) A s p r e v i o u s l y emphasized by KAHN e t al. ( ref. 6 ) tobacco smoking i s by far t h e main agent c a r r y i n g CO i n t o blood and r e s p o n s i b l e o f t h e i n c r e a s e o f COHb l e v e l . f i r t h e r m o r e , t h e decrease o f COHb a f t e r smoking is slow enough t o maintain i n i n h a l i n g smokers permanent v a l u e s a t a l e v e l ( 2 % ) which i s considered a b l e t o induce arterial w a l l l e s i o n s and coronary h e a r t disease. 2") The exposure t o atmosphere contamined by automobile exhaust emissions, even
though enhanced i n o u r s u b j e c t s ( policemen ) does not have a clear remanent effect. I n nonsmokers t h e r e i s a b s o l u t e l y no d i f f e r e n c e between exposed and
nonexposed s u b j e c t s . I n smokers, smoking j u s t b e f o r e examination has d o u b t l e s s a too gross e f f e c t t o r e v e a l any minor e f f e c t of a i r p o l l u t i o n exposure. Perhaps i n smokers who had n o t smoked f o r 8 t o 10 hours, a s l i g h t effect may be noticed. I n any case, t h i s effect i s o f very s l i g h t importance compared t o t h e massive a c t i o n o f tobacco smoking. REFERENCES 1 P. Astrup, in"Health E f f e c t s o f Carbon Monoxide Environmental Pollution'', Commission o f European Communauties Ed., Luxembourg, 1974, p. 289-326. 2 W.S. Aronow, C.N. H a r r i s and M.W. I s b e l l , Ann. i n t e r n . Med, 77 ( 1972 ),
669-676. 3 J. Lellouch, J.R. Claude, M. Thevenin, D. Schwartz and R. Truhaut, C.R. Acad. Sc. P a r i s , 278 s 6 r i e D ( 1974 ), 971-974. 4 C. Boudkne, J. Godin and A. Roussel, Arch. M a l . p r o f . , 34 ( 1973 ), 449-453. 5 B.T. Commins and P.J. Lawther, B r i t . J. ind. M e d . , 22 ( 1965 ), 139-143. 6 A. Kahn, R.B. Rutledge, G.L. Davis, J.A. Altes, G.E. Gantner, C.A. Thornton and N.D. Wallace, Arch. Environ. Health, 29 ( 1974 ), 127-135. T h i s work was supported by a g r a n t f r o m t h e Ministere de l a Culture e t de 1'Environnement ( 5600-093 ).
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
117
CARBONMONOXIDE-CONCENTRATIONS IN THE INSPIRED AIR AND THE RESULTING CARBOXIHEMOGLOBIN
.
H HAUCK , M. NEUBERGER and W. RESCH Institut f.Medizinische Physik and Institut f. Umwelthygiene der Universitat Wien, Wien (Austria)
AB STRACT Carbonmonoxide uptake and the resulting carboxihemoglobin in man is one of the fundamental mechanisms with respect to establishing an immission standard. To carry out relevant experiments, a reliable and accurate method to determine COHb below 5% is described. Furthermore the production of optional CO-concentrations and the monitoring of ventilation parameters is briefly mentioned. Finally the results of some inhalation experiments and some thoughts about a reasonable immission standard for CO are presented.
The toxic effect of carbonmonoxide (CO) inhaled is well known for a long time. While originally the main interest came from toxicologists, in recent times environmental hygienists became more and more interested in this problem. Although the ambient CO-concentrations are usually below 100 ppm, there seem to exist influences to cardiovascular and centralnervous system. The main source for carbonmonoxide within inhabitated regions is emission by traffic responsible for about 8 0 % . The rest is due to industry emissions, heating systems, natural sources (volcanoes) etc. Another important source for inhaling of CO is smoking which will not be considered in this paper. CO once inhaled diffuses in the lungs like oxygen into the red blood cells. The hemoglobinmolecule is capable of binding 4 molecules of O2 or CO. Since the affinity of CO to human hemoglobin is more than 200 times greater than the one of 02, consequently even low CO-concentrations - compared to oxygen concentrations - result in considerable carboxihemoglobin concentrations (COHb). The interesting range of carboxihemoglobin with respect to the effects mentioned
118
above starts at 2-3% COHb. The goal of the work partly presented in this paper is to investigate the influence of inhaled carbonmonoxide under different circumstances on the resulting amount of carboxihemoglobin. The first problem was to select a reliable and accurate method to determine COHb concentration below 5% COHb. All methods presently known are either below the accuracy required or very laborious. So it was necessary to improve one of these methods to match the standard required (ref.1 )
.
The basic method as proposed by v.Slyke (ref.2) is modified as follows. Hemoglobinbound carbonmonoxide is released chemically into a continuous stream of pure nitrogen. The pattern of the resulting CO-concentration in nitrogen is monitored by nondispersive infrared absorption. Fig 1 shows the scheme of the whole apparatus. A constant nitrogen stream enters the reactionvessel through a sinterglass and sparkles through the reagent. After passing a condenser to achieve constant humidity (the CO analyser shows still some cross sensitivity with respect to watervapour) and a flowmeter with a needlevalve the gas enters the CO-analyser. In this case an UNOR was used with a minimum range of 50 ppm. The reagent consists of potassiumhexacyano-ferrate (KjlFe (CN) ) , lactic acid, octanol for easing of surfacetension and saponin for hemolysis.
To determine the content of CO in a certain volume of blood, a sample of known volume is now inserted through a rubber cap by a syringe. Hemoglobin is destroyed by potassiumhexacyano-ferrate and bound CO is released - as is O2 - and results in a concentrationpeak at the monitoring CO-analyser. The integral over time of this signal which is obtained by electronical integration is a measure for the carbonmonoxide contained originally in the sample. Considering the gas flow one can easily compute the absolute CO volume per unit volume of blood. Using special saturation vessels (Fig 2) it is possible to get blood samples with 100% carboxihemoglobin by sparkling pure CO through the diluted samples. Sparkling for a few more minutes with pure nitrogen extrudes the physically solved carbonmonoxide which otherwise would cause an error. The relative carboxihemoglobin concentration in % COHb results now in the quotient of sample and saturated sample. Furthermore it is possible to get the absolute hemoglobin from these latter ones. The accuracy of the method discussed is very good. In the range from 1 to 10% COHb and sample volumes from about 2 to 0.2 ml
119
respectively the relative standard deviation is 2 . 5 % . The correlation coefficient of calculated values of samples from mixtures of CO free and CO saturated blood and the corresponding COHb values achieved by the method described is 0.9999. The detection limit is in the order of 0 . 0 2 % COHb. The average time for analysis of one sample is about 2 minutes without saturation. Another problem to be solved was the production of air with optional CO-concentrations. A very good device for controlled addition of pure CO to an airstream is a stepper motor driven peristaltic pump. Fig 3 shows the scheme of this device. Since it was possible to use a small computer on-line for all experiments this computer did all the control and monitoring. By this means it is possible to produce respirable air with CO-concentrations according to an actual immission concentration. Finally the relevant parameters of ventilation could be monitored and used for further calculations later on. Oxygen-uptake, alveolar ventilation from carbondioxide concentration, breathing frequency, the necessary parameters for corrections like temperature and pressure were all stored separately for every minute. In Fig 4 two examples of CO breathing and the resulting carboxihemoglobin for two hours are presented. In the first one a constant CO-concentration of 1 5 0 ppm was inhaled by the volunteer through a facemask. In intervals of about 10 minutes blood samples were taken from a cubital vein and analysed later on. In both cases the volunteer sat quietly on a comfortable chair. The straight line shows the computed COHb pattern using the well known formu1.a by Forster et al. (ref.3) whereas the dots represent the actual COHb values. In the other example the CO concentration of the inhaled air varied from 1 5 0 ppm to 2 0 and back to 1 5 0 ppm. The discrepances between computed and actual COHb may at least partly be due to the fact, that in both cases average ventilation parameters were used for the calculations. Another problem at present investigated is how the philosophy of an immission standard for CO has to be defined to guarantee that a certain level of COHb (e.g. 2 . 5 % as proposed by the WHO) will not be exceeded. If one considers the time it takes to come to a steady state of COHb, within the first 4 hours generally the greatest increase of COHb occurs. Since CO immission usually is strongly correlated to traffic the concentrations even in heavy populated regions go down to 2 till 4 ppm during the night. Peak concentrations up to 60 ppm and more assuming e.g. a pattern with two peaks
120
during the rushhours may still be within a daily mean of 10 ppm. The problem becomes even worse if one considers an annual mean. There may be short time local emissions e.g. caused by jammed traffic and certainly there are characteristic differences between working daysand holidays. From this point of view a daily and much more an annual mean does not make much sense. Generally one can say the longer the period for averaging, the better the chance for the occurence of periods with quite high CO-concentrations long enough to cause COHb concentrations above a limit of about 2.5% COHb, but still observing a quite low annual or even daily mean. A s a general rule for the averaging period of an immission standard can be said that this period has to be limited by the toxic effect of the component in question within this period. For carbonmonoxide a period of about 8 hours seems to be a reasonable intervall. In Austria (ref.4) the proposed immission standard for CO is a maximum of 9 ppm for an 8-hour mean, whereat any maximum hourly mean is 34 ppm. These limits are valid for any possible combination of subsequent halfhour means. Fig 5 shows the COHb calculated for an extreme situation whereat the limits mentioned above are still observed. At no time under realistic circumstances the carboxihemoglobin exceeds 3%, for a ventilation rate below 5 Il/min not even 2.5%. REFERENCES 1 H.Hauck, M.Neuberger and W.Resch, Arch.Toxicol.,37(1976)67-73. 2 D.D.Van Slyke and J.M.Neil1, J.biol.Chem.,61(1924)523-548. 3 R.F.Coburn, R.E.Forster and P.B.Kane, J.Clin.Invest.,44(196S)l89%19lQ 4 Vorlaufige Richtlinie Nr.1 - Kohlenmonoxid, BmfGuU , Wien, 1976.
COMPUTER PDP-11 CONDENSER
ir
Scheme of total measurement device
Fig 2 Saturation vessel
121
STEPPERMOTOR
Fig 3 Device for production
-
-
STEPPERMOTOR
AIR
co
200
1 0 0 l/min
T
of CO-loaden air
FACEMASK
COHB
1
2
8
COHB
150
6
co
100
4
50
2
7
30
60
40
60
90
120
min
30
---
I;.
V,
4
co
-.-..
5 thin 15 10
60
90
120
min
A trnospheric Pollution 1978, Proceedings of the 13th InternationalColloquium,Paris,France, April 25-28,1978, M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1
123
0 Elsevier ScientificPublishing Company,Amsterdam - Printed in The Netherlands
CHAMBER FOR THE STUDY OF THE BIOLOGICAL ACTION OF AEROSOL
C. TIRET Etablissement technique Central de l'hrmement - Section d'Etudes de Biologie et de Chimie ABSTRACT
A chamber and an automatic monitoring system for the study of the biological action of aerosols is described. Preliminary results are given about the aerosols alterations in the presence of animals.
Preliminary studies, using 20 liters tubular chambers, resulted in the design of a 2 cubic meter chamber and its monitoring system,
THE CHAMBER The chamber is a cylinder closed up at each end by a portion of a sphere, The animals for experiments are placed in containers suitable for their size and then put inside of six locks arranged around the cylinder; between the locks are placed delivery tubes for atmosphere sampling. The locks are provided with a separate ventilation system and can be either connected up with the chamber atmosphere or be i s o lated from it. Each lock chamber can contain 18 rats or 60 mice, 3 rabbits or one small dog. THE MONITORING SYSTEM Experiments can be monitored either automatically or manually. The monitoring commands are grouped on a pannelwhichis linked to the various elements o f the chamber by time-delay relays. The lock chambers can be independently or simultaneously connected up with the main chamber. CONTROL OF THE ATMOSPHERE The temperature and the relative humidity of the chamber atmosphere are recorded at six differents points. Control of mass concentration, particulate number concentration and particle size of the aerosol can be made. In the presence of animals, the oxygen and carbon dioxide concentrations are also controlled.
124 RESULTS Alteration of the atmosphere in the.-presenceof animals Oxygen concentration was controlled in experiments which were carried on groups of rats and mice in a distilled water aerosol. The animals were placed in the ventilated locks during the generation time ( 3 0 minutes). The variation of the oxygen concentration after the locks were connected up with the chamber showed that it could be neglected, the standard experimental conditions being 22'
C for the temperature
and 30 minutes for the time that the animals remain in the chamber atmosphere. Animals number
O
C
Relative humidity
Oxygen concentration after
(W)
3 0 mn
45 mn
60 % 70 %
20 20.4
20.4
90
21.5 25 17 - 2 0
85 %
19.7
19.3
90 %
19.6
18.7 18.7
120
21 - 2 2 . 5 20 - 21.5
77 % 66 %
20.4 20.5
20.3 20.3
54
Rats Mice
Temperature
2-4 23.5
6
-
26
6 0 mn __-
A 30 % relative humidity is always used at the beginning of an experiment. The variation due to the aerosol generation is about 5 Z using Jouan and Halpern generators and it rises to 25 % with a Jouan generator and 10 to 15 % with a Halpern generator in the presence of animal respiration. The temperature variation does not exceed 1 %. Animals behavior in the chamber atmosphere
-
Influence of the temperature for a 2 hours experiment :
Mortality is not observed if the temperature does not exceed 2 3 ' . However, the animals become wet (perspiration, feces). If temperature rises to 25" C, a 10 to 15 % mortality ratio is observed; provided the locks are not tightly closed (5m aperture) the ventiktion is sufficient to avoid animal death.
- Influence of relative humidity. No such influence was ever observed in the experiments. Study of atmosphere containing an aerosol Atmosphere homozeneity We did not observe a significant influence of the generators number, their location, neither of the number of locks confining animals or of the locks location relatively to the generators o r locks positions relatively to each other. Aerosol characteristicsThe animals used for experiments are female rats of a 2 5 0 g mean weight Jouan generator is used. Two different operating conditions were used :
125 The a e r o s o l generation was maintained f o r 3 0 minutes (A) and oncestopped, t h e animal r e s p i r a t i o n was introduced i n t o t h e chamber (B). Generators Lock- chambers number number
relative humidity % after after 3 0 mn 6 0 mn 1.4 IB
1 1
2
1 2 2
30 31 34
37 40.5 44
IB
IA xg
ag
xg
0.096 0.118
3.3 3.1 3.3
0.099 0.150
(u)
0.106
(P)
U %
I1 og
3.05 2.9
xg
ag
(!J)
0.122
2.8 2.8
0.185
3.3
0.087
after
30mn I1 36 % 46% 48 z
The preceding tableau shows flat t h e number of g e n e r a t o r s does not a l t e r p a r t i c l e s s i z e when t h e r e i s no animal r e s p i r a t i o n . In t h e presence of animal r e s p i r a t i o n , i t i s found t h a t p a r t i c l e s s i z e i n c r e a s e s with t h e number of animals. I n summary, t h e designed chamber o f f e r s t h e c h a r a c t e r i s t i c s we need
,
i.e.:
All t h e animals b r e a t h e t h e same atmosphere, which allows f o r t h e study of d i f f e r e n t s p e c i e s o r o f a g r e a t number of animals of t h e same kind. The presence of animals does not n o t i c e a b l y a l t e r t h e atmosphere temperature o r the oxygen and carbon dioxide c o n c e n t r a t i o n s . The manual o r automatic monitoring device f o r t h e v a r i o u s o p e r a t i o n s renders p o s s i b l e t o c a r r y o u t a g r e a t v a r i e t y of experiments with reduced t e c h n i c a l a s s i s t a n c e .
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25~28,1978,M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
127
EFFECT OF LEAD MCROPARTICLES ON TEE PULMONARY DEFENSE MECFIANISIIS OF THE MOUSE G. BOULEX, A. DUBREUIL, F. W A C and C1. BOUDENE
U. 122 I.N.S.E.R.M.,
Laboratoire de Toxicologie, Centre Pharmaceutique de
1'Universitt? Paris-Sud, 92290 Chatenay-Malabry (France)
ABSTRACT Lead microparticles (for test animals) or vegetal coal microparticles (for controls) were introduced in the respiratory apparatus of 532 mice, in a single dose, via the nasal route, under a mild ether anesthesia. Lead microparticles resulted from the pyrolysis of organic lead used as an anti-knock agent in gasoline. Io When 6 pg of lead were initially retained in the lungs (mean value per mouse) the resistance of the animals to experimental infection by aerosolized Pasteurella multocida, performed 6 and 1 8 hours later, was significantly lowe-
-
red (comparison with control mice, coal treated and infected similarly). When
3 pg of lead per mouse were initially retained, there was no significant difference in the mortality rates between lead treated and coal treated animals. 2O The mice receiving the lead in the amountiindicated above, but not in-
-
fected, showed no clinical symptom. With 6 pg of lead per mouse, retained in the lungs, no significant difference was observed 6 and I8 hours later, between the intoxicated and control groups, about the number of alveolar macrophages harvested by pulmonary washing ; but the ability of these cells to phagocytize latex particles was significantly reduced in lead exposed mice.
INTRODUCTION Lead oxides, halides and carbonates microparticles can be found in the atmosphere of heavy traffic areas (ref. I). They result mainly from the combustion of organic lead used as an anti-knock agent in gasoline. These particles are cytotoxic, specially for the alveolar macrophages of the lungs (ref. 2, 3 , 41, which constitute the main local defense mechanism against inhaled micro organisms. So that, we have tried to determine the effects of lead microparticles present in the mouse lungs, on the susceptibility of these animals to experimental airborne infection.
128
MATERIAL AND METHODS The lead used was a pyrolyzate (65OOC) of organic lead, suspended in distilled water to obtain particles of which 91-97$ (95% confidence limits) had a diameter smaller than 3 pm (ref. 4 ) . The lead dosages were performed using flameless atomic absorption spectrophotometry. The experiment involved a total of 532 specific pathogen free OF I female mice, 30 to 40 days old. A volume of 0.05 ml of lead or coal suspensions was inserted into the breathing apparatus of each animal via the nasal passage, under mild ether anesthesia. 2@ of the lead administered was found in the lungs immediatly after its introduction. One, 6 and 18 hours later, this lead content dropped respectively to 12,3, and 2$ of the original inoculum. Two doses of lead suspension were chosen : one leading to a mean pulmonary lead content of
3 pg per mouse (ispg per g of lung) and the other to 6 pg per mouse ( S O P per g of lung). These amounts were 100 and 200 times higher than those of the controls. The bacterial strain used was a typical Pasteurella multocida. The respiratory infection was provoked 6 and 18 hours after administering the above mentioned lead or coal suspensions, in the Henderson apparatus (ref. 5). All the mice infected, inhaled a previously calculated lethal dose 50$ (LD50) of 25000 viable germs per mouse. Twenty pulmonary lavages of 0.5 ml were performed, via the trachea of non infected mice, 6 and 18 hours after the lead or coal administration, in order to harvest the alveolar macrophages. The number of these cells and their ability to phagocytize 0.8 pm latex particles in vitro, were studied. RESULTS T.Mouse mortalite Io No death occured in mice with 3 and 6 pg of lead in their lungs at 0
-
hour, but not infected. 2O For mice infected by P. multocida 6 and 18 hours after administration
-
of the suspension leading initially to the mean pulmonary lead content of 3 pg, the mortality rate was not significantly different from the controls (coal treated and infected). But, with the pulmonary lead content of 6 pg, the susceptibility of the mice to the experimental airborne infection, performed 6 and 18 hours later, was significantly increased (table I). TABU I Death rate (dead/total tested) and mortality percentage in mice : I : lead treated ( 6 pg), not infected. I1 : coal treated and infected ( I DL50
of P . multocida ) . 111 multocida ) .
( I DL50 Of P.
: lead treated ( 6 pg ) and infected
Statistical test and p value.
129
coal treated and infected
lead treated not infected
lead treated and infected infection at 6th h.
infection at 6th h.
0/34 (0%)
30/46 (65%)
17/45 ( 36%) infection at 18th h. 23/65 135%)
0/33
(d)
infection at 6 th hour :
36/65 (55%)
k:.II.III. = 35 (2 d.f.) x;1.111.-
infection at 18 th hour :
infection at 18th h.
-
6.86 (I d.f.)
2
= 29 (2 d.f.) XI.II.III.
2 ~11.111.= 5.24 (I d.f.)
-8
p = 2x10
p = 0.009 p = SX~O-~ p = 0.02
5I.Number and phaaocytic activity of the alveolar macroRhages
TABLE I1 Phagocytic ability of alveolar macrophages harvested from mice after introduction of 6 pg of lead : Number of cells phagocytizing several numbers of particles. control mice (coal treated) 6th hour 0 particle : 1-3 particles: 4-6 particles: 7-9 particles: 10 particles:
statistical analysis
test mice (lead treated) 6th hour
87
290
145 104 374
total cell count : 1000
0 particle 1-3 particles 4-6 particles 7-9 particles 10 particles
: :
154 341
:
277
: 150 : 78
x2=
41 (4 d.f.1 p= 3x10
total cell count : 1000
18th hour 0 particle : 91 1-3 particles: 399 4-6 particles: 170 7-9 particles: 58 10 particles: 282
18th hour 0 particle : 1-3 particles : 4-6 particles : 7-9 particles : 10 particles :
total cell count : 1000
total cell count : 1000
214 461 165
39
121
x2=122
(4 d.f.1
p 5x10 -lo
130
Both 6 and 18 hours after introduction of the suspensions into the breathing apparatus of the mice ( 6 pg retained in the lungs at 0 hour), the number of macrophages and the percentage of dead cells (quick permeability to blue trypan) did not significantly differ between the lead treated mice and the controls group. But the ability of these cells for phagocytizing latex particles in vitro, was significantly lowered in the lead treated animals (table 11). We think that when the lead is administred in a single dose, as opposed to a prolonged exposure, the organism of the lead treated mice ensures the quick replacement of the destroyed alveolar macrophages. But it is possible that this renewal brings immature macrophages (ref. 6). ACKNOLEDCEMENTS Ve wish to thank J. Godin and H. Peronny for their precious collaboration. REFERENCES
I G. Ter Haar, Nature, 232 (1971) 554-555. 2 E.J. Beck, N. Manojlovic and A.B. Fisher, in Proceed. Int. Symp.
Environ. Hlth. Aspects Lead, Amsterdam, Oct. 2-6, 1972, C.E.C. and U.S. Environ. Protect. Agency, 1973, pp. 451-462. 3 E. Bingham, W. Barkley, 1. Zerwas, X. Stemmer and T. Taylor, Arch. Environ. Hlth. 25 (1972), 406-414. 4 A. Dubreuil, G. Bouley, J. Godin, F. Arsac and C1. Boudhe, in Atti
Io Conv. Int. sull' Ambiente, Torino, May 8-12, 1974, Torino Esp. Vol 4 (1974) Comm. no 13. 5 D.W. Henderson, J. Hyg. Cambridge, 50 (1952) 53-69. 6 A . Vlckova and R. Holusa, Arch. Arbeitsmed. 32 (1974) 233-242.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
133
POLLUTION ROSES : A SIMPLE WAY OF INTERPRETING THE DATA O B T A I N E D BY A I R POLLUTION
MEASUREMENT SYSTEMS I N THE PROXIMITY OF REFINERIES M . DUBOUE
S h e l l F r a n q a i s e , C e n t r e de Recherche de Grand-Couronne ( F r a n c e )
INTRODUCTION
The r e l a t i v e l y r e c e n t a d v e n t o f s t r o n g a c i d i t y and m e t e o r o l o g i c a l r e c o r d e r s i n t h e p r o x i m i t y of r e f i n e r i e s i n e v i t a b l y s e t s t h e q u e s t i o n of t h e i n t e r p r e t a t i o n o f t h e measures s o o b t a i n e d . A s i m p l e , s p e a k i n g approach c o n s i s t s i n forming p o l l u t i o n r o s e s p e r s t a t i o n ,
i . e . i n r e p r e s e n t i n g t h e p o l l u t i o n l e v e l s observed by e a c h r e c o r d e r a c c o r d i n g t o t h e wind d i r e c t i o n . Such a n approach mainly a l l o w s , o v e r a l o n g p e r i o d , t o d e t e r m i n e t h e geograp h i c a l o r i g i n and t h e importance o f s t e a t y s t a t e p o l l u t i o n s o u r c e s a f f e c t i n g each s i t e . We s h a l l i n d i c a t e , f i r s t , t h e i-easons f o r which such a model, very elementary
from a m a t h e m a t i c a l p o i n t of view, l o o k s r e l e v a n t , t h e n w e s h a l l d e s c r i b e t h e a p p l i c a t i o n s o f it i n t h e Compagnie Rhgnane d e R a f f i n a g e r e f i n e r y of R e i c h s t e t t and i n t h e S h e l l F r a n p i s e r e f i n e r y o f P a u i l l a c . SETTING THE PROBLEM The aim o f s t r o n g a c i d i t y r e c o r d i n g s t a t i o n s i n t h e p r o x i m i t y o f r e f i n e r i e s i s o f c o u r s e measuring t h e impact of t h e l a t t e r on t h e i r environment. Although t h e t a r g e t l o o k s v e r y c l e a r , it i s f a r more c r i t i c a l t o r e a c h i t f o r t h r e e main r e a s o n s :
- t h e r e f i n e r y i s n o t n e c e s s a r i l y t h e o n l y s o u r c e of p o l l u t i o n of t h e a r e a ,
-
t h e a c c u r a c y of e x i s t i n g r e c o r d e r s i s weak. I t can be e s t i m a t e d a t l e a s t t o 25 % o f t h e measured v a l u e ,
- t h e c o n c e n t r a t i o n s measured by t h e r e c o r d e r s are changing a t t h e mercy of wind, which can be v e r y c a p r i c i o u s l o c a l l y . The r e s u l t i s t h a t a p u n c t u a l measure i s n o t g r e a t l y s i g n i f i c a n t . I t g i v e s a t t h e b e s t a n i n a c c u r a t e i n d i c a t i o n on t h e p o l l u t i o n of t h e area b u t remains s i l e n t on i t s o r i g i n . The knowledge o f wind d i r e c t i o n i s t h u s e s s e n t i a l t o have a b e g i n n i n g of answer. O f c o u r s e , s e v e r a l r e c o r d e r s , l o c a t e d i n d i f f e r e n t s i t e s are n e c e s s a r y t o t r y t o distinguish the p o t e n t i a l pollution sources.
134 Finally, due to measurement inaccuracy, local atmospheric hazards, the statistical approach is the only one that is liable to give representative results. Moreover, the same reasons imply that but elementary treatments should become suitable. THE MODEL : POLLUTION ROSES The model lies on the simple idea of classifying the concentration measurements obtained in a given site for a given period according to the direction in which the wind blows at the moment of the measure (the plane is divided into 16 sectors of 22O5, hence 16 wind directions are considered).
Then, the average pollution level of a site for a wind direction is given by the mean of the concentrations belonging to the corresponding sector. As pollution crests are also significant, a pollution maximum is defined per wind direction : it is the concentration value exceeded but 5 % of time during which the wind blows in the given direction. However, in order to filter the inaccuracy of the measure set, this value is not the observed concentration that would be exceeded by 5 % of the observed values. It is on the contrary calculated with the assumption that the concentrations are log-normally distributed in function of the appearance frequency (which means that the logarithm of the concentrations follows a Gaussian law). And, to have a good estimation of the importance of the different pollution levels associated with the wind directions, the frequencies of wind are of course useful. An example of table is given in Appendix 1. It concerns a survey on the Pauillac site for 1976. APPLICATION Reichstett refinery (CRR) This refinery is located 20 km from Strasbourg, in the North-West direction in the Rhine valley. The proximity of a large town (and the pressure of local associations) led CRR to implement an air pollution measurement system including :
- 4 strong acidity Biolaffitte recorders located respectively at 3.4 km NNE from the refinery, 4 km W, 2.7 km SE and 2 km SSE.
- A weather cock (close to the refinery). - A concentrator, to which the six apparatus are connected by telephone, printing each hour on teletype the measures obtained and storing them on a punch-tape. So, high pollution levels and apparatus failures as well are quickly detected.
Monthly, the tape is converted to be treated on a Univac 1110 computer. The pollution roses, the daily and monthly computed means are analysed and sent to the Administration of Mines.
135 Pauillac refinery (Shell Francaise) The P a u i l l a c r e f i n e r y , on t h e Gironde s i d e , l i e s i n t h e h e a r t o f t h e Bordeaux v i n e y a r d . I t s c o n s t r u c t i o n was approved by t h e a u t h o r i t i e s under t h e c o n d i t i o n t h a t t h e v i n e y a r d be i n no way a f f e c t e d . T h i s i s why a measurement system, i d e n t i c a l with t h a t o f R e i c h s t e t t , w a s a l s o implemented. We d e s c r i b e h e r e , because it i s v e r y s p e a k i n g , t h e a n n u a l t r e a t m e n t f o r 1976 t h a t was achieved i n o r d e r t o b e t t e r a p p r e c i a t e t h e r e f i n e r y c o n t r i b u t i o n t o t h e low p o l l u t i o n l e v e l o f t h e a r e a . The r e s u l t s o f t h e s u r v e y a r e g i v e n i n Appendix 2 i n a g r a p h i c form. I n a g e n e r a l c o n t e x t o f v e r y low v a l u e s , t h e p o l l u t i o n r o s e s show c l e a r l y t h a t t h e h i g h e s t c o n c e n t r a t i o n s were observed when t h e wind w a s blowing from ESE, SE and SSE s e c t o r s , f o r e v e r y s i t e .
A s shown i n t h e f i g u r e , t h i s p e c u l i a r phenomenon i s i n f a c t v e r y u n d e r s t a n d a b l e ,
f o r a thermal p l a n t l i e s 5 0 km away i n t h e South-East o f P a u i l l a c , w i t h an i m p o r t a n t d a i l y SO2 e m i s s i o n . CONCLUSION The p o l l u t i o n r o s e s model i s a v e r y r u s t i c t o o l t h a t l o o k s w e l l adapted t o t h e t r e a t m e n t of d a t a o b t a i n e d from s t r o n g a c i d i t y r e c o r d i n g s t a t i o n s n e a r r e f i n e r i e s , i n view of d e t e r m i n i n g t h e r e l a t i v e importance o f p o l l u t i o n s o u r c e s a f f e c t i n g a g i v e n a r e a . I t can be used i n a v e r y a u t o m a t i c and r o u t i n e way. I t i s a b l e t o show as i n t h e P a u i l l a c area t h a t t h e n e a r e r p o l l u t i o n s o u r c e i s n o t n e c e s s a r i l y t h e more p o l l u t i n g one. APPENDIX 1 Pollution roses A r t i g u e s : NNE s e c t o r
_ - - - - _s-e-c_t o_r _ _ _ _ _ _ _
M (pg/rn3)
11.2
58 54 57
6.6 5.8
48
3.3
5.7
48 85
9.6 8.6 9.3 0.7 0.9
100
3.8
22 22 28 32
3.9
sso so oso 0
ON0 NO NNO Total
(k)
f
N NNE NE ENE E ESE SE SSE S
95
70
27
24
12.2
6.2 6.3 N
=
443 7603
n=nurnber of o b s e r v a t i o n s
-
I
5.8 100
f=wind f r e q u e n c y
-
rn-mean c o n c e n t r a t i o n
-
M=rnaxirnurn c o n c e n t r a t i o n
136
APPENDIX 2
I
1 km
I
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
137
A COMPLETELY LAGRANGIAN RANDOM-WALK MODEL FOR ATMOSPHERIC DISPERSION
A.K. RUNCHAL, A.W. BEALER, and G.S. SEGAL Dames
&
Moore, Advanced Technology Group, Los Angeles
ABSTRACT This paper presents a completely Lagrangian model for multidimensional atmospheric dispersion studies.
The computed results for four case studies are pre-
sented and compared with the known analytic solutions; it is shown that the two sets of results are in excellent agreement. The model is based upon the simple concept of advection by mean wind velocity with the superimposition of a suitably selected Random-Walk to simulate atmospheric turbulence.
The concept is free of any spatial grid or finite-differences
and is as simply applied to a one-dimensional steady-state problem as to an unsteady three-dimensional one. Unlike the more commonly used finite-difference methods, the present method is completely free from problems of numerical stability, numerical diffusion, and dimensionality. Further, it is easily adapted for small computing machines with limited core memory.
INTRODUCTION In recent years, much thought has been given to the use of probabilistic techniques for study of the atmospheric dispersion phenomena (ref. 1 , 2 , 3 ) .
This in-
creasing interest is partly because of the inherent simplicity and attractiveness of the probabilistic approach, and partly because of the shortcomings of the traditional analytic and numerical techniques in dealing with the problems of spatial and temporal resolution, terrain interaction, and numerical stability, economy, and accuracy. It can be argued that fluid turbulence is an inherently stochastic process. Thus, appropriate probabilistic methods should be best suited for prediction of such a process.
In line with the references cited earlier, the present paper de-
scribes the results of the application of such a method to a number of classical problems of atmospheric dispersion.
138 THE METHOD In deriving the groverning relations for a probabilistic simulation of atmospheric dispersion, the common. approach adopted is to start with the relevant transport equations and show how the probabilistic principles can be applied to simulate a solution to these equations (refs. 1, 2, 3).
In this paper, following
Chandrasekhar (ref. 4), the random motion of a particle is considered on purely probabilistic basis and the appropriate differential equations of transport are derived therefrom. Consider a particle which undergoes a series of
N
random displacements, with
the n-th displacement given by a probability distribution function, R
sition vector,
,
pn
.
The po-
of the particle is given by:
N
R = Cr n , n=l
where
r
are the displacement vectors.
The probability, R
defined by p
N
(R) =
%
and m
,
PN(R)
R
+
is obtained by Markoff's method (ref. 4) as:
dR
exp (-i s
that the position of the particle lies in the volume
.
R) A ( s ) ds
8 T -a,
where the Fourier transform,
N
AN
,
is given by:
N
Though, in principle, it is possible to select appropriate distribution functions, pn , for the random displacement vectors
r
,
to represent the differing atmo-
spheric conditions, turbulence spectrum, etc., the most convenient and generally suitable distribution is the Gaussian distribution,
where
l2
denotes the mean square displacement, in a random direction, to be ex-
pe-ted on the n-th occasion. tions (2) and (3) as:
where :
The probability function is then given from Equa-
139 For a particle suffering a large number of displacements at an average rate of
M
displacements per unit time, Equation (5) is written as: 2 exp ( - ( R J /4Dt)
P = (4TDt)-3'2 N
.
2 D = M L /6
,
(7)
To derive a transport equation for these particles, consider a particle which in an interval of time 6 t , such that the net
undergoes a net displacement 6 R
mean square displacement is small in comparison to displacements is large.
but the total number of
The probability of this occurrence is given by:
2 exp (-16RI /4D 6t)
F = ( 4 T D 6t)-3/2
R
Thus, the probability function at time
.
(8)
t
+
dt
can be written as:
Expansion of the probability function on the right-hand-side in Taylor series and integration leads to 2
2
Pt+ 6 t
= P + D 6 t (axP + 8 P t Y
where
x, y, and z
2
+
2
aZP) + 0 ( 6 t )
are cortesian coordinates.
,
(10)
,
In the limit 6t-0
this reduces to:
which is the standard diffusion equation with
D
as the diffusion coefficient.
In a similar manner it can be shown (ref. 4) that the assumption of a more general distribution function, pn
leads to the general transport equation:
2 2 ~ P + W ~ P = a xD p + ~a p + ~ ~ a : p , Y Y Y
atp+uap+v where
,
u, V, and
W
are the mean velocity components and
Dx
(12)
,
Dy
,
DZ
are
the diffusion coefficients given by:
with
Lx
function.
,
2 L
,
etc. as the various first and second moments of the distribution
140 THE RESULTS The method described above was incorporated in a random-walk model, named RADM.
Details of this model and various considerations related to the choice,
economy, and accuracy of the algorithm are discussed by Runchal et al. (ref. 5). The model was employed to simulate a number of classical problems of atmospheric dispersion for which analytic solutions are known to exist.
Four test
cases for which results are presented in this paper are described below. Test Case 1 - The Instantaneous Point Source The analytic solution for this case is given by Pasquill (ref. 6 ) as: 2 exp (-R /4 Dt) ,
-3/2 C = Q (4lTDt) where
C
is the local concentration at distance
Q
is the total amount released, and
D
R
from the source,
is the diffusion coefficient.
Test Case 2 - The Point Source With Uniform Wind The analytic solution for a continuous point source with uniform wind is given by (ref. 6 ) :
c L
=
2
2
Q ( 2 r u L L )-1 exp (-y2/2~2- z2/2~z)
Y Z
=
Y
,
2 D y/U
Y
2
Lz = 2 Dz/U
,
( 16)
.
(17)
In deriving this solution diffusion in the
x-direction has been ignored in
comparison to advection. Test Case 3
-
The Point Source With Wind Shear
In the presence of a constant wind shear, the analytic solution for an instantaneous point source may be expressed as (ref. 7 ) :
,
L
Test Case 4
-
L2 = 2 D t
2
=
2 2 2 L (1+C t /12)
,
X = x-Czt/2
,
C = a U / a z = constant.
The Line Source With Scale-Dependent Diffusion
For this case, in which the diffusion coefficient is related to the cloud size, the analytic solution is written as (ref. 3):
c
=
2 2 2 p (~xL~) -~ exp [ - (x +z ) / 4 ~I
L2 =
Lt
where
D (t') dt' , D
E
=
4C3 ft2/9
,
(20)
,
(21)
is the atmospheric energy dissipation rate, C taken as unity, and the maximum value of
D
is a constant which was 2 was limited to 100 m / s .
141 The RADM results for these four test cases, in comparison to the corresponding analytic results, are shown in Figures 1 through 4. sults compare well with analytic solutions.
1n all cases the model re-
These results were obtained with
2,000 to 4,000 particles, which were followed at 5- or 10-second time intervals.
Even closer agreement between the analytic solutions and the model results could have been obtained by increasing the number of particles.
However, no such at-
tempt was made because the emphasis was on the verification of the model rather than on the accuracy of solutions. The computing time on a CDC 6600 machine was typically on the order of 60 seconds; in view of the costs of a grid-based Eulerian or mixed Eulerian-Lagrangian method (refs. 1, 3 )
this is a very favorable number.
Further, the present method
suffers from no numerical stability or numerical diffusion problems.
Also, with a
model such as RADM it is possible to systematically improve the accuracy of a solution by superimposition of a number of solutions, each obtained with a small number of particles; such techniques, obviously ruled out with deterministic approaches, allow the method to be used on a small computer.
0
50
100
150
200
Fig. 1.
250
50 100 150 200 D I S T A N C E FROM CLOUD CENTER (METERS)
0
250
D I S T A N C E FROM CLOUD CENTER ( M E T E R S )
The instantaneous point source.
,
320 -
Q=lOO Q=lOO g / s Dy=lOO n2/s
280 -
g / ~
D Y = I O O n2/s
- * . )
I
D z = 1 0 n2/s
u=5 n/s MODEL P R E D I C T I O N -ANALYTIC SOLUTION
MODEL P R E D I C T I O N
-
-
400 -
:120 0 z
u
804o
00
Fig. 2 .
(B)
0 200 400 600 800 I000 DOWNWIND D I S T A N C E FROM SOURCE ( M E T E R S )
1200
0
50
100
150
200
250
300
3W
CROSSWIND D I S T A N C E FROM C E N T E R L I N E AT X = l O O O METERS
The continuous point source with uniform wind.
400
142 1200 I
-
1000-
Q=lOOO g D=lO M2/S
Q-1000
au/az=.1/s t-50 s
z
TIME STEP=IO S Q T I M E STEP= 5 S -ANALYTIC SOLUTION
Y
"
400-
au/az=.l/s
z
-
0
-
;so0
a
-
g
TIME STEP=IO S 0 T I M E STEP= 5 S -ANALYTIC SOLUTION
4000
-
200-
0
Fig. 3.
-0
r.l
1
10
20 30 40 w D I S T A N C E ALONG V E R T I C A L A X I S FROM CLOUO CENTER (METERS)
20 40 W 0 IW I20 140 164 D I S T A N C E ALONG X - A X I S FROM CLOUD CENTER (METERS)
80
0
The continuous point source with wind shear.
3-
-
x
x i -
Q=lOOO g/M
")
C=2
r?
M2/S3
? .
6 -
t=50 s
0
LL
MODEL P R E D I C T I O N A N A L Y T I C SOLUT I ON
z
MODEL P R E D I C T I O N -ANALYTIC SOLUTION
$
u
I 0
50
100
I50
l?W
D I S T A N C E FROM SOURCE ( M E T E R S )
Fig. 4.
250
-
(B)
0
0
50
100
IM)
200
D I S T A N C E FROM SOURCE (METERS)
The line source with scale-dependent diffusion.
coNcLusIoNs
1. The purely Lagrangian random-walk method permits economical and accurate solutions to a number of problems of atmospheric dispersion. 2.
The method is a flexible, simple, and elegant means of dealing with the stochastic phenomena of atmospheric diffusion.
3.
The method is economical in comparison with the other available grid-based Eulerian or Eulerian-Lagrangian methods.
It is easily adapted
for use on small computers. REFERENCES R.C. Sklarew, 63rd Annual Meeting of the Air Pollution Control Association, St. Louis, Missouri, June 14, 1970. R.S. Hotchkiss and C.W. Hirt, Los Alamos Scientific Laboratory Report LA-DC-72-364, 1972. R. Lange, Lawrence Livermore Laboratory Report UCRL-51462, 1973. S . Chandrasekhar, Reviews of Modern Physics, 15,1(1943)1-89. A.K. Runchal, A.W. Bealer, and G.S. Segal, Dames & Moore, Advanced Technology Group, in preparation. F. Pasquill, Atmospheric Diffusion, John Wiley & Son, N e w York, 1974. G.T. Csanady, Turbulent Diffusion in the Environment. D Reidel, DortrechtHolland, 1973.
A 280
143
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
A I R POLLUTION MODELING BY THE "SMEARED CONCENTRATION APPROXIMATION" Robin L. Dennis I n t e r n a t i o n a l I n s t i t u t e f o r A p p l i e d Systems A n a l y s i s
ABSTRACT T h i s paper d e s c r i b e s a s i m p l i f i e d method, t h e Smeared C o n c e n t r a t i o n Approximation, developed t o c h a r a c t e r i z e a i r p o l l u t i o n d i s p e r s i o n f o r use i n models concerned w i t h long-term p o l i c y analysis a t t h e regional level. around t h e urban s c a l e .
The methodology c e n t e r s
The main assumptions behind t h e a p p r o x i m a t i o n a r e d e s c r i b e d
and t h e SCA U i s p e r s i o n Parameter i s d e f i n e d .
Development o f t h e SCA D i s p e r s i o n
parameter, u s i n g d e t a i l e d a i r p o l l u t i o n d e s p e r s i o n models, i s d e s c r i b e d .
Illustra-
t i o n s of t h e use o f t h i s methodology i n r e g i o n a l energylenvironment a n a l y s i s a r e p r e s e n t e d and some c o n c l u s i o n s c o n c e r n i n g t h e use o f t h e method a r e g i v e n .
INTRODUCTION The purpose o f t h e paper i s t o d e s c r i b e a methodology t h a t has been developed a t I I A S A t o a l l o w the i n c l u s i o n o f a i r p o l l u t i o n dispersion i n large-scale, i n t e r d i s c i p l i n a r y r e g i o n a l and n a t i o n a l modeling e f f o r t s [ l ] . The methodology bypasses t h e d i r e c t need o f complex and l a r g e a i r p o l l u t i o n d i s p e r s i o n models.
The work
was s p e c i f i c a l l y designed t o be most r e l e v a n t f o r a n a l y s i s o f l o n g - t e r m s t r a t e g i e s and p o l i c y o p t i o n s c o n c e r n i n g a i r p o l l u t i o n a t t h e r e g i o n a l l e v e l .
The methodology
c e n t e r s around d i s p e r s i o n a t t h e urban o r m e t r o p o l i t a n s c a l e ; t h e e f f e c t o f an urban area on i t s e l f . By l a r g e - s c a l e ,
i n t e r d i s c i p l i n a r y modeling i s meant modeling e f f o r t s where a i r
p o l l u t i o n i s j u s t one o f many f a c t o r s considered, a l b e i t an i m p o r t a n t one.
Examples
o f t h e s e t y p e s o f models a r e t h e Brookhaven Energy Systems O p t i m i z a t i o n Model (BESOM) [ 2 ] ,
t h e K c o n s i n Energy Model (WISE) [3], and an Economic Environmental
P l a n n i n g Model o f t h e U n i v e r s i t y o f Maryland [ 4 ] . I f concern i s about e n v i r o n m e n t a l impacts, t h e emissions o f a i r p o l l u t a n t s a r e a poor p r o x y f o r an impact a n a l y s i s .
What m a t t e r s i s what happens t o those emis-
s i o n s ; a damage o r impact assessment i s d e s i r e d .
Accounting f o r d i s p e r s i o n i s
r e q u i r e d , even f o r long-range p o l i c y a n a l y s i s ; b u t t h i s i s n o t easy s i n c e d i s p e r s i o n models themselves a r e u s u a l l y l a r g e and d a t a i n t e n s i v e . What i s needed i s a s i m p l e method t h a t i s e a s i l y useable by a range o f models and modelers w o r k i n g on l a r g e i n t e r d i s c i p l i n a r y models aimed a t l o n g - t e r m p o l i c y
144 analysis.
The method s h o u l d c o n t a i n t h e e s s e n t i a l f e a t u r e s o f d i s p e r s i o n , y e t
r e s u l t i n a simple, useable a l g o r i t h m .
The Smeared C o n c e n t r a t i o n Approximation
method was developed w i t h t h i s need i n mind:
The SCA method c o n c e n t r a t e s on t h e
urban a r e a because t h i s i s where most o f t h e human h e a l t h impact f r o m a i r p o l l u t i o n occurs.
Main assumotions The b a s i c assumption i s t h a t an annual average g r o u n d - l e v e l c o n c e n t r a t i o n averaged o v e r t h e e n t i r e urban area i s a s u f f i c i e n t l y p r e c i s e i n d i c a t o r f o r l o n g t e r m impact a n a l y s i s .
People a r e good i n t e g r a t o r s o f a i r p o l l u t i o n ; t h e i r m o b i l i t y
i s h i g h r e l a t i v e t o t h e s p a t i a l v a r i a t i o n o f t h e p o l l u t i o n concentration.
This
average i n t e g r a t e d exposure i s t h e c o l l e c t i v e dose t o t h e urban area, o r t h e average dose an average person r e c e i v e s i n t h e urban a r e a .
Thus a s i n g l e exposure i s
a s s o c i a t e d w i t h each urban a r e a . T h i s average i n t e g r a t e d annual exposure n o r m a l i z e d by t h e t o t a l annual emissions f r o m t h e urban area i s d e f i n e d as t h e Smeared C o n c e n t r a t i o n D i s p e r s i o n Parameter, D. C h a r a c t e r i z a t i o n o f t h e e s s e n t i a l f e a t u r e s o f a i r p o l l u t i o n d i s p e r s i o n i s achieved by d e f i n i n g a s e t o f D ' s ; t h e d i s a g g r e g a t i o n o f t h i s s e t i s determined by b o t h d i s p e r s i o n and p o l i c y c o n s i d e r a t i o n s . F i r s t , t h r e e c l a s s e s o f composite SCA d i s p e r s i o n parameters, Dk, a r e d e f i n e d f o r each o f t h r e e c l a s s e s o f e m i s s i o n sources: D1:
D2:
SCA d i s p e r s i o n parameter f o r l o w - l e v e l o r area sources
SCA d i s p e r s i o n parameter f o r medium-level p o i n t sources
SCA d i s p e r s i o n parameter f o r h i g h - l e v e l p o i n t sources D3: The d i s p e r s i o n c h a r a c t e r i s t i c s o f t h e s e t h r e e c l a s s e s o f sources are, i n general,
d i s t i n c t l y d i f f e r e n t ; t h e d i f f e r e n c e s w i t h i n a c l a s s a r e smaller than d i f f e r e n c e s between c l a s s e s .
Broad p o l i c y o p t i o n s can be d e f i n e d i n terms o f t h e s e t h r e e
c l a s s e s o f e m i s s i o n sources.
The p o l i c y o p t i o n s can be q u i t e d i f f e r e n t between
t h e t h r e e c l a s s e s ; t h u s many p o l i c y s t r a t e g i e s can be analyzed by t h i s d i v i s i o n o f e m i s s i o n sources. Second, each Dk i s d e f i n e d as a composite o f a b a s i c s e t , Dkj,
d e f i n e d i n terms
Each D i s an SCA d i s p e r s i o n parameter kj d e f i n e d f o r a p a r t i c u l a r atmospheric s t a b i l i t y c o n d i t i o n and a p a r t i c u l a r wind
o f wind speed and atmospheric s t a b i l i t y . speed.
Experience has deemed t h a t t h r e e atmospheric s t a b i l i t i e s and f o u r wind
speeds i s an adequate d i s a g g r e g a t i o n t o c h a r a c t e r i z e t h e d i s p e r s i o n .
Differences
i n m e t e o r o l o g y can be accounted f o r w i t h t h i s s e t .
SCA D I S P E R S I O N PARAMETER DEVELOPMENT The area source SCA d i s p e r s i o n parameters were developed from computer
145 c a l c u l a t i o n s made w i t h a g r a d i e n t d i f f u s i o n a i r p o l l u t i o n model w i t h e x p l i c i t l y modeled wind and d i f f u s i v i t y p r o f i l e s . U n i v e r s i t y o f Wisconsin [ 5 ] .
T h i s numerical model was developed a t t h e
The p o i n t source SCA d i s p e r s i o n parameters were
developed u s i n g a Gaussian plume d i s p e r s i o n model, a v a i l a b l e a t Wisconsin and I I A S A [61.
Both models have been approved by t h e USEPA.
The SCA d i s p e r s i o n parameter,
a g a i n , i s d e f i n e d as t h e average g r o u n d - l e v e l c o n c e n t r a t i o n c a l c u l a t e d f o r t h e e n t i r e urban a r e a d i v i d e d b y t h e t o t a l emissions f r o m t h e urban area.
Ihe e s s e n t i a l f e a t u r s s
o f t h e SCA d i s p e r s i o n parameters were d e f i n e d w i t h t h e h e l p of t h e computer models.
Area Sources:
D1
The main d i s p e r s i o n f e a t u r e s o f t h e area source d i s p e r s i o n parameter, D1,
1.
are:
D1 i s n o t s e n s i t i v e t o t h e d i s t r i b u t i o n o f emissions i n a n urban a r e a .
2. D1 i s n o t s e n s i t i v e t o t h e roughness o f t h e urban a r e a . 3.
D1 i s a f u n c t i o n o f t h e average r a d i u s o f t h e urban area.
Several model c i t i e s were d e f i n e d w i t h d i f f e r i n g emissions d e n s i t y .
The d i f -
f e r e n c e s were b o t h w i t h r e s p e c t t o t h e r a t i o o f t h e maximum t o t h e minimum emission d e n s i t y and w i t h r e s p e c t t o t h e s p a t i a l d i s t r i b u t i o n o f t h e e m i s s i o n d e n s i t i e s . F i v e model c i t i e s a r e shown i n F i g u r e 1. Model c i t y A has a max-minimum emission d e n s i t y r a t i o o f 82, model c i t y 3, 29.8, model c i t y C, 82.3, model c i t y 0, 1.0 Model C i t y ( u n i f o r m ) , and model c i t y E ( a model c i t y o f Vienna, A u s t r i a ) , 38.5.
E i s shown as a c r o s s s e c t i o n t h r o u g h t h e c e n t e r . The r e s u l t o f c a l c u l a t i n g D
Ij
f o r t h e f i v e model c i t i e s w i t h a g i v e n atmospheric
s t a b i l i t y and g e o s t r o p h i c wind i s shown i n F i i u r e 2 .
For t h e l a r g e d i f f e r e n c e s i n
between t h e 5 1j The d i f f e r e n c e i s on t h e o r d e r o f + 10 p e r c e n t around t h e average o f f o r t h e model c i t i e s . I n t e r e s t i n g l y , t h e r a t i o o f t h e maximum concentra-
t h e p a t t e r n s o f emissions, t h e r e was o n l y a s m a l l change i n each D model c i t i e s . each D
1j
t i o n t o t h e urban average c o n c e n t r a t i o n was t h e same f o r model c i t y A and "Vienna", w h i l e t h e i r max-minimum e m i s s i o n d e n s i t y r a t i o was q u i t e d i f f e r e n t and Vienna's
Dlj
i s v e r y c l o s e t o t h e u n i f o r m c i t y Dlj.
The main c o n c l u s i o n i s t h a t t h e 0
are i n s e n s i t i v e t o the d e t a i l s o f the emission d e n s i t i e s .
1j
's
A s i m i l a r s e t o f c a l c u l a t i o n s was c a r r i e d o u t t o i n v e s t i g a t e s u r f a c e roughness. S i m i l a r r e s u l t s were o b t a i n e d as above. what g r e a t e r spread o f D
S u r f a c e roughness e f f e c t s produced a some-
f o r a l l p o s s i b l e combinations, b u t t h e c o n c l u s i o n i s
ij t h e same, s u r f a c e roughness d i f f e r e n c e s can be i g n o r e d .
The f a c t t h a t one does n o t
need t o w o r r y about t h e d e t a i l s o f t h e urban area i s an i m p o r t a n t f e a t u r e o f t h e SCA method; d a t a needs a r e reduced t o a minimum. The SCA d i s p e r s i o n parameter 0 i s a f u n c t i o n o f t h e s i z e of t h e urban a r e a . lj The average r a d i u s o f t h e urban area i s used as t h e parameter t o r e p r e s e n t i t s s i z e . F i g u r e 3 shows D
Ij
as a f u n c t i o n o f t h e average c i t y r a d i u s f o r one wind speed and
t h r e e atmospheric s t a b i l i t i e s .
The r e s u l t s f o r t h e o t h e r m e t e o r o l o g i c a l combinations
146
R=lOkm NEUTRAL STABILITY
Up = 10 m/s
km FROM URBAN CENTER
F i g . 1: Emission D e n s i t y CrossS e c t i o n f o r t h e F i v e Model C i t i e s
F i g . 2. SCA D i s p e r s i o n Parameter, D l j , C a l c u l a t e d f o r t h e F i v e Model C i t i e s
The f u n c t i o n a l f o r m o f t h e i n d i v i d u a l D ' s i s -b 1j a power l a w w i t h r e s p e c t t o t h e average r a d i u s , i . e . D . ( R ) = a.R j. a r e i d e n t i c a l i n f o r m t o F i g u r e 3.
15
P o i n t Sources:
J
D2 and D3
The main d i s p e r s i o n f e a t u r e s o f t h e o o i n t source d i s p e r s i o n parameters, D2 and D3 a r e :
1. D2 i s n o t s e n s i t i v e t o t h e l o c a t i o n o f t h e p o i n t sources i n t h e urban a r e a .
2.
D2 and D3 a r e n o t v e r y s e n s i t i v e t o t h e roughness o f t h e urban area.
3.
D2 and D3 a r e f u n c t i o n s o f t h e average r a d i u s o f t h e urban area.
These t h r e e c o n c l u s i o n s f o l l o w f r o m t h e p o i n t source c a l c u l a t i o n s as e a r l i e r i l l u s t r a t e d f o r t h e area sources.
The medium-level p o i n t sources show more response
t o s t r o n g changes i n s u r f a c e roughness t h a n t h e area sources; n e v e r t h e l e s s , changes due t o s u r f a c e roughness a r e n o t s i g n i f i c a n t .
F i g u r e 4 shows D
2j
as a f u n c t i o n o f
average c i t y r a d i i f o r v e r y l o w wind speeds and t h r e e atmospheric s t a b i l i t i e s . The v e r y low wind speeds emphasize t h e d i f f e r e n c e s between D
lj
and DZj;
r a d i i t h e plume i s r e a c h i n g t h e ground more and more o u t s i d e t h e c i t y .
f o r decreasing For h i g h
wind speeds, DZj as a f u n c t i o n o f average c i t y r a d i u s i s a s t r a i g h t l i n e on t h e l o g - l o g graph f o r a l l s t a b i l i t i e s , j u s t l i k e D l j .
The f u n c t i o n a l f o r m o f t h e
147
UNSTABLE
VERY LOW WINO SPEEDS
5.0
+ 2
2
1
10 20 30 40 URBAN RADIUS (km)
2
3 4 5
F i g . 3. SCA D i s p e r s i o n Parameter D a F u n c t i o n o f Average City Radius
2J
.
F i g . 4. SCA D i s p e r s i o n Parameter D as a 23 F u n c t i o n o f Average City Radius
I s and D . I s a r e o n l y power laws w i t h r e s p e c t t o R f o r l a r g e urban 33
individual D radii
'Jas
Forminq t h e composite SCA D ' s The composite d i s p e r s i o n parameters, an urban c o l l e c t i v e exposure.
Dk, a r e t h e parameters needed t o c a l c u l a t e
These parameters a r e d e r i v e d f r o m t h e Dkjls.
Each
f u n c t i o n D .(R) i s m u l t i p l i e d by t h e f r e q u e n c y o f occurance o f i t s combination
kJ
o f wind speed and atmospheric s t a b i l i t y .
The f u n c t i o n s a r e combined i n t h i s
weighted manner t o b u i l d a composite f u n c t i o n Dk(R) t h a t r e f l e c t s t h e r e g i o n a l meteorology.
F o r t h e m e t e o r o l o g i c a l f r e q u e n c y f a c t o r s o f M i l w a u k i e , Wisconsin,
the resulting
D (R) i s
D1 = 690
R-'03'
kj
(10-4pg/m3/ton)
.
(1)
F o r comparative pusposes, i f we o n l y c o n s i d e r t h e power l a w p a r t f o r D2(R > 5km),
148 the resulting D2 = 32.3
-
D2(R) i s
R-Oa8'
(10-4~g/m3/ton)
.
Equations 1 and 2 i l l u s t r a t e t h r e e i m p o r t a n t p o i n t s .
The f i r s t p o i n t i s t h a t
t h e c o e f f i c i e n t i n f r o n t o f R f o r D2, E q u a t i o n 2, i s more t h a n an o r d e r o f magnit u d e s m a l l e r t h a n t h e c o e f f i c i e n t f o r D1,
E q u a t i o n 1.
The c o e f f i c i e n t f o r D3 w i l l
be more t h a n two o r d e r s o f magnitude l o w e r t h a n t h e c o e f f i c i e n t f o r depending on s t a c k h e i g h t .
D1, o r l o w e r
These c o e f f i c i e n t s show t h e r e l a t i v e c o n t r i b u t i o n a
u n i t o f emissions f r o m each e m i s s i o n c l a s s w i l l have on t h e c a l c u l a t e d urban exposure, t h e l a r g e s t c o n t r i b u t o r b e i n g D1,
a r e a sources.
The second p o i n t i s t h a t
t h e f u n c t i o n a l dependence on R i s d i f f e r e n t f o r t h e d i f f e r e n t e m i s s i o n c l a s s e s ; t h u s t h e r e l a t i v e c o n t r i b u t i o n each c l a s s o f emissions makes t o t h e exposure w i l l change w i t h community s i z e .
The t h i r d D o i n t i s t h a t f o r a l l emission c l a s s e s ,
t h e urban s i z e makes a d i f f e r e n c e i n t h e D ' s .
Thus t h e D ' s change w i t h d i f f e r e n t
urban p a t t e r n s ; t h e s e may be d i f f e r e n t growth, f o r m o r d e n s i t y p a t t e r n s . The composite SCA d i s p e r s i o n parameters express t h e e s s e n t i a l f e a t u r e s o f urban a i r p o l l u t i o n d i s p e r s i o n f o r l o n g - t e r m p o l i c y a n a l y s i s ; d i f f e r e n c e s between m a j o r e m i s s i o n c l a s s e s a r e d e s c r i b e d , and t h e main urban s i z e dependence i s c h a r a c t e r i z e d . A minimum o f emissions d e t a i l i s r e q u i r e d f o r use o f t h e SCA method due t o t h e f e a t u r e s o f t h e SCA d i s p e r s i o n parameters.
By b u i l d i n g up f r o m a base s e t o f SCA
d i s p e r s i o n parameters, d i f f e r e n c e s can be accounted f o r i n r e g i o n a l meteorology. VALIDATION AND USE The SCA method has been v a l i d a t e d i n s e v e r a l c i t i e s where d e t a i l e d emissions i n v e n t o r i e s were r e a d i l y a v a i l a b l e , namely I l i l w a u k e e and Madison, Wisconsin and Vienna, A u s t r i a .
F o r these c i t i e s , t h e c a l c u l a t e d exposure was w i t h i n 10-20% o f
t h e expected exposure based on m o n i t o r i n g d a t a and, f o r Wisconsin, d e t a i l e d i s o p l e t h s f r o m c a l i b r a t e d d i s p e r s i o n models.
F o r s e v e r a l o t h e r c i t i e s i n Europe,
g e n e r a l checks have been made and c a l c u l a t e d SCA exposures appear t o be i n reasonable agreement w i t h d a t a . The SCA method has been used i n r e g i o n a l s t u d i e s o f energy and environmental management.
The most r e c e n t i s an A u s t r i a n case s t u d y [ 7 ] .
A s e n s i t i v i t y study
i s p r e s e n t e d f r o m t h e A u s t r i a n s t u d y t o i l l u s t r a t e t h e use o f t h e SCA method.
A
h e a l t h model 181 was used t o c o n v e r t SO2 exposure t o a h e a l t h impact, expressed as Person-Days-Lost (PDL).
The s e n s i t i v i t y l o o k s a t t h e e f f e c t i v e n e s s o f t h e SO2
e m i s s i o n s t a n d a r d s assumed i n t h e s c e n a r i o s developed f o r A u s t r i a . a r e shown g r a p h i c a l l y i n F i g u r e s 5 and 6 . have a s i g n i f i c a n t e f f e c t on t h e
The r e s u l t s
While each o f t h e e m i s s i o n standards
SO2 emissions, o n l y t h e p e t r o l e u m d e s u l f u r i z a t i o n
has a s i g n i f i c a n t e f f e c t on h e a l t h impact.
T h i s i s because t h e r e s i d e n t i a l and
c o m m e r c i a l - s e r v i c e emissions ( a r e a sources) were o n l y a f f e c t e d by t h e o i l
149
s1
s1 s1 s1 S1 '' , With Desulfurization S1
1971
u I-
With Desulfurization + Present Emission Standards , With Desulfurization + Anticipated New US Emission Standards
1980
1990
2000
.5 E 5:
N
2010
2020
F i g . 5. S e n s i t i v i t y o f SO Emissions t o SO2 R e g u l a t i o n s f o r Scgnario SI, Austria desulfurization.
19171
1980
1990
2000
2010
2020
F i g . 6. S e n s i t i v i t y o f A i r P o l l u t i o n P u b l i c H e a l t h t o S O p R e g u l a t i o n s f o r Scenario 1, Austria
W i t h d e s u l f u r i z a t i o n , t h e area sources were a l r e a d y a t t h e p r e s e n t
U.S. Standard, and t h e new U.S. s t a n d a r d was assumed t o o n l y a f f e c t p o i n t sources. The c o n c l u s i o n i s t h a t t h e e f f e c t i v e n e s s o f each new SO2 r e d u c t i o n i s l e s s t h a n t h e p r e c e e d i n g one i n terms o f h e a l t h impact.
A word o f c a u t i o n must be expressed;
l o n g - r a n g e t r a n s p o r t o f s u l f a t e s i s n o t i n c l u d e d here, t h u s t h e standards would a c t u a l l y be more e f f e c t i v e t h a n i n d i c a t e d h e r e . CONCLUSION The SCA method i s a b l e t o c h a r a c t e r i z e urban a i r p o l l u t i o n d i s p e r s i o n a t t h e urban l e v e l and i t r e q u i r e s a minimum o f emissions d e t a i l .
The method has been
shown t o g i v e v a l u a b l e i n s i g h t i n t o p o l i c y a n a l y s i s i n a c t u a l s t u d i e s ; i t p r o v i d e s a "first-cut"
a n a l y s i s f o r long-range p l a n n i n g and s t r a t e g y o p t i o n a n a l y s i s .
The
SCA method p r e s e n t s o n l y one s i d e o f t h e a i r p o l l u t i o n impact p i c t u r e , t h e s h o r t range u r b a n i m p a c t .
When t h e c a u s a l a g e n t s o f t h e impacts a r e chemical r e a c t i o n
p r o d u c t s , t h e n t h e SCA method must be supplemented by a long-range t r a n s p o r t method t o balance t h e a n a l y s i s o f p o l i c y o p t i o n s .
The SCA method i s a u s e f u l and useable
150 t o o l f o r a i r p o l l u t i o n impact a n a l y s i s f o r long-range s t u d i e s when used i n t h e proper context.
REFERENCES
1 R.L. Dennis, The Smeared C o n c e n t r a t i o n A p p r o x i m a t i o n Method: A S i m p l i f i e d A i r P o l l u t i o n D i s p e r s i o n Methodology, Research Report, I n t e r n a t i o n a l I n s t i t u t e f o r A p p l i e d Systems A n a l y s i s , Laxenburg, A u s t r i a , " i n p r e s s " , (1978). 2 W.K. F o e l l , J.W M i t c h e l l , and J.L. Pappas, I h e WISconsin Regional Energy Model: A Systems Approach t o Regional Energy A n a l y s i s , R e p o r t 56, I n s t i t u t e f o r Environmental S t u d i e s , U n i v e r s i t y o f Wisconsin Energy Systems and P o l i c y Research Group, 1975. 3 E.A.
Cherniavsky, Brookhaven t n e r g y Systems O p t i m i z a t i o n Model, Brookhaven N a t i o n a l
L a b o r a t o r y , BNL-19569, December 1974. 4 J.H. Cumberland and A.J.
Krupnick, An Economic Environmental P l a n n i n g Manual f o r
C o u n t r i e s , S t a t e s and M e t r o p o l i t a n Areas, Bureau o f Business and Economic Research, U n i v e r s i t y o f Maryland, BBER-HP-1,
(1977).
5 K.W. Ragland, R.L. Dennis, and K.W.
W i l k e n i n g , Boundary-Layer Model f o r T r a n s p o r t
o f Urban A i r P o l l u t a n t s , i n D.W. Cooper (ed.), Houston Conference, March 16-20,
A.1.Ch.E.
A i r S e r i e s , Proc. A.1.Ch.E.
1975, Houston, Texas, (1976).
6 K.W.
Ragland, " p e r s o n a l communication".
7 W.K.
F o e l l , K.L. Dennis, L . Hervey, A. H o e l z l , M. Hanson, E. P o e n i t z , and
J . Peerenboom, The I I A S A A u s t r i a n Regional Energy/Environment Study, I n t e r n a t i o n a l I n s t i t u t e f o r A p p l i e d Systems A n a l y s i s , Laxenburg, A u s t r i a , " i n p r e s s " , (1978). 8 W.A.
Buehring, R.L. Dennis, and A. H o e l z l , E v a l u a t i o n o f H e a l t h E f f e c t s f r o m
S u l f u r D i o x i d e Emissions f o r a Reference C o a l - F i r e d Power P l a n t , RM-76-23, t i o n a l I n s t i t u t e f o r A p p l i e d Systems A n a l y s i s , Laxenburg, A u s t r i a , (1976).
Interna-
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam -Printed in The Netherlands
151
R A P I D E S T I M A T I O N OF ANNUAL AVERAGE CONCENTRATION AROUND A SINGLE SOURCE
D. BADELLON and A. BENECH I n s t i t u t N a t i o n a l de Recherche Chimique Appliquee
91710 VERT-le-PETIT
-
-
B.P.
NO1
-
FRANCE
ABSTRACT
A r a p i d abacus system i s h e r e w i t h proposed f o r t h e simultaneous s o l u t i o n o f t h e P a s q u i l l d i s p e r s i o n e q u a t i o n and t h e B r i g g s plume h e i g h t f o r m u l a . Y e a r l y averages a r e b e i n g o b t a i n e d by s i m p l e g r a p h i c a l s t e p s .
INTRODUCTION F o r a c o n s t a n t r a t e source, T u r n e r (1) o u t l i n e d a s i m p l e method o f computation, which n e v e r t h e l e s s may need a computer t o c a l c u l a t e annual average c o n c e n t r a t i o n s . Indeed, one has t o c o n s i d e r f o r each p a r t i c u l a r d i r e c t i o n and p a r t i c u l a r downwind d i s t a n c e a d i s t r i b u t i o n o f homogeneous wind speed and s t a b i l i t y c l a s s e s . One o b t a i n s t h e average c o n c e n t r a t i o n by summing up a l l computed c o n c e n t r a t i o n s f o r each case ( s t a b i l i t y and wind speed c l a s s ) and w e i g h t i n g each one a c c o r d i n g t o i t s frequency. Moreover, t h e use o f d i s p e r s i o n f o r m u l a r e q u i r e s , f o r each c l a s s t h e knowledge o f e f f e c t i v e s t a c k h e i g h t H a t which t h e plume becomes e s s e n t i e l l y l e v e l . T h i s h e i g h t seldom corresponds t o t h e p h y s i c a l h e i g h t o f t h e s t a c k . Our purpose i s t o propose a r a p i d s o l u t i o n f o r t h e computation o f t h e annual average c o n c e n t r a t i o n s i n a way where P a s q u i l l f o r m u l a ( f o r d i s p e r s i o n o f p o l l u t a n t s ) and B r i g g s f o r m u l a ( f o r c a l c u l u s o f e f f e c t i v e s t a c k h e i g h t ) a r e b e i n g i m p l i c i t l y c o n s i d e r e d b y an abacus. OUTLINE OF THE METHOD F o r a g i v e n source s t r e n g t h ( c o n s t a n t e m i s s i o n r a t e Q
r a t e o f h e a t emissions QH g’ h e i g h t h ) and f i x e d r e c e p t o r d i s t a n c e , 18 p o s s i b l e d i s t r i b u t i o n s o f atmospheric events ( w i n d speed c l a s s e s and P a s q u i l l s t a b i l i t y c l a s s e s ) were c o n s i d e r e d . F o r each case o f a g i v e n d i s t r i b u t i o n , we used t h e B r i g g s f o r m u l a t o compute t h e plume r i s e Ah ( f r o m 10% t o more o f 100% o f p h y s i c a l h e i g h t f o l l o w i n g t h e case). Then, w i t h t h e e f f e c t i v e s t a c k h e i g h t , we computed t h e c o n c e n t r a t i o n a c c o r d i n g t o P a s q u i l l c o r r e s p o n d i n g t o each case. The d i s p e r s i o n c o e f f i c i e n t s used i n P a s q u i l l f o r m u l a were t h o s e proposed by
152
(2).
A.S.M.E.
F i n a l l y a p o n d e r a t i o n o f P a s q u i l l e s t i m a t e s f o r each case o f t h e c o n s i d e r e d d i s t r i b u t i o n by t h e c o r r e s p o n d i n g f r e q u e n c y gave an e s t i m a t i o n o f t h e annual averaoe concentration C(d). F o r c o m p u t a t i o n a l convenience, we used t h e q u a n t i t i e s
x
C(d) x Vm x l o 6 /
Q,
(Vm i s t h e annual average
0;
(d)
=
(1) wind speed i n t h e d i r e c t i o n s o u r c e - r e c e p t o r ) .
By a p p l y i n g E q . ( l ) t o e v e r y one o f t h e 18 d i s t r i b u t i o n s , one o b t a i n s 18 c o r r e s -
ponding
x
( d ) . I n view o f r a p i d e s t i m a t i o n o f
l i t y t o expand
x
x
( d ) , we have looked a t t h e p o s s i b i -
( d ) i n h e u r i s t i c terms o f d i s t r i b u t i o n o f atmospheric e v e n t s .
I t seemed a ready
solution, i n s t e a d o f e x p l i c i t formulas, t o e s t a b l i s h m u l t i p l e
r e g r e s s i o n e q u a t i o n s between
x
( d ) and Vm (annual average wind speed) and t o t a l
f r e q u e r i c i e s o f i n s t a b l e , n e u t r a l , s t a b l e c l a s s e s i n t h e d i r e c t i o n F I , FN, Fs. The r e l a t i o n s t h u s o b t a i n e d a r e :
x
(d)
=
A V . V,
llhere AV, AI,
+
AI.
FI
+ A.,
(2)
AN, AS depend o n l y f r o m :
- physical stack h e i g h t
h
- r a t e o f heat emission
-
FN + AS. FS
Q,
distance source-receptor d
these c o e f f i c i e n t s have been computed by v a r y i n g h, Q,
d.
A l l t h e p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s were l a r g e r t h a n 0.8 and o f t e n even l a r g e r t h a n 0.98, d e m o n s t r a t i n g t h u s v e r y h i g h s i g n i f i c a n c e . l e v e l s . We had t o do e s t i m a t e c o e f f i c i e n t s ( m u l t i p l i e r s ) (AV, AI,
AN, As) r e s u l t i n g f r o m t h e r e g r e s s i o n s
i n f u n c t i o n o f h, Q,,, d. Thus, we drew f o u r abacus ( f i g . 1, 2, 3, 4 ) , t h e use o f which i s shown by t h e f o l l o w i n g example.
EXAMPLE OF USE L e t us compute t h e annual average c o n c e n t r a t i o n o f p o l l u t a n t f r o m a s t a c k 80 m h e i g h t w i t h h e a t e m i s s i o n r a t e equal t o 100 KCal/s and Q
= 208 g / s . The d i s t a n c e 9 s o u r c e - r e c e p t o r s h a l l be 600 m. The atmospheric parameters, f o r t h e d i r e c t i o n
s o u r c e - r e c e p t o r , a r e : Vm = 5 m/s
FI
=
0.015
FN = 0.030 Fs = 0.005 Computation o f t h e c o e f f i c i e n t AV ( s e e f i g . 1): The i n t e r s e c t i o n o f h o r i z o n t a l l i n e g o i n g t h r o u g h t h e v a l u e o f 80 m o f t h e h e i g h t a x i s and t h e v e r t i c a l l i n e i s s u e d f r o m 0.6 km on t h e d i s t a n c e a x i s g i v e s , by v i s u a l i n t e r p o l a t i o n , A" = 1.6 Computation o f t h e c o e f f i c i e n t AI
(see f i g . 2 ) :
The i n t e r s e c t i o n o f v e r t i c a l l i n e g o i n g t h r o u g h 0.6 km on t h e d i s t a n c e a x i s and t h e
153 l i n e g o i n g t h r o u g h t h e v a l u e 80 m on t h e l e f t a x i s ( h e i g h t s ) and t h e 100 KCal/s on t h e r i g h t a x i s ( r a t e s o f h e a t e m i s s i o n ) S i v e s AI
= 8.
Computation o f t h e c o e f f i c i e n t AN ( s e e f i g . 3 ) : The i n t e r s e c t i o n o f v e r t i c a l l i n e i s s u e d f r o m 100 KCal/s on upper a x i s ( r a t e s o f h e a t e m i s s i o n ) and t h e s l a n t a c c o r d i n g t o 80 rn ( h e i g h t h ) g i v e s a s t a r t i n g p o i n t on the v e r t i c a l a x i s (h. QH). The i n t e r s e c t i o n o f h o r i z o n t a l l i n e g o i n g t h r o u g h t h i s p o i n t and t h e v e r t i c a l l i n e descending f r o m t h e v a l u e o f 0.6 km on t h e d i s t a n c e a x i s g i v e s AN = 3.2. Computation o f t h e c o e f f i c i e n t AS ( s e e f i g . 4 ) : same as A". I t f o l l o w s from equation ( 2 ) t h a t
x
( 0 . 6 km)
=
We f i n d AS = 2.5.
8.23 and C ( 0 . 6 am) =
(8.23 x 208. x 0.05 / 5 ) x F o r t h e c o n s i d e r e d emission, s o u r c e - r e c e p t o r d i s t a n c e and frequency, t h e annual average c o n c e n t r a t i o n e s t i m a t e i s equal t o 1 7 pg/m3.
LIMITS OF THE METHOD The f i r s t l i m i t s a r e t h o s e common of t h e a n a l y l i c a l models of d i s p e r s i o n : s t a t i o n n a r i n e s s o f t h e atmosphere, n e g l e c t e d e f f e c t s o f topography and roughness. Then, on does n o t c o n s i d e r t h e c o n t i n u o u s v a r i a b i l i t y o f atmospheric e v e n t s . The average o f a n a l y t i c a l r e s o l u t i o n s a c c o r d i n g t o t y o i c a l atmospheric cases r e f l e c t a superposition o f quantified states. Our abacus i s n o t a c c u r a t e f o r e v e r y case ( l o w h e i g h t s and i n t h e p r o x i m i t y o f t h e s t a c k ) . Moreover t h e abacus i s s p e c i f i c f o r t h e computation o f plume r i s e by B r i g g s f o r m u l a and f o r t h e d i s p e r s i o n by P a s q u i l l e q u a t i o n u s i n g A.S.M.E.
of s t a n d a r d d e v i a t i o n . Indeed, t h e use o f o t h e r f o r m u l a s would
coefficients
give a d i f f e r e n t
abacus. F i n a l l y , B e n a r i e ( 3 ) has shown t h a t t h e knowledge o f wind sneed d i s t r i b u t i o n i n t h e d i r e c t i o n s o u r c e - r e c e p t o r g i v e s d i r e c t l y t h e s l o p e o f log-normal frequency d i s t r i b u t i o n o f c o n c e n t r a t i o n s . With t h e above r a p i d e s t i m a t i o n o f t h e annual average concentration, i t i s possible t o estimate the p r o b a b i l i t y o f
of a c o n c e n t r a t i o n
exceeding a g i v e n l e v e l . REFERENCES
1 Turner, Workbook o f atmospheric d i s p e r s i o n e s t i m a t e s N . T . I . S . (1970) 2 A.S.M.E , Recommended Guide f o r t h e p r e d i c t i o n o f a i r b o r n e e f f l u e n t s (1968) 3 B e n a r i e Le c a l c u l de l a dose e t de l a nuisance du p o l l u a n t emis p a r une source po n c t ue l e . A t m . Env. 3 (1969) 467-473
154
t
A"
FIG.l
Ai
120
w
I
3
1
L
I I I I l l 5 6 I 8 91
D
I. F 10.4
Figures
1 t o 4.
C o e f f i c i e n t s acc o r d i n g t o Eq.(2)
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam
POLLUTION ZONES P.L.
-
- Printed
155
in The Netherlands
A WORKABLE CONCEPT?
SCUPHOLME and J . M .
SHARKEY
Environmental C o n t r o l C e n t r e , B r i t i s h P e t r o l e u m Co.Ltd.,
(UK)
SUMMARY T h i s p a p e r l o o k s a t some of t h e p r a c t i c a l problems a s s o c i a t e d w i t h t h e d e f i n i t i o n and c o n t i n u e d r e a s s e s s m e n t of p o l l u t i o n z o n e s , u s i n g a i r p o l l u t i o n measurements. F a c t o r s c o n s i d e r e d a r e t h e number and s i t i n g o f SO2 m o n i t o r s , measurement e r r o r and A t t e n t i o n i s drawn t o t h e
t h e i n f l u e n c e of y e a r l y m e t e o r o l o g i c a l v a r i a t i o n s .
importance of t h e s e c o n s i d e r a t i o n s i n t h e c a s e of a "marginal" zone.
INTRODUCTION L e g i s l a t i o n t o reduce atmospheric p o l l u t i o n is being introduced i n c r e a s i n g l y t h r o u g h o u t t h e world.
The l e g i s l a t i o n u s u a l l y r e q u i r e s some r e d u c t i o n of e m i s s i o n s
of t h e p o l l u t a n t concerned. SO2,
The p o l l u t a n t t h a t i s most w i d e l y l e g i s l a t e d f o r i s
and s i g n i f i c a n t improvements i n ambient a i r q u a l i t y have been a c h i e v e d by t h e
u s e of a l t e r n a t i v e f u e l s , p a r t i c u l a r l y i n t h e d o m e s t i c s e c t o r , by r e d u c i n g t h e s u l p h u r c o n t e n t of f u e l s , by t h e u s e of t h e " t a l l s t a c k s p o l i c y " ,
and t o a much
l e s s e r e x t e n t , by t r e a t i n g f l u e g a s e s t o remove SO
2'
Where n a t i o n a l o r r e g i o n a l a u t h o r i t i e s opt f o r t h e u s e o f low s u l p h u r f u e l s ,
it i s c l e a r l y c o s t - e f f e c t i v e t o c o n c e n t r a t e t h e u s e of t h e s e f u e l s i n t h e a r e a s where c r i t i c a l p o l l u t i o n l e v e l s a r e exceeded.
T h i s l e a d s t o t h e concept of
p o l l u t i o n z o n e s , which i n e v i t a b l y have t o b e e s t a b l i s h e d on t h e r e s u l t s of p r a c t i c a l measurements of a i r p o l l u t i o n l e v e l s . number o f p o s s i b l e l i m i t i n g f a c t o r s .
I n h e r e n t i n t h e s e measurements a r e a The p u r p o s e of t h i s p a p e r i s t o h i g h - l i g h t
these factors.
ZONAL DEFINITION P o l l u t i o n c o n t r o l must of n e c e s s i t y be a compromise between t h e t e c h n i c a l , s o c i a l and economic r e q u i r e m e n t s , i n c l u d i n g t h e l o g i s t i c s of low s u l p h u r f u e l supply. The r e l a t i o n s h i p s between t h e s e f a c t o r s are t o o complex t o be r e s o l v e d i n t h i s b r i e f p a p e r , b u t a c l o s e l o o k i s t a k e n a t some of t h e t e c h n i c a l a s p e c t s .
Zones c a n b e e s t a b l i s h e d i n e i t h e r a s t r i c t l y p r a c t i c a l way b a s e d on a n i n t e r p r e t a t i o n of h i s t o r i c a l a i r p o l l u t i o n d a t a , o r t h e y c a n be e s t a b l i s h e d by a combined modelling/measurement
a p p r o a c h u s i n g t h e measurements f o r model v a l i d a t i o n .
P r a c t i c a l measurements w i l l n o t o n l y be i m p o r t a n t a t t h e p l a n n i n g s t a g e b u t w i l l a l s o b e e s s e n t i a l i n m o n i t o r i n g t h e e f f e c t i v e n e s s of a d o p t e d c o n t r o l measures. T h e r e a r e t h r e e i m p o r t a n t f a c t o r s which i n f l u e n c e t h e measurement and i n t e r p r e t a t i o n of a i r q u a l i t y d a t a : -
(i)
Number and s i t i n g o f m o n i t o r s .
( i i ) Monitor accuracy. ( i i i )M e t e o r o l o g i c a l v a r i a t i o n s . T h e s e a r e p a r t i c u l a r l y i m p o r t a n t i n t h e c a s e of " m a r g i n a l " z o n e s , t h a t i s zones w i t h i n which t h e measured p o l l u t i o n i s n e a r t o t h e a i r q u a l i t y l i m i t f o r d e f i n i n g zones.
I n t h e f o l l o w i n g s e c t i o n s t h e i m p o r t a n c e of t h e s e f a c t o r s i s i l l u s t r a t e d
u s i n g comprehensive e m i s s i o n and a i r q u a l i t y d a t a c o l l e c t e d d u r i n g a y e a r ' s i n t e n s i v e a i r p o l l u t i o n survey i n Reading, L K ( r e f . 1).
NUMBER AND SITING OF MONITORS The p o s i t i o n i n g of a i r p o l l u t i o n m o n i t o r s r e q u i r e s c a r e f u l c o n s i d e r a t i o n , and depends l a r g e l y on t h e p u r p o s e of t h e measurements.
T h e r e i s no g e n e r a l formula
f o r d e t e r m i n i n g t h e optimum number and l o c a t i o n o f m o n i t o r s i n a g i v e n a r e a , a l t h o u g h g u i d a n c e can be o b t a i n e d from e x p e r i e n c e a t o t h e r l o c a t i o n s ( r e f . 2). I n g e n e r a l , z o n e s w i l l h a v e t o be i d e n t i f i e d from t h e r e s u l t s o f e x i s t i n g m o n i t o r s , however i n a d e q u a t e t h i s i n f o r m a t i o n may be.
A t Reading 40 SO2 m o n i t o r s w e r e p o s i t i o n e d t h r o u g h o u t t h e e n t i r e u r b a n area. The d i s t r i b u t i o n of t h e a n n u a l a v e r a g e SO2 c o n c e n t r a t i o n s w e r e d e t e r m i n e d u s i n g R
computer c o n t o u r i n g program ( f i g .
1).
F o r a h y p o t h e t i c a l s i t u a t i o n where t h e r e
a r e f e w e r m o n i t o r s t h e d i s t r i b u t i o n of SO2 l e v e l s may n o t be s o w e l l u n d e r s t o o d . Such a s i t u a t i o n h a s been s i m u l a t e d by randomly s e l e c t i n g 10 m o n i t o r s from t h e
40 at Reading.
T h r e e s i m u l a t i o n s w e r e c a r r i e d o u t and computer drawn c o n t o u r s
were produced b a s e d on t h e a n n u a l a v e r a g e SO2 l e v e l s a t e a c h s e t of 10 m o n i t o r s I f t h e a i r q u a l i t y l i m i t w e r e 80 ,pg/m3,
( f i g s . 2-4).
t h e n t h e r e s u l t s i n each
c a s e would j u s t i f y t h e s e t t i n g up of a z o n e , a l b e i t w i t h d i f f e r e n t s i z e s , whereas i f t h e l i m i t were 100 fg/m3,
t h e n o n l y t h e r e s u l t s of t h e s e l e c t e d m o n i t o r s i n
f i g u r e 2 would j u s t i f y a zone. This simple demonstration c l e a r l y i n d i c a t e s zone l i m i t s ,
d
p o t e n t i a l problem o f i d e n t i f y i n g
p a r t i c u l a r l y i n t h e case of a " m a r g i n a l " z o n e , when t h e r e are o n l y
a few m o n i t o r s .
I n r e a l i t y t h e number of m o n i t o r s i n most towns t h e s i z e o f
Reading would u s u a l l y be a b o u t 3.
I n " m a r g i n a l " cases c l e a r g u i d e l i n e s w i l l be
needed t o d e t e r m i n e m o n i t o r i n g r e q u i r e m e n t s .
157
Fiyure I Annual average
SO levels at 2 Reading, pg/m3. ( + indicates
monitor site)
MONITOR ACCUMCY Measurement error in air pollution studies can be significant, particularly with continuously monitoring equipment.
In the UK the Warren Spring method is
quoted as having an accuracy of 210% at low levels, for daily observations, whereas a widely used coulometric analyser claims an accuracy of better than
+Is%
for continuous measurement.
This could lead to significant errors in
annual average concentrations which, in the "marginal" case, could lead to the unnecessary introduction of zones.
One possible solution could he to have a
range of concentrations as the air quality limit rather than a fixed level, thereby allowing a safety margin.
METEOROIBGY It is well known that the meteorological conditions in any area vary from year to year.
These conditions, particularly atmospheric stability, affect SO
dispersion,
2
ground level concentrations and therefore the definition of zones.
T o demonstrate this effect, the dispersion model STACMAP (ref. 3 ) was used to calculate annual average SO2 levels using the Reading emission data and rneteorologica data for two years "A" and "B"
(figs. 5-6).
Since the emission data are the same
for both sets of calculations, the differing SO patterns are entirely due to the 2
differences in meteorological conditions.
In these examples, if the air quality
limit were 70pg/m3, then the data for year "A" (fig. 5) would not justify a zone. However the meteorological conditions for year "B" exceed 70 p g / m 3
(fig. 6) could cause levels to
and in this case there would be some justification for setting up
a zone. This study suggests that it would be preferable to average more than one year's air pollution measurements, thereby allowing a more reasonable assessment,
158
Figure 2 Annual average SO
2
levels a t
Reading, b g / m 3 ,
+u 1 n
based on 10
randomly s e l e c t e d
monitors. ( + indicates
monitor s i t e )
Figure 3 Annual average SO l e v e l s a t 2 3 Reading, p g / m
,
based on 10 randomly s e l e c t e d monitors. (+ indicates
monitor s i t e )
Figure 4 Annual average
SO
2
levels a t
,
Reading ,ug/m
3,
based on 10 randomly s e l e c t e d monitors
..
( + indicates
monitor s i t e )
159
Figure 5 Annual average
SO
2
levels
calculated using STACMAP and Meteorological Data "A".
Figure 6 Annual average
SO
2
levels
calculated using STACMAP and Meteorological Data "B".
consistent with the underlying trend in SO2 emissions, of the need for a zone in a "marginal" case. DISCUSSION
In this brief look at some of the practical aspects of zoning, it has been shown that a realistic interpretation of air quality data is required.
Full account must
be taken of the number and siting of air pollution monitors, monitor accuracy, and the important influence of yearly changes in meteorological conditions.
Similarly
the successful application of intermittent control systems to minimise the effect of pollution episodes would also be limited by these factors.
160 Pollution zones are undoubtedly an acceptable concept, but their effective working, particularly in marginal situation, will require a flexible approach. Zone definition and enforcement is a complex subject, and at some stage guidelines on monitoring, and the interpretation of monitoring data, will have to be provided.
By drawing attention to some of the important technical aspects of zones it is hoped that this paper will encourage a full discussion on the types of guidelines required
.
REFERENCES 1 K.J. Marsh and M.D. Foster, Atmospheric Environment, 1 (1967) pp.527-550. An Experimental Study of the Dispersion of the Emissions from Chimneys in Reading. 2 P.C. Blokker, CONCAWE Report N o 7/73. Major Aspects in Air Pollution Monitoring in Urban and Industrial Areas. 3 M.L. Huisman and C.M. Verheul, KIVI, 1974 (Koniklijk Instituut van Ingenieurs, Prinsessegracht 2 3 , The Hague). STACMAP Air Pollution Dispersion Model.
Atmospheric Pollution 1978, Proceedingsof the 13th InternationalColloquium,Paris,France, April 25-28,1978, M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
161
THE CHARACTERIZATION OF THE PARTICLE SIZE DISTRIBUTION FROM OIL-FIRED BURNERS WITH A BETA DISTRIBUTION
A.S.
GOLDFARB and J.W. G E N T W
Department of Chemical Engineering, University of Maryland, College Park, Maryland (U.S.A.)
ABSTRACT A modified Beta distribution has been developed to characterize the particle size distribution from an oil-fired boiler.
The properties of the distribution
are discussed and illustrated with applications to a filter and a cyclone. Experimental measurements of the particle size distribution were obtained with a seven stage Andersen-inertial impactor.
Experimental measurements were carried
out during soot blowing and for non-isokinetic sampling as well as for isokinetic sampling. The Beta distribution along with a numerical analogue of the impactor was used to characterize the data.
In comparison with the log-normal distribution, the
Beta distribution more closely described the experiments.
The standsri. deviation
of the Beta distribution did not vary for the experimental conditions.
INTRODUCTION In characterizing particles emissions from boilers, it is necessary to specify the particle size distribution as well as the particle loading.
Previous studies
have assumed a log normal distribution (ref. 1) with an average stage diameter (ref. 2 ) .
This paper discusses the correlation of experimental data, as well as
changes in the particle size distribution during soot blowing and for anisokinetic sampling.
BETA FUNCTION The modified Beta distribution F(X,a,b) is defined by
where the variable X is given by
x
= Ln (d/d
)/Ln (dmx/dMIN) (2) MIN are the maximum and minimum particle sizes respectively. The paradmx and d MIN meters a and b are used to characterize the distribution and the r(a), T(b), are
gamma functions.
Defined as above the Beta function is normalized with the value
of X lying between 0 and 1. The Beta distribution shows the following characteristics:
1. The distribution has a distinct upper and lower bound. 2 . The distribution can represent non-symmetrical distributions.
3. The distribution can fit monotonically decreasing distributions.
4. In the limit of a
=
b, the distribution is symmetrical and approaches a
log-normal distribution. 5. The distribution is mathematically convenient.
6. The distributioncan represent only unimodal functions.
The primary advantage of the distribution lies in that it represents a more general class of size spectra than the log-normal distribution.
It is convenient
mathematically, comparable to the log-normal distribution when an analogue computation is used.
However, there is no convenient analogy to the characteristic
diameter method for the log-normal distribution. For most applications the distribution is treated as if there were two unknown parameters -- a and b. be 100 pm and 0.001 pm.
The values of dmx
and dMIN were arbitrarily assumed to
However in some circumstances, it is possible to deter-
mine upper and lower bounds.
For example, the lower bound through a thin capil-
lary might be taken as the size where the collection efficiency due to diffusion was 99.98, or the upper bound for nuclepore filters would be the diameter of the pores.
For these cases, dmx
and dMIN can be determined.
In Figure 1, a comparison of the best fits obtained with a Beta distribution and with a log-normal distribution for a model of a membrane filter is given. Partial efficiencies for impaction, diffusion, and interception were taken from the literature.
The pore diameter was taken as d and dMIN and was determined MAX The circles represent the original
from the Kennedy-Gormley equation (ref. 3).
distribution before the filter, and the triangles with distribution after the filter.
The solid line corresponds to the best fit with the Beta distribution
and the dotted line the corresponding fit with the log-normal distribution.
The
results indicate the greater versatility of the Beta distribution.
EXPERIMENTAL PROCEDURES Experimental measurements of the particle size distribution and total particle loadings were carried out for two installations
--
a boiler stack with a height
of 61 m (sampling was at 33.5 m) and a diameter of 3.28 m, and a heater stack a height of 15.2 m and a diameter of 1.37 m.
Sampling was done at or near iso-
kinetic conditions using an eight stage Andersen impactor (ref. 4 ) .
A backing
filter was employed for the measurements with the boiler and there was some deposition on the first plate.
A schematic of the impactor is shown in Figure 2.
163 JET VELOCITY (FT/SEC) AT 314 CFM
80
C U M L A T M Mb5S FRACTlCN
Fig. 1 Comparison Between
Fig. 2 Schematic of Anderson Impactor
Beta and Log-Normal Distributions for Membrane Filter Sampling was carried out using standard source testing procedures although the duration of the sampling period was varied to reflect different ash contents in the fuel. Typical operations were at a boiler load of 350 kgm/min with the ash content of the fuel varying from 0.011 to 0.350.
The low ash content fuels were Libyan
crude oil and the higher ash fuel standard fuel oil.
The flow rate in the stack
was approximately 6 m/sec and the temperatures at the sampling locations were in the range of 155
-
196°C.
DATA PROCESSING The raw data consisted of the mass deposited on each stage.
From these data,
the cumulative mass fraction penetrating through all prior stages could be found. The simplest analysis consisted of assuming an ideal stage and a characteristic diameter.
This method was used with a log-normal distribution.
A more complicated procedure employed the experimental data of Ranz and Wong
to determine a curve relating the efficiency to particle size.
With this method
(called the analogue method), the initial distribution was assumed and the deposition on the subsequent stages calculated.
The parameters of the initial distribu-
tion were adjusted by standard optimization algorithms in order to determine the best fit of the data. Both the Beta and log-normal distributions were used, and the objective function was based upon the cumulative mass distribution.
Comparison of the three
164
2
>
W
CBETA I
I
0 I
'
'
,
,
,
,
,
,
,
,
0
0
0
0
0
0
0
0
'
I
'
'
I
'
'
1
A
I
2
3
4
5
6
SAMPLE
7
8
9
1
0 I
NUMBER
2
3
4
SAMPLE
5
d
6
7
8
9 1 0
NUMBER
Fig. 3 Geometric Standard Deviation
Fig. 4 Geometric Mean Diameter for
for 10 Samples
10 Samples
methods is given in Figures 3 and 4.
RESULTS In Figures 3 and 4 the geometric standard deviations and geometric mean diameters are presented for ten experimental measurements of the particle size distribution from the boiler stack.
The parameters were calculated by three methods:
(1) the log-normal distribution with a characteristic diameter for each stage, (2) the log-normal distribution with a numerical analogue, and (3) the Beta dis-
tribution with a numerical analogue. The most striking features of this analysis are the following: 1. 2.
3.
The standard deviation shows little variation between experiments for the Beta distribution The mean particle size as given by the Beta distribution and by the lognormal distribution with a characteristic stage diameter were approximately the same. In 60% of the experiments the Beta distribution gave a closer fit. In all cases the analogues gave better fits than the characteristic diameter.
The experimental conditions covered in these ten runs covered a wide range of conditions.
1.
2.
The most significant results can be summarized as follows:
Ash content had little effect on the particle size distribution. The sampling conditions for runs 2, 3, and 4 were almost identical except that the ash content in the fuel for runs 3 and 4 (essentially duplicate runs) was a factor of 10 higher than 2 . No significant difference in the particle distribution function was observed. No significant trends were observed with respect to stack gas velocity (1100 - 860 ft/min) or stack temperature (384 - 311°F).
In Table 1, the results are summarized comparing mean diameters and emission
rates as a function of fuel ash content and the extent of the departure from isokinetic sampling conditions.
The standard deviation remains constant for all of
The emission rate was found to be proportional to the ash content.
these runs.
The particle size with the possible exception of the lowest ash content was independent of ash content and all indications suggest that the sample was not altered by departure from isokinetic sampling.
TABLE I COMPARISON OF E M I S S I O N S WITH ASH CONTENT €OR BOILER
A s h *:ontent %
D e v i a t i o n from Isokinetic Sampling
Geometric M e a n Particle S i z e
(urn)
E m i s s 1 0 n Rate
(Gr/SCfl
0.011
10
.19
0.003
0.011
3
.1?
0.004
0.045
4
.20
0.013
0.043
1
.30
0.019
0.043
-11
.33
0.020
0.039
18 2
.33
0.022
.35
0.031
.33 .32 .30
0.054
0.040 0.300
10
0.350
7
0.330
15
0.047 0.050
The soot blowing measurements were taken with the heater stack where the velocity was at 6.9 m/sec and the temperature of the gas was at 420'C. heater showed a broader distribution than the boiler.
Typically the
The standard deviation was
2.1 for normal operation and 1.6 for soot blowing while the mean particle size increased from 3.5 to 2.1.
CONCLUSIONS The principal result of this study is that the Beta distribution appears to be a better method of characterizing particle size distribution than the log-normal distribution.
Sampling on a boiler at a sufficient height that the gas had cooled
to 150 - 200°C indicated that the shape of the distribution was not appreciably altered by the ash content or the departure from isokinetic conditions. particle loading was proportional to the ash content.
REFERENCES 1. 2. 3.
4.
T. Hatch and S . P . Choate, J. Franklin Inst., 207(1929)369. G. Kubie, J. Aerosol Science, 2(1971)23-30. P. Gormley and M. Kennedy, Proc. Roy. Irish Acad., 52A(1949)163. A.A. Andersen, J. Bacteriol., 76(1958)471-484.
Total
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris,France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
167
ANALYTICAL MODELING OF POLLUTANT DISPERSION DURING CALM WIND SITUATIONS. C1. DEMUTH, A. BERGER, Y. JACQUART and Ch. LEGROS Institut d'Astronomie et de Geophysique, Universitg Catholique de Louvain - Louvain-la-Neuve (BELGIUM)
ABSTRACT Most of the air pollution dispersion models are applicable only when the wind has a well defined direction. The purpose of this paper is to present and apply an analytical model €or calm wind situations when there is a finite mixing height. The region used in this first test is that of Antwerpen for which some meteorological parameters and a great number of point sources are available.
INTRODUCTION Most of the air pollution models do not take into account periods of "calm wind", which maybe defined as periodsduring which the wind speed at the anemometer level over a flat and open terrain is less than 1 knot. Such events are not unusual at all (generally 3 to 5 % of the total cases, depending on the region). Taking them into account requires more informations about the atmospheric boundary layer in order to determine the radial and vertical diffusivity parameters as a function of the time-space variables, and mainly of the ambient atmospheric stability. We wish to present here some results about an atmospheric stability analysis during calm wind situations and also an approach to the modeling of such conditions from a study by Berlyand et al. (ref.11, and a first application of the model we propose. I. ATMOSPHERIC STABILITY DURING CALM SITUATIONS The stability of the atmospheric boundary layer in which the plume rises almost vertically can be determined from synoptic data by means of an appropriate scheme, as for example Turner's (ref.2). If the
168
latitude and longitude of the station, the wind speed, the cloud cover and the ceiling are known, a procedure defined by Turner enables to determine the atmospheric stability. This maybe applied to calm wind situations, with the only remark that Turner does not consider the slightly stable condition (E class) occuring during calm wind. Table 1 shows the frequency of occurence of the different stability classes during calm wind situations over a period of 20 years at a station (Deurne) localised 6 km to the South-East of Antwerpen. The outstanding information of this table is that the day is divided in two parts, as far as stability is concerned: during the daylight the atmosphere is unstable, whereas it is stable during the night. The neutral stability appears almost equally during day or night. The C class (slightly unstable) is the most frequent of the unstable classes, while the G class (extremely stable) is two times more frequent than the F class (moderately stable).
All these properties
TABLE 1 Frequency of occurrenceof stability classes during calm wind situations at Deurne (Antwerpen) from Turner's scheme, for a twenty years period. Calm winds are observed for 3% of the total cases. Classifications Extremely unstable Moderately unstable Slightly unstable Neutral (day) Neutral (night) Slishtlv stable Moderately stable Extremely stable
Pasquill category A 1 B 2 C 3 Dj 4 Dn 4 E 5 6 F G
7
Frequency ( % ) 2 5
28
a
9 0 16 32
Moment of appearance day day day day night night night night
are not only very useful for the choice of a plume rise formula, but
also, because the physical mechanisms which determine the diffusion of the pollutants depend on stability. In case of unstability, the atmospheric turbulence is created by the deviations to adiabaticity. The warmest eddies are rising while the coldest ones are subsiding, the dimensions of this circulation being larger when the solar radiation is more intense. During a stable period, free convection does not appear any more and the diffusion is similar to the molecular diffusion.
169
11. MODELING This distinction between the physical processes must appear in the models for calm winds.
Therefore, we propose the following
simulation : for the unstable cases, we will take the model by Berlyand et al. (ref.1) defined by diffusivity coefficients varying in space, but where we introduce a reflection at the top of the mixing layer. For the stable cases, we will take a model with constant diffusivity coefficients. A difficulty is occuring, however, with the model by Berlyand when one tries to simulate real-time pollution, that means when one tries to determine the time-evolution of concentration during a whole period of calm wind during which it is possible to get synoptic observations. The model by Berlyand gives a stationary solution of the problem and not the unstationary solution, as will be presented, hereunder, through defining mathematically the problem of diffusion during calm wind situations. If we know the radial (K ) and vertical ( K ) diffusivity paramer ters, the estimation of the concentration (x) of a pollutant during a “calm” requires the solution of the following time-dependent problem
:
with the boundary conditions K Z S = O
lim
x
=
0
a t z = O
and
+
z 2 ?.
when r2
-
:
z = L
and the following condition, coming from the property of cylindrical symmetry around the vertical axis at the source.
The parameters of the problem are the mass output rate of pollutant ( Q ) ,the effective height (H), the mixing height or the altitude of
the inversion ( L ) and Dirac‘s function 6 (r). Very few analytical solution to this problem are existing : if Kr and KZ are constants, the concentration at the ground level is expressed by Ukeguchi et al. (ref.3) as
:
170
where
:
It is important to note that (5) is equal to the concentration in the stationary case : x(r,z
=
0
,
t
=-)
=
2rHK
m
1
[ -
r
g
+ n=l z
1
(-
R-
1 + -R+ )I
(7)
multiplied by a function that characterizes the transitional regime. It seems that there do not exist other solutions at present. Solutions to the stationnary case are more numerous. Berlyand-Kurenbin (ref.1) provides an example of a steady state solution when KZ = K1 zn and Kr = B 2 ry zm where n and m are real numbers, and y < 2. If there is no inversion and for y = 1 , the concentration at the ground is given by :
with A = 0 , 2q = m - n + 2 , u = (m+1)/2q and where the value of KZ and Kr for r = z = H is represented respectively by KZ(H) and Kr(H). If the plume rise is limited by a temperature inversion (L # - I , then the solution by Berlyand ( a ) , as proposed by Demuth et al.(ref.4) can be written under a more complicated form through the introduction of a non-zero term A into (8):
171
m
The analysis of the expression (8) with (9) shows that there is a concentration maximum when n > 0.2 Because of the difficulty to get the transitional part of the diffusion problem with variable coefficients, we suggest to take, in a first approach, the transitional part of the solution with constant coefficients and modify these coefficients in order to approximate as much as possible the evolutive solution that would result from the numerical solution of the problem (1). This way of handling is required because, during the time course, the concentration is always limited by its stationary value. If we want to compare the computed and measured concentrations, we have to average the time-solution over the period of calm, because most of the time, the observation is in fact a mean value over the sampling time. Then, the integration of the transitional regime is easy if one notes that : ]erfc ($)dT
=
-2a
A-
a2
a J;
- exp [- - I + erfc (-1 V
T
T
[2a2
+TI
111. APPLICATION The application of such a proposed model requires the definition of all the parameters connected with stability and the choice of a plume rise formula. For calm wind situations study, we found, at least, two formulas in the litterature : Bosanquet (ref.5) for the neutral case and Briggs (ref.6) for the stable case. These formulas are respectively : Ah
=
0.666 *v(~s-~~) [(t+to)3 / 4 t JA
T1
-
J: [
0.283
-r
0.5 to3 / 4 ,
’ 1/2
172
with : Ts T1
t+t, t to V
g
Qv
absolute temperature of the waste gas (OK) absolute temperature at which waste gas has : atmospheric density ( O K ) : 200 sec. maximum time since waste gas left the chimney (sec.) : time taken by waste gas to attain its exit momentum under the influence of buoyancy alone (sec.) exit velocity of waste gas (m.sec-1) :
F S
A
acceleration of gravity ( m.sec-2) volume of effluent measured at atmospheric density emitted in unit time ( 3.sec-1) buoyancy flux (m4.sec-'1 stabi1ity parameter ( sec- ) mean dilution coefficient (0.13)
The plume rise formula for the unstable case can be chosen with reference to table 1. Because the majority of the unstable cases during calm wind situations is found in the C class, which is very near the neutral class D, the formula of Bosanquet to compute the plume rise during the unstable cases, may probably be used. As an application, we intended to simulate the persistence of a calm wind situation and to compute the concentration from hour to hour in order to survey the evolution of the concentration. We chose the receptor ZR 826 in the region of Antwerpen (ref.4), receptor which is located inside an important industrial zone where many sources are concentrated within a circle of less than 1 km around this receptor. The constants defining the turbulent diffusivity parameters for the unstable case are taken as follows : m = 0.15
,
n = 1
,
K1
=
0.15 m/sec
and
B 2 = 0.09 ~3*85/sec(14)
In the stable case, the diffusivity parameters must be taken as 1.36 mz/sec. The model that we developed has been applied during a period of unstable calm wind situation (we do not have yet enough statistical information about stable conditions occurring during calm wind situations). Table I1 provides the concentrations at the receptor Z R 826 for each hour, due to the 142 nearly located sources.
173
TABLE I1 Concentrations in u,g/m3 computed during an unstable calm wind period, with L = 1500 m. hour 1 2 3 4 5 6
IV.
Ah = 0 1
12 28 44 58 70
Ah (Bosanquet) 0.1 2 5 11
16 20
CONCLUSION
Taking into account the uncertainties about the parameters characterizing the calm wind situations, these results seem to be encouraging. A more exhaustive analysis of the unstationary diffusion problem and the analysis of the statistics of calm wind situations, is now under way. ACKNOWLEDGEMENT This study is part of the Air Project of the Belgian National Programme on the Environment sponsered by the Ministry of Scientific Policy. The authors wish to express their gratitude for the financial assistance with the aid of which the work was carried out. REFERENCES 1 M.Ye Berlyand and 0.1. Kurenbin, in Atmospheric Diffusion of
2
3 4
5
6
impurities during a calm. American Institute of Crop Ecology Survey of USSR. Air Pollution Literature, Vol IV, edited by Nuttonson, 1970. D.B. Turner, J. Applied Meteorol., 3 (1964), 83. N. Ukeguchi, H. Okamoto and Y. Ide, in Proceedings of the third International Clean Air Congress, Dusseldorf, Federal Republic of Germany, 1973, B66-B68. C1. Demuth, A. Berger, Y. Jacquart and G. Schayes, in 8 th Intrenational Technical Meeting on Air Pollution Modeling and its Applications, Louvain-la-Neuve, September 20-23, 1977,Belgium. C.H. Bosanquet, Journal of the Institute of Fuel, 30(1957), 322-328. G.A. Briggs, in Plume Rise, U.S. Atomic energy Commission, 1969, 31. E.W. Ng and M. Geller, A table of integrals of the error functions., Journal of Research of the National Bureau of Standards, Vol 73B, 1969,l-20. Data-Bank Lucht S.C.K./C.E.N., Dee1 1, Werkgroep Mathematische Modellen, S.C.K./C.E.N. , Moll Augustus 1976.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
175
PEAK SHORT TERM DUSTFALL FROM DUST GENERATING INDUSTRY : ITS MEASUREMENT AND ASSESSMENT AND EFFECT ON RESIDENTIAL DEVELOPMENT R.H.
WILLIAMSON, J.H. ERKINS and A . CANTRELL
School o f Sciences, Deakin U n i v e r s i t y , Geelong, V i c t o r i a , A u s t r a l i a
ABSTRACT Because o f t h e l i m i t a t i o n s o f atmospheric d u s t e m i s s i o n c o n t r o l technology a v a i l a b l e , v a r y i n g m e t e o r o l o g i c a l c o n d i t i o n s and t h e o c c a s i o n a l p l a n t m a l f u n c t i o n , t h e cement i n d u s t r y may sometimes f i n d i t s e l f i n c o n f l i c t w i t h r e s i d e n t s l i v i n g i n i t s l o c a l i t y because o f nuisance d u s t f a l l l e v e l s . Rather t h a n r e l y on average d u s t f a l l f i g u r e s based on m o n t h l y d u s t d e p o s i t c o l l e c t i o n t h e a u t h o r s m a i n t a i n t h a t i t i s t h e s h o r t t e r m (e.g.
3
-
5 h r ) peak
d u s t f a l l i n a p a r t i c u l a r area which provokes a h o s t i l e r e a c t i o n f r o m r e s i d e n t s i n t h a t area. A t e c h n i q u e i s d e s c r i b e d by which t o measure s h o r t t e r m d u s t f a l l , t o assess t h e degree o f n u i s a n c e and t o d e f i n e an adequate b u f f e r zone. INTRODUCTION I n t h e manufacture o f cement, t h e c o m p l e x i t y and s c a l e o f o p e r a t i o n o f t e n poses l a r g e t e c h n o l o g i c a l problems and n o t l e a s t , i n t h e a r e a o f c o n t r o l o f d u s t discharged t o t h e atmosphere b o t h by s t a c k emissions and l o w l e v e l sources.
I t i s now g e n e r a l l y
r e c o g n i z e d t h a t b u f f e r zones a r e r e q u i r e d t o s e p a r a t e t h e s e i n d u s t r i a l d u s t sources and areas proposed f o r r e s i d e n t i a l development even though t h e i n d u s t r y complies w i t h t h e l e g i s l a t i v e r e s t r i c t i o n s imposed on t h e s e s t a c k d u s t emissions ( r e f . 1 ) . However, because o f t h e l i m i t a t i o n o f d u s t e m i s s i o n c o n t r o l technology, p l a n t malf u n c t i o n , m e t e o r o l o g i c a l c o n d i t i o n s and/or l o w l e v e l d u s t sources t h e i n d u s t r y may o c c a s i o n a l l y be i n c o n f l i c t w i t h r e s i d e n t s (and c o u n c i l s ) beyond t h e b u f f e r zone/ r e s i d e n t i a l area i n t e r f a c e , due t o nuisance d u s t f a l l l e v e l s . F o r t h e s e reasons, even though improved t e c h n o l o g i c a l c o n t r o l and good works 'housekeeping' w i l l e f f e c t i v e l y reduce atmospheric d u s t p o l l u t i o n and t h e degree o f d u s t n u i s a n c e i n t h e l o c a l i t y , t h e a u t h o r s m a i n t a i n t h a t measurement o f d u s t f a l l i n s e n s i t i v e areas i s s t i l l necessary and i m p o r t a n t . Among c e r t a i n l i m i t a t i o n s ( r e f . 2) i n t h e use o f t h e B r i t i s h Standard and N i l u t y p e gauges i n s t u d i e s o f d u s t f a l l f r o m s p e c i f i c sources t h e most i m p o r t a n t r e l a t e s t o t h e d u s t f a l l r e s u l t b e i n g an average f o r t h e c o l l e c t i n g t i m e used and g i v e s no
176
information or quantification of peak short term dustfall occurrences, a more precise knowledge of which would be more relevant for intelligent urban planning as well as accounting for complaints from residents. MEASUREMENT AND ASSESSMENT OF SHORT TERM DUSTFALL A method is described in this paper by which to measure short term (e.g. 3 - 18 hr) peak dust deposits, to attempt to assess nuisance levels of dustfall and to more accurately define an appropriate buffer zone between the industry and areas proposed for residential development with respect to the worst dustfall conditions. The dust deposit was measured by using a gauge 0.67 x 0.56 x 0.42 (depth) m dimension with a collecting area of 0.369 m2 and set 1.40 m above ground level. Whilst dust collection times varied between 3 - 18 hr a 5 hr period was generally found to be adequate to give analytically significant results. The wind speed and direction were continuously monitored as well as the dust burdens in the stack gases (Lear Siegler). Measurement has been largely concentrated in the area south of the works because of its interest to the Geelong Regional Commission for residential development. The gauges were placed downwind as indicated in Fig. 1 at distances varying from 300 m to 1200 m from the plant. The dust deposit in mg m-2 day-l is expressed as total 'cement' based on the analytically determined calcium content after allowing "or the calcium content in the background dust. P 50%
KEY D : DURATION
_c.
E : EMISSION(Visua1) :High LS : LEAR SIEGLER :0.2 w : WIND
s
P 100%
:O. 16-0.2 :5-6
(b)
NIL
:NW
:2-4
: 1-2
(e)
Fig. 1.
Short Term Dustfall Results (mg m-' day-')
RESULTS Dustfall at Drescribed distances downwind from the plant In Fig. 1 (a) the dustfall at the 300 m radial distance south of the plant demonstrates the relevance of short term dustfall levels together with known
m e t e o r o l o g i c a l and p l a n t c o n d i t i o n s . d i s t a n c e u s i n g t h e B.S. ( r e f . 3).
gauge
It i s s i g n i f i c a n t t h a t the d u s t f a l l a t t h i s
never i n d i c a t e d a r a t e h i g h e r t h a n 394 mg m-2 day-1
F i g s . 1 ( b ) and ( c ) show t h e e f f e c t o f d i f f e r i n g wind speeds and d i r e c t i o n ,
as w e l l as s t a c k emissions, on d u s t f a l l .
There was v i r t u a l l y no cement d u s t depos-
i t e d a t t h e 900 m and 1200 m d i s t a n c e w i t h a w i n d speed of 5 - 6 m sec-1 ( F i g . 1 ( b ) ) a r e s u l t p r o b a b l y due t o a h i g h degree of d i s p e r s i o n o f t h e plume by t h e g r e a t e r wind speed and a i r t u r b u l e n c e .
With a g e n t l e wind o f 1
-
2 m sec-l ( F i g . 1 ( c ) )
t h e d u s t f a l l r a t e s show a more even spread t o t h e 1200 m d i s t a n c e .
Fig. 1 (d)
shows a d u s t f a l l p a t t e r n under t h e i n f l u e n c e o f a v e r y l i g h t emission and a breeze o f 2 - 4 m sec-l.
W i t h l o w e r v e l o c i t y winds, t h e d u s t plume i s o f t e n observed t o
move away f r o m t h e ground s u r f a c e w i n d d i r e c t i o n , due t o upper a i r stream v a r i a t i o n s , as i n d i c a t e d by t h e range o f d e p o s i t a t t h e 1200 m zone. be c a r r i e d o v e r t h e 300
-
Sometimes, t h e plume can
600 m zone ( F i g . 1 ( e ) ) t o g i v e s u b s t a n t i a l d e p o s i t r a t e s
a t t h e 900 and 1200 m d i s t a n c e s .
In o r d e r t o assess t h e nuisance v a l u e o f a p a r t i c u l a r l e v e l o f d u s t f a l l , a s p e c i a l gauge, f i t t e d w i t h a b l a c k p o l y t h e n e base was p l a c e d n e a r t h e l a r g e gauge a t t h e same h e i g h t above t h e ground (1.40 m).
T h i s gave a d u s t d e p o s i t i n d e x (D.D.I.)
which i s based on t h e degree o f v i s i b i l i t y o f t h e d e p o s i t and expressed o v e r a range o f 0 t o 10 u n i t s .
Whilst the D.D.I.
i s q u i t e a r b i t r a r y and i s a s u b j e c t i v e
assessment, g e n e r a l agreement between o b s e r v e r s was o b t a i n e d .
A D.D.I.
of 1
( e q u i v a l e n t t o a cement d u s t d e p o s i t o f about 40 mg m-2) was b a r e l y p e r c e p t i b l e t o t h e naked eye, a
D.D.I. o f 5 was q u i t e apparent and would have some nuisance
e f f e c t w h i l s t an i n d e x o f 10 would be s e r i o u s , r e p r e s e n t i n g a h i g h nuisance l e v e l . (The p a r t i c l e s i z e range o f t h e d e p o s i t would have some i n f l u e n c e on t h e D.D.I.) The r e l a t i o n s h i p between t h e cement d u s t d e p o s i t e d (mg FI-~) and t h e D.D.I. shown i n F i g . 2.
is
I f t h e s t a c k plume p e r s i s t s i n a p a r t i c u l a r d i r e c t i o n f o r s u f f i c i e n t
t i m e t o d e p o s i t s u b s t a n t i a l l y more d u s t t h a n 40 mg rnd2 (e.g.
a D.D.I.
> 2 ) i n any
area, t h e n t h e d u s t f a l l would be a t n u i s a n c e l e v e l s such t h a t c o m p l a i n t s from r e s i d e n t s i n t h i s a r e a c o u l d be expected. D u r i n g t h e s e measurements a t t h e 600 m, 900 m and 1200 m d i s t a n c e s o u t h o f t h e works, t h e d u s t d e p o s i t i n d i c e s n e v e r exceeded v a l u e s o f two, one and l e s s t h a n one, r e s p e c t i v e l y o v e r t h e c o l l e c t i n g t i m e s i n d i c a t e d i n F i g . 1 . On t h i s b a s i s a s u i t a b l e b u f f e r zone dimension c o u l d be s e t a t 900
-
1000 m
r a d i a l d i s t a n c e f r o m t h e works s i t e , a f i g u r e i n agreement w i t h b u f f e r zones based
on ' f ' 1 3 0 v a l u e s ( r e f . 4) and w i t h t h a t recommended by P o l i s h and Russian a u t h o r i t i e s ( r e f . 5 ) and w i t h t h e A l k a l i I n s p e c t o r a t e o f t h e U n i t e d Kingdom ( r e f . 6 ) . The d i f f e r e n t i a t i o n o f d u s t d e p o s i t e d f r o m s e v e r a l sources, e i t h e r w i t h i n one i n d u s t r y o r from s e v e r a l d u s t g e n e r a t i n g i n d u s t r i e s i n a l o c a l i t y may q u i c k l y be made u s i n g t h e t e c h n i q u e .
e.g.,
i n o r d e r t o s t u d y d u s t f a l l f r o m t h e haulage roads
used f o r t r a n s p o r t o f l i m e s t o n e f r o m t h e q u a r r y t o t h e c r u s h i n g p l a n t , t h e a u t h o r s r e q u e s t e d t h e management t o s t o p t h e w a t e r i n g a c t i v i t i e s o f t h e r o a d p r o v i d e d t h e r e
178
Fig. 2. Dust Deposit Index
Fig. 3. Dustfall from Haulage Road
was no inconvenience to local residents. The dustfall results in mg m-2 obtained over a 3 hr collecting period under varying road conditions are shown in Fig. 3 and these highlight the importance and value of the dust suppression methods being used. The time taken to sample and complete the analysis (both physical and chemical) of any series of dust deposits involves one to two days. The B.S. gauge result, based on monthly collection, is misleading in the case of quarry and haulage road activities, for not only is it unable to provide information on peak dustfall under the worst conditions but it also fails to account for the fact that these activities only operate for 7 hr per day and 5 days per week. ACKNOWLEDGEMENTS The authors wish to express their appreciation for financial and other support for this study project to Blue Circle Southern Cement Limited, the Shire o f Barrabool, the Geelong Regional Commission, Alcoa of Aust. Ltd., and the Australian Bureau of Meteorology . REFERENCES 1. Senate Select Committee on Air Pollution (1969), Parliament of the Commonwealth of Australia, Canberra. 2. D.H. Lucas, J . Inst. Fuel, 30 (1957) 623 - 627. 3. R.H. Williamson, Search, Vol. 8, No. 10, October, 1977, p. 370 - 373. 4. A. Cantrell, W.H. Edwards and R.H. Williamson, Atmospheric Pollution, Proceedings of the 12th International Colloquium, Paris, 1976, p. 639 - 649. 5. F.J. Dreyhaupt and H. Bresser, Sanitary Zones as an Instrument in City and Regional Zoning with Relation to Air Pollution. Verlag,TUV,Rheinland,GmbH,Koln(1972) 6. Chief Alkali and Clean Air Inspector, Her Flajesty's Alkali and Clean Air Inspectorate, London (1976). Private communication.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1
179
0 Elsevier Scientific Publishing Company, Amsterdam -Printed in The Netherlands
CHARACTERIZATION OF AM ODOUR LEVEL AT ITS SOURCE ANE I N THE ENVIRONMENT BY MEASURING
THE DETECTABILITY INDEX U S I N G THE SIGNAL DETECTION THEORY A . REBOUX::,
P . ZETTWOOG::::
and M.F. THAL::::
:: IngGnieur, Responsable d e s problemes o d e u r s a u M i n i s t e r e d e l a C u l t u r e e t de
1'Environnement
.,., Commissariat '*--
1 1 ' E n e r g i e Atomique, I n s t i t u t d e P r o t e c t i o n e t de S t r e t G NuclGaire, Dgpartement d e P r o t e c t i o n , S e c t i o n Technique d'Etudes de P o l l u t i o n d a n s l ' h t m o s p h e r e e t dans l e s Mines. F r a n c e .
ABSTRACT
The measurement method of a t m o s p h e r i c odour l e v e l s u s i n g t h e s i g n a l d e t e c t i o n theor y was t e s t e d i n o u r l a b o r a t o r y . Experimental r e s u l t s of odour environmental d i s p e r s i o n s i m u l a t i o n a r e p r e s e n t e d . 1.
INTRODUCTION
I n t h e p r e s e n t s t a t e of knowledge, s e n s o r y a n a l y s e s
show themselves t o be t h e
o n l y v a l u a b l e methods of odour measurement : human o l f a c t i o n p l a y i n g t h e r o l e of both d e t e c t o r and a n a l y s e r . The most f r e q u e n t l y used method t o e x p r e s s an a t m o s p h e r i c odour l e v e l i s based on a concept of o l f a c t i v e t h r e s h o l d and expressed i n terms of t h e number of d i l u t i o n s n e c e s s a r y t o a t t a i n a n o d o u r l e s s c o n d i t i o n . T h i s method i m p l i e s t h a t t h e s t i m u l u s i n t e n s i t y i s t h e most i m p o r t a n t independent v a r i a b l e and t h a t u s i n g c a r e f u l l y t r a i n e d o b s e r v e r s e l i m i n a t e s t h e e f f e c t of v a r i a b l e s p e r i p h e r a l t o t h e s t i m u l u s . Opposed t o t h i s t h e o r y , t h e s i g n a l d e t e c t i o n t h e o r y i s based on t h e p r i n c i p l e t h a t t h e s u b j e c t s r e s p o n s e c r i t e r i a v a r y w i t h t i m e . I n f a c t , t h e e s s e n c e of t h e s i g n a l d e t e c t i o n t h e o r y i s d e t e r m i n a t i o n of t h e r e l a t i o n s h i p which e x i s t s between h i t s and f a l s e alarms ( c o r r e c t and i n c o r r e c t r e s p o n s e s ) ; f a l s e a l a r m s a r e a r e s u l t neous o l f a c t o r y s t i m u l a t i o n independent of odour p r e s e n t a t i o n ( i . e .
of e x t r a -
noise).
Sensory i m p r e s s i o n s r e s u l t i n g from t h e p r e s e n t a t i o n of e i t h e r a s t i m u l u s o r n o i s e , have s i m i l a r l y d i s p e r s e d normal d i s t r i b u t i o n s i n t h e same i n t e n s i t y continuum. The s t i m u l u s ( S ) i s always added t o t h e c o n t i n u o u s l y p r e s e n t n o i s e (N) and c a u s e s a d i s placement of t h e n o i s e d i s t r i b u t i o n a s shown i n f i g . I . We assume t h a t t h e s u b j e c t p o s s e s s e s a s u b j e c t i v e s c a l e of p e r c e p t i o n , which f o l l o wing a r e f e r e n c e s t i m u l u s w i l l d e f i n e a v a l u e ' p ' on t h e g e n e r a l p e r c e p t i o n s c a l e . T h e q u e s t i o n w e t h e n a s k t h e s u b j e c t a f t e r t h e p r e s e n t a t i o n of a s t i m u l u s ( t r u e o r f a l s e ) i s : -Do you c o n s i d e r t h e s t i m u l u s you have j u s t r e c e i v e d t o have a v a l u e super i o r t o ' p ' ? We p l o t t h e a f f i r m a t i v e r e s p o n s e p r o b a b i l i t y t o t h i s q u e s t i o n a s a
180 f u n c t i o n of t h e v a l u e chosen f o r ' p '
.
The w e a k e r t h e s t i m u l u s , t h e smaller t h e d i s p l a c e m e n t . The d i f f e r e n c e b e t w e e n t h e two d i s t r i b u t i o n s a l l o w s d e f i n i t i o n o f t h e D e t e c t a b i l i t y I n d e x I d ' . d
=
MSN - MN flN
where : MSN=mean o f t h e s i g n a l + n o i s e d i s t r i b u t i o n =
uN
mean of t h e n o i s e d i s t r i b u t i o n
= s t a n d a r d d e v i a t i o n of
the noise distribution. Constant i n t e n s i t y stimulus
density
Constant i n t e n s i t y s t 1mu 1 us
1 I
I
I
I I
I
I
Perception
181 or not. The experiment is repeated with the largest possible of subjects.
2. RESULTS Results are presented using the following table : YES
odour pure air where SN
=
NO
P (yes/SN)
p (no/SN) MISS
HIT
P (no/N) CORRECT REJECTION
P (yes/N) FALSE ALARM
signal + noise, N
=
noise
It is obvious that : p (yes/SN) + p (no/SN) p (no/N)
+
= 1
p (yes/N) = 1
We define p (yes/SN) as the frequency of hits and p (yes/N) as the frequency of false alarms. Our aim over the last months has been to determine the minimum number of presentations necessary to measure 'd' as well as the frequency with which these presentations must be made and to study the influence of signal variability on the 'd' value. Our results may be summarized as follows : 1)
Minimum number of presentations necessary depending upon the concentration, weak
(3 ppm) or strong (9 ppm)
= 1
200 and 300-400 respectively.
2) Frequencey of stimulus presentation : we consider 20 sec to be the optimum.
3) 'd' values for stimuli of non-fluctuating concentration results fig. 2 curve I . (simulaeion of constant environmental pollution - workshop case).
4) 'd' values as a factor of the mean concentration value of a series of stimuli of weakly fluctuating concentration - results fig. 2 curve 4 (simulation of stable atmospheric conditions). 5 ) 'd' values as a function of the mean concentration value of a series of stimuli of
strongly fluctuating concentration - results fig. 2 curves 2 and 3 (simulation of strong turbulence ; rapid variations in the direction and speed of the wind). 3. CONCLUSIONS A signal of strong fluctuations is more easily detected than that of weak fluctua-
tions. The former is apparent due to a decrease in "false alarms" and an increase in the number of "hits" and the latter by the reverse. This shows that the olfactory apparatus is better able to detect strong variations than constant levels. A s a results pollution forecasting using odour measurements must not be carried
out using atmospheric dispersion models since these will provide only average values. The discomfort suffered by the population could well be an increasing function of de tec tab i li ty .
182
I
I
I
I
I
Fig. 2 . f = odour presentation frequency. 1 = Constant odour concentration - no atmosphere disturbance ( f = 4 ) ; 2 = constant odour concentration - with atmosphere disturbance (f = i ) ; 3 = constant odour concentration - with atmosphere disturbance ( f = $); 4 = variable odour concentration - no atmosphere disturbance ( f = 4 ) .
REFERENCES 1 . THOMAS LINDVALL, M.D., Human Responses to environmental odors edited by Turk, J . W . Johnston, Jr, D.G. Moulton.
2 . T. ENGEN, Handbook of sensory physiology, vol 4 , Chemical senses I. Olfaction, Ed. Lloyd. N. Beidler, 1971. 3 . B. BERGLUND, U. BERGLUND, T. LINDVALL, J. of the Air P o l . Cont. Assoc., 2 4 , 2 , february 1974. 4. P. ZETTWOOG and al., Mesure de la distance critique caractcrisant 1'6tendue de la
zone polluge par les odeurs dans l'environnement d'une source odorante. (Etude effectu6e 1 la demande du MCE, 1976-1977, non publice).
183
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam -Printed in The Netherlands
PREVISIONNAL MAP OF POLLUTION EFFECTS I N O I C A T O R S J.M.
QUINAULT, Y .
BELOT and P. ZETTWOOG
C o m m i s s a r i a t 2 1 ’ E n e r g i e Atomique, I n s t i t u t de P r o t e c t i o n e t de SCretG N u c l B a i r e , DBpartement de P r o t e c t i o n . F r a n c e .
ABSTRACT The
pollution
effects
i n d i c a t o r s which are o f
a
such
on environment
c o u l d be r e p r e s e n t e d by
c a l c u l a t e d by a mathematical model.
calculation
a French town.
i s given f o r
An e x a m p l e
Results a r e discussed.
INTRODUCTION A mass o f
i t s constituents,
concentration o f etc..
..
less polluted,
more o r
air,
Thereforewe can
The p o l l u t i o n
t h e granulometry
”measure”
effects
can be characterised
t h e atmospheric
o f
i t s particles
pollution.
a r e n o t o f t e n measured d i r e c t l y ,
be traced by the use o f various
indicators,
simple
by t h e
but they
enough f o r
can
numerical
estimations.
I N D I C A T O R S OF POLLUTION The e f f e c t s
on
pollution
o f
t h e p o p u l a t i o n can appear
under various
form:
- e c o n o m i c a l loss ( c o r r o s i o n o f m a t e r i a l s , land,
destruction t o
farming
etc., ,1
- damage t o p u b l i c h e a l t h T
diminishing w e l f a r e .
We c a n t r y
to
resume these d i f f e r e n t p o l l u t i o n e f f e c t s by c o s t u n i t s
nevertheless the vast really applicable.
number
of
parameters.
when c o n s i d e r i n g
public
involve psychological notions which cannot To
a v o i d t h i s p r o b l e m i t seems
rnpasurable we u s e d i t
elements o f
and w e l f a r e which
be m a t h e m a t i c a l l y
p r e f e r a b l e t o chose one o f
expressed. the
p o l l u t i o n and w i t h a r e l a t i o n s h i p cause-effect
as i n d i c a t o r o f
F a r example,
However t h i s method i s n o t health
pollution.
concerning w i t h p u b l i c
h e a l t h we c a n
use. a s i n d i c a t o r
184 t h e amount
by
of
a representive
a population
a unit
of
t h e impact o f pollution
so,
Even an
o f
corrosion.
level i s an
l a n d and waste l a n d ,
METHODS OF
The introduction of them w i t h mathematical
indicators
f o r which a
used a multi-source
but
quantity of
t h e amount o f
area,
sulphur present
these p o l l u t i o n models.
indicators
I n what
knowledge
o f
allow u s t o estimate
a years scale is sufficient,we t y p e PASQUILL-MARTIN
data.
In fact
t h e mean
secteur depends e s s e n t i a l l y on t h e regime of
the different
,
( >
t h e results
areas.
<
t h e annual
s t r o n g and w e a k winds that
for
mean c o n c e n t r a t i o n s c o r r e s p o n d i n g -1 2.5 m s 1.
obtained did
n o t c h a n g e v e r y much f r o m
C o n s e q u e n t l y w e may d e f i n e s t a n d a r d m e a n
c o n c ~ n t r a t i o n sv a l i i a h l e w h a t e v e r t h e pprreritage of
near
concerns t h e above-mentioned
i n it. I n u s i n g t h e g e n e r a l model w e have c a l c u l a t e d ,
We r l o t i c e d
is
t h e e f f e c t s on f a r m i n g
mean c o n c e n t r a t i o n model o f
four d i f f e r e n t a r e a s ,
on
CALCULATIONS
concentrations i n a
t h e wind
emphasised
means.
on a n i n h a b i t e d
s i m p l i f i e d f o r t h e need of m e t e o r o l o g i c a l
radial
t o
of
...linhaled
.
etc..
PREVISIONNAL
deposited
The t o t a l
indicator
in fact,
by r e s p i r a t i o n
sulphur
etc
[SO2, N O x ,
T h i s is,
surface.
o n man,
t h e amount o f
indicator
ground
pollutant
t h e weak a n d
s o we o n l y n e e d
t h e a r e a may b e ,
strong winds,
sector
by s e c t o r .
APPLICATION applied a
We
the public
map o f We
s i m i l a r model
calculated
health
sources of
t h e volume
of
unknown,
SO2, i n g r a m m e s ,
repartition,
inhaled
of
stack
number o f
p o p u l a t i o n and
of
t h e important
f a c t o r i e s were
heightsto calculate the
here i n Table 1.
1
Source height m fill
80 100
hectares
inhaled curves obtained.
f r o m one
s o we r e t a i n t h r e e p o s s i b l e
S u r f a c e when
by
physical characteristics
a i r i n h a l e d f o r e a c h d a y by a n i n h a b i t a n t . F i g u r e 1
c o n c e n t r a t i o n s shown Table
of
SO2, l o c a l w i n d r e p a r t i t i o n ,
represents t h e iso-quantity The height
French town t o o b t a i n a p r e v i s i o n n a l
indicator.
t h e quantity
and annually, w i t h g e o g r a p h i c a l o f
t o a
2 (Km I
t h e c o n c e n t r a t i o n i s s u p e r i o r t o a threshold
.
50 357 356 350
.
Threshold
100 160 154 145
.
ng/m3
150 70 56 44
.
o f
180
36 21 12
SO2
.
200 23 10 5
.
300 3 0 0
'
400 1 0 0
185 Figure 1
-
Previsionnal
inhaled quantity of
SO2 g / h e c t a r e / y e a r
for a
f r e n c h town.
&
inhabited
area
If
we
on s i t e we o b t a i n e d
c o u n t t h e q u a n t i t i e s o f SO2 i n h a l e d
h e a l t h i n d i c a t o r w h i c h we m i g h t
an
know t h e s o u r c e s r e s p o n s i b i l i t i e s .
is represented i n Figure 2.
That
Figure 2
-
R e s p o n s i b i l i t y graph of
domestic
industries
three factories
(VI), a n d
o f
heating
(OH), o f v a r i o u s (FI,F7,F31.
L
0
L
m
.-0 U C
._ -5 C 4 r
0
-
a m m
E
0 4
0
a
6 DH/
o /
I
I
20
10
30
I
40
Percentage o f e m i s s i o n
CONCLUSION
T h i s t y p e of previsionnal you
an example,
various parameters of
population,
c i t i e s and
etc
advantage of
which
o f
...1
on t h e i n d i c a t o r s Consequently it
management
surrounding.
we h a v e j u s t g i v e n
studying the i n f l u e n c e of
(physical characteristics
environment.
for industrial
calculations,
presentsthe
o f
sources,
pollution
repartition e f f e c t s on
is an indispensable t o o l
Atmospheric Pollution 1978. Proceedings ofthe 13th International Colloquium,Paris,France, April 25-28,1978, M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
187
APPLICATION OF A MESOSCALE AIR QUALITY MODEL TO LONG RANGE AIR POLLUTION PROBLEMS C. SHEPHERD BURTON and MEI-KAO LIU Systems Applications, Incorporated 950 Northgate Drive San Rafael, California 94903 (U.S.A.)
ABSTRACT A
mesoscale air quality model has been applied to such recently recognized
environmental problems as visibility reduction and acid rain caused by transport and dispersion of
SO2
and its derivative, sulfate. The grid-based, numerical meso-
scale model is composed of two interconnected modules:
a mixing layer model, which
treats transport and diffusion in the mixing layer, and a surface layer model, which calculates the pollutant l o s s to the ground due to dry deposition.
In addition, the
model accounts for chemical reactions and dry and wet deposition. Visual ranges are computed from pollutant concentrations using empirical relationships. This model has been applied to the U.S. Northern Great Plains coal development area to assess potential sulfate and visibility problems.
INTRODUCTION
In the past, concerns over the fate of air pollutants from anthropogenic sources have been primarily confined to the urban area or region of the emissions sources. Recently, vigorous monitoring efforts on both sides of the Atlantic have shown that pollutants can travel long distances in the atmosphere, sometimes up to several hundred kilometers or more.
This finding has catapulted air pollution studies into
interregional and international arenas. With the increasing utilization of fossil fuels and widespread use of indirect control techniques, such as tall stacks, SO --a primary emission from fossil-fuel 2
combustion processes--has become the most important pollutant species in long range transport studies.
Its half-life ranges from a few hours to a few days, and it con-
verts in the atmosphere to sulfate through homogeneous and heterogeneous chemical reactions. Many studies have attempted to link impairments of human health to SO2 and sulfate, but their results so far are inconclusive (ref. 1). Many adverse impacts of these pollutants on the environment, however, have been confirmed.
For
example, recent investigations have shown that dry and wet deposition of sulfur compounds is responsible for acid precipitation and increased acidity in soil and lakes
188 (refs. 2, 3).
Moreover, several studies have also implicated sulfate in the degra-
dation of visibility in polluted environments (refs. 4, 5). nificant impacts, further studies on the fate of
SO2
In view of these sig-
and sulfate in the atmosphere
are warranted. This paper describes a mesoscale air quality model that can be used as an analytic tool to address a variety of long range air pollution problems.
By linking the emis-
sions with the observed air quality, this model simulates the movement, dispersion, and removal of
SO2
and sulfate.
THE MESOSCALE AIR QUALITY MODEL Two general approaches to air quality modeling have been attempted:
approach and the Eulerian approach.
the trajectory
Aside from theoretical considerations, the tra-
jectory approach suffers from two shortcomings.
First, a choice must be made among
the various air trajectories that are representative of the air pollution episodes of interest to the long range studies. arbitrary.
Such a choice is usually difficult and often
Second and more important, the trajectory model is cumbersome to apply to
multiple-source situations. Thus, the Eulerian approach was adopted in this study. The governing equation is based on the time-dependent multiple-species atmospheric diffusion equation in two dimensions, which can be expressed as: ac. ac. ac. l + u l + v - = at ax ay
a
ax
(K
i = 1, 2 ,
). '
+
x ax
...,
N
$ (K Y 2) + D f(D) + Ri + Si aY
,
(1)
,
where c. is the vertically averaged concentration of species i in the mixing layer, u , v, Kx,
and K are wind velocities and turbulent diffusivities in the x and y direcY tions, respectively, D is the two-dimensional divergence (= du/dx + dv/dy), Ri and
S.
1
are chemical reaction and volumetric source terms, respectively, and
where c . is the concentration of species i aloft. Although this study considered iA only SO2 and sulfate formed through a first-order reaction, the regional model can be extended to handle multiple reactive species. The main feature of this model equation is that the pollutant distribution has been assumed to be nearly uniform in the vertical direction. With this assumption, the model equation can be formally derived from the more general atmospheric diffusion equation.
The compelling reason for this assumption is that the vertical dif-
fusion term is about 100 times greater than the transport term, and the horizontal diffusion term is only a fraction of the transport term (ref. 6). Because of the
189 relatively large spatial scale, however, psuedo-diffusion associated with the numerical solution of Eq. (1) can be overwhelming. Consequently, an accurate scheme must be used for the simulation of the transport term.
Consideration of both predictive
accuracy and computational speed led to the choice of the SHASTA method (ref. 6) for this study. DRY DEPOSITION
The importance of dry deposition of SO2 and sulfate in long range transport problems necessitates treatment of this process in the model.
For pollutants originating
from either elevated or distant ground-level sources, most of the pollutant mass is contained in the mixing layer.
The removal processes consist of the diffusion of the
pollutants through the surface layer to the ground, followed by absorption or adsorption at the atmosphere-ground interface.
A unique feature of the surface layer is
its diurnal variation in temperature, which is a result of daytime heating and nighttime cooling of the surface. This variation affects the vertical pollutant distribution through atmospheric stabilities and, consequently, the rate of surface uptake of pollutants. The surface layer can be viewed as two layers: cous sublayer.
the turbulent layer and the vis-
With this simplification, the pollutant flux to the ground surface
due to dry deposition, F, can be obtained through the following equation:
where
I-
and where k is the von Karman constant, u* is the frictional velocity, B is the Stanton number,
I$
is the dimensionless wind shear (ref. 7 ) . and zo and h are the
surface roughness and the height of the surface layer, respectively. The parameters y and a represent the reaction rate and reaction order, respectively, for the uptake of air pollutants by chemical reaction or catalytic decomposition at the ground surface. For a = 1, 2, and 3 , closed-form solutions can be found for F:
a = 2
where
(4)
190
These formulas reduce t o t h a t of Thom ( r e f . 7) f o r t h e s p e c i a l c a s e of a f i r s t - o r d e r s u r f a c e r e a c t i o n and a n e u t r a l l y s t r a t i f i e d atmosphere. Both washout and r a i n o u t have long been recognized a s t h e cause f o r a c i d Frecipitation.
Although i n c o r p o r a t i o n of t h e s e phenomena i n t h e model i s r e l a t i v e l y simple,
c a r e f u l a n a l y s i s i s r e q u i r e d t o parameterize t h e s e processes.
They w i l l be included
i n t h e model i n t h e f u t u r e . VISIBILITY
For a homogeneous medium, v i s u a l range i s l i n e a r l y r e l a t e d t o t h e s c a t t e r i n g c o e f f i c i e n t of t h e atmosphere ( r e f . 8 ) :
VR = 3.91/bscat.
I n c o n t r a s t , l i g h t scat-
t e r i n g depends on t h e mass c o n c e n t r a t i o n , chemical composition, and s i z e d i s t r i b u t i o n of atmospheric a e r o s o l s .
Recent s t u d i e s have shown, however, t h a t t h e
s c a t t e r i n g c o e f f i c i e n t c o r r e l a t e s poorly with t h e t o t a l a e r o s o l m a s s , but reasonably well with s u l f a t e ( r e f s . 4 , 5 ) .
Using a l e a s t - s q u a r e s f i t of Los Angeles d a t a ,
White ( r e f . 4 ) obtained t h e following r e l a t i o n s h i p , which w a s used i n t h e present study : bscat
2 -1 = 7.6 m g [ S u l f a t e ]
+
2.4 m2g-'[Nonsu1fate
Aerosol]
.
(6)
RESULTS I n t h e a p p l i c a t i o n of t h e mesoscale a i r q u a l i t y model t o t h e Northern Great Plains i n t h e western United S t a t e s t o a s s e s s t h e impact of energy development t h e r e , the wind f i e l d w a s taken t o be a t t h e 850-mb l e v e l . and s u r f a c e d a t a were a l s o compiled. f o r SO2.
Emissions and o t h e r meteorological
Figure 1 shows t h e p r e d i c t e d s u r f a c e uptake
Figure 2 p r e s e n t s t h e p r e d i c t e d s c a t t e r i n g c o e f f i c i e n t s and v i s u a l ranges
obtained assuming a f i r s t - o r d e r r e a c t i o n between SO2 and s u l f a t e and a 3 percent per hour conversion r a t e . ACKNOWLEDGMENT This work was supported by t h e U.S. Contracts 68-01-3947
and 68-01-3591.
Environmental P r o t e c t i o n Agency under
191
cm/sec
00-2
a rn
I Fig. 1.
2-4 4-6 6-8
Predicted surface deposition velocity.
Fig. 2 . Predicted scattering coefficient parentheses)
.
(XI-')
and visual range (km in
192 REFERENCES
4 5 6 7 8
Air Quality and Stationary Emission Control, National Academy of Engineering, Washington, D.C., 1975, pp. 58-169. G. E. Likens, F. H. Bormann, and N. M. Johnson, Environment, 14(1972)33-39. H. Dovland, E. Joranger, and A. Semb, in F. H. Braekke (Ed.), Impact of Acid Precipitation on Forest and Freshwater Ecosystems in Norway, SNSF Research Report, Oslo, Norway, 1976, pp. 14-35. W. H. White, Nature, 264(1976)735-736. G. M. Hidy, et al., Characterization of Aerosols in California, Final Report, California Air Resources Board, Sacramento, California, 1974. M. K. Liu and D. Durran, The Development of a Regional Air Pollution Model and Its Application to Northern Great Plains, EPA-908/1-77/001, Systems Applications, Incorporated, San Rafael, California, 1976. A. S. Thom, Quart. J. Roy. Meteor. SOC., 98(1972)124-134. W.E.K. Middleton, Vision Through the Atmosphere, University of Toronto Press, Toronto, Canada, 1952.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
193
THE OVERLAY TECHNIQUE - A SIMPLE APPROACH TO THE TOPOGRAPHY PROBLEM: 1 LONG TERM CONCENTRATIONS
James W. S. Young, Ph.D. Beak C o n s u l t a n t s L i m i t e d , Toronto, Canada
AE5STRACT Most two d i m e n s i o n a l a i r p o l l u t i o n d i s p e r s i o n models i n u s e today a r e a p p l i e d t o a r e a s h a v i n g s i g n i f i c a n t topography o r land-sea e f f e c t s .
To model t h e s e t y p e s o f
areas more r e a l i s t i c a l l y i n v o l v e s t h e n u m e r i c a l s o l u t i o n of t h e c l a s s i c a l t h r e e dimensional equations.
T h i s r e q u i r e s , however, t h e complete s p e c i f i c a t i o n of t h e
flow f i e l d , e i t h e r e x p e r i m e n t a l l y o r t h e o r e t i c a l l y , which i s a d i f f i c u l t and expensive p r o p o s i t i o n f o r t h e c a s u a l model u s e r . T h i s paper p r e s e n t s a s i m p l e o v e r l a y t e c h n i q u e , t h a t can b e a p p l i e d to t h e s t a n d a r d long-term Gaussian f l a t p l a i n m o d e l l i n g o u t p u t , t o g i v e a s p a t i a l l y improved p r e d i c t i o n . The method p r e s e n t e d i s a p p l i e d t o t h e p r e d i c t i o n of t h e long-term concent r a t i o n s of suspended p a r t i c u l a t e m a t t e r from b o t h area and p o i n t s o u r c e s around an iron ore processing f a c i l i t y .
INTRODUCTION
Methods abound i n t h e l i t e r a t u r e f o r t h e p r e d i c t i o n of d i s p e r s i o n from s t a t i o n a r y s o u r c e s i n complex t e r r a i n .
D i s p e r s i o n estimates have been improved by
(1) a l t e r i n g t h e s t a b i l i t y p a r a m e t e r s , ( 2 ) by u s i n g t u r b u l e n c e measurements t o
s p e c i f y d i f f u s i o n c o e f f i c i e n t s o r ( 3 ) by s o l v i n g t h e complete three-dimensional flow f i e l d . The major problems w i t h t h e e x i s t i n g a p p r o a c h e s , from a u s e r s p o i n t of view, are t h a t (1) d e t a i l e d measurements a r e r e q u i r e d i n e a c h area t o b e modelled, ( 2 ) nont u r b u l e n t p r o c e s s e s can i n f l u e n c e plume d i s p e r s i o n , ( 3 ) t h e c o s t of r u n n i n g t h e computer model i s h i g h , and ( 4 ) t h e c a s u a l u s e r may n o t have a s u f f i c i e n t understandi n g of t h e i n t e r a c t i o n s t o a v o i d n o n - r e a l i s t i c s c e n a r i o s a n d / o r programming b i a s e s c a u s i n g anomalous o u t p u t . The b a s i c p r e m i s e s f o r t h e work p r e s e n t e d h e r e were:
(1) t h a t e x i s t i n g two-dimen-
s i o n a l models must b e used ( h e r e t h e C l i m a t o l o g i c a l D i s p e r s i o n Model ( R e f . 1 ) ; ( 2 ) t h a t t h e method b e s i m p l e t o u s e and n o t c o s t l y ; and ( 3 ) t h a t a s i g n i f i c a n t l y improved o u t p u t b e r e a l i z e d i n areas of moderate t o p o g r a p h i c a l i n f l u e n c e .
194 ASSUMPTIONS The f o l l o w i n g assumptions were made i n t h e development of t h i s t e c h n i q u e : ( 1 ) 100 p e r c e n t t e r r a i n r i s e w a s assumed w i t h a t e r r a i n - f o l l o w i n g
streamline.
There are t h r e e models (Ref. 2 ) i n g e n e r a l use i n t h e United S t a t e s today. One i s t h e Half-Height T e r r a i n Model which assumes t h a t t h e s t r e a m l i n e through a plume from a t a l l s t a c k i s i n t e r m e d i a t e between a t e r r a i n - f o l l o w i n g streamline p a r a l l e l t o the sea-level plane. t h i s is v a l i d f o r near-neutral
s t r e a m l i n e and a
Wind t u n n e l s i m u l a t i o n s s u g g e s t t h a t
atmospheric conditions.
The second model i s t h e V a l l e y Model which i s used f o r s t a b l e c o n d i t i o n s and i t assumes t h a t t h e plume s t r e a m l i n e , a t e f f e c t i v e plume h e i g h t , i s p a r a l l e l t o t h e sea-level plane. The t h i r d model i s t h e LAPPES Model which assumes a 65 t o 100% t e r r a i n r i s e depending upon t h e f l o w regime - 65% w i t h moderate t o s t r o n g winds and 100% with l i g h t winds. I t s h o u l d b e n o t e d h e r e t h a t a l l of t h e s e models a r e s h o r t term models and a r e used t o estimate t h e w o r s t c a s e 1 t o 24 hour a v e r a g e c o n c e n t r a t i o n s .
(2)
The e f f e c t i v e plume h e i g h t r e l a t i v e t o a f i x e d datum i s used as i n p u t t o
t h e model.
T h i s h e i g h t i s m o d i f i e d by changing t h e v a l u e i n p u t f o r t h e i n d i v i d u a l
stack heights. The s t a n d a r d Gaussian models a l l assume t h a t two i d e n t i c a l e m i t t e r s , one i n a v a l l e y and t h e o t h e r on t o p of a h i l l , i n f l u e n c e t h e downwind r e c e p t o r s e q u a l l y . I n t h i s t e c h n i q u e , t h e plumes a r e more r e a l i s t i c a l l y d i s t r i b u t e d s p a t i a l l y .
(3)
P l u m e s t h a t a r e below a r e c e p t o r ' s h o r i z o n do n o t i n f l u e n c e t h e concentration
a t that receptor. On t h e l o n g t e r m a t l e a s t h a l f of t h e c o n d i t i o n s t o b e modelled o c c u r when t h e r e
i s no s u r f a c e h e a t i n g .
I n areas w i t h topography, downslope o r k a t a b a t i c winds
o c c u r d u r i n g t h e s e p e r i o d s and p o l l u t i o n o c c u r r i n g on h i l l s i d e s i s c a r r i e d i n t o v a l l e y s below (Ref. 3 ) . i s t r a p p e d i n t h i s flow.
A l s o p o l l u t i o n e m i t t e d a t a low l e v e l ( n e a r t h e ground) I t i s w e l l known t h a t t h e o n l y way t o e n s u r e t h a t e f f l u e n t
i s n o t t r a p p e d i n a v a l l e y i s t o p l a c e t h e l e v e l of emission above, o r a t t h e very
l e a s t o n l y a v e r y s m a l l d i s t a n c e below, t h e l e v e l of t h e s u r r o u n d i n g h i l l s .
(4)
P o l l u t a n t s e m i t t e d a t a given e l e v a t i o n w i l l f i n d t h e i r way t o a l l receptors
a t that elevation.
T h i s i s t h e same a s assuming mass c o n t i n u i t y f o r each two-
d i m e n s i o n a l e l e v a t i o n l a y e r , a r b i t r a r i l y s e l e c t e d a s 30.5 m t h i c k i n t h i s technique.
DATA SET The d a t a s e t used c o n s i s t s of t h e f o l l o w i n g 4 components: (1) t h e m e t e o r o l o g i c a l i n f o r m a t i o n , ( 2 ) t h e p o i n t s o u r c e i n f o r m a t i o n , ( 3 ) t h e observed c o n c e n t r a t i o n s a t ground l e v e l and ( 4 ) t h e estimates of e m i s s i o n s from a r e a s o u r c e s .
195 THE METEOROLOGICAL INFORMATION
The climate of n o r t h e r n O n t a r i o may b e c l a s s i f i e d as m o d i f i e d c o n t i n e n t a l , t h e m o d i f i c a t i o n b e i n g mainly due t o t h e p r e s e n c e of t h e Great Lakes on t h e s o u t h and t o a minor e x t e n t , t o Hudson Bay on t h e n o r t h . The m e t e o r o l o g i c a l d a t a s e t used w a s t h e Day-Night STAR j o i n t f r e q u e n c y d i s t r i b u t i o n f o r t h e Atikokan a i r p o r t .
This gives
t h e j o i n t f r e q u e n c y of o c c u r r e n c e of a wind d i r e c t i o n s e c t o r , a wind speed c l a s s and a s t a b i l i t y c a t e g o r y and w a s p r e p a r e d f o r t h e 10 y e a r p e r i o d 1967-1976. s t a t i o n i s a t an e l e v a t i o n of 427m.
This
The a v e r a g e a f t e r n o o n mixing h e i g h t used w a s
1 0 2 1 m and t h e a v e r a g e n o c t u r n a l mixing h e i g h t used w a s 1 2 5 m.
The mean atmospheric
t e m p e r a t u r e used w a s 1.7"C.
THE POINT SOURCES
Twenty-three (23) p o i n t s o u r c e s w e r e d e f i n e d f o r t h i s area.
F o u r t e e n ( 1 4 ) of
them had e x c e l l e n t i n f o r m a t i o n on e m i s s i o n r a t e s based on s t a c k t e s t i n g and m a t e r i a l balances.
The remaining n i n e (9) are b e s t estimates from t h e O n t a r i o M i n i s t r y of
t h e Environment e n g i n e e r i n g s t a f f .
All v a l u e s used a s model i n p u t s w e r e c a l c u l a t e d
t o b e e q u i v a l e n t t o long-term a v e r a g e e m i s s i o n r a t e s .
THE AREA SOURCES
E i g h t (8) area s o u r c e s w e r e d e f i n e d f o r i n p u t t o t h i s model.
One of t h e s e w a s
a n estimate o f e m i s s i o n s from s o u r c e s i n t h e town and i s f e l t t o be q u i t e good b u t t h e r e m a i n i n g seven a r e e m i s s i o n s from open p i t mines and t a i l i n g s a r e a s and are f e l t t o b e o n l y f i r s t h i g h estimates of t h e a c t u a l e m i s s i o n s .
Three b a s i c c a l c u l a -
t i o n methods were a p p l i e d which gave e m i s s i o n s (from t h e p i t w i t h t h e most informat i o n ) r a n g i n g from 100 t o 790 g / s . The a c t u a l r a t e used f o r t h i s p i t was 366 g / s b a s e d on t h e method of Cowherd and Hendriks ( R e f . 4 ) .
I t i s f e l t t h a t t h e emission
r a t e s used may b e t o o h i g h by a f a c t o r of 50 p e r c e n t .
IXE OBSERVED SUSPENDED PARTICULATE MATTER CONCENTRATIONS
Suspended p a r t i c u l a t e matter h a s been monitored i n t h i s a r e a s i n c e 1966.
The
v a l u e s used f o r c a l i b r a t i o n of t h e model are from 1 2 m o n i t o r s l o c a t e d w i t h i n a 7 km r a d i u s of t h e major s o u r c e s .
The a v e r a g e c o n c e n t r a t i o n s used r e p r e s e n t v a r y i n g
l e n g t h s of r e c o r d from 1 t o 9 y e a r s w i t h s t a n d a r d d e v i a t i o n s r a n g i n g from 8 t o over 90 p e r c e n t of t h e a v e r a g e long-term v a l u e s .
The observed long-term v a l u e s of SPM
a t t h e s e s t a t i o n s i s given i n Table 1. T h i s d a t a i s t y p i c a l of t h e q u a l i t y of i n f o r m a t i o n from s o u r c e m o n i t o r i n g programs, and a v a i l a b l e f o r e n v i r o n m e n t a l impact a s s e s s m e n t s .
196 TABLE TABLE 31 Long-term Long-term Suspended S u s p e n d e d PP aa rr tt ii cc uu ll aa tt ee Matter Matter (SPM) (SPM) C C oo nn cc ee nn tt rr aa tt ii oo nn ss ii nn ug/rn3 ug/rn3
XX
R R ee cceeppttoorr
L L ooccaatt ii oo nn
153.5 153.5 1155 44 .. 77 152.7 152.7 115 2 . 8 150.0 150.0 150.9 150.9 150.6 150.6 148.6 148.6 148.5 148.5 115 0 . 8 1144 99 .. 77 152.2 152.2
1 1 22 33 44 55 66 77 88 99 1100 1 11 1 11 22
YY
Observed Observed
46.9 46.9 49.2 49.2 48.2 48.2 40.8 40.8 47.6 47.6 47.a 47.a 50.4 50.4 48.2 48.2 46.5 46.5 44.6 44.6 4488 .. 33 4488..11
50 50 120 120 98 98 42 42 194 194 162 162 54 54 46 46 40 40 331 1 118 118 222 222
C C aa ll cc uu ll aa tt ee dd SS t a n d a r d O Ov e r l a y CDM Technique CDM Technique 506. 506. 272. 272. 1354. 1354. 101. 101. 549. 549. 938. 938. 315. 315. 317. 317. 282. 282. 505. 505. 574. 574. 1587.
448. 448. 84. 84. 170. 170. 95. 95. 422. 422. 761. 761. 29. 29. 36. 36. 40. 40. 41. 41. 368. 368. 1144 66 00 ..
METHOD METHOD The C l i m a t o l o g i c a l D i s p e r s i o n Model (CDM) d e t e r m i n e s l o n g - t e r m p o l l u t a n t concent r a t i o n s a t any g r o u n d - l e v e l
r e c e p t o r u s i n g a v e r a g e e m i s s i o n s r a t e s from p o i n t and
area s o u r c e s and a j o i n t f r e q u e n c y d i s t r i b u t i o n o f wind d i r e c t i o n s and s p e e d , and
s t a b i l i t y f o r t h e same p e r i o d . ground-level
(Ref.
1).
The c o n c e n t r a t i o n s a r e o u t p u t a t t h e
r e c e p t o r s f o r which o b s e r v a t i o n s e x i s t and a s t r a i g h t l i n e e q u a t i o n
of t h e form: Observed = A
+ B*(Calculated)
i s f i t t o c a l i b r a t e t h e model o u t p u t . F o r
t h e test d a t a used, t h e c o e f f i c i e n t of determination ( r 2 ) i s 0.43, with c o r r e l a t i o n c o e f f i c i e n t s A = 40.9 a n d B = 0.0940.
The model o u t p u t d a t a used f o r t h i s c a l i b -
r a t i o n a r e g i v e n i n T a b l e 1 under " S t a n d a r d CDM".
The c a l i b r a t e d s t a n d a r d r u n o u t -
p u t i s shown i n F i g u r e 1 f o r t h e whole area.
55
-
.................. .. \
50 50 -
-
\ I
45 45
i
/
-
i ..............
/
/
cc ll
/
-40 40
,,
II
,,
II
11
11
11
11
1145 45 1150 50 155 1160 I 155 FFiigg.. 1. a t t e r -- SSttaa nn d a r d C 1. Ground Ground LL ee vv e l Suspended S u s p e n d e d PP aa rr t i c u l a t e M Matter Caalliibbrraatteedd CDM CDM O 80 g/m Ouuttppuutt (-120, (-120, 8 0 and--60 and--60 g/m ))
197 For t h e o v e r l a y t e c h n i q u e , e a c h r e q u i r e d r e c e p t o r - h e i g h t
(here the centre point
of each s q u a r e k i l o m e t r e ) i s c l a s s i f i e d i n t o a topography l a y e r .
The l o w e s t ( o r b a s e )
l e v e l used i n t h i s l o c a t i o n w a s 366 m - t h a t b e i n g t h e approximate e l e v a t i o n of t h e
area s o u r c e e m i s s i o n s .
The mid-point
topography w a s c a t e g o r i z e d i n t o 30.5 m l a y e r s
so t h a t e a c h r e c e p t o r f e l l i n t o t h e 366 (366 - 396 m), t h e 396 (396 - 427 m), t h e
427 ( 4 2 7
-
4 5 7 m) o r t h e 4 5 7 m e t r e l a y e r ( 4 5 7 + ) .
The r e l a t i v e v e r t i c a l p o s i t i o n s
of a l l s o u r c e s ( p o i n t and a r e a ) w e r e r e f e r r e d i n i t i a l l y t o t h e 366 m datum and t h e i n p u t s t a c k h e i g h t s w e r e modified t o s u i t . 366 m u n c a l i b r a t e d o v e r l a y .
The CDM run f o r t h i s c a s e p r o v i d e s t h e
The i n p u t s t a c k h e i g h t s were t h e n reduced t o model a
30.5 m t e r r a i n r i s e (by s u b t r a c t i n g 30.5 m from t h e s t a c k h e i g h t s used i n t h e 366 m o v e r l a y ) .
Any s t a c k h e i g h t s t h a t became n e g a t i v e ( s o u r c e s below t h i s t e r r a i n
h e i g h t ) were o m i t t e d and t h i s modified d a t a set produced t h e 396 m o v e r l a y o u t p u t . This p r o c e d u r e w a s c o n t i n u e d f o r t h e remaining two 30.5 m t o p o g r a p h i c l a y e r s producing t h e 427 and 457 m o v e r l a y s .
By u s i n g t h e r e c e p t o r - h e i g h t c l a s s i f i c a t i o n one can
then e x t r a c t t h e u n c a l i b r a t e d c o n c e n t r a t i o n s f o r each r e c e p t o r , and c a l i b r a t i o n p o i n t s from t h e a p p r o p r i a t e o v e r l a y .
For example, a r e c e p t o r a t 404 m i s i n t h e 396 - 427 m
l a y e r and t h e g r o u n d - l e v e l c o n c e n t r a t i o n i s b e s t r e p r e s e n t e d by t h e 396 m o v e r l a y . Using t h e d a t a from t h e o v e r l a y t e c h n i q u e ( T a b l e 1 ) and t h e observed d a t a t o produce a c a l i b r a t i o n e q u a t i o n , a s b e f o r e , w e f i n d t h a t t h e c o e f f i c i e n t o f determinat i o n ( r 2 ) i s 0 . 6 4 , w i t h c o r r e l a t i o n c o e f f i c i e n t s of A
=
5 7 . 3 and B = 0 . 1 2 4 .
The composite model o u t p u t can now be c a l i b r a t e d t o g i v e t h e o u t p u t shown i n Figure 2 .
145
150
155
F i g . 2 . Ground L e v e l Suspended P a r t i c u l a t e Matter i n ug/m3 C a l i b r a t e d Overlay Technique
160
145
150
155
10
F i g . 3. 427 Metre E l e v a t i o n Contour ( d a r k a r e a s a r e above and l i g h t areas are below 4 2 7 m)
198 OBSERVATIONS When one compares t h e c o n c e n t r a t i o n s ( F i g u r e 2 ) t o t h e a c t u a l topography, one o b s e r v e s t h a t t h e h i g h SPM v a l u e s o c c u r i n t h e p i t a r e a s and n o t on t h e h i g h ground s u r r o u n d i n g them as i n t h e s t a n d a r d CDM o u t p u t , t h a t i s , t h e method a p p e a r s t o g i v e a b e t t e r s p a t i a l l y defined output. Some anomolies do a p p e a r , however, such a s an i n c r e a s e d g e n e r a l background l e v e l (57 v s 4 1 pg/m3) and some u n i q u e l y h i g h ground l e v e l v a l u e s . good example, a t x = 154 and y
=
One s t a n d s o u t a s a
45 we have a ground l e v e l c o n c e n t r a t i o n of 97 ug/m3.
This p o i n t i s i n a v a l l e y ( F i g u r e 3) w i t h a b a s e e l e v a t i o n o f about 366 m.
The
r e c e p t o r s c l o s e s t t o i t , a l o n g t h e v a l l e y , (mid-points of a s q u a r e k i l o m e t r e ) , j u s t happen t o f a l l h a l f way up t h e v a l l e y w a l l ( i n t h e n e x t t o p o g r a p h i c l a y e r ) and t h e c o n c e n t r a t i o n s are, t h e r e f o r e , c o r r e s p o n d i n g l y l o w e r .
This points o u t t h a t a user
must c a r e f u l l y choose h i s o u t p u t p o i n t s because t h e model i s o n l y two-dimensional i n a s p e c i f i c l a y e r and c a n n o t make t h e c h o i c e s f o r t h e u s e r . This p a r t i c u l a r anomaly r e p r e s e n t s w e l l t h e normal s p a t i a l v a r i a b i l i t y observed i n n a t u r e . r u n n i n g t h i s model i s v e r y r e a s o n a b l e
-
p e r h a p s , i n g e n e r a l , o n l y t w i c e t h a t of t h e
s t a n d a r d CDM r u n s i n c e s o u r c e s d i s a p p e a r as t h e t e r r a i n r i s e s . tion
The c o s t of
If t h e a c t u a l eleva-
of a r e c e p t o r p o i n t i s used t o i n t e r p o l a t e a c o n c e n t r a t i o n , t h e c o e f f i c i e n t
of d e t e r m i n a t i o n i s n o t as good ( r 2 = 0 . 6 0 ) a n d , t h e r e f o r e , n o t worth t h e e f f o r t i n volved.
The method d e s c r i b e d rounds a l l e l e v a t i o n s down t o t h e n e a r e s t 3 0 . 5 m.
If
one rounds up, t h e c o e f f i c i e n t o f d e t e r m i n a t i o n a g a i n i s n o t a s good ( r 2 = 0.60) s u g g e s t i n g t h a t l e s s than a 100% t e r r a i n rise may be b e n e f i c i a l .
CONCLUSION The o v e r l a y t e c h n i q u e g i v e s a n improved c o r r e l a t i o n between model o u t p u t and obs e r v e d ground l e v e l c o n c e n t r a t i o n s .
I t a l s o g i v e s a s p a t i a l l y improved p r e d i c t i o n i n
an area with s i g n i f i c a n t topographical influences.
The t e c h n i q u e u s e s a n e x i s t i n g
long-term model (CDM) and i s b o t h s i m p l e t o a p p l y and c o s t e f f e c t i v e .
The o u t p u t
a p p e a r s t o r e p r e s e n t t h e observed n a t u r a l v a r i a b i l i t y b e t t e r t h a n most two-dimensional models, ACKNOWLEDGEMENTS The a u t h o r i s i n d e b t e d t o S t e e p Rock I r o n Mines L i m i t e d f o r l e t t i n g him u s e t h e emissions d a t a f o r t h i s paper.
REFERENCES
1. A.D. Busse and J . R . Zimmerman, EPA-R4-73-024, (1973) 2. A . A . Slowik, J . M . A u s t i n and G . N . P i c a , P a p e r 77-29.1, p r e s e n t e d a t t h e 7 0 t h Annual Meeting o f t h e AF'CA, (1977) 3 . R. S c o r e r , A i r P o l l u t i o n . Pergamon P r e s s 1968, 1 5 1 pp. 4 . C. Cowherd and R.V. H e n d r i k s , P a p e r No. 77 - 6.2 p r e s e n t e d a t t h e 70th Annual Meeting of t h e APCA, (1977)
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
201
TRANSPORT O F CONTINENTAL S U L F U R COMPOUNDS OVER T H E MEDITERRANEAN B a Cuong NGUYEN a n d B e r n a r d BONSANG C e n t r e d e s F a i b l e s R a d i o a c t i v i t & s , l a b o r a t o i r e m i x t e CNRS-CEA 9 1190 - G i f - s u r - Y v e t t e ( F r a n c e ) ABSTRACT
4 c o n c e n t r a t i o n s , o v e r the S e v e r a l m e a s u r e m e n t s of a t m o s p h e r i c SO2 and SO= M e d i t e r r a n e a n along t h e F r e n c h c o a s t , show t h a t , i n c o n t r a s t with SO,
the
SOz d e c r e a s e s v e r y q u i c k l y with a half l i f e a b o u t 12 h o u r s . T h e c o n t i n e n t a l
s u l f u r c o m p o u n d s a r e c o n s e q u e n t l y being t r a n s p o r t e d p r i n c i p a l l y i n the f o r m of sulfate. INT ROD UC TION T h e r e m o v a l rate of s u l f u r c o m p o u n d s (SO2, SO;)
i n t h e a t m o s p h e r e i s dependent
m m a n y m e t e o r o l o g i c a l a n d c h e m i c a l p a r a m e t e r s . In t h e c a s e of SO2, t h e humidity, t h e p r e s e n c e of c a t a l y s t s a s s o c i a t e d t o t h e p a r t i c l e s a n d t h e n a t u r e of the s u r f a c e u n d e r l y i n g t h e a i r m a s s e s ( l a k e , f o r e s t , o c e a n , e t c , . .) p l a y a p r o m i n e n t p a r t i n t h e o x i d a t i o n t i m e a n d i n t h e d i r e c t a b s o r p t i o n rate of t h i s g a s . S e v e r a l s t u d i e s on t h e r e s i d e n c e t i m e of t h e s e c o m p o u n d s i n t h e a t m o s p h e r e n e a r u r b a n and i n d u s t r i a l a r e a s h a v e b e e n a l r e a d y u n d e r t a k e n ( r e f . 1). In c o n t r a s t , f e w of t h e m h a v e b e e n r e a l i z e d i n t h e r e m o t e a r e a s f a r f r o m polluted c e n t r e s , p a r t i c u l a r l y i n t h e m a r i n e a t m o s p h e r e . C o n s e q u e n t l y , i t would be i n t e r e s t i n g t o s t u d y the d e c r e a s e of SO2 a n d s u l f a t e c o n c e n t r a t i o n s a b o v e t h e M e d i t e r r a n e a n , s i n c e t h e r e a r e a r e a s of i n d u s t r i a l d e v e l o p m e n t along its n o r t h e r n l i t t o r a l . SAMPLING AND ANALYSIS TECHNIQUES O F S U L F U R COMPOUNDS IN MARINE ATMOSPHERE T h e s a m p l i n g a n d a n a l y s i s techniquffi of s u l f u r c o m p o u n d s (SO2 and s u l f a t e s ) o v e r t h e o c e a n s a r e d e s c r i b e d by Nguyen e t al. ( r e f . 2 ) and Bonsang e t al. ( r e f . 3 ) . The SO2 c o n c e n t r a t i o n m e a s u r e m e n t s a r e m a d e u s i n g t h e W e s t - G a e k e m e t h o d while h y d r o s o l u b l e s u l f a t e s a r e a n a l y s e d by b a r i u m s u l f a t e t u r b i d i m e t r y .
202
STUDY O F CONTINENTAL S U L F U R DIOXIDE AND S U L F A T E S OVER THE MEDITERRANEAN F r o m 1973, two c a m p a i g n s h a v e b e e n u n d e r t a k e n i n the M e d i t e r r a n e a n . The f i r s t one took p l a c e i n the Genova gulf f r o m O c t o b e r 2 1 s t t o N o v e m b e r 7th, 1973, following two t r i p s : V i l l e f r a n c h e - s u r - M e r Livorno
- Nice.
-
Calvi
-
V i l l e f r a n c h e and Nice
-
T h e s e c o n d one h a s been u n d e r t a k e n along the F r e n c h l i t t o r a l
f r o m V i l l e f r a n c h e - s u r - M e r to L a Grands-hdottte from A p r i l 19th t o A p r i l 26th 1974. T h e s e c a m p a i g n s took p l a c e p r i n c i p a l l y on b o a r d of the o c e a n o g r a p h i c s h i p " K o r o t n e f f " e x c e p t d u r i n g t h e t r i p N i c e - L i v o r n o when the v e s s e l "Lutin" w a s used. C a m p a i g n i n the C e n o v a ~vulf During t h i s c a m p a i g n , t h e wind w a s e s s e n t i a l l y f r o m the n o r t h e a s t e r n s e c t o r with a v e r y low v e l o c i t y a b o u t 3 m / s e c , the t r i p Livorno
- Nice.
e x c e p t a t t h e end of the c a m p a i g n during
W e note ( F i g . 1 ) a v e r y r a p i d d e c r e a s e of SO2 by a f a c t o r 1 0 a t about 60 k m f r o m Nice d u r i n g the t r i p V i l l e f r a n c h e - C a l v i . At t h i s d i s t a n c e f r o m the c o a s t , the SOz c o n c e n t r a t i o n r e a c h e s a v a l u e of 0.15 1g/m3, which i s similar t o the o c e a n i c value 3 (0. 1Wg/m3) ( r e f . 2). T h i s c o n c e n t r a t i o n 0.15pg/m is o b s e r v e d a l s o d u r i n g the t r i p Nice-Savona ( f r o m Oh t o 11 h 3 0 , O c t . 4 ) a t only a b o u t 8 k m f r o m t h e c o a s t . I n contrast;the
s u l f a t e c o n c e n t r a t i o n d e c r e a s e s v e r y slowly ( F i g . 1 ) . F o r the
s a m e d i s t a n c e , the s u l f a t e c o n c e n t r a t i o n d e c r e a s e s by only a f a c t o r of 2 . The SO2 r e s i d e n c e t i m e seems, t h e r e f o r e , to be v e r y s h o r t i n r e l a t i o n t o t h a t of sulfate aerosols,
F i g . 1 SO2 a n d SO; a t m o s p h e r i c c o n c e n t r a t i o n s o v e r the Genova Gulf ( f r o m O c t o b e r 30th t o N o v e m b e r 7 t h 1973).
203
C a m p a i g n alonp the F r e n c h c o a s t ( V i l l e f r a n c h e - s u r - M e r
-
La G r a n d e - M o t t e )
During t h i s c a m p a i g n , we undertook s i m u l t a n e o u s m e a s u r e m e n t s a t s e a on b o a r d the "Korotneff" a n d a l s o on land i n a m o b i l e l a b o r a t o r y . The F r e n c h Medit e r r a n e a n c o a s t w a s u n d e r the influence of a well e s t a b l i s h e d anticyclone. The wind v e l o c i t y w a s v e r y low ( 3 m / s e c ) a n d of i n d e t e r m i n a t e direction.During the r e t u r n t r i p f r o m M a r s e i l l e t o V i l l e f r a n c h e , h o w e v e r , the m e t e o r o l o g i c a l conditions b e c a m e u n f a v o r a b l e (wind v e l o c i t y 2 0 m / s e c , wild s e a ) . T h i s c a m p a i g n c o n f i r m s the p r e c e d i n g r e s u l t s . Indeed, we o b s e r v e d a v e r y r a p i d d e c r e a s e of SO2 a t 70km f r o m the c o a s t , w h e r e the c o n c e n t r a t i o n w a s only 1/10 of the c o a s t a l value. The s u l f a t e c o n c e n t r a t i o n a t the bame p l a c e w a s only half of i t s value a t the c o a s t (Fig.2).
I
Fig.2
1.0
SO2, SOZ, 2 1 2 P b a n d 2 2 2 R n a t m o s p h e r i c c o n c e n t r a t i o n s o v e r the M e d i t e r r a n e a n along the F r e n c h c o a s t ( f r o m A p r i l 19th t o A p r i l 26th, 1974).
DISCUSSION a ) R e s i d e n c e t i m e of SO7 The r e m o v a l of SO2 i n the m a r i n e a t m o s p h e r e d e p e n d s o n four p r i n c i p a l p r o c e s s e s 1 ) oxidation t o s u l f a t e i n the a t m o s p h e r e ; 2) d i r e c t a b s o r p t i o n by the sea s u r f a c e ;
3 ) u p w a r d m i x i n g into h i g h e r l a y e r s of the a t m o s p h e r e ; 4) p r e c i p i t a t i o n washout. T h i s l a s t r e m o v a l p r o c e s s h a s not b e e n c o n s i d e r e d i n o u r a n a l y s i s , b e c a u s e no p r e c i p i t a t i o n o c c u r e d d u r i n g o u r e x p e r i m e n t s . The effect of the v e r t i c a l mixing p r o c e s s e s h a s b e e n d e t e r m i n e d by m a k i n g s i m u l t a n e o u s m e a s u r e m e n t s of n a t u r a l r a d i o a c t i v e g a s e s e m i t t e d f r o m e m e r g e d s o i l s : 2 1 2 P b (half-life 1 0 , 6 h o u r s ) and
t
222Rn (half-life 3 , 8 2 5 d a y s ) which are i n t r o d u c e d i n t h e l o w e r p a r t of the continental
204
t r o p o s p h e r e along with a n t h r o p o g e n i c SO2 a n d , p r e s u m a b l y , a r e d i s p e r s e d i n the s a m e way. With the s i m u l t a n e o u s m e a s u r e m e n t s of SO2 a n d t h e s e r a d i o a c t i v e g a s e s , the SO2 half-life by the two p r o c e s s e s : oxidation t o s u l f a t e a n d a b s o r p t i o n by s e a w a t e r , h a s b e e n d e t e r m i n e d a s 12 h o u r s ( r e s i d e n c e t i m e T = 1 7 , 5 h o u r s ) a c c o r d i n g t o o u r e x p e r i m e n t s d u r i n g the c a m p a i g n Villefranche - L a G r a n d e Motte ( r e f . 4 ) . T h i s half-life of SO2 ( I 2 h o u r s ) is c l o s e to the r a d i o a c t i v e h a l f l i f e of 2 1 2 P b ( 1 0 , 6 h ) . We o b s e r v e , t h e r e f o r e , the r a p i d d e c r e a s e of c o n c e n t r a t i o n f o r t h e s e two s p e c i e s i n the F i g u r e s 2a and 2b. A s i m i l a r r e s u l t w a s found i n o u r e x p e r i m e n t d u r i n g GATE o v e r t h e A t l a n t i c o c e a n , 2 0 0 0 Km West of D a k a r , w h e r e we found a n oxidation r e s i d e n c e t i m e of 1 3 , 5 h o u r s ( r e f . 5). The r e s i d e n c e t i m e of SO2 o v e r the s e a s e e m s t o be s h o r t e r t h a n t h a t o v e r the continent. Indeed, i n F i g u r e 3 , we note a d e c r e a s e of SO2 m u c h f a s t e r o v e r the s e a t h a n o v e r the continent a r o u n d F o s - s u r - M e r .
T h i s phenomenon c a n be e a s i l y
e x p l a i n e d , s i n c e i n the m a r i n e a t m o s p h e r e , the h u m i d i t y a s s o c i a t e d with the p r e s e n c e of s e a s p r a y a n d h e a v y m e t a l s a n d the p r e s e n c e of v a r i o u s a t m o s p h e r i c r e a c t i v e s p e c i e s ( i n p a r t i c u l a r , f r e e r a d i c a l s ) c a n a c c e l e r a t e the oxidation of SO
2'
b ) R e s i d e n c e t i m e of s u l f a t e s . The s u l f a t e a e r o s o l s a r e r e m o v e d e s s e n t i a l l y by upward m i x i n g , fixation on the c o n d e n s a t i o n n u c l e i of c l o u d s , t r a n s p o r t by a i r m a s s e s a n d d e p o s i -
lo
'
5.
('1
tion i n d r y and h u m i d fallout f o r m .
', ',
T h e s e r e m o v a l p r o c e s s e s c a n be
1,
c o m p a r e d t o t h o s e of r a d o n a c t i v e d e p o s i t s fixed on a t m o s p h e r i c p a r t i -
a n d s u l f a t e s ( F i g . Z c , 2d) d e m o n s t r a tes t h i s e f f e c t . ?he r e s i d e n c e t i m e of s u l f a t e a e r o s o l s i n the l o w e r t r o p o s ( 0 t o 3 K m ) c a n be e s t i m a t e d
f r o m o u r r e s u l t s a s about 3 days. T h i s f i g u r e is r e a s o n a b l e , s i n c e
Lai
3 ~ 0 (sp o r t )
~ ~ a v e r a
', 5 - B e r r e -+ 6-Port de Ro
Q5.
c l e s . The similar d e c r e a s e of 2 2 2 R n
phere
1-Martigues
'@? 2-Plage du
ABOUT 30 K M
100
50
50
100 150
F i g . 3 SO2 a n d SO; a t m o s p h e r i c c o n c e n t r a t i o n s o v e r the Rhone v a l l e y a n d the M e d i t e r r a n e a n s e a ( f r o m A p r i l 2 3 r d t o A p r i l 30th 1974).
the r e s i d e n c e t i m e of a e r o s o l s i n the l o w e r t r o p o s p h e r e is of the s a m e o r d e r according to Flohn (ref. 6 ) .
205
T h e M e d i t e r r a n e a n which h a s a r e l a t i v e l y s m a l l s u r f a c e , is c r o s s e d by a c o n t i nental air mass i n about 3 days
. T h i s e x p l a i n s why the s u l f a t e c o n c e n t r a t i o n s a r e
s o m e t i m e s quite s i m i l a r on the l i t t o r a l a n d o v e r the s e a a t 100 o r 200 k m f r o m the c o a s t , f o r e x a m p l e , off F o s - s u r - M e r a n d H y e r e s ( F i g . 2 ~ ) .The a v e r a g e d e c r e a s e of s u l f a t e s is r e l a t i v e l y low, by a f a c t o r 2 at about 70 k m f r o m the c o a s t . CONCLUSION During the s e c o n d c a m p a i g n u n d e r t a k e n b y o u r m o b i l e l a b o r a t o r y along the F r e n c h M e d i t e r r a n e a n c o a s t f r o m V i l l e f r a n c h e t o L a G r a n d e - M o t t e and i n the Rhone v a l l e y , the SO2 c o n c e n t r a t i o n s v a r i e d f r o m 1 t o 20pg/m3 e x c e p t i n the a r e a n e a r F o s , w h e r e c o n c e n t r a t i o n s w e r e h i g h e r a n d v a r i e d f r o m 2 t o 30pg/m3. F o r the sulfate a e r o s o l s , t h e s e c o n c e n t r a t i o n s v a r i e d r e s p e c t i v e l y f r o m 8 t o 2Opg/m3 and n e a r F o s f r o m 10 t o 40pg/m3.
T o g e t a n o r d e r - o f - m a g n i t u d e e s t i m a t e of the i m p o r t a n c e of the p r o d u c -
tion of s u l f u r compounds which a r e p r i n c i p a l l y a n t h r o p o g e n i c f o r S O z , we have a t t e m p t e d t o e s t i m a t e t h i s p r o d u c t i o n along the F r e n c h M e d i t e r r a n e a n c o a s t . If we c o n s i d e r t h a t the a v e r a g e SO2 c o n c e n t r a t i o n i n the l o w e r t r o p o s p h e r e ( 0 t o 1 km) along a I 0 k m c o a s t a l b e l t is about 3pg/m3 a n d t h a t the wind velocity is about 3 m / s e c , we c a n e s t i m a t e the SO2 production a s 3 0 0 T / y r - l . k m - ' .
In the M e d i t e r -
r a n e a n b a s i n , we note t h a t t h e r e is a non-negligible n a t u r a l s o u r c e of SO2 due t o the E t n a volcano. H a u l e t e t a l . ( r e f . 7 ) h a v e e s t i m a t e d i t s production a t about 3700 T/day, i. e . 1 ,3.106T/yr.
T h e r e f o r e it r e p r e s e n t s p r a c t i c a l l y 6 t i m e s the anthropogenic
production over Mediterranean F r e n c h coast. O v e r the M e d i t e r r a n e a n s e a , the SO2 d e c r e a s e s v e r y quickly, s o t h a t the t r a n s p o r t of the a n t h r o p o g e n i c s u l f u r compounds o v e r the s e a t a k e s p l a c e principally i n the f o r m of s u l f a t e (S04H2, (NH4)2 SO4) d e r i v e d f r o m SO2 oxidation, ACKNOWLEDGEMENTS : We a r e v e r y g r a t e f u l t o P r . P . B o u g i s a n d D r . M.Aubert, M r . J. L . P a s q u i e r a n d M r . P. P a u l h i a c a n d the c r e w of the "Korotneff" and the "Lutin" f o r t h e i r help and a s s i s t a n c e . REFERENCES 1. W . WKellogg, R . D . C a d l e , E . R. A l l e n , A . L . L a z r u s a n d E . A . M a r t e l l , The s u l f u r c y c l e , S c i e n c e 175(1972)587-596. 2 . B . C . Nguyen, B , B o n s a n g , G . L a m b e r t , T e l l u s 26(1974)241-249. 3. B. Bonsang a n d B . C . Nguyen, T h i s i s s u e . 4. B . C. Nguyen, B. B o n s a n g , G . L a m b e r t a n d J . L . P a s q u i e r , R e s i d e n c e t i m e of SO2 i n t h e m a r i n e a t m o s p h e r e , P u r e a n d Appl.Geophys. 123( 1975)489-500. 5 . B . C . Nguyen, B . B o n s a n g , A. G a u d r y and G . L a m b e r t , IAGA/IAMAP Joint A s s e m b l y , S e a t t l e August 1977, USA. 6. H . F l o h n , In B o n n e r M e t e o r . A b h a n d l u n g e n , W e s t d e u t s c h e r V e r l a g , 1973,75-117. 7. R . H a u l e t , P. Zettwoog a n d J . C . S a b r o u x , N a t u r e 268(1977)715-717.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M.Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
207
ASSESSMENT OF AN OECD STUDY ON LONG RANGE TRANSPORT OF A I R POLLUTANTS (LRTAP) INVOLVING SOME ASPECTS OF A I R CHEMISTRY. M. BENARIE I n s t i t u t N a t i o n a l de Recherche Chimique Appliquee - BP 1 91710 VERT-le-PETIT (FRANCE)
P. D E T R I E Centre I n t e r p r o f e s s i o n n e l Technique D'Etudes de l a P o l l u t i o n Atmosph6rique 28 Rue de l a Source P A R I S 16 (FRANCE)
ABSTRACT Y e a r l y , m o n t h l y and even d a i l y averages o f s u l p h a t e and hydrogen i o n i n p u t by r a i n w a t e r most o f t e n a r e u n c o r r e l a t e d . Good c o r r e l a t i o n seems l i m i t e d t o a few s t r o n g l y l o c a l i z e d areas. T h e r e f o r e even advanced knowledge o f s u l p h a t e t r a n s p o r t cannot c o m p l e t e l y e x p l a i n r a i n a c i d i t y . General and l o c a l e f f e c t s such as : widely v a r i a b l e sulphur d i o x i d e t o sulphate o x i d a t i o n rates, c a t a l y t i c accelerat i o n o r l o c a l n e u t r a l i z a t i o n , and l a s t b u t n o t l e a s t n i t r i c and h y d r o c h l o r i c o r o t h e r a c i d genesis s h o u l d a l s o be c o n s i d e r e d b e f o r e a d e f i n i t i v e view about t h e a c i d r a i n phenomenon i s e s t a b l i s h e d .
INT RO DUC T I0 N ROSSBY and EGNER (1955) and ERIKSSON (1959, 1960) observed t h a t p r e c i p i t a t i o n a t many European A i r Chemistry Network (EACN) s t a t i o n s was becoming g r a d u a l l y more a c i d . T h i s o b s e r v a t i o n was a s s o c i a t e d w i t h t h e a c i d i f i c a t i o n o f t h e r i v e r and l a k e waters i n Scandinavia. One o f t h e reasons f o r r e c o n s i d e r i n g t h e EACN programme were i t s inadequacies p o i n t e d o u t by PATERSON and SCORER (1973) and by PATERSON ( 1 9 7 5 ) . I n 1972 a " L o - o p e r a t i v e T e c h n i c a l Programme t o Measure t h e Long Range T r a n s p o r t o f A i r P o l l u t a n t s " (LRTAP) was accepted by t h e OECD C o u n c i l (OECD, 1972). The o b j e c t i v e f o r t h e programme was d e f i n e d as : " t o determine t h e r e l a t i v e importance o f l o c a l and d i s t a n t sources o f s u l f u r compounds i n terms o f t h e i r c o n t r i b u t i o n t o t h e a i r p o l l u t i o n over a region, special a t t e n t i o n being paid t o t h e question o f a c i d i t y i n atmospheric p r e c i p i t a t i o n s " . The scope o f t h e p r e s e n t paper i s t o a n a l y z e t h e e x t e n t t o which t h e accumulated r e s u l t s o f t h i s programme (OECD,
1977)
quoted f u r t h e r as " F i n a l R e p o r t " may l i n k t h e e f f e c t : a c i d i t y i n p r e c i p i t a t i o n , t o t h e presumed cause : s u l p h u r compounds. The OECD (1977) r e p o r t a t t e m p t s t o answer t h e q u e s t i o n o f how sudphur compounds a r e t r a n s p o r t e d . The F i n a l Report, based m a i n l y on p r e v i o u s works, assumes t h a t an o v e r a l l correspondence e x i s t s
208
between s u l p h u r compounds and a c i d i t y i n r a i n , w i t h perhaps n i t r o g e n o x i d e s p l a y i n g a second-order r o l e . I t w i l l be shown below t h a t t h e s t a t i s t i c a l - e m p i r i c a l evidence o f r a i n c h e m i s t r y does n o t c o n f i r m t h e i n i t i a l assumption t h a t s u l p h u r e m i s s i o n and t r a n s p o r t e x p l a i n t h e a c i d i t y , as expressed i n t h e F i n a l Report. Many more f a c t s have t o be g a t h e r e d b e f o r e t h e main q u e s t i o n o f g e o g r a p h i c a l d i s t r i b u t i o n and chemical genesis o f a c i d i t y may be answered.
THE DATA Table 3.4 o f t h e F i n a l Report c o n t a i n s , a l o n g w i t h o t h e r d a t a o b t a i n e d from t h e LRTAP ground sampling network f o r t h e main o b s e r v a t i o n y e a r o f 1974, t h e mean weighted c o n c e n t r a t i o n s o f s u l p h u r and H+ ( s t r o n g a c i d ) i n t h e p r e c i p i t a t i o n s . -F i a u r e 1 shows t h e SO4 /2H+ r a t i o s as computed f r o m t h e s e r e s u l t s . Near-equivalence between p r e c i p i t a t e d s u l p h a t e and s t r o n g a c i d i t y can be r e c o g n i z e d i n some areas only. F i g u r e 2 shows t h e c o r r e l a t i o n c o e f f i c i e n t between t h e weighted monthly mean c o n c e n t r a t i o n o f s u l p h a t e and s t r o n g a c i d , computed f r o m t h e f i g u r e s o f t h e LRTAP 3/76 document (SCHAUG, 1976). Most c o e f f i c i e n t s were computed f r o m 12 p a i r s o f weighted means excepted a few where no p r e c i p i t a t i o n has been recorded d u r i n g one o r two rnonths.As t h e s e (0,O) v a l u e s f o r c e t h e r e g r e s s i o n l i n e t h r o u g h t h e o r i g i n , s i m u l a t i n g i n t h i s way s p u r i o u s c o r r e l a t i o n , t h e y were n o t t a k e n i n t o c o n s i d e r a t i o n . Due t o t h e f a c t t h a t i n t h e most concernedarea - S o u t h e r n
Norway-the
high d e n s i t y
o f t h e ground sampling network f o r e c l o s e s a t t h i s s c a l e t h e r e p r e s e n t a t i o n o f a l l r e g r e s s i o n c o e f f i c i e n t s , a map o f t h i s a r e a was p r o v i d e d i n F i g . 3, on a more adequate s c a l e . Except Southern Norway, S c o t l a n d and t h e F e d e r a l R e p u b l i c o f Germany, s u l p h a t e and s t r o n g a c i d c o n c e n t r a t i o n s seem m o s t l y u n c o r r e l a t e d . T h i s was a l r e a d y n o t e d i n t h e F i n a l Report ( p . 3 - 3 7 ) :
"
c o r r e l a t i o n between s t r o n g a c i d
and o t h e r i o n s , e.g. s u l p h a t e , v a r i e s f r o m l o w v a l u e s t o about 0.9 r i s o n o f F i g u r e s 1 and 2
shows t h a t t h e areas where S O ; ' :
'I.
The compa-
H+ c o r r e l a t i o n i s
s i g n i f i c a n t , a near a n i o n / c a t i o n e q u i v a l e n c e e x i s t s . On t h e o t h e r hand, most s t a t i o n s w i t h low c o r r e l a t i o n p r e s e n t wide v a r i a t i o n s o f t h e SO4
--
/2Ht
ratio.
As a r u l e , t h e c o r r e l a t i o n o f grouped d a t a r e p r e s e n t i n g m o n t h l y r e s u l t s i n t h i s case, s h a l l be h i g h e r t h a n t h e c o r r e l a t i o n on day-to-day b a s i s . T h i s l a t t e r was a l s o computed f o r each month o f t h e y e a r 1974 and f o r e v e r y s t a t i o n where d a t a were a v a i l a b l e . Space c o n s i d e r a t i o n s do n o t a l l o w t h e r e p r o d u c t i o n o f a 70 ( s t a t i o n s ) b y 12 (month) t a b l e , t h e r e f o r e o n l y some t y p i c a l values a r e shown i n Table 1 which c o n f i r m t h e g e n e r a l i m p r e s s i o n d i s p l a y e d by F i g u r e s 2 and 3 . I n Southern Norway good c o r r e l a t i o n seems t h e r u l e , w h i l e o t h e r w i s e t h e c o r r e l a t i o n between H+ and SO4--
i o n s i s weak o r i n e x i s t e n t . Most i n s t r u c t i v e a r e some German
s t a t i o n s , f o r example DO3 where t h e m o n t h l y means show a c o r r e l a t i o n c o e f f i c i e n t o f 0.76, though t h e f i r s t l i n e o f T a b l e 1 demonstrates t h a t t h i s e f f e c t i s s p u r i o u s .
209
__
F i g . 1. The SO4 /2H+ r a t i o as observed i n 1974 by t h e LRTAP ground sampling network, computed f r o m Table 3 . 4 o f t h e OECD ( 1 9 7 7 ) F i n a l Report.
210
- 32
F i g . 2 . The g e o g r a p h i c a l d i s t r i b u t i o n o f t h e c o r r e l a t i o n c o e f f i c i e n t between t h e weighted m o n t h l y mean c o n c e n t r a t i o n o f s u l p h a t e and s t r o n g a c i d , computed from OECD 3/76 (SCHAUG, 1976).
211
F i g . 3. The g e o g r a p h i c a l d i s tribution o f the correlation c o e f f i c i e n t between t h e weighted m o n t h l y mean c o n c e n t r a t i o n o f s u l p h a t e and s t r o n g a c i d i n Southern Norway - e n l a r g e d s e c t i o n o f F i g u r e 2. Computed f r o m OECD 3/76 (SCHAUG 1976).
TABLE 1
-Day b y day c o r r e l a t i o n c o e f f i c i e n t between Ht and SO4 c o n c e n t r a t i o n i n r a i n f o r 1974
Station DO3
DO4 F03
NO1 NO7 N 08 N26 SO5 SF3 UK 1
1 2 - .O2 - .57 .47 .45 -.35 .23 .97 .92 .96 .49 .97 .97 .93 .92 .40 .48 - . 79 .70 .55 -.85
M
3 4 .31 .76 .62 .81 .54 -.43 .99 --.86 .92 --.90 -.80 .86 .33
--
--
0 n t 5 6 7 .82 .I7 - .49 .68 .76 .55 .16 ---. 56 .14 .94 .23 .88 .89 .94 .75 .ll .97 .13 - .20 .99 - .07 - .03 .96 .42 .63
--
--
--
h
8 .93 .16
9 1 0 1 1 1 2 .72 .63 .35 .44 .04 .91 .60 .69
.95 .97 .76 .97 .94 .65
.85 .87 .76 .94 .77 .30
--
--
-_
--
--
.68 .36 .59 .68 .84 .11
--
.40
.88 .73 .80 .90 .85 .09
--
DISCUSSION The l a c k o f chemical e q u i v a l e n c e ( F i g u r e 1) and o f c o r r e l a t i o n between i o n i c c o n c e n t r a t i o n s ( F i g u r e 2) c o u l d be i n t e r p r e t e d i n t h r e e ways : ( a ) N e u t r a l i z a t i o n by some b a s i c components as
NH4 io r Ca".
--
.80 .68 .86 .94 .77 .61
S t r o n g arguments
--
212
f o r t h i s assumption have been f o r w a r d e d by KAYSER e t a l . (1974). ( b ) A s i g n i f i c a n t f r a c t i o n o f t h e s t r o n g a c i d i s produced by o t h e r r e a c t i o n s t h a n SO2 o x i d a t i o n . T h i s p o s s i b i l i t y ( t h e r o l e o f n i t r o g e n o x i d e s ) was suggested i n v a r i o u s p o i n t s o f t h e F i n a l Report. ( c ) S u l p h u r o x i d a t i o n i s a cause o f r a i n a c i d i f i c a t i o n b u t d i f f e r e n t mechanisms and/or r e a c t i o n rat.es may be engaged a t d i f f e r e n t p l a c e s and/or v a r i o u s meteorol o g i c a l circumstances. BROSSET e t a l . (1975) observed on t h e Swedish West Coast two d i s t i n c t t y p e s o f a c i d p a r t i c l e s w i d e l y d i f f e r i n g by t h e i r S04--/2H+
ratio,
e x p l a i n e d a p p a r e n t l y by a t l e a s t two d i f f e r e n t chemical processes i n v o l v e d i n t h e i r formation. Anyway,even
ifj u s t one o f t h e s e e v e n t u a l i t i e s occurs, t h e u n d e r s t a n d i n g o f t h e
l o n g range t r a n s p o r t o f s u l p h u r compounds cannot y i e l d t h e f u l l e x p l a n a t i o n o f t h e presence o f s t r o n g a c i d . O b v i o u s l y , these t h r e e assumptions a r e n o t m u t u a l l y e x c l u s i v e and may occur s i m u l t a n e o u s l y . Besides t h e s e c a u s a t i v e e f f e c t s , l a c k o f c o r r e l a t i o n m i g h t happen when b o t h v a r i a b l e s a r e o f c y c l i c a l n a t u r e and o u t o f phase. Table 2 shows t h a t w i n t e r and summer c o n c e n t r a t i o n means o f s u l p h a t e i n r a i n w a t e r a r e i n d i s t i n g u i s h a b l e . TABLE 2 Average w i n t e r ( W ) and summer ( S ) c o n c e n t r a t i o n s o f SO4
--
and H+ i n r a i n .
The w i n t e r v a l u e s a r e t h e means o f seven weighted averages, October t o A p r i l ( i n c l . ) and f o r summer, t h e y a r e t h e means f r o m May t o September ( i n c l . )
1 H+
so4 mg/l 1.45 1.99
ueq/ 1 6.7 21.8
NO8
5.97 6.41
34.0 48.5
N26
W
7.35 4.90
59.1 30.9
NL1
F05
w
7.38 6.71
SO3
NO6
w
30.5 56.4
3.24 3.86
58.9 54.4
SO5
W
3.96 3.61
57.4 50.9
SF2
CH1
W
DO2 FO1
NO7
UKl
h!
so4 mq/1 1.56 2.49
H+
w/ 1 32.1 40.0
W
2.87 3.27
65.2 48.1
W
7.35 6.26
57.9 75.1
W
5.51 5.66
57.2 47.2
w
2.31 2.10
40.5 24.3
W
2.70 2.79
44.8 37.8
w
4.00 4.79
70.5 94.9
There i s no h i n t o f annual c y c l e . The a c i d i t y v a r i e s somewhat b u t i n agreement w i t h t h e l a c k o f c o r r e l a t i o n between s u p l h a t e and s t r o n g a c i d as demonstrated b y F i g u r e 2, no s y s t e m a t i c v a r i a t i o n i s r e v e a l e d .
213
By t h e way, Table 2 r e p r e s e n t s a s t r o n g argument a g a i n s t t h e assumption t h a t t h e e m i s s i o n of s u l p h u r compounds i n Europe i s t h e one and o n l y cause o f observed a c i d i t y i n t h e r a i n w a t e r o f Southern Norway. I n t h e presence o f a c a u s e - t o - e f f e c t l i n k , a t l e a s t some seasonal response t o t h e seasonal v a r i a t i o n o f h e a t i n g demand c o u l d be expected. A s i t i s know, space h e a t i n g accounts f o r f r o m 25% t o 54% of t h e t o t a l e m i s s i o n of s u l p h u r d i o x i d e ( F i n a l Report, p.2-15). F i g u r e 3 shows how r a i n a c i d i t y o r i t s absence may be i n f l u e n c e d by s h o r t - r a n g e o r m i c r o c l i m a t i c f a c t o r s ; areas o f s t r o n g c o r r e l a t i o n a l t e r n a t e w i t h groups o f s t a t i o n s o f l o w c o r r e l a t i o n . I t i s d i f f i c u l t t o a s c r i b e t h e l a t t e r t o an e f f e c t o f chance, as t h e s e s t a t i o n s seem g e o g r a p h i c a l l y c l u s t e r e d . The a r e a covered by t h e map o f F i g u r e 3 i s c o n s i d e r e d as " h i g h l y e p i s o d i c " by t h e F i n a l Report. T h a t means t h a t wet d e p o s i t i o n o f any substance ( s u l p h a t e , s t r o n g a c i d . . . ) occurs on l e s s t h a n 5% of t h e annual wet days. T h e r e f o r e i t would -be o f i n t e r e s t t o l o o k a t t h e SO4 /2H+ r a t i o s r e c o r d e d d u r i n g a t y p i c a l episode day
-
January 11, 1974 f o r example
-
t h a t was t h e o b j e c t o f a thorough t r a j e c t o r y
a n a l y s i s i n Chapter 6 o f t h e F i n a l Report. F i g u r e 4 r e v e a l s t h e same k i n d o f
I
I
F i g . 4. The S04--/2Ht recorded d u r i n g t h e episode-day o f Jan.11, 1974 i n Southern Norway (Source :Chapter 6 of t h e F i n a l Report).
I
I
,
I
I
1 I
I
1 I
I
-.
,
\
,I
C -
I
,
214
patchy pattern f o r a s i n g l e event occuring within 24 hours and within a limited perimeter, in the same way as did Figure 1 f o r t h e y e a r l y average and t h e whole continent. The sulphate/strong acid r a t i o s vary widely f o r example from 0.15 t o 4.18 over l e s s than 150 km distance. A c e r t a i n consistency in t h e r a t i o pattern can be observed so t h a t chance and e r r o r may be excluded, a l l t h e more t h a t the days preceding and following January 11 ( n o t presented here) display similar tendencies as those shown i n Figure 4 , t h o u g h apparently d i f f e r e n t t r a j e c t o r i e s were involved. I f such local v a r i a t i o n s e x i s t f o r t h e sulphate/strong acid r a t i o , we may be convinced t h a t the long range t r a j e c t o r y history of sulphur i s not an exhaustive explanation of t h e acidity-episode and consequently we have t o revert t o the t h r e e assumptions exposed a t the beginning of t h i s subsection.
OTHER C O N C U R R I N G RESULTS
This i s not t h e f i r s t paper t o point out the f a c t t h a t t h e t r a n s p o r t of sulphates o r even t h e i r presence i s only a p a r t i a l explanation of rain a c i d i f i cation. GRANAT (1972) remarked t h a t " I f looking f o r a r e l a t i o n between anthropogenic sulphur emissions and the acid content of p r e c i p i t a t i o n , one will not find a c l e a r r e l a t i o n unless several other components a r e being considered ... n i t r i c acid created from nitrogen oxides i s not unimportant". Several papers of the " F i r s t International Symposium on Acid P r e c i p i t a t i o n and Forest Ecosystems" (Flay 12-15, Columbus, Ohio) e i t h e r point in the same d i r e c t i o n or propose a l t e r n a t i v e and/or complementary chemical mechanisms ( Y U E and FIOHNEN, 1976; ROWE, 1976). LIKENS e t a l . (1976), analyzing t h e r e l a t i o n s h i p between the annual input of H+ and other ions f o r t h e Hubbard Brook Experimental Forest (within the White Mountain National Forest, North Hampshire, USA) during 1964-1974, found t h a t t h e input of Ht was n o t s i g n i f i c a n t l y r e l a t e d t o sulphate input over t h e 10 years period. On t h e contrary, the annual n i t r a t e input was highly c o r r e l a t e d with t h e annual H'ion
input.
CONCLUSIONS
I n general, sulphate and hydrogen ion input by rainwater over a given area a r e n o t r e l a t e d . Therefore even advanced knowledge of sulphate t r a n s p o r t cannot completely explain r a i n a c i d i t y . Transport models of say 100 by 100 km g r i d square seem not -adequate, because s i g n i f i c a n t v a r i a t i o n s in t h e SO4 /2H+ r a t i o occur a t a l e s s e r s c a l e in t h e endangered areas. General and local e f f e c t s such as : widely variable sulphur dioxide t o sulphate oxidation r a t e s , c a t a l y t i c acceleration o r local n e u t r a l i z a t i o n , and l a s t b u t not l e a s t n i t r i c and hydrochloric o r other acid genesis should a l s o be considered before a d e f i n i t i v e view about the acid r a i n phenomenon i s established.
215
REFERENCES E r i k s s o n , E. 1959,1960 : The y e a r l y c i r c u l a t i o n o f c h l o r i d e and s u l p h u r i n nature; 11, 375m e t e o r o l o g i c a l , geochemical and p e d o l o g i c a l i m p l i c a t i o n s . P a r t I , T e l l u s 403. P a r t 11, T e l l u s 63-109
12,
B r o s s e t C . , Andreasson K. and Ferm M. 1975 : The n a t u r e and p o s s i b l e o r i g i n o f 9, 631-642. a c i d p a r t i c l e s observed a t t h e Swedish West Coast. A t m . Env. Granat L. 1972 : On t h e r e l a t i o n between pH and t h e chemical c o m p o s i t i o n i n 24, 550-560. atmospheric p r e c i p i t a t i o n . T e l l u s Kayser K., Jesse1 U., K o h l e r A. and Ronicke G. 1974 : D i e pH- Werte des N i e d e r s c h l a g e s i n d e r B u n d e s r e p u b l i k Deutchland 1967-1972. Deutche Forschungsgem e i n s c h a f t , Kommission z u r E r f o r s c h u n g d e r L u f t v e r u n r e i n i g u n g M i t t e i l . I X , 21. L i k e n s G.C., Bormann F.H., Eaton J.S., P i e r c e R.S. and Johnson N.M. 1976 : Hydrogen i o n i n p u t t o t h e Hubbard Brook Experimental F o r e s t , New Hampshire, 6, 435-445. d u r i n g t h e l a s t decade. Water, A i r and S o i l P o l l . OECD, 1972 : D e c i s i o n o f t h e OECD C o u n c i l o f 18 A p r i l 1972, C(72)13 ( F i n a l ) . OECD, 1977 : The OECD programme on l o n g range t r a n s p o r t o f a i r p o l l u t a n t s Measurements and f i n d i n g s , 7 J u l y 1977. P a t e r s o n H . P . 1975 : The atmospheric t r a n s p o r t o f n a t u r a l and man-made substances. Thesis, Univ. o f London, 132 pp. Paterson M.P. and S c o r e r R.S. 1973 : Data q u a l i t y and t h e European A i r Chemistry Network. A t m . Env. 7, 1163-1171. Rossby, C.G., Egner, H. 1955 : On t h e chemical c l i m a t e and i t s v a r i a t i o n w i t h 7, 118-133. t h e atmospheric c i r c u l a t i o n s . T e l l u s Rowe R.D. 1976 : A s u l p h u r budget f o r s o u r gas p l a n t s . Water, A i r and S o i l 6, 321-327. Poll. Schaug J. 1976 : LRTAP ground sampling s t a t i o n s - p r e c i p i t a t i o n and mean concent r a t i o n v a l u e s - January 1974 - March 1975 - LRTAP 3/76, 91 pp. Yue G.K. and Mohnen V.A. and Kiang C.S. 1976 : A mechanism f o r h y d r o c h l o r i c a c i d p r o d u c t i o n i n c l o u d . Water, A i r and S o i l P o l l . 6, 277-294.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
217
DETERMINATION OF ELEMENTARY DEPOSITION VELOCITIES OF SO2 ONTO LEAVES C.
PETIT, M. LEDOUX and M. T R I N I T E
L a b o r a t o i r e de Thermodynamique, L . A . n o 230 du C.N.R.S., Facultd des Sciences e t d e s Techniques d e Rouen, B.P. 6 7 , 76130 MONT-SAINT-AIGNAN (FXANCE).
ABSTRACT I t i s p o s s i b l e t o r e l a t e t h e SO2 f l u x t h a t i s c a l c u l a t e d above a f o r e s t t o t h e
e l e m e n t a r y d e p o s i t i o n v e l o c i t y on l e a v e s when t h e l e a f area d e n s i t y and SO2 conc e n t r a t i o n s i n s i d e t h e canopy are known. F o r t h a t p u r p o s e , e x p e r i m e n t s i n a windt u n n e l have been performed i n o r d e r t o g e t a s i m p l e r e l a t i o n . Furthermore, k i n e t i c c o n s t a n t s and l e a f l e n g t h s i n t h e case o f a f o r e s t are s u c h t h a t a c o u p l i n g between t h e boundary l a y e r r e s i s t a n c e rCLand t h e s u r f a c e r e s i s t a n c e r
S
has t o
b e t a k e n i n t o a c c o u n t . D e p o s i t i o n v e l o c i t i e s f o r l e a v e s i n t h e l a b o r a t o r y and t h o s e deduced from measurements i n t h e f o r e s t show h i g h d i s c r e p a n c i e s i n g e n e r a l . Some e x p l a n a t i o n s o f t h i s f a c t are g i v e n i n t h i s p a p e r .
INTRODUCTION
I n a preceding
p a p e r ( r e f . 1) e x p e r i m e n t a l p r o c e d u r e s have been d e s c r i b e d .
D i f f e r e n t e x p r e s s i o n s t h a t e n a b l e one t o d e t e r m i n e SO2 f l u x e s have been g i v e n i n d i f f e r e n t c o n d i t i o n s of a t m o s p h e r i c s t a b i l i t y : g r a d i e n t , c o r r e l a t i o n and Thom's methods. Comparison between d e p o s i t i o n v e l o c i t i e s found and t h o s e p u b l i s h e d by o t h e r x o r k e r s ( r e f s . 2-5)
shows r a t h e r good agreement. F u r t h e r m o r e , a s i g n i f i -
c a n t c o r r e l a t i o n between SO2 f l u x and t h e p r e s e n c e of h u m i d i t y on t h e v e g e t a t i o n
i s c l e a r . D i r e c t measurements in t h e f o r e s t are o b v i o u s l y d i f f i c u l t because of t h e e l a b o r a t e e x p e r i m e n t a l s e t - u p t h a t i s n e c e s s a r y . For t h i s r e a s o n , t h e knowl e d g e o f t h e r e l a t i o n between SO2 f l u x and t h e e l e m e n t a r y d e p o s i t i o n v e l o c i t y of t h i s p o l l u t a n t i s very necessary. RELATION BETWEEN SO2 FLUX ABOVE THE FOREST AND THE ELEMENTARY DEPOSITION VELOCITY L e t u s w r i t e t h e f o l l o w i n g formulation of t h e absorbed f l u x =
-
h h0
;(Z)
.
a(Z)
.
pC(2)
.
r$
:
dZ
where ho : h e i g h t o f t h e lower p a r t of t h e canopy, h : t o p o f t r e e s ;(Z)
:
mean e l e m e n t a r y d e p o s i t i o n v e l o c i t y , a ( 2 ) : l e a f area d e n s i t y .
(1)
218 However, t h e value of concentration i n s i d e t h e v e g e t a t i o n i s not very d i f f e r e n t from t h e mean value of t h a t concentration i n t h e same p a r t . So,
Therefore ( 1 ) becomes :
In order t o s i m p l i f y t h i s expression, some values of ; ( Z ) purpose, s t u d i e s i n a wind-tunnel
a r e needed. For t h a t
have been performed.
MEASUREMENTS OF SO2 CAPTURE BY SOME PLANE SURFACES, WATER AND LEAVES Some r e s u l t s have been r e c e n t l y published ( r e f . 6 ) . The a i r f l o w v e l o c i t y and t h e dimension of t h e l e a v e s i n s i d e a v e g e t a t i o n canopy lead one t o consider t r a n s f e r phenomena as only occuring i n laminar boundary l a y e r s . For t h a t reason t h e a u t h o r s have been i n t e r e s t e d i n studying t h e SO2 t r a n s f e r a c r o s s such boundary l a y e r s developed over plane s u r f a c e s ( w a t e r a t d i f f e r e n t pH, l e a v e s ) which are a b l e t o adsorb o r absorb
sop
through a chemical r e a c t i o n on t h e surface.
S t u d i e s of t h e s e phenomena a r e u s u a l l y made by assuming a c o n s t a n t concentrat i o n on t h e s u r f a c e ; t h i s value i s g e n e r a l l y s e t equal t o zero which i s i n f a c t t h e case f o r a p e r f e c t s i n k . However measurements which a r e presented here demonst r a t e t h a t i n c e r t a i n c a s e s t h i s assumption i s no longer t r u e . So t h e more r i g o rous c a l c u l a t i o n i n d i c a t e d below h a s t o be used. SO,
t r a n s f e r between an a i r f l o w and a s u r f a c e a c r o s s a laminar boundary l a y e r
can be described by t h e t h r e e following equations :
(3)
Jw = wpCe
Jw = hCL(PCe-PCw)
(4)
Jw = kpCw
SO2 capture i s considered a s a f i r s t o r d e r chemical r e a c t i o n .
can be expressed as follows
W,
hCL and k
:
< 1
w = - 1
=
(6)
rG
In t h e preceding
equations
:
p : mass of u n i t volume of c a r r y i n g f l u i d Cw : mass f r a c t i o n on t h e s u r f a c e
tion velocity (ms-’)
,
,
S
,
Jw : SO,
Ce
:
mass f r a c t i o n i n e x t e r n a l flow
f l u x (pg m-’s-’)
,
w
hcL : convection t r a n s f e r c o e f f i c i e n t ( m s - ’ )
t i c c o n s t a n t of t h e chemical r e a c t i o n ’ (ms-’
rG, rcL and r
(5)
: SO2
,k
deposi:
kine-
f o r f i r s t order r e a c t i o n ) .
a r e r e s p e c t i v e l y c a l l e d t r a n s f e r r e s i s t a n c e s a s a whole, boundary
l a y e r r e s i s t a n c e and s u r f a c e r e s i s t a n c e . Definitions ( 3 ) t o ( 8 ) lead t o :
,
219 (9)
rG = rcL + rS
hcL which a p p e a r s i n ( 2 ) i s a f u n c t i o n o f s e v e r a l p a r a m e t e r s c h a r a c t e r i z i n g t h e a i r f l o w and t h e s u r f a c e . Thus, r
i s a function of r
CL
S
because
hCL = f ( U e , V , x , D , k ) where U
:
airflow velocity,
v
: kinematic v i s c o s i t y of a i r , x : c h a r a c t e r i s t i c
d i m e n s i o n , D : m o l e c u l a r d i f f u s i v i t y o f SO2.
Two p r o c e d u r e s of c a l c u l a t i o n may b e used : 1 ) rcL i s assumed t o be i n d e p e n d a n t o f rs. I n t h e s i m p l i f i e d method proposed by B a r r y and Chamberlain ( r e f . 7 ) , two h y p o t h e s e s a r e i m p l i c i t : h
CL
i s t h e value
found i n t h e c a s e of C ( x ) c o n s t a n t and k i s v e r y l a r g e . These l e a d t o an e x p r e s -
-
W
s i o n f o r rCLl (mean v a l u e of r namely
r
cL1
=
-
S
-
c a l c u l a t e d by i n t e g r a t i o n o v e r a l e n g t h 1) ;
x1/2.D-2/3.v1/6
(10)
0.664 Uel"
The p r e c e d i n g with r
CL
2
0
,
a s s u m p t i o n s i n v o l v e a p e r f e c t s i n k . So ( 1 0 ) s h o u l d o n l y be used whence
rG1 = r C L l we s h a l l d i s c u s s t h i s question i n a following paragraph.
2 ) rCLand rs a r e c o u p l e d . A r e l a t i o n e x i s t s between t h e reduced c o n c e n t r a t i o n m
=
CW
- and t h e p a r a m e t e r s d e t e r m i n g h CL t h r o u g h a u n i q u e c u r v e o f mW v e r s u s a
'e v a r i a b l e 2 g i v e n by :
V D
where 0 = 0.332 S c 1 l 3 and Sc = -
.
T h i s method l e a d s t o t h e mean v a l u e of rCLf o r a l e n g t h 1 :
Jq-
2[1
-
The e x p e r i m e n t a l p r o c e d u r e s have a l r e a d y been d e s c r i b e d ( r e f . 6 )
.
EXPERIMENTAL RESULTS Values o f k i n e t i c c o n s t a n t s k are p r e s e n t e d i n T a b l e 1 f o r water s u r f a c e s a t d i f f e r e n t pH and f o r 3 t y p e s o f l e a v e s on t h e i n n e r and o u t e r s u r f a c e s . I t should be n o t i c e d t h a t t h e h y p o t h e s i s of a c o n s t a n t C
W
is unrealistic.
Elementary v e l o -
c i t i e s may be t y p i c a l l y t a k e n as f o l l o w 5.10-4 m / s f o r t h e i n n e r s u r f a c e and m/s f o r the outer surface.
220 The r a t i o
rCL1
( F i g . 1 ) . While t h e s e r e s i s t a n c e s can be very
can reach 0 . 7 5
d i f f e r e n t t h e e r r o r concerning r
G
i s never very important.
TABLE 1
Values of k f o r water and some l e a v e s Water
Leaves Polygonum
/
m/s
kt0.5
0
Rumex
20
40
60
80 length ( mm)
1. Ratio of r e s i s t a n c e s a s a f u n c t i o n of l e a f l e n g t h and of t h e k i n e t i c constant.
Fig.
EXPERIMENTAL DETERMINATION OF ELEMENTARY DEPOSITION VELOCITY FROM FLUX MEASUREMENTS I N THE FOREST. Using values of t h e k i n e t i c c o n s t a n t s k c a l c u l a t e d from l a b o r a t o r y work and a i r f l o w v e l o c i t i e s g e n e r a l l y found i n s i d e allows u s t o s e t t h e l o c a l elementary d e p o s i t i o n v e l o c i t y G ( Z ) equal t o t h e value of t h a t v e l o c i t y c a l c u l a t e d f o r t h e mean value of t h e a i r f l o w v e l o c i t y i n s i d e t h e f o r e s t SO
where h
s
=
1
h0
( 2 ) may be w r i t t e n :
a ( Z ) .dZ
i s t h e l e a f a r e a index.
Gh
ho*
221 T a b l e 2 g i v e s s o m e examples of tions in a forest. TABLE
;(Gh
ho
)
from measurements i n d r y and w e t c o n d i -
2
Values of e l e m e n t a r y d e p o s i t i o n v e l o c i t i e s i n t h e f o r e s t from measurements
I n a l l cases r e g a r d l e s s o f method o f c a l c u l a t i o n o r c h o i c e o f k i n e t i c const a n t t h e e l e m e n t a r y d e p o s i t i o n v e l o c i t i e s found i n l a b o r a t o r y are l e s s t h a n 1 m/s. So t h e r e i s a s i g n i f i c a n t d i s c r e p a n c y w i t h t h e s e g i v e n i n Table 2 . DISCUSSION The d i s c r e p a n c i e s r e g a r d i n g t h e e l e m e n t a r y d e p o s i t i o n v e l o c i t i e s c o u l d be e x p l a i n e d as f o l l o w s :
- The l a w chosen f o r
a(Z)
i s perhaps n o t s a t i s f a c t o r y b u t a m o r e appropriate
one i s d i f f i c u l t ‘lo d e t e r m i n e and would c e r t a i n l y n o t e x p l a i n t h e whole d i f f e r e n c e .
- The g r e a t e r a b i l i t y t o
SO2 c a p t u r e found i n t h e
case o f t h e f o r e s t c o u l d be
due t o t h e i n f l u e n c e o f t h e h i g h t u r b u l e n c e i n t e n s i t i e s i n s i d e t h e canopy. These c a u s e t h e movement o f t h e l e a v e s and i n c r e a s e t r a n s f e r a c r o s s t h e l a m i n a r l a y e r .
- Numerous and v a r i o u s c h a n g e s i n t h e d i r e c t i o n o f a i r f l o w c e r t a i n l y i n v o l v e a less i m p o r t a n t t r a n s f e r of SO2 t h a n t h i s p r e d i c t e d by use of t h e mean v e l o c i t y .
- Another f a c t o r t h a t s h o u l d be c o n s i d e r e d i s t h e r e l a t i v e importance o f t h e k i n e t i c c o n s t a n t toward t h e i n t e g r a l s c a l e of a i r f l o w v e l o c i t y i n s i d e t h e f o r e s t .
C. P e t i t , M. T r i n i t i . and P. V a l e n t i n , S t u d y o f t u r b u l e n t d i f f u s i o n above and w i t h i n a f o r e s t . A p p l i c a t i o n i n t h e c a s e o f S o n , Atmospheric Environment, 10 (1976) 1057-1063. J . A . G a r l a n d , D e p o s i t i o n o f g a z e o u s s u l p h u r d i o x i d e t o t h e g r o u n d , Atmospheric Environment, 8 ( 1 9 7 4 ) 75-79. M.J. Owers and A.W. P o w e l l , D e p o s i t i o n v e l o c i t y of s u l p h u r d i o x i d e on l a n d and water s u r f a c e s u s i n g a 5 S t r a c e r method, Atmospheric Environment, 8 ( 1 9 7 3 ) , 63-67. J . C . Shepperd, Measurements of t h e d i r e c t d e p o s i t i o n of s u l p h u r d i o x i d e o n t o g r a s s and w a t e r by t h e p r o f i l e method, Atmospheric Environment 8(1974)69-74. D.M. Whelpdale and R.W. Shaw, S u l p h u r d i o x i d e removal by t u r b u l e n t t r a n s f e r o v e r g r a s s , snow and water s u r f a c e s , T e l l u s 26(1975)195-204. C. P e t i t , M. Ledoux and M. T r i n i t e , T r a n s f e r r e s i s t a n c e s t o SO2 c a p t u r e by s o u r c e p l a n e s u r f a c e s , w a t e r and l e a v e s , Atmospheric Environment, l I ( 1 9 7 7 ) 1123-1 126. P . J . B a r r y and A.C. Chamberlain, D e p o s i t i o n o f i o d i n e o n t o p l a n t l e a v e s from a i r , H e a l t h P h y s i c s , 9 ( 1 9 6 3 ) 1149-1157.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
225
EVALUATION O F L E V E L S O F P b , V, C d , Zn a n d Cu IN T H E SNOW O F
M T BLANC DURING T H E LAST 25 YEARS M. BRIAT
L a b o r a t o i r e de G l a c i o l o g i e du CNRS, 2 r u e T r b s - C l o l t r e s G r e n o b l e ( F r a n c e )
ABSTRACT F o r evaluating t h e i n f l u e n c e of pollution o n t h e a t m o s p h e r e i n t e m p e r a t e r e g i o n s , s a m p l e s f r o m a snow c o r e c o v e r i n g t h e p e r i o d 1948-1974 and s i t u a t e d a t t h e 4250 m l e v e l of t h e Mt B l a n c massif w e r e a n a l y s e d f o r c h e m i c a l c o m p o s i t i o n . All t h e e l e m e n t s a n a l y s e d , e x c e p t C1 which i s p r o d u c e d p r i m a r i l y by m a r i n e s o u r c e s , a r e m o s t l y of c o n t i n e n t a l o r i g i n a n d c a n b e e x p l a i n e d a s s u c h . H o w e v e r l e v e l s of P b , V a n d C d h a v e i n c r e a s e d u p t o a n e t f a c t o r of 2 s i n c e 1950 which p a r a l l e l s i n c r e a s e d p r o d u c t i o n of g a s o l i n e a d d i t i v e s ( P b ) , i n c r e a s e d u s e of h e a v y o i l s (V) a n d i n c r e a s e d c o n s u m p t i o n of g a s o l i n e (Cd).
INTRODUCTION M e a s u r e m e n t s a t South P o l e i n t h e s n o w (Ref. 1) and i n t h e a t m o s p h e r e (Ref. 2) s h o w t h a t a s t r o n g c o r r e l a t i o n of c h e m i c a l c o m p o s i t i o n e x i s t s b e t w e e n t h e two. By u n d e r t a k i n g c h e m i c a l s t u d i e s o n p o l a r snow f i e l d s , t h e influence of h u m a n a c t i v i t y on t h e a t m o s p h e r e o v e r t h e c o u r s e of t i m e c a n b e i n f e r r e d ( R e f s . 1 , 3, 4, 5). T h e s a m e t y p e of s t u d i e s c a n b e a p p l i e d t o t h e high A l p s , which a r e m u c h
c l o s e r t o t h e i n d u s t r i a l a r e a s of t h e N o r t h e r n H e m i s p h e r e .
S A M P L E S AND ANALYTICAL TECHNIQUE S a m p l e s ( e a c h c o v e r i n g a b o u t 1 y e a r ) w e r e c o l l e c t e d f r o m a pit ( c o v e r i n g the 3 l a s t y e a r s ) a n d f r o m a 21 m c o r e ( c o v e r i n g 26 y e a r s ) a t t h e Col du GoGter i n t h e
Mt B l a n c m a s s i f ( a l t i t u d e 4250 m, m e a n a n n u a l t e m p e r a t u r e
-
1 4 "C). S a m p l e s
w e r e t a k e n u n d e r clean c o n d i t i o n s a n d p r e s e r v e d in a f r o z e n state u n t i l a n a l y s i s . D a t a t i o n of t h e c o r e w a s m a d e by
B a r t i f i c i a l radioactivity m e a s u r e m e n t s .
C h e m i c a l c o m p o s i t i o n w a s d e t e r m i n e d u s i n g , without p r e c o n c e n t r a t i o n , n e u t r o n
226 activation and flameless atomic absorption methods.
R E S U L T S AND DISCUSSION A s u m m a r y of r e s u l t s c a n b e found i n t a b l e 1. E a c h m e a n f r o m S e c t i o n s A a n d B is a v e r a g e d f r o m 19 s a m p l e s . By c o m p a r i n g the c r u s t a l e n r i c h m e n t f a c t o r s ( E F ) ( r e f e r r e d t o Al) of o u r s a m p l e s to t h o s e of c o n t i n e n t a l a e r o s o l s ( R e f . 6) a n d by using t h e c o r r e l a t i o n s of c o n c e n t r a t i o n s e x i s t i n g a m o n g s t t h e d i f f e r e n t e l e m e n t s a n d t h e c o r r e l a t i o n s with t i m e we c a n conclude :
- A l , F e , V , Mn, C a , K a n d Na a r e m a i n l y of t e r r e s t r i a l o r i g i n , - 35 % of t o t a l s o d i u m (Na T ) cannot b e e x p l a i n e d t o b e f r o m c o n t i n e n t a l s o u r c e a n d i s l i k e l y of m a r i n e o r i g i n . T h i s m a r i n e s o d i u m (Na
M
) is calculated from :
as a r e f e r e n c e f o r the m a r i n e contribution, one o b s e r v e d a n e x c e s s M of C1 b e t w e e n 50 a n d 100 '$ of t o t a l m e a s u r e d C1. Such a n e x c e s s , a l r e a d y
T a k i n g Na
o b s e r v e d i n A n t a r c t i c a , (Ref. 7) c a n b e a t t r i b u t e d t o pollution, t o v o l c a n i s m o r m o s t l i k e l y t o t h e p r o d u c t i o n of g a s e o u s C1 f r o m t h e o c e a n s u r f a c e .
-
Cu is M' c o r r e l a t e d with C1 a n d Na but n o t t i m e . It c o m e s then, f r o m a n a t u r a l s o u r c e
C u , Zn, P b a n d Cd a r e v e r y e n r i c h e d with r e s p e c t t o A1 and Na
of p o s s i b l e m a r i n e o r i g i n . P b a n d C d a r e c o r r e l a t e d with t i m e a s well a s V, although t h e l a s t i s l e s s e n r i c h e d but more abundant i n t h e u p p e r s n o w l a y e r s
(EF = 3 ) . TABLE I R e s u l t s of c h e m i c a l a n a l y s i s f o r 2 8 y e a r s
(A) : M e a n a n d s t a n d a r d deviation v a l u e s of c o n c e n t r a t i o n s i n 10'' g g - l ( B ) : M e a n a n d s t a n d a r d d e v i a t i o n v a l u e s of c r u s t a l EF ( C ) : C o r r e l a t i o n c o e f f i c i e n t s with r e s p e c t t o Al, Na a n d t i m e (t) ; " " i n d i c a t e s a c o e f f i c i e n t with s i g n i f i c a n c e > 95 %
*
(A)MEAN SD (B)MEAN SD (C)wrt:Al N
t
Na A1 C1 4 0 119 81 2 8 110 4 2 1. 8 1 860 1 . 2 1 950
*
a
*
*
*
x
*
K 36 24 1. 7 1.0
*
x
Ca 220 220 4.8 4.3 rt
*
V 0. 1 7 0. 15 1.4 1.2 j,
*
*
Mn 3.88 2. 77 4.5 3.9
*
*
Fe 61 59 0.8 0.2
* *
Cu 0.8 0.5 21
19
*
Zn 2. 7
1.6 65 57
Cd 0. 10 0.06 800 850
*
*
Pb 2.0 1.2 250 270
*
227
I n t a b l e 2 r e s u l t s f r o m Mt B l a n c a n d o t h e r r e g i o n s a r e p r e s e n t e d o v e r c o m p a r a b l e p e r i o d s of t i m e . TABLE 2 C o m p a r i s o n of Mt B l a n c with o t h e r sites. (A) : c o n c e n t r a t i o n s i n lo-’ g g-1 (B) : c r u s t a l E F (using only v a l u e s p r i o r t o 1950 f o r t i m e dependent e l e m e n t s )
\
Antarctica [Greenland (Refs. 3 , 4 , 5,S)I Alps IGreat Britail;’ ( R e f . 1) E~~~~~~ Ddme C South C a m p Dye 3 M i l c e n t Mt Blan(iRef. J ung f r9) au (Ref. 10) \ p o l e Century 10. 7 118 43 6 160 A1 A 1. 13 1. 34 Na A 21.8 9.5 12. 3 40 59 2300 N k A 21.5 9. 1 9. 2 6 47 2250 0.016 0. 1 7 0.057 4. 1 V A 0. 9 0. 8 CU A 0.063 0.027 0. 850 0. 8 3. 7 23 B 94 41 21 21 1.05 0.224 Zn A 0.039 0.050 2.73 85 B 23 23 19 8 65 0.008 0. 100 0 . 0 8 6 18i Cd A 0.013 0.017 0.003 0.639 B 385 5020 486 412 299 5 80 0. 144 2. 0 39 Pb A 0.028 0.020 0.210 0. 620 B 56 56 26 27 42 230 Site
1
-
*
-
-
-
-
Adding s o l u b l e a n d i n s o l u b l e f r a c t i o n s T h e e n r i c h e d e l e m e n t s (V, C u , Zn, Cd, P b see fig. 1) a r e 10 t o 100 t i m e s
m o r e abundant i n t h e A l p s than i n G r e e n l a n d a n d A n t a r c t i c a b u t m u c h l e s s abundant than i n G r e a t Britain. T h e E F o b s e r v e d i n t h e A l p s b e f o r e 1950 (a p e r i o d of l e s s i n d u s t r i a l a c t i v i t y t h a n now) a r e v e r y c o m p a r a b l e t o t h o s e of p o l a r r e g i o n s . T h e u n i f o r m i t y of the E F s u g g e s t s , a t l e a s t f o r t h i s p e r i o d of time, t h e e x i s t e n c e of a n a t u r a l effect of e n r i c h m e n t ( p r e f e r e n t i a l v o l a t i l i s a t i o n a t t h e c r u s t s u r f a c e , v o l c a n i s m ,
b i o l o g i c a l m e c a n i s m s ) . T h e o v e r e x c e s s of P b a n d Zn i n t h e A l p s could c o m e f r o m l o c a l n a t u r a l o r weak artificial s o u r c e s . Only P b i n c r e a s e d by a f a c t o r of 2 t o 3 t i m e s o v e r t h e c o u r s e of t i m e i n both t h e A l p s a n d p o l a r r e g i o n s ( R e f s . 1 , 5) s i n c e 1950. T h i s c a n b e linked with t h e i n c r e a s i n g w o r l d p r o d u c t i o n of l e a d anti-knock compounds (M. L A F L E C H E Soci6t6 O C T E L - P e r s o n a l c o m m u n i c a t i o n ) . T h e i n c r e a s e s i n t h e A l p s f o r Cd a n d V (by a f a c t o r 2) a r e n o t found i n t h e p o l a r r e g i o n s . If one t a k e s t h e 1950’s a s a b a s e l i n e a n d a s s u m e s n a t u r a l t e r r e s t r i a l a n d m a r i n e i n p u t s h a v e not i n -
c r e a s e d , 50
%
of Cd a n d V would b e f r o m a n t h r o p o g e n i c s o u r c e s .
228
I
I
I
I
1
1
I
1
\--I
1
1
~~
tc
F i g . 1. C o l du GoCter (Mt B l a n c ) : c o n c e n t r a t i o n s of Pb, V , Cd, Zn a n d Cu v e r s u s a g e of s a m p l e s . ACKNOWLEDGEMENTS T h i s w o r k w a s s u p p o r t e d in p a r t by M i n i s t k r e d e la QualitC de l a Vie e t de 1’E n v i r o n n e m e n t . REFERENCES 1 C . Boutron, S. M a r t i n a n d C. L o r i u s , 9th I n t e r n . Conf. on Atmosph. A e r o s o l s Condensation a n d I c e Nuclei, Galway, I r e l a n d , 21-27 sept. 1977. 2 W. Maenhaut a n d W. H. Z o l l e r . J . Geophys. R e s . (in p r e s s ) . 3 M. M u r o z u m i , T . J . Chow a n d C. P a t t e r s o n , Geochim. C o s m o c h i m . A c t a 33 (1969) 1247-1294. 4 J . H. C r a g i n , M. M . H e r r o n a n d C. C. Langway J r , USA, C R R E L R e s e a r c h R e p . , 341 (1975). 5 M. M. H e r r o n , C. C. Langway J r , H. V. W e i s s a n d J . H. C r a g i n , Geochim. C o s m o c h i m . A c t a , 41 (1977) 915-920. 6 K. A. R a h n , T e c h n i c . R e p , U n i v e r s i t y of Rhode I s l a n d , Kingston USA (1975) 7 M. B r i a t , C. B o u t r o n a n d C. L o r i u s , J . R e c h . A t m o s . 8 (1974) 895-901. 8 H . V. W e i s s , K. K. B e r t i n e , M. Koide a n d E. D. G o l d b e r g , Geochim. C o s m o c h i m . A c t a , 39 (1975) 1-10. 9 A. Wyttenbach, R. R a u t e r , B. S t a u f f e r a n d U. S c h o t t e r e r , J. Radioanalyt. C h e m . 38 (1977) 405-413. 1 0 D . H. P e i r s o n , P. A. C a w s e , L. S a l m o n a n d R. S. C a m b r a y , N a t u r e , 241 (1973) 252-256.
Atmospheric Pollution 1978, Proceedings of the 13th InternationalColloquium,Paris,France, April 25-28,1978, M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
229
STUDY OF AEROSOL EVOLUTION FROM PHOTOOXIDATION OF SO2
D. BOULAUD, G. MADELAINE and M.L. PERRIN Commissariat B 1'Energie Atomique, Institut d e Protection et de SGretG Nuclgaire, DGpartement de Protection, Section Technique d'Etudes de Pollution dans l'AtmosphPre et dans les Mines, BP n o 6, 92260 Fontenay aux Roses, France.
ABSTRACT Results obtained using a simulation chamber for the study of the concentration and particle dimensions produced with time due to photolysis of the mixture SO -NO 2 2 H 0 are presented. Preliminary results in the case of an SO2 atmospheric air mixture 2 are also given. From these experiments we provide a qualitative analysis of homogeneous and heterogeneous nucleation processes of vapour products of t h e s e mixtures.
I . INTRODUCTION
It is now well known that photooxidation of SO2 in the atmosphere causes production Gf sulphuric acid and sulphates which are normally found in submicronic particle form. Knowledge of the evolution of these particles is therefore of great importancewhen characterising atmospheric
pollution. The principal physical parame-
ters neccesary to characterize an aerosol are its concentration and s i z e distribution. Inthe case of ultrafine aerosols formed by the photooxidation of SO2, the concentrationis determined using a condensation nuclei counter (CNC), the size distribution beingmeasured using techniques such as the Electrical Aerosol Analyser (EM) or the Diffusion Battery Method (DBY). In the present study we have taken advantage of recent developements in these techniques to analyse the evolution of aerosol products in both acontrolled atmosphere (SO -NO -H 0 and a natural atmosphere. 2 2 2 2. METHOD The apparatus used for both controlled and natural atmospheric conditions and their detection methods have been described in previuous publications ( I ,
2).
3. RESULTS
3.1. Controlled atmosphere study During the gas-aerosol conversion, the evolution of particle concentration with time may be described in the following manner (2, 3) : a rapid increase corresponding essentially to embryon formation by nucleation ; a maximum indicating an equilibrium between embryon nucleation and coagulation ; a gradual decrease corresponding to a stationary state, essentially representing an equilibrium-betweenparticle production and losses due to coagulationthe slight decrease indicating a succession "of station-
230 nary states" due tothe increase of the polydispersion of the aerosol. For longer time intervals, particles which develop by condensation and coagulation can attain a total surface such that nearly all the nucleogenic vapour condenses on particles already formed and will not therefore be available to produce new embryons. Fig. I represents the evolution with time of the concentration, the surface and total volume of particles of diameter greater than
um and secondly, the condensation
nuclei concentration. Section A of the curve represents the three stages described above, where particle evolution is principally governed by nucleation andcondensation On the contrary, section B corresponds to the diminution of the nucleation rate when vapour condensation
on the particles present becanes preponderant. Embryon production
being strongly diminished, evolution of the concentration, corresponds then to
coagw
lation of small embryons still present on the largest particles. The coagulation constant in this case is 4 . 5 . 1 0 - 9
cm3s-]. Section C represents the development of the
aerosol still under the effect of coagulation, the coagulation constant being of a lower value (2.5.
cm3.sec-I) due to the decrease in polydispersion of particles
after embryon fixation on the largest particles. Comparison of the curves representing evolution of the condensation nuclei concenum respecti-
tration and the concentration of particles of diameter superior to
vely, further confirms the hypothesis of vapour condensation which, strongly diministing nucleation, provides evidence of coagulation of embryons still present on the largest particles. In fact, these curves which are easily distinguished insections A and B could well be confused in section C. Study of curves (fig. I ) showing the evolution of the surface and the total volume of the aerosol, shows that the surface is appreciably constant after irradiation when the volume increases with time with a constant dv/dt h-' or 1 . 2 5 . 10-15sec-1.In this particular case (dv/dt
=
1
or 2 hours of 3 4.5 u3m c m
=
cte) Friedlander predict the
development of an auto-conservative surfacewhich is proportional to the 3/5 power of the variation of aerosol volume (dv/dt), the variations of this surface being very small after one hour of evolution. From his calculations one can therefore foresee that for a volume increase rate of 1.25.10-15sec-1 one would obtain after 1 hour a 2 in gas volume units a value of 6.10-6 cm-' (600 Um 2 3 cmd3) which is very near our experimentally measured value of 650 um cmtotal aerosol surface having
.
Examination of the evolution with time of size distribution determined using the EAA also confirms the hypothesis of heterogeneous nucleation following homogeneous nucleation, see fig. 2. In fact, for measurementscarried out at 20 and 80 mins, a fraction of the distribution is below the detection limit of the EAA (7.5.10-3 um). One can
suppose that this fraction of the aerosol comprises embryons which have just
been formed by homogeneous nucleation and whose life time is too short for their development by condensation and coagulation to be sufficient to pass the threshold detection of the EAA. In the case of measurements at 150 and 280 mins this small fraction no longer exists due to vapour condensation on already formed particles.
231
id
0
750-30
1
2
4
3
5
F i g . I . V a r i a t i o n s w i t h time of v a r i o u s p a r a m e t e r s c h a r a c t e r i z i n g t h e a e r o s o l : conc e n t r a t i o n of t h e c o n d e n s a t i o n n u c l e i (C.N.) ; c o n c e n t r a t i o n of t h e p a r t i c l e s o f w h i c h um (N), t o t a l s u r f a c e a r e a ( S ) , and volume (V) of t h e e s e diameter i s g r e a t e r than particles. These t h e o r e t i c a l and e x p e r i m e n t a l c o n s i d e r a t i o n s a l l o w us t o condlude t h a t when homogeveous P u c l e a t i o n c e a s e s , development of t h e a e r o s o l i s c o n t i n u e d by h e t e r o g e neous n u c l e a t i o n . I n f a c t , a l t h o u g h t h e r e i s no f u r t h e r embryon p r o d u c t i o n and t h a t , by d e f i n i t i o n , t h e p r o c e s s of c o a g u l a t i o n c o n s e r v e s t h e t o t a l volume and d i m i n i s h e s t h e t o t a l s u r f a c e of t h e a e r o s o l , we c o n s i d e r t h a t t h i s s u r f a c e remains c o n s t a n t and t h a t t h e volume i n c r e a s e s due t o t h e vapor c o n d e n s a t i o n on p a r t i c l e s s t i l l p r e s e n t .
3 . 2 . N a t u r a l atmosphere The above e x p e r i m e n t s i n c o n t r o l l e d atmosphere (S02-N02-H20)
were extended t o t h e
c a s e where t h e g a s c a r r i e r i s f i l t e r e d n a t u r a l a t m o s p h e r i c a i r which can be e n r i c h e d with SO2.
In t h e s e experiments s i z e d i s t r i b u t i o n of t h e a e r o s o l produced by photoly-
s i s i s c a r r i e d o u t u s i n g t h e d i f f u s i o n b a t t e r y method (D.B.M.) coupled t o a condensat i o n n u c l e i c o u n t e r (CNC) ( 5 ) . The advantage of t h i s method i s t h a t i t a l l o w s measurement of t h e u l t r a f i n e p a r t of t h e a e r o s o l
(4
urn) w h i l e t h e EAA g i v e s s a t i s -
f a c t o r y r e s u l t s o n l y when t h e p a r t i c l e d i a m e t e r i s s u p e r i o r t o t h i s l i m i t . F i g . 3 . shows a n example o f t h e s i z e d i s t r i b u t i o n w e
o b t a i n w i t h t h e D.B.M.
I n t h i s example
t h e v a r i a t i o n of volume w i t h time i s a p p r e c i a b l y c o n s t a n t and h a s a v a l u e of d v / d t = 4.10-"sec-1.
One r e a l i z e s h e r e t h e n t h a t we can monitor t h e f i n e s t p a r t of t h e aero-
s o l which was o n l y assumed t o e x i s t f o l l o w i n g t h e p r e v i o u s e x p e r i m e n t s . These p r e l i m i n a r y r e s u l t s a r e e s s e n t i a l l y q u a l i t a t i v e s i n c e u s e of t h e D . B . M .
requires a l s o the
u s e of a CNC of which t h e p r e c i s i o n i s s t i l l n o t f u l l y known i n t h e c a s e o f p a r t i c l e s i n t h e range i n f e r i o r t o lo-'
um.
232
l
d
7
18-
2 0 mir 80 150 8’
-
280
lo”
‘?E
**
10 -
0
4
: D
’0
10”-
U
10’-
:1
:I,‘
,
5
15 mir
,--35 ”
I1
I1
8
cn
z
...
*:
j k,
Gld
I\
z
z U
\
*’
*
1
Fig. 2. Evolution against the time of the size distribution of the particles produced by the irradiation of SO . 2 ’ NO2 ; H 0 mixtures.(Measurements made with E.2.A.).
D yn
Fig. 3 . Evolution against the time of the size distribution of the particles produced by the irradiation of SO2 and filtered atmospheric air mixture (Measurements made withD.B.MJ
A . CONCLUSION
From a study of aerosol evolution in a controlled atmosphere we have been able to show in qualitative terms the homogeneous and heterogeneous nucleation processes of
vapour products in SO2 photooxidation systems, the distinction between these two mechanisms being important since we wish to precast the size of particle carriers of sulphuric acid and sulphates. A quantitative analysis of these phenomena would necessitate a precise means of
measuring the ultra fine part o f the produced aerosol
um
6R&
-2
10
um)
. The
DBM coupled with an CNC is, as we have shown, the only method which allows us to
monitor qualitatively this fraction of the aerosol. Furthermore, correct standardization of the CNC in this area would allow quantitative determination of particle size distribution. Work on these aspects of aerosol measurement is currently being undertaken in our laboratories. REFERENCES I . J. BRICARD, M. CABANE, G. MADELAINE and D. VIGLA, J. Colloid Interface Sci., 3 9 , (1972) 42-55.
2. D. BOULAUD, ThSse de Doctorat d’Etat, 1977. 3 . D. BOULAUD, G. MADELAINE, D. VIGLA and 3. BRICARD, Water, Air, Soil Pollution, 4 , (1975) 435-445. 4 . S . K . FRIEDLANDER, Atmosph. Environ., ( 1 9 7 8 ) “in press“. 5. J.P. MAIGNE, ThSse de Doctorat d’Etat, (1977).
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28, 1978, M.M. Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
233
R E C E N T EVOLUTION O F STRONG ACIDITY O F SNOW AT MT BLANC
R. DELMAS a n d A. ARISTARAIN
*
L a b o r a t o i r e de G l a c i o l o g i e du CNRS, 2 r u e T r ' e s - C l o f t r e s G r e n o b l e ( F r a n c e )
ABSTRACT One h u n d r e d eighty s a m p l e s of snow c o l l e c t e d f r o m the Mt B l a n c massif (4250 m a l t i t u d e ) h a v e b e e n a n a l y s e d f o r s t r o n g a c i d i t y . A m e t h o d w a s s p e c i a l l y d e v e l o p e d to m e a s u r e t h e s t r o n g a c i d i t y without i n t e r f e r e n c e f r o m c a r b o n i c a c i d . T h e t i m e p e r i o d c o v e r s a l m o s t continuously f r o m 1940 to 1976. An i n c r e a s e of s t r o n g a c i d i t y w a s o b s e r v e d , p a r t i c u l a r l y d u r i n g t h e l a s t 12 y e a r s . T h i s p h e n o m e n o n c a n b e c o r r e l a t e d with t h e evolution of t h e e u r o p e a n e m i s s i o n s of sulfur compounds into the at mo s p h er e.
INTRODUCTION T h e " n o r m a l " a c i d i t y of r a i n is a pH of 5. 7 c o r r e s p o n d i n g to a n e q u i l i b r i u m b e t w e e n p u r e w a t e r a n d a t m o s p h e r i c C 0 2 . H o w e v e r s i n c e twenty y e a r s o b s e r v a t i o n s i n t h e N o r t h e r n H e m i s p h e r e (USA, S c a n d i n a v i a ) h a v e shown " a c i d r a i n s ' ' with p H ' s s i g n i f i c a n t l y l e s s t h a n 5. 7. T h i s c a n r e s u l t i n s e r i o u s a l t e r a t i o n s of e c o l o g i c a l e q u i l i b r i u m on t h e r e g i o n a l o r e v e n continental s c a l e . T h i s i n c r e a s e of a c i d i t y ( m o r e t h a n 2 u n i t s of pH i n some c a s e s i n the s p a c e of 2 0 y e a r s ) is g e n e r a l l y a t t r i b u t e d t o long r a n g e a t m o s p h e r i c pollution f r o m l a r g e i n d u s t r i a l centers. S u l f u r c o m p o u n d s a r e r e s p o n s i b l e f o r a b o u t 2 / 3 of t h i s pollution with t h e r e m a i n i n g t h i r d due t o n i t r o g e n a n d c h l o r i n e d e r i v a t i v e s ( R e f s . 2 , 3). In t h e N o r t h e r n H e m i s p h e r e a n t h r o p o g e n i c e m i s s i o n s c o n t r i b u t e about a n e q u a l a m o u n t to a t m o s p h e r i c sulfur as n a t u r a l s o u r c e s (volcanoes, m a r s h l a n d s ) (Ref. 4). T r a c i n g t h e h i s t o r y of t h e a c i d i t y of p r e c i p i t a t i o n s using t h e e x i s t i n g d a t a is d i f f i c u l t (Ref. 2). T h e a n a l y s i s of i c e - c o r e s f r o m c o l d g l a c i e r s c o n s t i t u t e s t h e m o s t adequate
- perhaps the
only
- method permitting
* R e s e a r c h e r f r o m the Instituto Antartico Argentino
t h e r e c o n s t i t u t i o n of t h e
234 e v o l u t i o n of t h i s pollution. T h e M t B l a n c , s i t u a t e d i n t h e h e a r t of t h e f i r s t i n d u s t r i a l continent, i s a f a v o r e d s i t e f o r study.
SAMPLES T h e s a m p l e s a n a l y s e d c a m e p r i n c i p a l l y f r o m a n i c e - c o r e of 30. 6 m d r i l l e d i n J u n e 1976 a t C o l du DBme ( a l t i t u d e 4250 m) j u s t u n d e r t h e s u m m i t of Mt Blanc. Only 23. 3 m of t h e c o r e w e r e u s a b l e f o r c h e m i c a l a n a l y s i s . A 2 m d e e p p i t a t t h e s a m e p l a c e a n d a s e c o n d c o r e n e a r l y c o m p l e m e n t e d a l m o s t all of t h e m i s s i n g y e a r s . T h e s a m p l e s (180 i n t o t a l ) , s t o r e d i n a f r o z e n s t a t e u n t i l being a n a l y s e d , w e r e cleaned i n clean air bench. T h e s a m p l e s w e r e d a t e d by f3 a r t i f i c i a l r a d i o a c t i v i t y m e a s u r e m e n t s . T h e t 2 y e a r s f o r t h e y e a r s s i n c e 1953. p r e c i s i o n of c h r o n o l o g y i s e s t i m a t e d t o b e t 5 years. T h e b o t t o m of t h e c o r e c o r r e s p o n d s t o t h e y e a r 1940
-
-
MEASUREMENTS T h e d i r e c t m e a s u r e m e n t of t h e pH of n a t u r a l p r e c i p i t a t i o n s g i v e only the a p p r o x i m a t e v a l u e of s t r o n g a c i d i t y ( t h a t of s t r o n g a c i d s s u c h a s HzSO,, HC1.
..)
HNO,,
due t o i n t e r f e r e n c e of c a r b o n i c a c i d ( R e f s . 1 , 5). We h a v e developed a
m e t h o d t h a t p e r m i t s t h e r a p i d d e t e r m i n a t i o n ( 5 m i n u t e s ) of t h e s t r o n g a c i d i t y i n v o l u m e s of 1 to 2 m l . We u s e a c o m b i n e d p H - e l e c t r o d e (Ingold R e f . LOT 403) a n d a c o m p l e t e M e t t l e r t i t r a t i o n s y s t e m (DK10, DK15, DK31, D V l l a n d GAZO). By known a d d i t i o n s of 0. 5. 10-
N Hp SO, a n d employing G r a n ' s plot (Ref. 6)
f o r t r e a t i n g t h e r e s u l t s , w e e l i m i n a t e d t h e i n f l u e n c e of C O z on t h e m e a s u r e m e n t s (Ref. 7). In e f f e c t , t h e e x p e r i m e n t a l p o i n t s plotted on s u c h a d i a g r a m f o r m a s t r a i g h t l i n e only when t h e pH of t h e s o l u t i o n b e c o m e s l e s s than 5, t h a t i s , when t h e d i s s o c i a t i o n of c a r b o n i c a c i d is n e g l i g e a b l e (Ref. 1). In the G r a n ' s p l o t , t h e e x t r a p o l a t e d l i n e t h r o u g h t h e e x p e r i m e n t a l p o i n t s f a l l s t o t h e l e f t ( c a s e of a s a m p l e i n i t i a l l y a c i d i c ) o r t o t h e r i g h t of z e r o . H e r e , t h e l a t t e r d o e s not i n d i c a t e a n i n i t i a l l y b a s i c s a m p l e , but r a t h e r , a s p r o p o s e d by G r a n a t (Ref. 8 ) , t h e t i t r a t i o n of c a r b o n a t e s ( s a l t s of w e a k a c i d ) b y H p SO, ( s t r o n g a c i d ) following t h e r e a c t i o n : H,SO,
t MCO,
j
MSO,
t H,O
t CO,
(M i s a m e t a l l i c c a t i o n , g e n e r a l l y Ca+
+
).
235 R E S U L T S AND DISCUSSION E x a m i n i n g the obtained r e s u l t s ( o v e r a l l m e a n : 2. 8 p E q / l a s HCO;)
one
f i n d s t h a t t h e s n o w m e l t - w a t e r d o e s n o t h a v e , g e n e r a l l y , a s t r o n g a c i d i t y a s it is thought t o b e f o r t h e a c i d pH v a l u e s of snow (4. 6 t o 6. 8, B. S t a u f f e r p e r s o n a l c o m m u n i c a t i o n ) at t h e s e a l t i t u d e s , but r a t h e r a pseudo- a l k a l i n i t y linked with the p r e s e n c e of c a r b o n a t e s . B e s i d e s , t h e a v e r a g e v a l u e s of c a l c i u m known f o r t h i s s i t e ( z 11
u
E q / l ) a r e of the s o m e m a g n i t u d e a s t h o s e of s u l f a t e
11 E q / l ) . H o w e v e r a m o r e c o m p l e t e i n t e r p r e t a t i o n of the snow c h e m i s t r y
( z 14
-
r e q u i r e s t h e knowledge of, a t l e a s t , NH,+ a n d NU, i o n s a s well a s SO;
-, H+
and Cat+. T h e v a l u e s of a c i d i t y r e p o r t e d i n f i g u r e 1 A r e p r e s e n t the running m e a n s t for 3 samples (experimental e r r o r 1 IJ E q / l ) . T h e y show a n e t i n c r e a s e
-
( m o r e than 2 0
u E q / l of Hf i o n s ) of t h e s t r o n g a c i d i t y o v e r the l a s t 35 y e a r s .
I
I
I
2s
x)
+ DEPTH 10
I
I
15
20
10
( rn of snow
I
-
5
1
1
A
0
10
0
lyyl i'l/
\, Irj
?+ I
50
YPI I
CHRONOLOGY
-+
I
B
?+ I
B
40
30
++
20
F i g . 1.
A
B
+ + +
a?+ I
z? I T
+
Evolution of t h e s t r o n g a c i d i t y of t h e snow of Mt-Blanc during the last 35 y e a r s . F o r i n t e r p r e t a t i o n i n H+ a n d HCO, e q u i v a l e n t s see the text. T h e m e a s u r e m e n t s in p a r e n t h e s e s a r e t h o s e of the complementary core. I n d u s t r i a l e m i s s i o n s of SO, i n E u r o p e a f t e r F j e l d (Ref. 12).
236 T h i s phenomenon s e e m s t o a c c e l e r a t e d u r i n g the l a s t t e n y e a r s w h e r e unfortunately the l a c k of continuity of c o r e d u r i n g t h i s p e r i o d m a d e a d e t a i l e d study difficult. T h e g e o c h e m i c a l s t u d i e s conducted p r e v i o u s l y on a neighbouring c o r e (Ref. 9) do not show a d e c r e a s e of the input of n a t u r a l e l e m e n t s ( m e t a l s of c a r b o n a t e s ) d u r i n g the m o r e r e c e n t y e a r s . T h e r e f o r e i t s e e m s t h a t the i n c r e a s e of s t r o n g a c i d i t y i s l i k e l y due t o an i n c r e a s e of t h e fallout of s t r o n g a c i d s ( H 2 S 0 4 , HNO,, HC1.
. . ).
T h e s e r e s u l t s c a n b e c o m p a r e d t o t h o s e obtained f o r r a i n i n E u r o p e
( R e f . 3). W e think t h a t they a r e r e p r e s e n t a t i v e of a phenomenon o c c u r r i n g on a r e g i o n a l o r even continental s c a l e b e c a u s e t h i s p a r t of M t B l a n c , s i t u a t e d p e r m a n e n t l y o v e r the a t m o s p h e r i c b o u n d a r y l a y e r , i s w e l l p r o t e c t e d f r o m l o c a l pollution by alpine v a l l e y s . P e r i o d s of i n t e n s e v o l c a n i s m could explain c e r t a i n fluctuations d u r i n g s o m e y e a r s , p a r t i c u l a r l y b e t w e e n the y e a r s 1964-70 ( R e f s . 10, 11). Although the e x a c t n a t u r e of t h e a c i d i s n o t w e l l known, it a p p e a r s t o u s m o s t p r o b a b l y that t h i s e f f e c t i s p r i n c i p a l l y d u e t o i n d u s t r i a l pollution of the a i r by s u l f u r compounds. F j e l d (Ref. 12) h a s t r a c e d i t s evolution f o r E u r o p e s i n c e the t u r n of the c e n t u r y ( F i g u r e 1 B). T h e r e i s a similar i n c r e a s e i n both g r a p h s of f i g u r e 1 although the f o r m of t h i s pollution h a s changed c o n s i d e r a b l y with the r e p l a c e m e n t of c o a l by oil as t h e p r i n c i p a l e n e r g y s o u r c e ( s e e f o r ex. Ref. 2). T h e m i n i m u m of a c i d i t y between 26 a n d 28 m e t e r s could c o r r e s p o n d to the l o w i n d u s t r i a l a c t i v i t y d u r i n g the Second World War. In t h e p a s t , c a r b o n a t e s n e u t r a l i z e d c o m p l e t e l y a c i d i m p u r i t i e s . It a p p e a r s t h a t now t h i s "buffering" c a p a c i t y h a s b e e n o v e r c a p a c i t a t e d a n d t h a t a s t r o n g a c i d i t y ( u p t o 15 p E q / l of H'ions)
e x i s t s in the p r e c i p i t a t i o n s of r e c e n t y e a r s .
ACKNOWLEDGEMENTS T h i s s t u d y w a s p a r t l y financed by "Minist'ere d e la Qualitk de la Vie e t d e 1 E n v i r o n n e m e nt " . REFERENCES 1 2 3 4
J . N. Galloway, G. E . L i k e n s a n d E. S. E d g e r t o n . S c i e n c e 194 (1976) 722-24.
G.E. L i k e n s a n d F . H . B o r m a n n . S c i e n c e 184 (1974) 1176-79.
L. G r a n a t . A t m . E n v i r o n m e n t (in p r e s s ) . L. G r a n a t , H. Rohde a n d R. 0. H a l l b e r g . E c o l . Bull. (Stockholm) 22 (1976) 89-134 S C O P E R e p o r t 7. 5 G . E . L i k e n s , N . M. J o h n s o n , J. N. Galloway a n d F. H. B o r m a n n . S c i e n c e 194 (1976) 643-45.
237
6 G . G r a n . A n a l y s t 77 (1952) 661-71. 7 M . P o s s a n z i n i a n d D. B r o c c o . A t m . E n v i r o n m e n t (in p r e s s ) . 8 L. G r a n a t . T e l l u s 2 4 (6) (1972) 550-60.
9 M. B r i a t . T h i s symposium. 10R. D e l m a s a n d C. Boutron. A t m . E n v i r o n m e n t (in p r e s s ) , I1 C . U. H a m m e r . N a t u r e 270 (1977) 482-86. 12 B. F j e l d . N o r s k I n s t i t u t t f o r Luftforskning. T e c h n i c a l Note N r 1/76.
O s l o 1975.
A tmospheric Pollution 1978,Proceedings of the 13th InternationalColloquium,Paris,France,
April 25-28,1978, M.M.Benarie (Ed.),Studies in EnvironmentalScience,Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
239
THE INTERACTION BETWEEN NOx, O3 AND AIRBORNE PARTICLES H.M. TEN BRINK, J.A. BONTJE, H. SPOELSTRA AND J.F. VAN DE VATE
*
Netherlands Energy Research Foundation ECN, Petten, The Netherlands
ABSTRACT The role of airborne particles in the chemistry of the nitrogen oxides has been investigated. Experiments were performed in mixtures of air with NO
and
particulates at concentrations slightly above levels commonly encountered in polluted air. Starting with air containing NOp it is found that appreciable concentrations of HN02 and NO are formed. The production rate of HN02 is greatly enhanced by the presence of certain particulates (Cu, 140 and Zn). This may be of importance in photochemical air pollution where the photolysis of HN02 is considered to play a dominant role in trophospheric OH'-production. From the nitrogen balance in the gasphase it is deduced that relatively large quantities of nitrate are formed on the wall in the course of the experiments. The removal rate for the nitrogen oxides is enhanced by particulates. This is evidence for nitrate formation on the particles. A small decrease in the oxidation rate of NO by molecular oxygen due to the
presence of aerosol particles is observed. Addition of aerosols to vessels containing an air/0 mixture gives rise to 3 increased removal rates of 0 3 . Extrapolated half-life values show that 0 3 destruction at aerosol particles might compete with destruction of 0 3 attributed to the Earth's surface.
INTRODUCTION Part of the aerosol found in densily populated areas belong to the class of the condensation aerosols, which are produced in high-temperature processes. These aerosols are found in high concentrations near iron works and in automobile exhaust 11
/ . After
formation of small primary particles (0.01 pm dia-
meter) a rapid coagulation 121 follows until the size-range between 0.1 and 1 pm is reached. This size fraction is of particular interest because of its
stability in the atmosphere. Also, these particles have the greatest capability of penetrating into the lungs. The specific surface of condensation aerosols is large due to the web-like structure. Condensation aerosol therefore could act
240
as a sorption surface for noxious gases to take them into the lung system. Surface reactions of gaseous pollutants might take place to a great extent and if so they should be incorporated in the modeling of air pollution chemistry. It is in view of the above considerations that a study was performed about the role of particles in the chemistry of NOx and 0 3 . Whereas in another recent study the aerosol was stabilized on an inert bed 131, the experiments presented in this paper were performed with airborne particulates so as to obtain the best simulation of the actual atmospheric conditions. EXPERIMENTAL Experiments were performed in rather large reaction chambers: a 300 1 pyrex vessel and a 500 1 polyethylene tank. Under these conditions the deposition rate o f the aerosols is small and the influence of wall reactions is diminished. Gas production and monitoring NO and NO2 were obtained from Matheson (pure), used without further purification and mixed with filtered air at ambient pressures to a concentration of 'i,
1 ppm. Experiments were mostly performed at high ( 2 75 %) relative humidities
(R.H.).
HN02 was prepared after the method of Nash 141 by adding diluted NaN02
to a 5 % solution of H2S04. NO
concentrations were determined by the chemo-
luminescence method (Thermo Electron, NO monitor). Both NO 2 and HN02 are measured as "NO2" by this apparatus. HN02 was determined by a substraction method in leading the sample stream through a alkaline washer after the method of Cox 151. The absorption efficiency for NO2 of this washer ranged from 15 % to 40 2 depending on the NO : NO 2 ratio, so complicating the HNO2 measurements. HNO concentrations at higher levels (: 200 ppb) were measured by means of 2 second-derivative spectrometry (fig. 1) with a Lear-Siegler SM-1000 monitor. Aerosol generation and detect ion The aerosols of metal oxides were generated by means of an electrical explosion of metal wires, thereby producing aerosols with a structure identical to that of aerosols sampled outdoors 1 1 I. The oxide nature of Fe, Cu and Pb
aerosol was confirmed by X-diffraction. Average mass-concentrations ranged from 2.5 to 25 mg/m 3 Carbon aerosols were produced by an electric arc between
.
movable carbon rods (cf. fig. 2). The concentration of the aerosols was monitored during experiments by a Condensation Nuclei Counter (C.N.C.).
Observed
decreases in the concentration are due t o both deposition and coagulation, between which the C.N.C. does not discriminate. Aerosol samples for electron microscopic investigations were obtained by means of electrostatic precipitation with a microscope grid as the cathode 16 1
. Electron micrographs were
241 used t o a s s e s s t h e m i c r o s t r u c t u r e of t h e a e r o s o l s and t o search f o r p o s s i b l e morphological changes of t h e a e r o s o l s on exposure t o NO2. RESULTS
Measurements of NO2 decay curves a t 85 % R.H.
showed a s u b s t a n t i a l e f f e c t of
t h e presence of Cu, Mo and Zn a e r o s o l on t h e gasphase r e a c t i o n s of NO2 ( c f . f i g . 3). Cu 0 p a r t i c l e s were i n a s e r i o u s s t a t e of d e t e r i o r a t i o n a f t e r exposure t o 1 - 2 ppm of NO2 ( f i g . 4 ) . Unfortunately no electron-micrographs a r e a v a i l a b l e y e t f o r Mo and Zn. The following a e r o s o l s : Fe304, PbO, C , Ti0 and A u , did not show a measura2 b l e i n f l u e n c e on t h e gasphase decomposition of NO n e i t h e r a t low nor a t high 2 R.H.. Only a t high N02-concentrations (30 ppm) and long exposures times the metals did show t r a c e s of a t t a c k by NO2, Carbon did n o t . In t h e presence o f Cu, Mo, Zn a e r o s o l a g r e a t l y increased formation r a t e of
i s observed ( f i g . 3 ) . The increased removal r a t e f o r t o t a l gas-phase NO 2 (including HNO ) i n t h e presence of t h e s e a e r o s o l s i s apparent. 2 I n measurements s t a r t i n g w i t h a mixture of predominantly HN02 a second-
HNO
o r d e r decay f o r HN02 was found w i t h a decay r a t e of 0.8
2
0.2
.
ppm-lmin-l.
A small decrease of t h e o x i d a t i o n rate of NO by molecular oxygen i s seen on 3 a d d i t i o n of Fe304 (5 mg/m ) . This r a t e i s diminished from 3.2 t o 2.6 pprn-lmin-l.
The observed decay r a t e of O3 on a d d i t i o n of a e r o s o l s (Fe304 and Cu 0) a t a X -4 -1 concentration of 5 mg/m3 i s found t o be 10 sec
.
DISCUSS I O N
The increased d e s t r u c t i o n of NO2 and of t o t a l gaseous NO
i n the presence of
Cu 0 i s r e f l e c t e d i n t h e d r a s t i c morphological changes of t h e a e r o s o l . Very probably t h i s i s due t o n i t r a t e formation on t h e a e r o s o l . Measurements on NO
2 i n r e a c t i o n v e s s e l s however a r e complicated by t h e e x i s t e n c e of wall r e a c t i o n s
a s evidenced by t h e dependence of t h e r e a c t i o n s on t h e s u r f a c e t o volume r a t i o
17
I
of t h e r e a c t o r s . A s f o r t h e HN02 formation i t i s seen t h a t p a r t i c u l a t e s g r e a t l y enhance t h e
from NO2. However, i n t h e course of t h e experi2 l e v e l s become equal t o t h e values i n t h e blank experiments, indica-
i n i t i a l formation r a t e of HNO ments HNO
2 t i n g a s e r i o u s l o s s of HNO
molecules on t h e p a r t i c l e s . One t e n t a t i v e experi2 ment s t a r t i n g w i t h HN02 and Cu 0 f u l l y confirms t h i s assumption: A six-fold i n c r e a s e of t h e HNO
X
2
decomposition r a t e was found on a d d i t i o n of t h e a e r o s o l .
The second-order decay r a t e of HN02 i s i n e x c e l l e n t agreement with t h e observed r a t e a t higher c o n c e n t r a t i o n s a s measured by Kaiser and Wu 181. Further i n v e s t i g a t i o n s on t h e r o l e of p a r t i c l e s i n t h e photochemistry of p o l l u t e d a i r a r e i n progress w i t h a c e n t r a l r o l e a l l o t t e d t o t h e HNO
2 molecule (as t h e major
242 source for OH'-radicals). The extrapolated half-life values of O3 destruction at particle surfaces show that decomposition of O3 by aerosols in the atmosphere might compete with the postulated contribution by the Earth's surface to this destruction 191. ACKNOWLEDGEMENT The investigations were financially supported by the Ministry of Public Health and Environmental Hygiene of the Netherlands. REFERENCES 1
2 3
4
5 6 7
8
9 10
J.F. van de Vate et al., in "Proceedings of the Fourth International Clean Air Congress", Tokyo, (1977) 637. N.A. Fuchs, "The Mechanics of Aerosols", Pergamon Press, Oxford (1964). H.S. Judeikis, S. Siege1 et al., EPA report 600/3-77-038 (1977). T. Nash, Tellus (1974) 175. R.A. Cox, J. Photochem. 2 (1974), 175. J.F. van de Vate, ECN report 77-008 (1977), ECN, Petten, The Netherlands. J.F. van de Vate and Th.M. Pouw, ECN report 76-125 (1976), ECN, Petten, The Netherlands. E.W. Kaiser and C.H. Wu, J. Phys. Chem. 81 (1977) 1701. H. van Dop et al.,IG-TNO report 564 ( 1 9 7 g , TNO Delft, The Netherlands. G.W. King and D . Moule, Can. 3. Chem., 40 (1962) 2057.
3m
Fig. 1 .
340
I
360
380
U.V. absorption spectra of HN02 gas. The "normal" absorption spectrum is taken from ref. 1101.
243
F i g . 2. E l e c t r o n micrographs. A. Coagulates as encountered i n t r a f f i c a e r o s o l from Amsterdam. B. Carbon a e r o s o l g e n e r a t e d i n t h e l a b o r a t o r y .
. ,
'
1000
m
7 I
2000
I
3000
F i g . 3. C o n c e n t r a t i o n p r o f i l e s of NO2, NO, HN02 w i t h o u t a e r o s o l ( s o l i d l i n e s ) and i n t h e p r e s e n c e of Zn-aerosol a t a c o n c e n t r a t i o n of 25 mg/m3 (broken l i n e s ) .
244
Fig. 4
Copper o x i d e a e r o s o l a f t e r a 3-hours exposure t o an atmosphere of 95 % R.H.
Above : w i t h o u t N 0 2 . Below : w i t h I ppm of NO2.
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
245
H E T E R O G E N E O U S CONVERSION O F SO2 T O S U L F A T E
H.S. JUDEIKIS, T . B . S T E W A R T and A.G.
WREN
C h e m i s t r y a n d P h y s i c s L a b o r a t o r y , T h e Ivan A. Getting L a b o r a t o r i e s , T h e A e r o s p a c e C o r p o r a t i o n , E l Segundo, C a l i f o r n i a , U. S. A.
A BST RA C T L a b o r a t o r y s t u d i e s w e r e c o n d u c t e d to m e a s u r e t h e r a t e s of i n t e r a c t i o n of SO2 w i t h s o l i d s t h a t a r e of i n t e r e s t in u r b a n a e r o s o l s .
Results f r o m these studies
i n d i c a t e t h a t , f o r m o s t of t h e s o l i d s e x a m i n e d , S O 2 r e m o v a l o c c u r s by c a p a c i t y l i m i t e d r e a c t i o n s that c o n v e r t t h e SO2 t o a d s o r b e d s u l f a t e .
Atmospheric projec-
t i o n s of the l a b o r a t o r y r e s u l t s s u g g e s t t h a t t h e s e r e a c t i o n s w i l l be m o s t i m p o r t a n t a t o r n e a r the e m i s s i o n s o u r c e .
INT ROD U C T I 0 N A t m o s p h e r i c c o n v e r s i o n of SO2 to s u l f a t e a e r o s o l c u r r e n t l y r a n k s a s one of t h e l e a d i n g p r o b l e m s in e n v i r o n m e n t a l c h e m i s t r y .
A n u m b e r of h e t e r o g e n e o u s
a nd homogeneous p r o c e s s e s can contribute t o this conversion. oxidation of SO
Heterogeneous
by s o l i d s r e p r e s e n t a t i v e of u r b a n a e r o s o l s i s c o n s i d e r e d h e r e .
2 R e s u l t s f r o m flow r e a c t o r e x p e r i m e n t s a r e d i s c u s s e d .
o r other b a s e s o r acids, i s considered.
T h e influence of a m m o n i a ,
T h e r e s u l t s of t h e s e s t u d i e s a r e c o m -
bined w i t h a s i m p l e g a s - a e r o s o l r e a c t i o n m o d e l to p r o j e c t a t m o s p h e r i c c o n v e r s i o n rates. EXPERIMENTAL T h e s e s t u d i e s w e r e c a r r i e d out in a c y l i n d r i c a l flow r e a c t o r in w h i c h the w a l l s of an i n n e r , c o n c e n t r i c c y l i n d e r w e r e c o a t e d w i t h the s o l i d of i n t e r e s t [ r e f . I]. T h e flow of g a s m i x t u r e s , containing t r a c e a m o u n t s of SO2, t h r o u g h t h e r e a c t o r r e s u l t e d in diffusion of SO2 to t h e c o a t e d w a l l s w h e r e i t w a s h e t e r o g e n e o u s l y removed. f o r SO2.
T h i s l e d to both r a d i a l and a x i a l (flow d i r e c t i o n ) c o n c e n t r a t i o n g r a d i e n t s T h e l a t t e r w a s m e a s u r e d by m e a n s of a s e r i e s of s m a l l p r o b e s whose
i n t a k e s w e r e c e n t e r e d along the c y l i n d e r a x i s a t v a r i o u s d i s t a n c e s in the flow direction.
T h e s e p r o b e s w e r e coupled, by m e a n s of a r o t a r y valve, to a mass
spectrometer
.
246 Data f r o m t h e s e e x p e r i m e n t s w e r e analyzed using l a m i n a r flow m o d e l s that specifically accounted for m a s s t r a n s p o r t by diffusion and flow [ r e f . 11.
This
a n a l y s i s yielded r e a c t i v i t i e s f o r SOz in t e r m s of collision efficiencies o r @ values, the fraction of SOZ-solid collisions that w e r e effective in removing SOz f r o m the gas mixtures. S u r f a c e reaction products w e r e m e a s u r e d by wet c h e m i c a l and x - r a y photoe l e c t r o n spectroscopic ( E S C A ) techniques [ r e f . 23.
RESULTS Data f r o m a r e p r e s e n t a t i v e e x p e r i m e n t f o r SOz r e m o v a l by f l y a s h f r o m the Mohave power plant on the Colorado R i v e r in California, U . S . A . Fig. 1 .
a r e shown in
T h e s e data w e r e obtained f r o m a f r e s h l y p r e p a r e d coating of the fly ash. 1.0
0. 1
0
4
2
0.01
6
Distance along cylinder a x i s (flow d i r e c t i o n ) , c m Fig. 1. Removal of SO2 by Mohave fIy ash. The t r i a n g l e s r e p r e s e n t e x p e r i m e n t a l l y m e a s u r e d SO2 concentrations r e l a t i v e to the concentration of SO2 in the T h e solid curve was calculated f r o m the l a m i n a r influent g a s s t r e a m , [SOz]. flow model f o r @ = 4 . 4 x 10-4. E x p e r i m e n t a l conditions: total p r e s s u r e , 55 t o r r ; 0 2 p r e s s u r e , 6 t o r r ; p a r t i a l p r e s s u r e of S O 2 in the influent g a s s t r e a m , 9 m i l l i t o r r ; r e l a t i v e humidity, 0 percent.
.
A s indicated, a n a l y s i s of the d a t a f r o m this experiment yielded a 0 value of
4.4 x
Additional e x p e r i m e n t s with o t h e r f r e s h l y p r e p a r e d coatings of this
m a t e r i a l indicated a n a v e r a g e collision efficiency of 5 x 1 0
-4
, with an uncertainty
( s t a n d a r d deviation) of rt3070. T h e s e r e s u l t s , along with o t h e r s f r o m s i m i l a r e x p e r i m e n t s on additional m a t e r i a l s of a t m o s p h e r i c i n t e r e s t a r e s u m m a r i z e d in Table 1 .
Also given in that
table a r e m e a s u r e d BET s u r f a c e a r e a s and r a t e s calculated f o r r e m o v a l of SO in the a t m o s p h e r e by g a s - a e r o s o l reactions. in the following section.
2 The l a t t e r calculations a r e d i s c u s s e d
241
TABLE 1 M e a s u r e d s u r f a c e a r e a s and collision efficiencies and calculated a t m o s p h e r i c SO2 r e m o v a l r a t e s for various m a t e r i a l s r 9ET
Material
surface a r e a
lo5
.
(m'9-l) MgO Fe203 Mohave fly a s h *I203 MnO 2 Cholla fly a s h River Bend f l y a s h Shawnee fly a s h (M)d Louisville fly a s h PbO Shawnee fly a s h (M)d Charcoal Shawnee fly a s h (E)d Shawnee fly a s h ( E ) d NaCl Louisville fly a s h River Bend fly a s h a
Calculated initial SO2 removal rates (percent hr-')
100
55 50b9 40 30 30b9 3OC 1oc 7c 7 5b 3 2c 0.4b 0.3 0. Zb 0. l b
27. 3 15. Z b 215 109
35 21 19 16 12 12 12 4 3 3 2 1 1 0.2 0.1 0.09 0.04
Uncertainties a r e *30%.
b M e a s u r e m e n t s on m a t e r i a l as received. 'Measurements on m a t e r i a l a f t e r washing with distilled w a t e r . d F r o r n mechanical precipitator (M), o r e l e c t r o s t a t i c p r e c i p i t a t o r (E). T h e 9 values given in Table 1 w e r e found to be independent of SO2 and oxygen concentrations, a s well a s r e l a t i v e humidity and total p r e s s u r e to within a f a c t o r of two [ref. 21.
Wet c h e m i c a l and ESCA a n a l y s e s indicated a quantitative (factor
of two) conversion of SO
to adsorbed sulfate, with the exception of A1 0 and 2 2 3 possibly c h a r c o a l w h e r e the e x p e r i m e n t a l r e s u l t s indicated SO removal o c c u r r e d 2 by r e v e r s i b l e physical adsorption [ref. 21. ESCA a n a l y s i s of s e v e r a l of the a s received fly a s h m a t e r i a l s indicated very high sulfate contents.
T h i s r e s u l t , along with low initial collision efficiencies
suggested that t h e s e m a t e r i a l s m a y a l r e a d y have undergone substantial reaction with SOz, before o r during collection.
E x p e r i m e n t s w e r e t h e r e f o r e repeated on
these m a t e r i a l s , a f t e r f i r s t washing t h e m with distilled w a t e r to remove soluble sulfates.
As indicated in Table 1, this p r e t r e a t m e n t led, in many c a s e s , to
substantial i n c r e a s e s in initial collision efficiencies. T h e r e s u l t s of the l a t t e r e x p e r i m e n t s suggest that t h e s e m a t e r i a l s have a finite capacity f o r SOz removal.
Indeed, this was found to be the c a s e f o r all of
the m a t e r i a l s examined in t h i s study. SO
T h i s effect i s illustrated in Fig. 2 for
r e m o v a l o v e r Mn02, where the collision efficiency relative to the initial
2 value, is plotted v e r s u s t i m e (SO
2 exposure).
Data such a s those in Fig. 2 can
248 SO2 exposure ( h r )
60
40
20
1.0 0. 8
cp cpe
0. 6
0.4 0.2 0.0
200
so2
400
exposure
600
(4)
'
800
mgSO
-
Fig. 2. Collision efficiency a s a function of SO2 exposure for SO2 removal o v e r MnOZ. SO2 in nitrogen, 95% relative humidity. The a r r o w indicates the stoichiometric point for the reaction Mn02 t SO2 MnS04. be used to d e t e r m i n e the total SO given in Table 2.
uptake. Results for various m a t e r i a l s a r e 2 A s in the c a s e of collision efficiencies, capacities w e r e found
concentrations and total p r e s s u r e [ r e f . 21. A s 2 noted in Table 2, however, capacities in some c a s e s w e r e found to be very to be independent of SO2 and 0
dependent on the relative humidity of the reaction mixture. The effects of acids and b a s e s on the SO2 reactions w e r e a l s o examined, since
to sulfate conver2 In one s e r i e s of e x p e r i m e n t s with Mn02, it was found
many authors have suggested the importance of pH on the SO sion [e. g., refs. 3 and 41.
that p r e t r e a t m e n t of this m a t e r i a l with 0. 1 N solutions of base (NH OH o r NaOH) i n c r e a s e d initial collision efficiencies f o r SO eight.
4
removal by f a c t o r s of t h r e e to
2 Conversely, acidic p r e t r e a t m e n t s (0.1 N solutions of H SO o r HCL) 2 4
reduced initial 9 values by f a c t o r s of s i x to fifteen.
In another experiment, a
s a m p l e of Mohave fly a s h was exposed to SO2 until i t s capacity to remove this s p e c i e s was completely expended. amounts ( r e l a t i v e to the SO
The m a t e r i a l was then exposed to s m a l l
exposure) of gaseous ammonia and then reexposed
2 to SOz, with the r e s u l t that the reactivity of the spent m a t e r i a l was r e s t o r e d to
-
50% of i t s initial value.
249
TABLE 2 Capacities f o r SO2 removal o v e r selected solids Relative humidity
Solid ~
~
Capacity f o r SO2 removal
(70)
(mg S 0 2 ) ( g solid)-'
~
4 12 400
0 50 95
MgO
Fe203 Mohave fly a s h a
0 50
0. 6
0 50 95
0.5
1.2
0.2
1.4
25 5 17
0 53 95
A120 3
0 25 58 50- 95 95
MnOZ
4
78 3 20 2 10 >530
aAs received. DISCUSSION The collision efficiencies given in Table 1 can be combined with a simple collision m o d e l to e s t i m a t e SO removal r a t e s by g a s - a e r o s o l reactions [ r e f s . 2 2 and 51. The calculated r e m o v a l r a t e s a r e given in the l a s t column of Table 1. These r a t e s w e r e d e t e r m i n e d assuming an atmospheric a e r o s o l burden of -3 100 pg m having the same reactivity a s the indicated solid. Thus, for example, if the
total a t m o s p h e r i c
a e r o s o l burden of 100 pg m - 3 had the s a m e reactivity 1 a s MgO, the initial SO2 removal r a t e would be 35% h r -
.
In s o m e c a s e s , actual r e m o v a l r a t e s could approach the values in Table 1. e. g., in power plant plumes with high a s h and m e t a l oxide concentrations. In other situations, r e a c t i v i t i e s would be the s u m of contributions f r o m the individual a e r o s o l components.
T h e s e would not n e c e s s a r i l y v a r y in proportion to relative
abundances, however, since c e r t a i n elements can be m o r e concentrated on the s u r f a c e of a e r o s o l p a r t i c l e s [ r e f . 61. T h e capacity limited n a t u r e of the reactions observed h e r e suggests that these reactions will be m o s t important a t o r n e a r the e m i s s i o n source.
Quantitative
e s t i m a t e s indicate a n active lifetime f o r the a e r o s o l s toward SO2 removal of N
1-10 h r , depending upon the a e r o s o l burden [ref. 21.
ammonia could, however, extend the active lifetime.
Reactions with atmospheric
250
The r e s u l t s of t h i s study suggest that only a f r a c t i o n of gaseous SO2 in the a t m o s p h e r e c a n be converted to sulfate by SO - a e r o s o l reactions. Moreover, 2 the extent of this conversion will be determined by a e r o s o l burdens r a t h e r than SO
l e v e l s , because of relative SO and a e r o s o l burdens and the capacity limited 2 2 n a t u r e of t h e s e reactions. ACKNOWLEDGMENT Financial a s s i s t a n c e f r o m the A e r o s o l R e s e a r c h Branch, U. S . Environmental Protection Agency under G r a n t Number R-802687-02 i s gratefully acknowledged. The contents do not n e c e s s a r i l y r e f l e c t the views and policies of the Environm e n t a l P r o t e c t i o n Agency, n o r does mention of t r a d e n a m e s o r c o m m e r c i a l products constitute endorsement o r recommendation f o r use. REFERENCES
1 H.S. Judeikis and T. B. Stewart, Atmos. Environ. 10 (1976) 769-776. 2 H. S. Judeikis, T. B. S t e w a r t and A. G. Wren, Laboratory Studies of Heterogeneous Reactions of SOz, Atmos. Environ., in p r e s s . 3 C. E. Junge and T. G. Ryan, Quart. J o u r . Royal Meteorol. SOC. 84 ( 1 958) 46-55. 4 A. R. Van den Heuvel and B. J , Mason, Quart. Jour. Royal Meteorol. SOC. 89 (1963) 271-275. 5 H.S. J u d e i k i s and S. Siegel, Atmos. Environ. 7 (1973) 619-631. 6 R. W. Linton, A. Loh, D. F.S. Natusch, C.A. Evans, J r . , and P. Williams, Science 191 (1976) 852-854.
Atmospheric Pollution 1978, Proceedings of the 13th InternationalColloquium,Pans,France, April 25-28,1978,M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1 0
251
Elsevier Scientific Publishing Company. Amsterdam - Printed in The Netherlands
PILOT-SCALE STUDY OF ABSORPTION WITH CHEMICAL REACTION IN A VENTURI-JET SCRUBBER by Andr6 LAURENT ( * ) , Christian FONTEIX ( * ) , G6rard BESSON (**) and Jean-Claude CHARPENTIER (*) (*)
Laboratoire des Sciences du Ggnie Chimique - CNRS-ENSIC, I , rue Grandville 54042
-
-
NANCY CEDEX (FRANCE)
(**) SAPS Anticorrosion - LE COUDRAY-EN-THELLE
-
60790
-
VALDAMPIERRE (FRANCE)
ABSTRACT A study has been made of the performance of a venturi-jet scrubber of 50 mm nominal diameter. The hydrodynamic characteristics have been established firstly. These are illustrated by the curves of entrained gas flow as a function of the flowrate of injected liquid (or of the corresponding liquid supply pressure). Next, applications of the technique -of gas-absorption with chemical reaction permits the determination of interfacial area and of the mass transfer coefficient in both gas and liquid phases in the venturi-jet scrubber. The influence of the gas and liquid flowrates and of the diameter of the ejector nozzle have been examined. The results obtained permit potential applications of this type of scrubber in the fight against air pollution and odours.
INTRODUCTION The venturi-jet scrubber is a device that permits the pumping of large quantities of gas by the action of the kinetic energy of a jet of liquid acting as the motive fluid. Its simple mode of action has encouraged its more and more frequent use in the fight against air pollution (ref. 1 ) . Usually, three distinct functions are employed at the same time : they are dust collection, cooling and absorption. While the first two functions have received considerable attention (refs. 2
-
5),
data concerning gas-liquid mass transfer performance are scarce, particularly for units producing gas flow by their own pumping action alone (refs. 6
-
9).
APPARATUS A venturi-jet scrubber of 50 mm nominal diameter was used. It comprises a standard venturi diffuser and an ejector nozzle designed so that the liquid is injected as a conical sheet entirely filling the cross-section of the diffuser, giving
252
a good contact between the gas and the liquid and producing a satisfactory aspiration effect by a good conversion of the kinectic energy of the motive liquid. Three such nozzles were used, having diameters A , B and C. At the exit of the diffuser the two fluids flowing downwards together are separated in a gravity separator equipped with a jet breaker. The results reported below concern the complete assembly of scrubber and separator. HYDRODYNAMICS The venturi-jet scrubber is characterised by performance curves showing the suction pressure of the unit as a function of the volumetric gas flow G . Such curves for the three nozzle sizes and the several liquid supply pressures employed are shown in Figure 1 . This graph defines the auto-aspiration performance of the scrubber. The liquid holdup, the volume of liquid in the scrubber only, is in the range 3-5 Z of the total o
A
O
B
volume. With no gas flow, the holdup changes with the liquid flow
* c
and for all nozzle sizes. m3.
20
10
30
h-: 40*G
MASS TRANSFER Methods for the experimental determination of mass transfer coefficients k S and k S and of interL G facial area S for a gas-liquid
Fig. 1 . Pumping characteristics of the
reactor by absorption with chemi-
venturi-jet scrubber.
cal reaction have been reported in the literature. A slow irreversi-
ble reaction is used for the measurement of k S, a fast pseudo-mth order reaction L
for S and an instantaneous surface reaction for the determination of k S (refs. G
10, 1 1 ) .
Liquid-phase coefficient k S L The product k S was determined by the absorption of carbon dioxide from a mixL
ture with air into an aqueous solution of potassium carbonate and bicarbonate in
253 the presence of sodium hypochlorite. Figure 2a shows, for each size of nozzle, the variation of k S with gas and liquid flowrates. L I n the range of conditions examined here, the product k S for any particular nozzle depends principally upon the liquid flowrate L
L
so
long as the device acts
as an auto-aspirator, But when gas is forced through the unit, the influence of gas flowrate becomes significant. This effect becomes more important as the size of the liquid nozzle is increased. Interfacial area S The interfacial area S was determined by the absorption with fast pseudo-first order chemical reaction of carbon dioxide from a mixture with air into an aqueous solution of sodium hydroxide. Figure 2b shows all of the values of S as a function of the liquid flowrate L for all gas flows and nozzle sizes.
A
k,S
(cm3. s-'1
86-
42-
h") 1 L
L/G 0.05 01'
I 0.5 0 0.5 1 1[ ' 0 (m3.
0
I
1
I
I
Fig. 2. Liquid-side mass transfer coefficient (Za), effective interfacial area (2b) and gas-side mass transfer coefficient (2c) in the venturi-jet scrubber.
In the region studied, the interfacial area is independent of gas rate for any given liquid rate. This result agrees with the work of NAGEL (ref. 8) carried on in a contactor having a cylindrical body.
254 Gas-phase coefficient k S G The product k S was determined by experimental measurements of the rate of abG sorption with irreversible and instantaneous surface chemical reaction displayed in the transfer of sulphur dioxide from a dilute mixture with air into an aqueous solution of sodium hydroxide. The results are shown in Figure 2c where the ratio of k S to the gas flowrate is plotted against the ratio of the liquid and gas G flowrates L/G for the three nozzle diameters. These last results are directly indicative of the practical value of the venturi-jet scrubber for the treatment of gaseous effluents to prevent atmospheric pollution. Indeed the ordinate of Figure 2 c is directly proportional to the definition of the Number of Transfer Unit NG of the gas phase that is related to the efficiency by the relation ln(l-E ) = - NG. Thus it is possible to conclude from G the results shown that the efficiency of the scrubber improves as the ratio L/G is increased. Over the operating range studied here the removal efficiencies of the scrubber varied from 8 2 % to 9 9 . 9 9 %.In practice, for a given liquid injection pressure, a satisfactory scrubbing efficiency will be obtained in the part of the capacity curve corresponding to small gas flows. REFERENCES Anonyme, Informations Chimie, 119 ( 1 9 7 3 ) 127-133. S . Calvert, Chem. Engng., August 29 (1977) 54-68 and October 24 (1977) 133-140. K.T. Semrau, Chem. Engng., September 26 (1977) 87-91. W. Gibert, Chem. Engng., October 24 ( 1 9 7 7 ) 140-144. T.H. Gleason, Chem. Engng., October 24 ( 1 9 7 7 ) 145-148. L.S. Harris and G.R. Haun, Chem. Eng. Progress, 60 (1964) 100-103. P.E. Barker, Trans. Instn. Chem. Engrs., 40 (1962) 221-226. R. Hoffmann, H. Kurten and 0. Nagel, Chemie Ing. Techn. 45 ( 1 9 7 3 ) 881-887. P. Krotzsch, Chemie Ing. Techn. 47 (1975) 213. 10 P.V. Danckwerts, Gas-liquid reactions, Mc Graw Hill, New York, 1970, ch. 10, p. 238. I I A. Laurent, C. Prost and J . C . Charpentier, 3. Chimie Physique, 72 ( 1 9 7 5 )
I 2 3 4 5 6 7 8 9
2 3 6-2 44.
Atmospheric Pollution 1978, Proceedingsof the 13th InternationalColloquium,Paris, France, April 25-28,1978,M.M.Benarie (Ed.), Studies in Environmental Science, Volume 1 Q Elsevier ScientificPublishing Company, Amsterdam - Printed in The Netherlands
255
A STUDY OF THE ADSORPTION OF ORGANIC MICROPOLLUTANTS ON CHRYSOTILE AND CROCIDOLITE J.P. CONTOUR, I. GUERIN and G. MOUVIER Laboratoire de Physico-Chimie Instrumentale, Universit6 de PARIS VII 2,
place Jussieu
-
F
-
75221 PARIS CEDEX 05.
ABSTRACT Adsorption of diethylamine, nicotine, N-nitrosodimethylamine and N-nitrosodiethylamine on chrysotile and crocidolite has been studied by gas solid elution chromatography and X-ray photoelectron spectroscopy. Chrysotile adsorbs 3 to 10 times more of organic pollutants than crocidolite. This phenomenon is especially marked in the case of chemisorbed nicotine which is not desorbed after 15 hours at 450 "C under vacuum.
INTRODUCTION The carcinogenic properties of asbestos have been clearly demonstrated by the studies of Selikoff et al., who also point out the synergetic effect of some organic micropollutants when they are associated with asbestos pollution (ref. 1 , 2) In this respect, tobacco smoke appears to be one of the more active (ref. 3 ) . We thought therefore that it would be interesting to undertake a study of the interactions occuring between asbestos (chrysotile, crocidolite, amosite and antophyllite) and some carcinogenic organic pollutants (N-nitrosamine) (ref. 4 ) or precursors of carcinogenic compounds (nitrogen dioxide, dimethylamine, diethylamine, nicotine) (ref. 5). In this paper, we report the first results concerning adsorption of diethylamine, nicotine, N-nitroso- diethylamine and -dimethylamine on chrysotile and crocidolite.
EXPERIMENTAL Adsorption isotherms and isobars were determined by the dynamic adsorption method which is derived from gas phase chromatography. The adsorbed species were identified by X-ray photoelectron spectroscopy (XPS, ESCA).
256
Adsorption The dynamic adsorption method is based on the theory of gas-solid elution chromatography and has been fully described in several papers (ref. 6 , 7). Either reversible or irreversible adsorptions can be studied by this method. X-ray photoelectron spectroscopy XPS is a recent method for solid and surface analysis which has been described in a large number of papers during the last ten years (ref. 8). It is possible by XPS
to
study the chemical interactions of gaseous pollutants with atmospheric
particles (ref. 9, 10). The mean free path of induced photoelectrons being I0 - 40 A, XPS is a method particularly suitable for the investigation of interactions occuring in adsorption. Photoelectron spectra were recorded on an AEI ES 200 B spectrometer using MgKa radiation as excitation source (MgKa
= 1253.65
eV). The binding energies were
determined by using the Is peak of carbon contamination
as
internal reference.
The binding energy of these electrons is set at 2 8 5 eV, relative to the Fermi level (ref. 1 1 ) . The preparation of the sample and the adsorption are performed in the preparation chamber attached to the spectrometer. The adsorption pressure i s set at 1 torr at room temperature. After adsorption, the gas is pumped out and the chamber evacuated -6
until a pressure of 10
torr is reached.
Asbestos fibres were compressed onto a copper grid and cleaned by heating in vacuum at 450 'C overnight. Materials The origin and the surface areas of the asbestos samples used in this study are given in table 1. TABLE 1 Sample
Origin
Chrysotile
Canada
Crocidolite
South Africa
2
-1
Surface area (m g
)
26.7 8.5
RESULTS AND DISCUSSION Adsorption Irreversible adsorption. This type of adsorption is only detected when diethylamine and N-nitrosodiethylamine are adsorbed on chrysotile. No adsorption is detected on crocidolite, N-nitrosodimethylamine decomposes on chrysotile, and nicotine adsorption has not been studied because its boiling point ( 2 4 5 . 5 "C) is too high.
257
The adsorption isobar of diethylamine on chrysotile shows a maximum around 6 5 "C. At 25 'C, chrysotile adsorbs about 2.5 p1.g-I 0 . 4 p1.g-'
(S.T.P) of diethylamine and about
(S.T.P) of N-nitrosodiethylamine.
Reversible adsorption. The linear transforms of the reversible adsorption isotherms of diethylamine on chrysotile from 6 0 to 175 "C show that diethylamine is adsorbed in agreement with Langmuir theory (ref. 1 2 ) . However, this adsorption occurs on two types of adsorption sites as shown by the fact that the graphs of the linear transform in which P/V is plotted against P, consist of two straight lines. It can be assumed that the low pressure part of the isotherm corresponds to adsorption on the outer surface of chrysotile fibril and the high pressure one to capillary condensation in the hollow part of the fibril (ref. 1 2 ) . XPS of adsorbed species The binding energies corresponding to the principal lines of the photoelectron spectra of chrysotile and crocidolite are given in table 2 . The samples are seen to be slightly contaminated by ammonium nitrate. The binding energies and the intensities of the N Is line recorded after adsorption of diethylamine, nicotine, N-nitrosodimethyl- and N-nitrosodiethylamine and/or nitrogen dioxide are reported in table 3 . These results show that no chemical interaction between the amines and nitrogen dioxide can be detected at room temperature. Nicotine has a high affinity for chrysotile and crocidolite. The amount of chemisorbed nicotine is higher than that of the other amines. The intensities of the N I s peaks reveal that the adsorbing capacity of chrysotile is 3 to 10 times greater than that of crocidolite. A l l compounds except nicotine are desorbed after heating for 15 hours at 4 5 0 OC under vacuum. TABLE 2
Binding energies in chrysotile and crocidolite
Samples
0 Is
Si 2p
Mg 2p
Chrysotile
531.5
102.9
49.6
Crocidolite
532.1
102.8
50.5
N Is
Ca 2p
/
402.1 407.6
I
711.0
407.5 402.0
Fe 2p
350.6
Na 2 s
I 63.1
258
TABLE 3 Binding energies of N Is electrons after adsorption o f gaseous pollutants on chrysotile and crocidolite Chrysotile Adsorbate
EB(eV)
I*(c.F1)
401.8
20
407.5
23
407.6
139
Diethylamine
403.0
100
Diethylamine
Crocidolite
Chemical Species
Ee(eV)
I*(c.sl)
I
I
407.6
75
Amine
I
I
NO,
-
N03
Chemical Species
N03
402.8
25
20
407.6
100
Amine NO-
403.1
+ NO,,
407.2
80
NO
130
Amine
402.7
42
Amine
55
I
402.8
33
I
-
402.6
38
408.0
35
Amine -
Nicotine
402.75
After 15 h. at 450 OC
403.0
Nicotine
402.8
90
I
407.4
66
NO
+ NO2
N-nitroso
403.9
45
Amine
402.6
32
dimethylamine
406.0
30
-
NO
4 0 5 ,9
10
-
NO
I
I
N-ni tro so
403.9
67
diethylamine
405.8
42
the detection limit is 5
C.S.
I
-1
Amine
--
NO
Amine
259 CONCLUSION This preliminary study confirms that the adsorbing capacity of chrysotile is very much higher (3 to I 0 times) than that of crocidolite. This property cannot be attributed simply to the higher surface aera of chrysotile. One must also assume that chemical interactions promote the chemisorption of organic compounds particularly for diethylamine. It also appears that nicotine is strongly adsorbed even at room temperature and that i t is not desorbed at 450 'C under vacuum, so that in dusty atmospheres containing tobacco smoke, the fibrils of chrysotile are heavy loaded with nicotine. NOTE Results on the adsorption of amines and N-nitrosamines on crocidolite are not at present available, but will be reported in a complementary paper during IRCHA Colloquium in April 1978. REFERENCES 1 J.
Bignon, M. Bientz, P. Sebastien and G. Bonnaud, Poll. Atm., 26 (33) (1976)
2353-57.
2 J . S . Harington, A.C. Allison and D.V. Badarni, Adv. Pharmacol. Chemother., 12 (1975) 291-402. 3 I.J. Selikoff, E.C. Hammond and J. Churg, J.A.M.A.,
204(2)
(1968) 104-110.
4 C.L. Walters, Act. Chim., 2 (1977) 9-11. 5 P.L. Hanst, J.W. Spence and M. Miller, Environm. Sci. Technol., 1 1 (4) (1977) 403-5.
6 C. Vidal-Madjar, M.F. Gonnord and G. Guiochon, in J.C. Giddings, E. Grushka, R.A. Keller and J . CAZES (Eds.), New York, Adv. in Chromatography, V o l . 13, ch. 4 , pp. 197-205. 7 E. Cremer and H.F. Huber, in N. Brenner, J.E. Callen and M.D. Weiss (Eds.), (1962), Gas Chromatography, Vol. 4, ch. 12, pp. 169-182.
8 K. Siegbahn, C. Nordling, A. Fahlman, R. Norberg, K. Hamrin, J. Hedman, G. Johansson, T. Bergmark, S.E. Karlsson, I. Lindgren and B. Lindberg, Ann. Phys. (1968) 281-329. 9 B. Barbaray, J.P. Contour and G. Mouvier, Atmosph. Environm., 1 1 (1977) 351-356. 10 T. Novakov, S.G. Chang and B. Harner, Science, 186 (1974) 259-262. 1 1 J.P. Contour and G . Mouvier, 3. Electron Spectrosc., 7 (1975) 85-90.
12 J.E. Germain, in Dunod Paris (Ed.), Catalyse HStGrogSne, 1959, ch. 2.
Atmospheric Pollution 1978, Proceedingsof the 13th International Colloquium,Paris,France, April 25-28,1978, M.M.Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific PublishingCompany,Amsterdam - Printed in The Netherlands
263
PARTICLE SIZE DISTRIBUTION OF COMBUSTION AEROSOLS H.J. FISSAN, H. FRANZEN*, c. HELSPER
AerosolmeRtechnik, Gesamthochschule Duisburg, Duisburg (G.F.R.) "Lehrstuhl fur Technische Thermodynamik, RWTH Aachen, Aachen (G.F.R. )
INTRODUCTION It has been observed that carcinogenic plycyclic aromatic hydrocarbons (PAH) are present in the atmosphere. combustion processes are considered to be the most important sources for PAH. Among these the burning of coal produces the highest emission, but in cities with high traffic density and low meteorological exchange activities, vehicle emissions determine the immission situation, especially in narrow streets. Therefore for estimating the potential health effects caused by PAH, it is sufficient to characterize the emission of PAH with respect to their physical state, concentrations and as far as the particulate phase is concerned with respect to size distribution.The size distribution is imuortant for transport Phenomena, inhalation and deposition in the respiratory tract. The above mentioned parameters mainly depend on the combustion system, on system operating conditions, on the exhaust system and exhaust cooling conditions. EXPERIMENTAL RESULTS Experiments were performed with a water-cooled six-cylinder spark ignition engine, which was operated with leadfree fuel on a chassis dynamometer. The exhaust gas has been cooled to about 3 0
-
50°C in a model exhaust system consisting of a water-cooler
with wall temperatures about
2OoC.
The same model exhaust system was used for cooling
the exhaust emitted from an oil burner to study the effect of cooling conditions on the exhaust gases. Fractionation for size dependent gravimetric and chemical analysis of the exhaust aerosols was achieved with a six-stage cascade impactor (CI, Andersen Stack Sampler). Because of the limited fractionation range of the CI ( 0 . 5 Aerosol Analyzer ( E m , TSI
-
-
10 pm) an Electrical
Model 3030) was used for the determination of the par-
ticle number distribution below 1 pm. Figure 1 shows the mass distribution of the spark ignition engine exhaust aerosol (n = 2500 min-l; X = 0.9) over the particle size range 0.01 - 10 pm. The mass distribution below 1u m was calculated from the measured number distribution on
264 t h e assumption of s p h e r i c a l p a r t i c l e s with u n i t d e n s i t y .
c .EAA
rn C I
0,Ol
0,l
1
Particle Diameter D
10
P
{urn]
Fig. 1. Mass d i s t r i b u t i o n of a spark i g n i t i o n engine exhaust a e r o s o l . The agreement between t h e d i f f e r e n t measuring instruments i s reasonably w e l l and w a s a l s o observed with t h e o i l burner exhaust a e r o s o l . The majority of t h e p a r t i c l e s l i e s i n t h e r e s p i r a b l e s i z e range, t h e g r e a t e s t amount being concentrated between 0 . 1 and 1 pm. Figure 2 shows t h e spread of t h e cumulative mass d i s t r i b u t i o n s which were measured with t h e C I f o r both systems. The i n d i c a t e d range f o r t h e spark i g n i t i o n engine includes working c o n d i t i o n s with numbers of r e v o l u t i o n from 2000 t o 3000 min-'
and
oxydation r a t i o s i n t h e range between 0.9 and 1.1. I n t h e c a s e of t h e o i l burner t h e CO -concentration v a r i e s from about 10 t o 13 2 1 to 6 .
%
and t h e Bacharach Number from
With t h e model exhaust system used, no s i g n i f i c a n t dependence of t h e shape of the d i s t r i b u t i o n on t h e system and i t s o p e r a t i n g c o n d i t i o n s could be observed. There a r e only s l i g h t d i f f e r e n c e s i n t h e mass median diameter. The mass median diameter of t h e exhaust a e r o s o l of t h e spark i g n i t i o n engine is about 0 . 3 pm, t h e corresponding value f o r t h e o i l burner i s about 0.5 pm. The main r e s u l t i s t h a t i n a l l cases i n -
265 v e s t i g a t e d , t h e majority of t h e p a r t i c l e mass l i e s i n t h e r e s p i r a b l e s i z e range.
99
95
90
50
- Oilburner (CO2:
10
5 1
11 1 I
10.6
-
x
= 0.9
-
%
1.1)
I
1
1
10
Particle Diameter D
P
Fig. 2 .
12,8
Bacharachnumber: 1 - 6 ) Spark Ignition Engine (n = 2000 - 3000 nun-’
{pm}
Range of cumulative mass d i s t r i b u t i o n s f o r t h e o i l burner and t h e spark i g n i t i o n engine.
The t o t a l particle-mass c o n c e n t r a t i o n values a r e between 15 and 65 mg/m3 f o r t h e spark i g n i t i o n engine, with t h e higher value f o r f u e l r i c h conditions ( A = 0.9).The o i l burner y i e l d s a p a r t i c l e mass concentration between 5 and 15 mg/m3. Since t h e p a r t i c l e s a r e i n t h e r e s p i r a b l e s i z e range, it i s important t o know t h e amount of m a t e r i a l i n t h e p a r t i c l e mass, considered t o belcarcinogenic, e s p e c i a l l y t h e amount of PAH. For t h e a n a l y s i s , which was performed a t t h e “ I n s t i t u t f u r Angewandte Thermodynamik RWTEi Aachen“, gas chromatography
was used. As an example f o r t h e r e s u l t s , Fig. 3
shows t h e mass p o r t i o n of s e v e r a l PAH on t h e t o t a l p a r t i c l e m a s s f o r t h e spark i g n i t i o n engine f o r two d i f f e r e n t o x i d a t i o n r a t i o s . The shown p r o f i l e of PAH i s very s i m i l a r i n both c a s e s . The mass p o r t i o n i n t h e c a s e of f u e l r i c h conditions i s about t e n times higher than i n t h e case of f u e l l e a n c o n d i t i o n s . I n t h e c a s e of
the fuel
r i c h c o n d i t i o n t h e t o t a l amount of PAH i s s t i l l f u r t h e r increased because of t h e higher t o t a l p a r t i c l e m a s s emitted. The PAH emission of t h e o i l burner i s very much
266 lower than t h a t of t h e spark i g n i t i o n engine. Only under extreme c o n d i t i o n s some of t h e considered PAH were found i n d e t e c t a b l e c o n c e n t r a t i o n s .
L-I
LI
x x
10
= 0.9
Fluoranthene
= 1.1
Pyrene Chrysene+ B (a)
Anthracene B (bjk) F l u o r a n t h e n e
~ ( e P)y r e n e ~ ( a P) y r e n e Perylene
Dib (ah+aj) Anthracene + Indeno ( 1 , 2 , 3 - C d ) Pyrene
B (ghi) P e r y l e n e
Fig. 3 .
Mass p o r t i o n of PAH on t h e t o t a l p a r t i c l e mass f o r t h e spark i g n i t i o n engine.
Because of t h e r a t h e r s t r o n g dependence of t h e mass p o r t i o n of PAH on t h e working c o n d i t i o n s of t h e spark i g n i t i o n engine, it seems t o be impossible t o use t h e t o t a l e m i t t e d p a r t i c l e m a s s c o n c e n t r a t i o n a s a measure f o r t h e emitted amount of PAH. The measurements considered so f a r , were performed with r a t h e r low exhaust gas temperat u r e s a t t h e e x i t of t h e water-cooler.
The r e s u l t s , t h e r e f o r e can be considered t o
be v a l i d f o r c a s e s i n which t h e r e a l exhaust system it a t low temperatures. For higher temperatures t h e r e w i l l occur changes i n t h e phase of t h e emitted PAH, depending o n t h e b o i l i n g temperatures of t h e components, so t h a t t h e amount of PAH emitted a s a gas w i l l i n c r e a s e .
SUMMARY The t o t a l p a r t i c l e mass c o n c e n t r a t i o n of t h e two considered combustion processes, spark i g n i t i o n engine and o i l burner, a r e about two o r d e r s of magnitude higher than t h a t i n t h e atmosphere. The p a r t i c l e s a r e r a t h e r s m a l l with t h e l a r g e r p a r t of t h e p a r t i c l e mass i n t h e
r e s p i r a b l e s i z e range. The t o t a l p a r t i c l e mass a s w e l l a s t h e
amount of PAH emitted with t h e p a r t i c l e s are s t r o n g l y dependent on t h e combustion system and i t s working c o n d i t i o n s . A t exhaust g a s temperatures i n t h e range of ambient a i r temperatures almost t h e whole emission o f PAH t a k e s p l a c e a s p a r t i c u l a t e matter. Because of t h e s t r o n g c o r r e l a t i o n between emission and immission i n t h e discussed s i t u a t i o n s , t h e r e s u l t s can be used f o r d i s c u s s i n g h e a l t h e f f e c t s .
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.),Studiee in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
267
INFLUENCE OF GASEOUS IMPURITIES ON THE CONDENSATION OF WATER VAPOR J . L . CMVELIN and P. MIRABEL I n s t i t u t de Chimie, Universitb Louis Pasteur, Strasbourg, France
ABSTRACT The nucleation of water i n presence of sulfuric acid and n i t r i c acid as pollutants
i s examined. I t i s concluded that only sulfuric acid can have an appreciable effect on the rate of nucleation of water under atmospheric conditions.
INTRODUCTICN Although many gaseous impurities are present i n the atmosphere, only those which exhibit large free energy of mixing with water (such as H2S04, HN03) may mix with water vapor and undergo binary (or heteranolecular) nucleation t o form binary solution droplets. Sulfuric acid formed by oxidation of SO2 i n the atmosphere is of special interest since it is known t o be a t the origin of a large part of sulfate aerosols. Although the detailed mechanism of SO2 oxidation remains unclear, the numerous results of smog chamber simulations leave l i t t l e doubt t h a t photochemistry plays an important role i n the formation of sulfuric acid and sulfate s a l t s . Sulfuric acid aerosol formation can be summarized as follows. 1. Oxidation of S 2 t o SO3 i n the gas phase followed by hydration of SO3 t o form gaseous sulfuric acid molecules. 2. Binary (or heteromolecular) nucleation of sulfuric acid and water vapor molecules t o form embryonic solution droplets. 3. Growth of the droplets by heteromolecular condensation and thermal coagulation. Based upon t h i s three step mechanism, several numerical kinetic models have been recently developped t o study the tine evolution of the number concentration, size distribution, e t c . . o f the newly formed liquid aerosols as a function of So2
.
concentration, W intensity, and other relevant atmospheric conditions. Many experimental efforts have been made t o verify these kinetic models using smog chambers. As these experiments generally measure the overall effect of this three step mechanism, it is d i f f i c u l t t o ascribe precisely t o one of these steps any disagremnt between the predictions of the kinetic model and the experimental results. I t seems thus desirable t o study each step independantly, i n particular
268
binary homogeneous nucleation, as it appears t o be the most crucial step. Although several theoretical predictions are available f o r the nucleation rates i n the sulfuric acid - water and nitric acid - water systems, there are only two experinaental studies of which we are aware, studies which allow only semi quantitative comparisons with theory [ 1 , 2 ] . Presented here are the measurements on the s u l f u r i c acid - water and n i t r i c acid - water systems obtained using an upward thermal diffusion cloud chamber. This chamber, which has been used extensively t o study uniary [3,41 as well as binary [ 51 homogeneous nucleation, possesses many advantages inherent i n i t s design and allows experimental determination around 2 5 O C i.e. the temperature where most of the thermodynamic data needed f o r the theory are available. EXPERIMENTAL Since a detailed description of the design and operating procedure of the chamber
has already been published [ 3 1, only the modifications necessary f o r the study of these two highly corrosive mixtures w i l l be given here.
The plates used were made out of copper. A l l parts of them which might come i n contact with the liquid were covered with a t h i n layer (0.2mm) of an enamel specially prepared f o r this study by the " I n s t i t u t de Mineralogie, Universite Louis Pasteur". The calibrated sensors f o r measuring the temperature of the evaporating pool are very small thermistors (diameter 0.5m) which have been sealed into a piece of glass tubing. Each thermistor passes through a conical rubber plug inserted i n t o holes d r i l l e d i n the b o t t m p l a t e and compressed by a screw device. The L shaped xubber gaskets used as s e a l s between the plates and the glass ring as w e l l as the rubber plugs were made specially for t h i s study by "Le Joint Franqais". They w i l l r e s i s t any s u l f u r i c or n i t r i c acid solution. Only pure and warm n i t r i c acid w i l l discolor and s l i g h t l y attack t h i s rubber. A special limitation a r i s e s with the s u l f u r i c acid
- water mixture which does
not allow measurements f o r water a c t i v i t i e s i n the gas phase below unity (or r e l a t i v e humidities l e s s than 100%). D u e t o the very l m vapor pressure of HZS04 compared t o t h a t of water, the liquid film on the top p l a t e i s nearly pure water. For an i n i t i a l acid concentration i n excess of X = 0.20 (58% by weight) and for the temperature needed t o achieve nucleation, i.e. approximately 78'C f o r the lower p l a t e and 1Ooc f o r the upper p l a t e , the p a r t i a l pressure of water on the top p l a t e becornes greater than t h a t on the bottom p l a t e leading t o chamber instability. This concentration (X = 0.20) corresponds t o a maximum r e l a t i v e humidity of 108%.
269
RESULTS Results for the n i t r i c acid - water system with helium as the carrier gas are shown i n Fig. 1 . Each c i r c l e represents the experimental a c t i v i t i e s of each compound needed t o obtain a r a t e of nucleation of 2 - 3 nuclei un-3 sec-l. The results are given f o r two temperatures : 298.2 K (upper s e t of data) and 278.2 K (lower set of data). These data are cmpared with the corresponding predictions of the theory of binary homogeneous nucleation for a rate of 1 and -3 -1 100 nuclei cm sec , The predicted rates were calculated from equation (1): J
=
Cexp(-AG/kT)
where AG i s the free energy required t o form a c r i t i c a l nucleus and C i s a slowly varying frequency factor. (For detailed calculations of C and A G , see Reiss [ 6 1, Mirabel and Katz [ 71, Mirabel and Clavelin [ 8 ) ) .
i
298.2 K
I
5
1.0
15 2.0 23 WATER ACTIVITY
30
!
1
33
Fig. 1. Comparison of experiment and theory (J = 1 , solid line; J = 100, dashdotted line) f o r the homogeneous nucleation of the mixture HN03 - HZO.
As can be seen from Fig. 1 , the agreement between theory and experiment i s very g o d , especially f o r water a c t i v i t i e s between 0 and 2.5. Under atmospheric -2 conditions, n i t r i c acid w i l l nucleate water a t a c t i v i t i e s i n the range 10 t o 1. This corresponds t o p a r t i a l pressures of HN03 above 1 t o r r , pressure much too high t o be found i n the atmosphere. Experimental r e s u l t s for the sulfuric acid - water system w i t h helium or hydrogen a s a c a r r i e r gas are shown in Fig. 2 and are compared with theory. Two of the upper curves were calculated from equation (1) but, taking into
270
account hydrate formation i n the gas phase (see reference 9 ), and for a r a t e of nucleation J = 1 (solid line) and J = 100 (dotted line). The third upper l i n e was determined from the theory of S H U W e t al. [ 91, equally taking i n t o account hydrate formation, and for a r a t e of nucleation J = 1 (dashed line). The l m e r two curves were determined without taking i n t o account hydrate formation, and are given for a r a t e of nucleation of J = 1 (dash - dotted line) and J = 100 (dash - dash - dotted line).
298.2 K
-8 10
-
0.5
1.0
1.5 2.0 2.5 WATER ACTIVITY
3.0
33
Fig. 2. Comparison of experiment and theory for the homogeneous nucleation of the mixture H2S04 - HZO. As can be seen from F i g . 2 , agreement between theory and experiment i s very good i f one considers hydrate formation, while there are no water a c t i v i t i e s for which our results verify the “non hydrated” theory. Our experimental method does not allow measurements f o r r e l a t i v e humidities lower than 1008, but the r e s u l t s can be e a s i l y extrapolated t o atmospheric conditions. Under these conditions, s u l f u r i c acid w i l l nucleate water a t a c t i v i t i e s i n the range lo-’ t o i.e. a t -6 p a r t i a l pressures i n the range 3 10 t o 3 t o r r corresponding roughly t o concentrations of 4 lom4 t o 4 lov3 ppm f o r one atmosphere t o t a l pressure. Such concentrations occur frequently near heavily populated area.
CONCLUSION Among the mo pollutants examined here, only sulfuric acid w i l l have an appreciable e f f e c t on the nucleation of water under atmospheric conditions. O t h e r pollutants having a weaker f r e e energy of mixing with water (such as W03, SOz, NH3) w i l l have no e f f e c t on t h i s nucleation.
271
REFERENCES
1 H. Reiss, D . I . Margolese and F.J. Schelling, J. Colloid Interface Sci., 56
(1976) 511 - 526. 2 D. Boulaud, G. Madelaine and D. Vigla, J . Chen. Phys., 66 (1977) 4854 -4860. 3 J . L . Katz, C . J . Scoppa, N.G. Kumar and P. Mirabel, J. Chm. Phys., 62 (1975) 448 465. 4 J . L . Katz, P. Mirabel, C . J . Scoppa and T.L. Virkler, J. Chm. Phys., 65 (1976) 382 392. 1704. 5 P. Mirabel and J . L . Katz, J. Chan. Phys., 67 (1977) 1697 6 H. Reiss, J. Chan. Phys., 18 (1950) 840 - 848, 7 P. Mirabel and J . L . Katz, J . Chem. Phys., 60 (1974) 1138 - 1144. 8 P. Mirabel and J.L. Clavelin, J. Aerosol Sci., i n press. 9 W.J. Shugard, R.H. Heist and H. Reiss, J. Chen. Phys., 61 (1974) 5298 5305.
-
-
-
-
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.), Studies in Enuironmentd Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam -Printed in The Netherlands
273
EXPERIMENTAL INVESTIGATIONS ON THE COLLECTION EFFICIENCIES OF SPHERES FOR SUBMICRON AEROSOLS N T H REGARD TO WASHOUT IN THE ATMOSPHERE iG. Rijbig, J. Porstendorfer, A. Ahmed Institut fur Biophysik, Strahlenzentrum der Justus Liebig- Universitat Giessen, Leihgesterner Weg 217, (G.F.R.) , ABSTRACT The collection efficiencies for spheres (simulated drops) and submicron, monodisperse droplets of di-2-ethylhexyl-sebacate (DES) were studied in a wind channel and com ared with theories. The droplets were labelled with radioactive 2112Pb. The retention efficiency of DES droplets up to 4 p diameter on spheres between 0.35 - 7 mm diameter was measured to be unity. The influence of drop shape, compared to the shape of the volume equivalent sphere, on the collection efficiency was checked and found to be negligible. The washout coefficients for submicron aerosols at different rainfall rates were calculated. INTRODUCTION Essentially all air pollution is eventually cleansed from the atmosphere by the natural processes generally referred to as precipitation scavenging and dry deposition. The purpose of this report is to present below-cloud rain scavenging rates or washout coefficients for submicron aerosols, which are the integrated product of the flux densities of the raindrops, their cross sections, and their collection efficiencies. The flux densities of the drops are obtained from the number distribution for the raindrops (1) and their terminal velocities (2). The collection efficiencies of the raindrops were studied in a wind channel using spheres as simulated drops, Here, phoretic and electrical forces are not considered.
214
MEASURING TECIqJI9UI’SS
The main part of the wind channel is a one meter long tube with an inner diameter of 4 em. A sluice exists at the end of the tube, where an iron sphere is held by means of a thin wire. Monodisperse droplets in the submicron size range down to 0.1 pm diameter were produced by a generator of the Sinclair-LaMer type. Monodisperse particles between 0.01 and 0.1 pm were produced by means of a nuclei source and an electrostatic classifier (1 1). The particles were labelled with radioactive 212Pb and sucked into the wind channel, where the windvelocities agreed with the terminal Iall velocities of the rain drops simulated by spheres. To measure the activity concentration within the wind channel a filter probe was taken simultaneously. The precipitated activity on the sphere and on the filter is measured by a NaJlTl well counter, and the wind velocities are measured by a hot wire anemometer or a pitot tube. With this technique collection el‘ficiencies were measured for spheres in the size range of 0.357 mm diameter and for monodisperse aerosol particles with diameters between 0.04 and 4 pm (standard deviation 3- 7%). The particle size was measured by means of a laser spectrometer (3) for particle diameters between 0.15- 0.6 p, a small angle scattering instrument (4) for particles between 0.6 and 5 p and a diffusion batterie for the particle size below 0.1 pm. Also, the aerodynamic diameters and the activity distribution of particles could be measured by means of a spiral duct aerosol centrifuge (5) (6) for the particle size range of 0.08 up to 2 p diameter. RESULTS The retention efficiencx The collection efficiency of a raindrop is that proportion of the particles in its paths which is collected. It is the product of the collision efficiency and the retention efficiency. Studying the collection efficiencies of spheres and comparing the experimental results with theories we have to know the retention efficiency, being the proportion of those particles making contact which is retained. Fig.1 shows the collection efficiency as a function of thickness of a grease layer on a 4 mm diameter sphere. The windspeed was 8 m/s and 15.8 m/s, respectively, and the diameter of the monodisperse droplets of di-2-ethylhexyl-sebacate (DES) was 2.63 p. There is no significant influence of grease layer thickness on the collection efficiency, even at velocities of about 16 m/s. Measurements with
275
spheres of 1 mm and 0.6 mm diameter and droplets of 2.3 p and 2.55 pm diameter resulted. in no different collection efficiencies for grease coated and uncoated spheres, too. These measurements show, that there is no bouncing off for particles and therefore the retention efficiency is unity. Influence of dropshape on collection efficiency In our experiments the simulated raindrops are spheres. To check the influence of drop shape on collection efficiency, spheres and drop- shaped Porms of parafin with equivalent spherical diameters of 4,5,6 and 7 mm were exposed in the windchannel in each case under the same conditions. The experiments resulted in no significant differences between collection efficiencies for spheres and drop shaped forms. For example, the ratio of collection efficiencies for spheres and drop shaped forms with an equivalent spherical diameter of 7 mm is M 1.05 f 0.1. Because the greatest number of raindrops has diameters between 0.2 and 2 mm, where drop shapes are close to spherical, the influence of drop shape on collection efficiency is negligible.
-
The collection efficiency for spheres Fig.2 shows the experimental collection efficiencies for spheres as a function of particle size. The used aerosol material, DES, is a liquid of low vapour pressure and has a density of 0.91 g at 25OC (Handbook of Chemistry and Physics, 1968). DIeasurements with radioactive 212Pb atoms were made, too (10). A suggested semiempirical expression for the measured collection efficiencies, E, which accounts for particle diffusion, interception and inertial impaction, is
C
=
2/3
- S,
and S,
=
12/10 + 1/12 ln(l+Re) 1 + ln(l+Re)
where d is the aerosol particle diameter, dTr is the drop diameter, vE is t e drop terminal velocity, 3 is the kinematic viscosity of air, D is the particle diffusion coefficient and -C is the particle relaxa-
R
276
tion time. The term for particle diffusion agrees within a factor with the theory o€ Suneja (7) for 8 =0, and there is a good agreement with experimental data except for d 0.01 pm and dTr> 1 mm. The collecP tion efficiencies for spheres, resulting from the interception effect, are = 3 X for potential flow and3 3 / 2 X 2 for viscous flow (from Fuchs ( 8 ) ) . The empirical interception term in equation (I), proportional to de seems to be correct €or the finite Reynolds numbers in our experiments. The inertial impaction term is a semi- empirical expression used by Slinn (9). Washout coefficients Pig.3 shows the calculated washout coefficients as a function of particle diameter for rainfall rates of 1 and 10 mm. 'h 1 There is an increase in the washout coefficients with increasing rainfall rate, Thermophoresis and diffusiophoresis must be considered if the drop is undergoing evaporation or condensation. The effect during evaporation is to enhance scavenging through a net force on particles towards the drop along the temperature- vapor concentration gradients, However, this mechanism is probably minimal within the rain where relative humidities are high and will be neglected here. The influence of electrostatic forces on collection efficiency will be investigated in the near future.
.
'This research project is supported by the Bundesministerium des Innern, F-,R.G,, under contract St. Sch. 627. This study is a part of the Ph. D. Thesis of G. Robig, REFERENCES (1) Best, A.C. (19501, Quart. J. Roy, Meteor. Soc., 76,pp.16-36. (2) Best, A.C. (19501, Quart. J. Roy. Meteor. Soc., 76, 302-311. (3) Heyder, J., Roth, C. and Stahlhofen, W. (1971) J. Aerosol Sci. 2,341. (4) Gebhart, J. Roth, C. (19731, Aerosole in Physik, Medizin und Technik, Annual fieeting of the Association for Aerosol Res. (GAF), Bad Soden, p.41. (5) Stober, W. and Flachsbart, H. 1369, Environmental Science and Technology 3, 1280. (6) PorstendSrfer, J. 1973, J. Aerosol Science, 4, 345-354.
217
( 7 ) Suneja, S.K. (1374) i n Kerker, PI. (1974) J. of Atoms. Sci, 31,5, p e p . 1368-1376. (8) Fuchs, IJ.A., Nechanics of Aerosols, Pergamon P r e s s , N.Y. (1964). (9) S l i n n , 'N.G.N., !Later, Air and S o i l P o l l u t i o n 7 (1977) 513-543. (10) Rijbig, G. and Porstendijrfer, J. (1977) Aerosole i n Naturw i s s e n s c h a f t , Pledizin und Technik, Annual Meeting of t h e Assoc. f o r Aerosol Res. (GAT), Karlsruhe. (11) I h u t s o n , 13.0. and Vhitby, U.T., J. Aerosol Sci., 1975, V01.6, p. 443.
x x x v = 15.8 m l s moo v = 8.0 m l s
t 2 L 6 8 10 12 THICKNESS OF GREASE-LAVER
1L
h(lrm1
16
Fig.1: The c o l l e c t i o n e f f i c i e n c y f o r a g r e a s e coated sphere as a f u n c t i o n of g r e a s e l a y e r t h i c k n e s s .
218
acot
x
d,,:015mm.
.
d,,:
Re1175
0 6 mm. R e - 5 0
dTr = 2 0 mm. R e = LI1 d ~: , 70 mm. Re= 2198
GI I PARflCLE DIAMETER. dplllml
10
I0
r'ig.2: Xxpcrimcntal collection efficiencies for simulated drops ( s p h e r e s ) at terminal velocities of rain drops as a function of particle size, thin lines: calculated values.
n
Fig.3: Calculated washout coefficients as a function of particle diameter €or rainfall rates of 1 and 10 mm*h' 1 ,
Atmospheric Pollution 1978, Proceedings of the 13th International Colloquium, Paris, France, April 25-28,1978, M.M. Benarie (Ed.),Studies in Environmental Science, Volume 1 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
279
A. bhmed, J. Porstendorfer, G. Robig Institut fur Biophysik, Strahlenzentrum der Justus LiebigUniversitat Giessen, Leihgesterner lieg 217, (G.F.I?.) ABSTMCT The deposition of monodisperse aerosols (0.07- 4 pm 0) tagged with 212Pb onto simulated surfaces was studied in a wind tunnel, The deposition velocity v was measured as two components, v due to 6s the collection of parficles by the roughness elements, and v due gb to the collection on the substrate. v was also measured f o r a filter g paper surface. It was found that v+ = v /us depends on the particle size and the surlace roughness. The hig deposition velocity (v') to G' the filter paper showed the importance of the microstructures €or the collection of the particles.
"
INTRODUCTI0N The dry deposition of particles from the air to smooth and rough surfaces on the earth is one means by which air borne pollution is removed from the atmosphere. It can be also of major importance in the study of the atmospheric aerosol, the movement of trace elements and it provided informations on the effects of a source on the surrou'ndingregion.The major mechanisms d the particle transport are eddy diffusion, sedimentation by gravity, Brownian diffusion and inertial forces. The steady- state flux to a horizontal rough surface can be described as: F(d) = -6- dC(z) - vsC(z) (1) dz
where d is the particle size, C(z) is the particle concentration at a height z above the surface, vs is the absolute value of the gravity
280
settling velocity, E is the eddy diffusion coefficient, crhcre k is the I<arman constant, and us is the friction velocity. After dctcrriination of ux equation (1) c a n be integrate? jn order to p r c d i c t particle deposition and concentratjon profiles abovc a surface. The particle flux F to a surCace is:
If the particles are small ( v s s O ) or u+ is very large equation (3)
!:quation (3) and (4) can be used to estiriatc the flux to thc earth surface if the wind velocity distribution Pnd partlcle concentrations at two heights are measured. The deposition velocity is defined as the €lux of the particles to the surface P ;liviiled by the mean aerosol concentration C(z) in the gas phase. It was assumed that the cl'fective sinks of momentum and particles are at the same height ( l ) , (2). This means that the eddy diffusion becomes the doninant process of trans€er for submicron particles. IIowever previous vorks (I), (3) showed that vg depends on the particle size and surface structure. The inlluence of these two parameters on particle transfer can be explained by the assumption that the dry deposition over surfaces is devided in two directions: a) The transfer by eddy diffusion takes p l a c e in the direction of the substrate. The flux b'1 is a function of the friction velocity uwFand the collection efficiency €or the surIacc, db:
b -- r!*u,*I
irhere P= n. A is a factor of structure, A is the effective area of an element normal to the wind velocity, Es is the collection efficiency of an element, a is the characteristic length of the roughness
281
clcwnt and Ei cnc‘ ‘li are the mean concentration sliced insjdc the rou;lincss layer. Iri the casc of ro11gliricss elements covered uith c.:. hairs on l c a v c s , thp col_lectionefficiency ;5, Therclore thc t o t n l f l u x 01 particle deposited on F
=
M.ux.Eb.C(z)
+ P.ui.Ci.Es+v,C(z)
and the )man wind microstructures, is enhanced (5) ,(’I). the surlacc is
(7)
x p c r i n e n t a l ‘i‘cchniques: “or our experiments nonodisperse droplets of di-2-ethylhexyl 7
s e bacatc iiere produced by a generator of the Sinclair Lailer type in the size ranee bctueen 0.07 and 1 pn diameter. The aerosols irere taLLccl irith 212Pb and had standard deviations betireen 7 and 71,. The 1)article size was measured by a laser aerosol size spectroneter (0.15- 0.6 pm) (61, a snall angle scattering a e r o s o l sizc spectronetcr (1- 6 pm) (7) and a s:)iral duct acrosol centrifuge (0.07- 21-1”) (31, (9). The radioactive particles iicre led into a wind tunnel (circulating system), 2 m long and with a cross section oC 20 em x 20 en, where the a c r o s o l s could be sampled isokinetically with a filter probe. The floor o€ the working section tias completely
covered 1,rjt’n the test surface. The activity deposited on the surface and on the filter- probe was measured b:j means 01 a €?aJ/Tl well-countec The used test surfaces consisted of: plants (barley), filter paper and simulated grass, constructed by metal cylinders (2 mm cliaraeter) planted in a plasticine layer, The plasticine layer was covered with filter paper to measure the flux to the substrate. Uith this arranpicnt the fractions o€ particles filtered by the roughness elenents and deposited on t h e substrate could be measured separately. Thc height of the roughness elements, iI, as the nmber of elenents per unit area, n, were varied. The wind speeds were meamred by a hot wire anerioneter or a pitot tube. From the measured wind profile the roughness length zo, and us were calculated. RJCSULTS AKD DISCUSSIONS The measured wind speed profiles can be devicled. in two zones: a) the zone above the zero plane displacement z = 1 which is fitted by the law z - l + z o u(z) = u* In (81 k =0
-
b) the zone which is inside the roughness layer which is fitted by the relation
282
u ( z ) = ~(11) I{xp C-m (l-z/H)]
(z<11)
(9)
where the p a r a n e t e r rn depends on t h e s u r f a c e s t r u c t u r e s , In t h e F i g . ( l ) t h e r e s u l t s a r e shown f o r t h e d e p o s i t i o n v e l o c i t y v i ( z ) as a f u n c t i o n of t h e i w c t j c l e s i z e (v' = v /u*). t ? g 'the \rind s p e d was v a r i e d betueen 0.9 m/s and 8 m/s and C(z) 1Jas d m y s d e t e r n i n e d at 6 en above t h e h e i g h t of t h e roughness e l e a e n t s IT. For p a r t i c l e s i z e s between 0.2 and 0.5 /urn diameter t h e r e i s an exliibit mininuii 01 v+ f o r all use6 s u r I a c e s , due t o t h e low 6 c r l e c t OC Brownian d i f f u s i o n and i n e r t i a l f o r c e s on t h e p a r t i c l e s a t t h i s s i z e range. The r e s u l t s are presented f o r n = 0.25/cm 2 and l/cm 2, r e s p e c t i v c l y . I n t h i s case v+ increased n e a r l y by f a c t o r 2. g The measured v: values € o r f i l t e r paper a r e i n agreement with t h e r e s u l t s of l,!,;Lb e t a1(10), and a r e n e a r l y t h e same as f o r our simulated g r a s s s u r f a c e s i n s p i t e of t h e g r e a t difPerences between t h e i r s u r I a c e s t r u c t u r e s and P r i c t i o n v e l o c i t i e s . The high c o l l e c t i o n e f f i c i e n c y 01 I ' i l t e r paper can be explained by t h e g r e a t in-Cluence of t h e m i c r o s t r u c t u r e of the s u r I a c e . The d a t a r e p o r t e d p r e v i o u s l y by XLLS e t a1 (10) and SCID'lKL (11) f o r the d e p o s i t i o n v e l o c i t y on sirooth metal s u r f a c e s (broken l i n e ) a r e n e a r l y 10 times s m a l l e r than on I i l t e r paper o r siinulated grass. The experimental r e s u l t s €rom CIIAiIf3XIILAIILr (1 1, CIILOUGH (121, and LITTLE e t a1 (5) f o r l a b o r a t o r y rieasurenients and of IIOBEIIT e t a1 (13) f o r f i e l d measurements a r e shown i n t h e Fig. ( 1 ) t o o , There i s a good agreement with our r e s u l t s , except € o r t h e values from C ~ ~ ~ S R L Afor I N particle s i z e s l a r g e r than 1 pm diameter. Fig, ( 2 ) shows t h e measured values of v+ and v& as a f u n c t i o n oi" p a r t i c l e s i z e . The two curves have similar s ape T h s means t h a t v& i s p r o p o r t i o n a l t o v+ and witli equations (5) and (6) E b i s gs p r o p o r t i o n a l ds i n agreement w i t h t h e o r e t i c a l values f o r smooth s u r f a c e s ( 1 4 ) and c y l i n d e r s (15): iJ
gb .
Eb
'L
E,
=
E
'L
D -2/3 .rn
,n
=
1.5 -2
Accordingly equation ( 7 ) can be sirrlpliIied and can be w r i t t e n as
F
= Fb
-t
Fs
=
&(U,)
f ( P ) ' 2.c
I n agreement w i t h t h e experimental r e s u l t s (Fig. 1) t h e influence of t h e s u r f a c e s t r u c t u r e s upon vs i s small. b"
+-
This study i s a p a r t of t h e Ph. D. Thesis of A. Ahmed.
283
LITl3PL4TURIC
1) Chamberlain, A.C. (1367) 11. Soc. Lmd. A. 236, 45-70. 2) Sehmcl, G. (1372). Ass. of Airborne Particles (Ldited by Ikrcer, T.T., llorrov, P. and Stobcr, 'Y,), pp 18-42 Charles C.Thonss Springfield, 111. ( 3) Ahmcd, A. and Parstendorfcr, J, Annual iicetin:, of the Assoc. for Aerosol lies. (GAF) 1977 ( 4) Groime, L., (1374) Atmosph. environ., 8,801. ( 5) Little, P. and liiffen, .:I (1977) Atmosph. environ. 11, 437. (1371) J. Aerosol. ( 6) IIeyder, J., Roth, C. and Stahlhofcn, I:., Sci, 2, 341. ( 7) Gebhart, J. a n d Roth, C., Annual rleeting of the Association for Aerosol Res. (GFA), (1973). ( 8) Stijbcr, !/., and Flachsbart, €I., (1963), Xnviron. Sci, Technol. 3, 1280. ( 3) Porstendorfer, J., (1373) J. Aerosol. Sci. 4,345. (10) !Jells, A.C. m , Ci Chamberlain, A.C., (1967) Brit. J. b p p l . Thys. 18,1793. (11) Sehmel, G. (1973) J. Aerosol. Sci., 4, 125. (12) Clough, V., (1975) Atmosph. envirnm. 9, 1113. (13) Horbert,TJ., Vogt.K. and Angeletti,L. (1376) Rerichte der Kernforschungsanlage Jiilich, 1288. ( 1 4 ) Davis, C.M. (1966) Aerosol Sci. Academic Press,438. (15) Pich J. (1370) J. Aerosol. Sci. 1,17. (
(
:.
284
Fig.1: Plot of velocity of deposition v+ against particle size d. g - present measurements for simulated grass 7 cm high: x n= l/cm 2, 0 n= 0.25/cm 2, A barely -.+.-present measurements for filter paper, d= 9 x10-4pm 0 is lead atoms ( 212Pb); + Chamberlain,a Clough, 0 Little ct al, 0
, A , II Rorbert et a1 for soil, grass and trefoil.
2 0
.is
'"ib
H =lcm
P = 1.4
10- 510.2
10-1
100
10 d ( p )
Fig.2: The variation of the velocities of deposition v+ and v+ gb €P against particle size d.
Atmospheric Pollution 1978, Proceedingsof the 13th International Colloquium,Paris,France, M.M.Benarie (Ed.), Studies in Environmental Science, Volume 1 April 25-28,1978, 0 Elsevier Scientific Publishing Company,Amsterdam - Printed in The Netherlands
FORMATION OF A COMBINED BENZO(A)PYRENE
285
AND CARBON BLACK AEROSOL
K.R. SPURNY and H.P. BAUMERT Fraunhofer-Gesellschaft, Institut fiir Aerobiologie, Grafschaft (G.F.R.)
ABSTRACT Two methods for the preparation of carbon black aerosols have been investigated: incomplete combustion of acetylene, acetylene + benzene and other hydrocarbons as well as a "resublimation" of amorphous carbon. The first method was developed for generating soot aerosols in animal experiments, but the latter method needs more basic investigation. Using radioactive acetylene and benzene the produced soot aerosol could be labelled by I4C. Benzo(a)pyrene
aersol was prepared by means of vapour condensation and was
also radioactive labelled. With a combination of both generators, a combined carbon black and benzo(a)pyrene
aerosol was prepared. The benzo(a)pyrene
amounts
bound to the soot were in the range of from 1 ng to 50 ug per 1 mg of soot. Experiments dealing with adsorption and desorption of benzo(a)pyrene the gas phase have shown, that benzo(a)pyrene
on soot in
is relatively tightly adsorbed and
cannot be easily or completely desorbed.
INTRODUCTION Carbon black (soot) particles in the polluted atmosphere are totally respirable and they are carriers of many, mostly organic toxic substances, incl. polycyclic aromatic hydrocarbons (PAH). It has also been observed in human and in animal experiments that benzo(a)pyrene
(BaP) or other PAH remained much longer in the
lung and produced more tumors, if they were bound to insoluble aerosol particles (refs. 1, 2). The preparation of a combined soot + BaP aerosol is described in this study.
EXPERIMENTS and RESULTS Preparation of a reproducible soot aerosol The designation "soot" means very fine dispersed "carbon" particles which are formed during incomplete combustion of organics or by thermal decomposition of hydrocarbons. Soot is not a simple chemical substance and the formation mechanisms of soot in flames is very complex and as yet not clearly understood (refs. 3 - 5 ) .
286 In our experiments a soot aerosol production by an incomplete combustion of acetylene or acetylene
+
benzene was studied by using the process demonstrated
in Fig. 1 . A more detailed description of experiments and results has been published elsewere (ref. 6).
M U
Fig. 1 . Schematic diagram of the equipment for preparation of soot aerosol Mixtures of acetylene (A) or acetylene and benzene (B) were introduced with oxygene (0 ) into the spherical glass chamber (M). This mixture could be labelled 2
with a radioactive gas or vapour (e.g. I4C-acetylene, I4C-benzene, etc.) which was available in glass vials. The opened vial could be heated (D) so that the rate of diffusion of the radioactive labelled gas through the glass frite into the chamber (M) could be controlled. The original gas mixture is then labelled with radioactive gas or vapour and is introduced into the combustion chamber K or K2. By means of the pump (VP), the gas pressure in the cylinder K l can be
1
regulated so that combustion occurs at pressures from 10 to 750 Torr (manometer P). I n the glass bell K2 combustion takes place at atmospheric pressure (two laboratory
burners).
Soot samples from both chambers could be taken with sampling tubes
( S 1 , S2, etc.).
Using Nuclepore filters (filter holder F 2 ) or thermal precipitator
(TP) soot aerosol samples for microscopic investigations could be taken. Particle concentrations were measured by means of a condensation nuclei counter (CNC) and particle sizes were estimated using a diffusion battery (DB). After different physical properties of the generated soot aerosols size and concentration
-
-
particle
had been measured, the following dependencies were observed:
particle size, particle form and particle concentration were functions of the
287
composition of the combustion hydrocarbons, of the ratios of hydrocarbon flow rate to oxygen flow rate, and of the pressures at which the mixture is burned. For combustion of acetylene with oxygen, very small ( B 50
2
particle diameter)
single particles (no agglomerates) could be obtained at pressures approximately 50 Torr. At atmospheric pressure the particles were large aggregates. It was
important to suck the highly dispersed soot aerosol directly from the top of the flame and to dilute it immediately. As it is difficult to find conditions such that an agglomerate-free carbon black aerosol is formed, we have also attempted to try to produce a soot aerosol by means of a "sublimation" procedure (ref. 6). Preparation of BaP-aerosols BaP is a solid yellow powder with a melting point at approximately 180 OC. It can be easily sublimated and by means of a regulated condensation procedure a fine dispersed aerosol can be prepared. Data for vapour pressure and enthalpy of sublimation have been published (refs. 7, 8). Its solubility in water is very low. In some organic liquids (benzene, cyclohexene, etc.) the solubility is good. In certain water solution (e.g. coffein) BaP is also soluble. Both of these properties
-
sublimation at higher temperatures and the solubility
in organic liquids or in aqueous solution of coffein (ref. 6)
-
have been utilized
in our experiments for preparing BaP-aerosols. In Fig. 2 is a schematic of an equipment for a direct sublimation of the solid BaP substance. Cleaned Nitrogen
(N 2 ) flows through the tube furnace
O 1 or O2 in which fine NaC1- or soot-aerosols
are prepared (also flame soot aerosols FR were used). This aerosol, which is a function of the condensation nuclei, flows then in a glass flask ( E ) . Here BaPpowder (B) is heated to a temperature ranging from 50 to 180 (reheater R).
OC
and evaporated
BaP-aerosol can, also, be prepared without any condensation nuclei
(spontaneous condensation). In this case, clean Nitrogen flows directly into the flask E. After fast mixing of BaP-vapour with cooled Nitrogen in the flask C, fine BaP-aerosol is formed. After being cooled it is introduced into a glass sampling sphere. Using Nuclepore filters (F2) this aerosol can be sampled for further physico-chemical investigations. For the preparation of a radioactive
labelled BaP-aerosol, radioactive labelled 3,4-benzo(3,6- 14C)-pyrene was used.
Representative examples of resulting aerosol properties are shown in Fig. 3. It demonstrates the dependency of BaP-concentration C on the temperature T in the flask E (i.e. on the supersaturation degree) and on the type of condensation nuclei.
Also particle sizes of BaP are dependent on the sublimation temperature. In our experiments the particle size range for BaP-aerosol was of about 0.3 to 3 um (optical particle diameter).
288
Fig. 2. Schematic diagram of the "sublimation" generator for preparation of a condensed BaP-aerosol.
Fig. 3. The dependency of the BaP-aerosol concentration on the temperature in the flask E ( 0 no nuclei, 0 soot nuclei, INaC1-nuclei and A mixed nuclei of soot + NaC1). The pointed curve demonstrates the formation of a coffein aerosol.
289
Combined aerosols The experiences with the preparation of a soot- and of a BaP-aerosol were then used for generating combined aerosols (e.g. s o o t + BaP, Fe203 + BaP, asbestos + BaP, etc.). The amount of BaP coated on soot particles could be regulated by means of the vapour pressure in the condensation glass sphere (e.g. by regulating the temperature in the flask E). In the temperature range from approximately 40 to 100 OC, the adsorption of BaP on soot particles was perhaps the prevailing coating mechanisms; at temperatures above 100
OC,
the condensation of BaP-vapour
on soot nuclei was more important process, The condensation is faster than the
adsorption. The amounts of BaP coated on the soot fraction is increasing with increasing temperature. Under our conditions the BaP-amounts were in the range of from 1 ng to 5 0 pg per 1 mg of soot. Some fraction of BaP semmed to be tightly bound on the s o o t (ref. 6 ) .
REFERENCES 1
L.M. Shabad, L.N. Pylev and T.S. Kolesnichenko, J . Natl. Cancer Inst., 33(1964)135-141.
2 L.N. Pylev, F.J.C. Roe and G.P. Warnick, Brit. J. Cancer, 23(1969)103-115. 3 K.H. Homann and H.G. Wagner, Berichte der Bunsen-Gesellschaft, 69(1965)20-35. 4 K.H. Homann, Angew. Chem., 80(1968)425-438. 5 K.H. Homann and H.G. Wagner, Bild der Wissenschaft (1970)763-769. 6 K.R. Spurny, H.P. Baumert, H. Opiela and G. Weiss, Zbl. Bakt. Hyg. Abt. I Orig. B 165(1977)139-173. 7 J.J. Murray, R.F. Pottie and C. Pupp, Canad. J . of Chem. 52(1974)557-563. 8 C. Pupp and R.C. Lao, Atmospheric Environ. 8(1974)915-925.
291
AUTHOR Ahmed A . A r i s t a r a i n A. Arsac F. B a d e l l o n D. Baumert H.P. B e a l e r A.W. Belot Y. B e n a r i e M. Benech A. Berger A. Besson G. Bouley G. Bodin D. Bonsang B. B o n t j e J.A. Boudene C1. Boulaud D. B r i a t M. B u l t y n c k H. B u r t o n C. C a n t r e l l A. Caput C . Charpentier J.Chuong B.T. C l a v e l i n J.L. Claude J.R. Contour J.P. Courbon P. Delmas R. Demuth C1. Dennis R. De Wiest F . D e t r i e P. D u b r e u i l A. Duboue M. Duhameau W. Elsokkary I . H . E r k i n s J.H. F i s s a n H.Y. F o n t e i x Ch. Franzen H. G a u t h i e r D. G e i p e l W. Gelbwachs J. Gentry J.W. Go1 d f a r b A. S Gunduz G. Guerin I . Hauck H. H a u l e t R. Helsper C. Hol 1ander W. Hyun Y. J a c q u a r t Y. J u d e i k i s H.S.
.
INDEX
Page
273,279 233 127 151 285 137 183 73,207 151 167 251 127 73 77,201 239 127 229 225 3 187 175 63 251 73 267 113 255 83 233 167 143 17 207 127 133 29 25 175 263 251 263 63 101 49 87,107,161 161 37 255 117 63 263 91 a7 167 245
Page Kemp K. K l e i n C. Krestschmar J.G. L a u r e n t A. L a u r e n t D. Ledoux M. Legros Ch. L e l l o u c h J. Madelaine G. Mei-Ko L i u M i r a b e l P. Mouden A . Mouvier G. Neuberger M. Nguyen B. C. Noel R. O p i e l a H. P e p e r s t r a e t e H. P e r r i n M.L. P e t i t C. Peyrous R. Porstendorfer J. Q u i n a u l t J.M. Reboux A. Renoux A. Resch W. Robig G. Runchal A.K. Schumann G. Schormann J. Scupholme P.L. Segal G.S. Seif e r t B Sharkey J .M. Simon G.E. Somer S.N. S p o e l s t r a H. Spurny K.R. S t e w a r t T. B. S t r a u b e l H. Ten B r i n k H.M. Thal M.F. Thevenin M. T i r e t C. T r i n i t G M. U l l r i c h D. Van de Vate J.F. V a r e i l l e J. Weiss G. Wessel J. W i l l i a m s o n R.H. Young W.S. Zettwoog P.
.
57 49 3 251 11 217 167 113 33,229 187 267 33 255 117 77,201 29 107 3 229 217 11 273,279 183 179 33 117 273,279 137 91 91 155 137 69 155 7,43 37 239 107,285 245 97 239 179 113 123 217 69 239 21 107 49 175 193 179,183
