Environmental chemistry a review of the literature published up to mid 1980

Methods for Specific Aerosols Collection of Dry Deposition and Rainwater Total Suspended Particulates Measurement of Particle Size Determination of Atmospheric Turbidity Remote Sensing o

E nvi ron me n t a I C h e m ist ry

A Specialist Periodical Report

J D Burton, University of Southampton

P J Statham, University of Southampton

A M Ure, Macaulay Institute for Soil Science, Aberdeen

The Royal Society of Chemistry

Burlington House, London, W I V OBN

British Library Cataloguing in Publication Data

Environmental chemistry - Vol 2 - (Specialist

periodical report/Royal Society of Chemistry)

1 Environmental chemistry - Periodicals

I Royal Society of Chemistry

ISBN 0-85 186-765-0

ISSN 0305-7712

Copyright 0 1982

The Royal Society of Chemistry

All Rights Reserved

No part of this book may be reproduced or transmitted in any form

or by any means - graphic, electronic, including photocopying, recording, taping, or information storage and retrieval systems - without written permission from The Royal Society of Chemistry

Printed in Great Britain by Spottiswoode Ballantyne Ltd

Colchester and London

Preface

When the first volume of this series was published in 1975, it was hoped to produce

a sequel within two years In the event a change of editorship, combined with a certain inertia, have greatly extended the publication gap beyond what was originally intended During this period the subject has passed through successive phases of hysteria (with respect to Cd, Hg, Pb, PCBs, efc.) and grant-grabbing (a governmental response to the first phase), and has now achieved moderate respectability in the more forward-looking academic centres It is still a young subject and there are immense areas of ignorance inviting future study

The first volume emphasized environmental organic chemistry and this second volume is deliberately slanted towards inorganic chemicals, covering the broad fields of the atmosphere and the hydrosphere, soils, and human diets Reviewers of all these subjects agree that far too little information is available on the chemical

forms of the elements in environmental reservoirs, thus laying down a challenge to analytical chemists Patterson’s broad review of mycotoxins is included partly to redress the balance of inorganic topics and partly because his article was produced far ahead of the deadline for contributions 0 si sic omnes! It is not proposed to

segregate organic, inorganic, and physical contributions in future volumes of this series, though the editor would be glad to hear from anyone who thinks this is desirable He would also welcome suggestions for reviews in subsequent volumes

November 1981

H J M BOWEN

Methods for Specific Aerosols

Collection of Dry Deposition and Rainwater

Total Suspended Particulates

Measurement of Particle Size

Determination of Atmospheric Turbidity

Remote Sensing of the Atmosphere

Microscopy of Dusts and Fibres

Biological Sampling and Monitoring Techniques

Inorganic Particulate-Organic Interations

Particle-size Associations of Elements

Photochemical and Gas-phase Reactions

Atmospheric Monitoring and Surveillance Networks

Trends in Atmospheric Particulate Concentrations

4 Characteristics of Emissions from Specific Sources

Combustion of Fossil Fuels

Other Industrial Processes

Emission from Motor Vehicles

Source Identification Studies and Methods

viii Contents

5 Atmospheric Transport and Dispersion of Particulates

Regional and Long-distance Transport

Dispersion Modelling

Cycling of Elements and Global Inventories

6 Removal of Particulates from the Atmosphere

Dry Deposition to Land

Precipitation Scavenging

Total (Wet + Dry) Deposition

The Air-Sea Interface

7 Effects of Airborne and Deposited Particulates

Hazard to Man

Air-quality Indices and Standards for Particulate Pollutants Effects on Visibility

Effects on Global Albedo and Climate

8 Future Research Needs and Conclusions

Chapter 2 The Elemental Content of Human Diets and

Toxicities of the Elements

Group IA: Li, Na, K, Rb, Cs

Group IB : Cu, Ag, Au

Group IIA: Be, Mg, Ca, Sr, Ba, Ra

Group IIB : Zn, Cd, Hg

Group IIIA: B, Al, Sc, Y, Lanthanides, and Actinides

Group IIIB: Ga, In, T1

Group IVA: Ti, Zr, Hf

Group IVB: Si, Ge, Sn, Pb

Group VB: P, As, Sb, Bi

Group VIB: S, Se, Te, Po

Group VIIB: F, C1, Br, I

Transition Metals of Groups V-VII: V, Nb, Ta; Cr, Mo, W;

Transition Metals of Group VIII: Fe, Co, Ni, Ru, Rh, Pd,

Contents

Chapter 3 The Elemental Constituents of Soils

ByA M Ure andM L Berrow

Soil Contents Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Soil Contents

Geochemistry Soil Contents Geochemistry Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geoc hemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility

Soil Contents Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Gold and the Platinum Metals Geochemistry

Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility

Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility

xii Contents

13 Carbon, Silicon, Germanium, Tin, and Lead

Carbon

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Weathering and Mobility Soil Contents

Geochemistry Soil Contents Geochemistry Soil Contents

xiv Con tents

3 The Importance of Mycotoxins in the Environment

Mycotoxins in Food and Feeds

Toxicological Potencies of Mycotoxins

General Attributes of Mycotoxic Disease

Clinical Diseases of Farm Animals Caused by Mycotoxins Human Mycotoxicosis

4 Analysis of Mycotoxins

The Analytical Problem

Sampling Procedures

Analytical Methods

5 Occurrence in Food and Animal Feed

Contamination Resulting from Direct Fungal Attack

Indirect Contamination of Food

6 Metabolism and Mode of Action of Mycotoxins

Metabolic Activation and Detoxification

Reactive Toxin Molecules

Aflatoxin and Related Compounds Ochratoxin A

T2-toxin and Related Trichothecenes Zear alenone

Metabolism and Toxic Residues

7 Control of Mycotoxins in the Food Chain

Gener a1

Control of Fungal Infection

Control by Selection

Detoxification of Aflatoxin

Promising Decontamination Processes

Mycotoxins other than Aflatoxin

Speciation of some Minor Dissolved Constituents

provide a small contribution to particle loads in the atmosphere

Particulates in the stratosphere will be subject to a global distribution, whereas material injected to the troposphere will be transported in the zonal circulation before returning to the earth's surface These transport pathways from sources to sinks determine the local, regional, and global nature of pollution, and eventually, possible effects on biological targets.'

The inorganic fraction generally comprises 80-90% of the total suspended particulates (TSP) in the atmosphere; of the remainder, benzene-saluble organic

compounds may amount to 5% and biological debris, including bacterial and fungal

spores, are also present In the Antarctic aerosol practically all of the mass is attributed to SO:-,* but in a non-urban area at Chilton (Oxon) for example, 50% of TSP was accounted for by SO:-, NOT, NH;, and NaCl with a further 3% from Ca,

K, and Mg:3 Fe and A1 can typically account for 2-3% of the particulate m a s 3 Potentially toxic metals such as Pb can constitute 1% in urban environments, but

0.1% in remote areas.4 Concentrations of suspended particulates in urban environments throughout the world show annual mean values between 60 and 500

pg m-3.5

The changing quality of the atmosphere in England since medieval times6 and public concern towards increasing industrial pollution demonstrate the historical importance of anthropogenic inputs to the atmosphere and disturbance to the natural background of airborne particulates Today we are faced with changes in

I T M Sugden, Philos Trans R SOC London, Ser A , 1979,290,469

W Maenhaut and W H Zoller, J Geophys Res., 1979,842421

P A Cawse, AERE Harwell Report R 7669, H.M.S.O., London, 1974

W Bach, Rev Geophys Space Phys., 1976, 14,429

World Health Organisation, Environ Health Criteria 8, W.H.O., Geneva, 1979

P Brimblecombe, J Air Pollut Control Assoc 1976 26, 94 1

P Brimblecombe, J Air Polluf Control Assoc., 1978, 28, 115

1

2 Environmental Chemistry

systems of energy production and manufacturing processes that will affect both the output and nature of particulate emissions Trends in atmospheric composition must therefore be recorded to assess the impact of these changes on the environment and to decide on the need for controls on emissions The annual consumption of coal in England and Wales is now approaching 80 million tonnes, a record level, and activities of this magnitude demand very careful assessment of environmental consequences.*

Total particulate concentrations in the atmosphere and levels of associated elements of potential toxicity such as As, Cd, Pb, and Se may present a nuisance or serious hazard to man and animals by inhalation and ingestion of contaminated food Deposition of aerosols may induce a response in soil and water ecosystems, for example by acidification and accumulation of metals Deterioration in visibility caused by suspended particulates and their role in modification of the world climate

by disturbing the transfer of radiant energy are of major concern.’ The presence of increased concentrations of water soluble ions such as SO:- and NO: in polluted aerosols may influence natural processes of nucleation.’ Hence, pollution is now being recognized as a complex international as well as a national problem

This report is aimed at broad coverage of recent advances in research on inorganic particulates in the atmosphere, mainly from 1975 onwards Studies on the fate and effects of such materials are included Within this remit, some 1500 references have been identified of which a selection are quoted here to demonstrate the diversity of research developments Advances in industrial engineering techniques to control emissions and improve workroom atmospheres are exten- sively reviewed elsewhere ’O-I4

Over the past 25 years, a contrast is evident between earlier localized investigations of the atmosphere and present day research projects on a global scale not only in the troposphere but also extending to the ~tratosphere.’~ Classification

of papers submitted to ‘Atmospheric Environment’ from 1973-1977 has shown more emphasis on aerosol (physico-chemical) research, comprising 46% of papers, than on gaseous species (34%); atmospheric transport and modelling account for

20% and cover both particulate and gaseous forms.I6 In fact the total number of articles has increased exponentially since 1960 l 6

Research on inorganic particulates in the atmosphere, their transfer pathways and effects has now become more inter-disciplinary, demanding the efforts of meteorologists, oceanographers, agriculturists, and medical and veterinary special- ists, in addition to atmospheric chemists and physicists

Terminology.-An aerosol is a system of fine solid or liquid particles in gaseous suspension, collectively referred to as ‘particulates’ Dust refers to a relatively

World Meteorological Organisation Spec Environ Rep 10, W.M.O., Geneva, 1977

l o H E Hesketh ‘Understanding and Controlling Air Pollution’, 2nd Edn., Ann Arbor, Michigan, 1974

I ’ H E Hesketh ‘Fine Particles in Gaseous Media’, Ann Arbor, Michigan, 1977

l 3 L Theodore and A J Buonicore, ‘Jndustrial Air Pollution, Control Equipment for Particulates’,

l 4 A C Stern (ed.), ‘Air Pollution’, Academic Press New York 1977, Vol IV

I ’ 1 - l W Georgii, Pugeoph B a s k , 1978, 116, 215

R Dennis (ed.), ‘Handbook on Aerosols’, NTIS, Springfield, VA, 1976

CRC Press, Cleveland Ohio, 1976

Inorganic Particulate Matter in the Atmosphere 3

coarse range of solid particles (diameter, d > 1 pm), produced by disintegration of minerals or from resuspension by wind when sand-blasting of soil particles may often cause comminution Fine particles formed from the gas phase by condensation are termed ‘smoke’ and ‘fume’ In the case of fume the particles are generally from 0.01-1 pm diameter, and are often observed as agglomerates of smaller particles Suspended particulate matter < 15 ,um diameter is usually defined

as smoke

Liquid droplets are often referred to as mists (d > 40 pm) and fogs (d = 5 - 4 0

pm) Small hygroscopic particles, or condensation nuclei, are classified into Aitken

nuclei (d < 0.2 p), large (d = 0.2-2 pm), and giant (d > 2 p ) types The term

‘haze aerosol’ is frequently encountered in optical studies and includes any airborne particles that affect visibility The fundamental properties and behaviour of aerosols and their formation from gases are the subject of several texts,11,17~18 Research on aerosol electrical properties have been discussed by several authors at a recent conference l 9

2 Methods of Sampling and Analysis

Collection Systems.-Several collection systems are available for sampling ‘total’ particulates in the atmosphere by filtration, for determination of mass or detailed chemical analysis;20 the EPA High Volume sampler and the German ‘LIB’ unit21 are examples However, errors in sampling associated with various systems and devices used out-of-doors are well r e ~ o g n i z e d ~ ~ - ~ ~ Errors may result from particle impaction or diffusion to the sampling probe or inlet manifold, and from the influence of increasing wind speed on the inertia of larger particles and thus on the particle size spectrum that is collected at a given intake velocity The intake efficiency of 17 sampling devices under outdoor conditions showed great variation for particles between 20-50 pm diameter.25 Tests on a sampler with inlet velocity

of 70 cm s-I established that at wind velocities >4 m s-l, particles over 10 pm diameter were collected with < 15% efficiency: 26 sampling of this restricted range of particle size may be considered adequate if the objective is to assess respirable particles

Other workers have recommended that high volume samplers are operated inside shelters to prevent particles being deposited on2’ or blown off 28 the filter during idle hours B e n a ~ - i e ~ ~ concluded from laboratory tests of the EPA High Volume sampler

” S K Friedlander, ‘Smoke, Dust and Haze’, J Wiley, New York, 1977

I 8 A C Stern (ed.), ‘Air Pollution’, Academic Press, New York, 1976, Vol 1

l9 H Dolezalek, R Reiter, and H Landsberg, ‘Electrical Processes in Atmospheres’, D Steinkopff,

*’ A C Stern (ed.), ‘Air Pollution’, Academic Press, New York, 1976, Vol 111

24 M Zier, Z Meteorol., 1977, 21, 35 1

26 N J Pattenden and R D Wiffen, Atmos Environ., 1977, 11,677

’’ H S Chahal and D J Romano, J Air Pollut Control Assoc., 1976 26,885

28 L C Thanukos, J A Taylor, and R E Kary, J Air Pollut ControlAssoc., 1977, 21, 1013

M

Darmstadt, 1977

E Herpetz, Staub Reinhalt L u f , 1969, 29, 408

4 Environmental Chemistry

under turbulent rather than laminar air-flow conditions, that outdoor sampling can

be achieved without significant distortion of the size spectrum of urban particulate matter that is collected

Special procedures are required for certain types of aerosol Mercer 30 describes a technique for collection of sulphuric acid mist and particles emitted by copper smelters For Saharan dust an isokinetic sampler is proposed, which is battery operated and collects by electrostatic prẽipitation,~’ with an efficiency > 90% for most particlệ^' To separate fibrous material from spherical particulates, the aerosol can be electrically charged and separated in an electric mobility spectrometer, when fibres show high mobilitỵ33 An impingement sampler has been designed to collect salt aerosols at maritime locations or from cooling tower drift near to power stations.34

Stratospheric aerosols have been collected by balloon-borne equipment designed

to impact particles on carbon or copper films for subsequent electron m i c r o ~ c o p y , ~ ~

or by direct photoelectric counting of particles in sit^.^^ Measurements by both techniques have been c ~ m p a r e d ~ ’ Collection of large ( d > 50 pm) cosmic dust particles was made by balloon-borne apparatus at an altitude of -30 km.38

Development of personal air samplers has continued and is reviewed by Wallacẹ39 General approaches to air sampling for occupational hygiene purposes are discussed by M o l y n e ~ x ~ ~ A miniature prototype personal dust sampler, the

‘CIP’, is based on the annular impaction principle within a rotating housing to achieve separation into respirable and non-respirable particlệ^' Another prototype instrument relies on the particle charging principle and was originally designed for

detection of fire hazard in mines by spontaneous combustion: it is adapted for continuous monitoring of submicrometre particles in ambient air and is portablẹ42 Two types of self-contained personal samplers are available to measure respirable and non-respirable fractions of dust in quarries.43

Filters.-The selection of filters for collection of air particulates must take into account not only collection efficiencies and effects of loading on flow rates but also interferences from metals present in the filter medium and its hygroscopic naturẹ These properties must be considered in relation to the objectives of the sampling and the method of a n a l y ~ i s ~ Cellulose acetate, glass fibre, and polytetrafluoro- ethylene filters showed higher efficiencies (> 99%) for ambient dust particles

3 1 B Steen, ‘Saharan Dust’, ed C Morales, J Wiley, New York, 1979, p 279

32 B Steen, Atmos Environ., 1977, 11,623

3 3 G Zebel, D Hochrainer, and C Boose, J Aerosol Scị, 1977,8, 205

34 B C Moser, ‘Cooling Tower Environment’, NTIS, Springfield, VA, 1975, p 353

’’ Ẹ K Bigg, J A m o s Scị, 1975, 32,910

36 D J Hoffmann, J M Rosen, and T J Pepin, Rep DOT-TSC-OST-74-15, NTTS, Springfield, VA,

38 R Wlochowicz, C L Hemenway, D S Hallgren, and C D Tackett, Can J Phys., 1976, 54, 3 17

39 L Wallace, in ref 30, p 390

40 M K Molyneux, Safety Surveyor, 1977, 5 , 11

4 1 P Courbon, ‘Atmospheric Pollution 1978’, ed M M Benarie, Elsevier, Amsterdam, 1978, p 83

4 2 C D Litton, M Hertzberg, and L Graybeal, in ref 30, p 712

1976

1978, p 34

1974

Inorganic Particulate Matter in the Atmosphere 5

than nucleopore (0.8 pm) and Whatman 41 cellulose filters, which were 72%

and 64% efficient at a face velocity of 49 cm s - ’ ~ ~ Although the collection

efficiency of cellulose fibre filters increases markedly with loading, other types of

filter are preferred for retention of Pb in urban aerosol if only light loadings are

c o l l e ~ t e d ~ ~ In fact, Whatman 1 and 40 grade cellulose filters approached 100%

efficiency after 24 hours collection of the ambient aerosol at Stevenage, UK,46 but

this was dependent on particle size and face velocitỵ In the Cleveland USA

environment, a side-by-side comparison of total suspended particulate retained by

Whatman 41 cellulose filters with glass fibre filters showed no difference at 16

sampling sites operated for 13 months.47

The collection of aerosols by nuclepore filters has been reviewed by M a n t ~ n ~ * * ~ ~ with respect to impaction, interception at the pore orifice, and diffusion by

Brownian motion both to the filter face and to the walls of the pores Problems of

pore clogging have been investigated by both theoretical and experimental

appro achệ^^^ 5 1 Two modes of clogging are recognized, namely uniform pore filling

and cap formation, the latter being pred~minant.~’

Evaluation of four types of glass filters for high-volume air sampling revealed

small differences in collection of TSP and Pb, but large variations in SO:- and

NO, : catalytic oxidation of SO, and NO, on the filter surface was suspected.s2 This

reaction may ađ 64% to true SO:- levels and 5% to TSP; because filter alkalinity

is implicated, use of the neutral pH quartz fibre type is advised if glass fibre must be

used.53

Methods of generation of fine particle aerosols (d < 3.5 pm) for research and

calibration purposes are the subject of a symposium-reviẽ.~~ The practice of

collection and storage of aerosols in aluminized mylar bags prior to analysis may

lead to loss of submicrometre particles by electrostatic precipitation, but this can be

alleviated by the use of antistatic agents.ss

Methods for Specific Aerosols.-Techniques for collection of sulphate aerosols

prior to determination of total SO:- or sulphate species are summarized by

B l ~ k k e r , ~ ~ with a review of the behaviour of sulphates in the atmospherẹ The

problem of SO, conversion to SOP during sampling is insignificant if filters of

PTFE microfibre or matrix are used, or alternatively, acid-treated quartz filtemS7

101

5 5 G Cooper, G Langer, and J Rosinski, J Appl Meteorol., 1979, 18, 57

” P C Blokker, CONCAWE Rep 7/78, Den Haag, 1978

J 7 R L Tanner, R Cederwall, R Garber, D Leahy, W Marlow, R Meyers, M Phillips, and L

Reinhalt Lujị, 1975, 35, 77

6 Environmental Chemistry

The use of glass fibre filters to sample particulate NO; is beset with interferences from gaseous N compounds, mainly HONO, and NO,.58 This is more serious than

the formation of artifact Of several types of filters tested for accumulation

of artifact NO; only a teflon type (‘Fluoropore’) gave negligible error.6o

Determination of particulate and vapour-phase arsenic has been made by using a nuclepore pre-filter to retain particulate As and impregnated cellulose fibre filters to

absorb As vapour; collection efficiencies were established with arsenic trioxide

vapour.61 From measurements in the ambient atmosphere, most As was in the particulate form.61 A similar scheme was reported for determination of particulate and gaseous Br, C1, and I;62 low uptake of gaseous halogens by the nuclepore

pre-filter is an advantage when sampling in remote continental regions where the

gaseous halogens exceed particulate forms by two orders of magnitude A sampling

technique has been devised to permit collection of particulate (organic + inorganic) and volatile organic pollutants separately for analysis.63

Methods for sampling and identification of asbestos and asbestiform minerals are given by several authors at a recent Workshop.64 The UK Health and Safety Commission65 have made recommendations for monitoring asbestos dust (chrysotile, amosite, and crocidolite) in both non-occupational and workplace environments

Collection of Dry Deposition and Rainwater.-Steen 66 has summarized current techniques for measuring dry deposition of particulates from the atmosphere by direct accumulation on flat filter plates, natural surfaces, vertical deposit gauges, or

open buckets of various diameter From a theoretical examination of the British Standard Directional Dust Gauge it was concluded6’ that chemical analysis of the deposit would help to identify different sources and their strengths: the gauge is

strongly directional A method of short-term dustfall measurement was developed

to study nuisance levels up to 1.2 km from a cement plant, to relate to complaints

by residents: monthly operated gauges were misleading and inappropriate for this purpose.68

Rainwater is most frequently collected together with the dry deposition to the funnel, and in many cases deliberately, to represent the total (wet + dry) deposition

to the ground To exclude the dry deposition, various mechanical devices are now available that incorporate a moisture sensor to trigger exposure of the rain collector only when precipitation ’O Results from one such device, originally

5n C W Spicer and P M Schumacher, Atmos Enuiron., 1979, 13,543

J 9 R W Coutant, Environ Sci Technol., 1977, 11, 873

“ B R Appel, S M Wall, Y Tokiwa, and M Haik, Atmos Environ., 1979, 13, 319

6 1 P R Walsh, R A Duce, and J L Fasching, in ref 9 p 140

6 2 K A Rahn, R D Borys, and R A Duce, in ref 9, p 172

63 W Cautreels and K van Cauwenberghe, Atmos Environ., 1978, 12, 1133

64 C C Gravatt, P D La Fleur, and K F J Heinrich, Natl Bur Stand ( U S ) , Spec Publ., 1978, 506

65 Health and Safety Commission, ‘Asbestos Measuring and Monitoring Asbestos in Air’, H.M.S.O.,

6 6 B Steen, in ref 3 1, p 287

67 A W Bush, M Cross, R D Gibson, and A P Owst, Atmos Environ., 1976, 10,991

’” D G Benham and K Mellanby, Weather, 1978, 33, 151

London, 1978

R H Williamson, J H Erkins, and A Cantrell, in ref 41, p 175

Commission, 1976, p 259

Inorganic Particulate Matter in the Atmosphere 7

developed to separate wet and dry deposition of radioactive fallout71 have been

obtained by operation for one year at Chilton, Oxon, with monthly sample

changes72 (see also Section 6, Total Deposition) Special apparatus is described to

collect rainwater in forests, as throughfall and ~ t e m - f l o w ~ ~

Total Suspended Particulates.-Standard methods for sampling and measuring total suspended particulate matter (TSP) are listed in a manual issued by the

W.H.0.74 to encourage their use and thereby assist comparisons of data from

worldwide networks of monitoring stations Three methods are based on

gravimetry, and employ pre-weighed glass fibre filters They are suitable for

standard 24 h sampling periods and are (i) a high-volume method with constant

flow, (ii) an EPA high-volume method, constant flow not maintained, and (iii) an

OECD method, modified by the British Standards Institute Two photometric methods are described, using sampling periods from 1-24 h:74 the soiling of glass fibre or cellulose filters is measured in a reflectometer Improved accuracy in

weighing particulates collected on cellulose and other filters is obtained by using a constant temperature and humidity chamber for all handling operation^.^^

Comparative studies with filter tape samplers, whereby the thickness of

particulate deposit is measured by attenuation of beta-radiation, prove the value of

this technique to measure short-term (3 h) concentrations of TSP.76 A semi- continuous beta-monitor (Philips 9790) has been successfully used by B e t ~ a r i e ~ ~ Infrared extinction has been applied to measurement of aerosol mass

concentration, at wavelengths between 9 and 12 this method requires knowledge of the average refractive index and mass density of particles, but

extinction is independent of particle size distribution at the selected wavelengths

Measurement of Particle Size.-Various aspects of particle size analysis are presented in a series of conference papers, which includes a description of standard particulate reference materials for checking and calibration purposes.78 Deter- mination of particle-size distributions by impactor devices is reviewed by S h a ~ ~ ~ Operational difficulties with high-volume cascade impactors occur mainly from particle bounce effects that cause displacement from the impaction surface to the smaller size stages of the collector.80-82 Modifications to the design of cascade impactors to improve performance have been proposed and tested.83 Wangens4

’I R S Cambray, E M R Fisher, L Salmon, and W L Brooks, AERE Harwell Report R 5898,

72 P A Cawse, ‘Inorganic Pollution and Agriculture’, H.M.S.O., London, 1980, p 22

7 3 J D Miller and H G Miller, Lab Practice, 1976, 25, 850

74 W.H.O., ‘Selected Methods of Measuring Air Pollutants’, World Health Organisation, Geneva, 1976

7s J Strand, T Stolzenberg, and A W Andren, Atrnos Environ., 1978 12 2027

76 S Dalager, Atrnos Environ., 1975, 9, 687

7 7 P Chylek, J T Kiehland, and M K W KO, Atmos Enniron., 1979, 13, 169

7 8 M J Groves, ‘Particle Size Analysis’, Heylen, London, 1978

79 D T Shaw, ‘Fundamentals of Aerosol Science’, J Wiley, New York, 1978

H.M.S.O., London, 1970

T Allen, ‘Particle Size Measurement’, 2nd Edn., Chapman and Hall, London, 1975

83 G J Newton, 0 G Raabe, and B V Mokler, J Aerosol Sci., 1977,8, 339

8 Environmental Chemistry

coated nuclepore (polycarbonate) filters with grease to reduce particle bounce on

impaction and obtained a multi-element analysis of the particulates without

interferences except for C1 and Cr Investigations on bounce-off and wall-loss of fly ash particles sampled by a seven-stage impactor are reported;85 the use of scanning electron microscopy to confirm impactor sizing data is advised, particularly for particles collected on the final ‘backup’ filter Alterations to the sampler inlet and stages of an Andersen cascade impactor are described 86 that improve the collection

of larger particles by reducing the effects of wind and turbulence, and reduce wall losses from 32% to 9% for test particles of 10 ,um diameter

A cascade quartz crystal microbalance has been used to measure the size distribution of particulates from a rocket exhaust The crystal mic- robalance is basically a cascade impactor with a piezo-electric crystal as an impinging surfacẹ88 A decrease in resonant frequency occurs as the deposited mass increases and subsequently, scanning electron microscopy may be carried out on particles adhering to the face of the crystals The great sensitivity of this instrument means that a sampling time of 6 min is adequate at TSP loadings of 50-100 ,ug

As an alternative to cascade impactors, centrifugal particle-size separators (cyclones) have been adapted to high-volume measurements, with continuous operation for a week in urban atmospheres to obtain five size fractions.90

For measurement of specific particle-size ranges, the application of inertial, diffusion, optical, and electrical methods, and statistical treatment of data are the subject of recent b o o k ~ ’ * * ~ ~ ~ ~ ~ The cloud condensation nucleus (CCN) fraction of TSP has been measured by a real-time aircraft borne detector to evaluate the effect

of CCN (d = 0.01-1 ,um) on cloud microstrilcture and p r e c i p i t a t i ~ n ~ ~ A modified Aitken nucleus (AN) counter that will operate automatically has been developed for the NASA Global Atmospheric Sampling Programme: it can detect particle concentrations of < 10 AN ~ m - ~ and has’been used at flight altitudes between 6 and

13 km.93 The instrument is calibrated against a Pollak (photoelectric nucleus) counter

The integrating nephelometer can provide continuous measurement of particle mass in the accumulation mode, within the size range 0.1-2 pm, by relating light scattering to TSP.94p 9 5 In the Chicago environment the light scattering coefficient was highly correlated with particulate weights in the size range 0.38-1.3 ,um obtained by cascade impactor, and was independent of humiditỵ96 The neph- elometer is suited to short-term measurements of peak concentrations of airborne

particulatệ^^

87 R L Chuan and D C Woods, in ref 30, p 610

91 R D Cadle, ‘The Measurement of Airborne Particles’, J Wiley, New York, 1975

92 V K Saxena and N Fukuta, ‘Proc Int Conf Cloud Phys.’, Boulder, CO, 1976, p 607

Environmental Pollution’, Rep EUR 5360, C.ẸC., Luxembourg, 1975, p 1371

Assoc., 1976, 26, 1069

Inorganic Particulate Matter in the Atmosphere 9 Separate collection of non-respirable and respirable fractions of ‘I’SP suitable for elemental analysis has been achieved by using two nuclepore filters in series, with pore diameters of 12 pm and 0.2 pm, respectively, at 12.7 cm s-’ face velocity for

acceptable collection effi~iency.~’ Coarse and fine fractions of the TSP have been collected by a two-stage impactor suitable for on-line measurements, based on the beta-attenuation principle.98 The ‘anthropogenic’ fraction of TSP has been derived

from analysis of air-filter deposits for C1 and Si to eliminate the contribution from soil dust, and is claimed to show better correlation with public concern and reduction in v i ~ i b i l i t y ~ ~

Continuous measurement of carbonaceous particles is reported using a spectrophone to measure their light absorption.Io0 The absorption coefficient for aerosols of graphitic carbon type (rather than natural ‘organic’ type) is 17 m2 g-’ carbon at 416.6 nm, employing a helium-cadmium laser source.1oo Sizing of single particles by laser interferometry using a cross beam laser velocimeter is described

by Roberds,lo1 and relies on forward scattering of light by the particle to obtain size information by means of data-inversion methods lo2

Submicrometre particle size distributions have been determined by application of three continuous integral aerosol sensors, namely a condensation nucleus counter,

an electrical aerosol charger, and an integrating nephelometer to measure the number, surface, and volume parameters of the aeros01.l~~ The authors apply

a special data-inversion procedure to derive the particle-size distribution Sub- sequently, this method was used to study power station plumes.’o4

Recent types of Knollenberg (light scattering) aerosol counters have been evaluated with monodisperse test aerosols in the size range 0.1-10 pm, with the

conclusion that resolution was poor for particles >0.5 pm radius.lo5 Other

laboratory and field tests on optical particle counters indicated that frequent calibration is necessary, but agreement was generally good for submicrometre particles.lo6I lo’ Calibration in the field is possible with a specially designed inertial impactor lo*

A particle-size spectrometer supplemented by a microcomputer can obtain a

differential size distribution for the ambient aerosol over 19 intervals of equal logarithmic size from 0.3-11 pm diameter, with the option to select a number, surface, or volume representation.lo9

554

T J Truex and J E Anderson, Atmos Environ., 1979, 13, 507

A L Fymat, in ref 30, p 7 19

V A Marple and K L Rubow, J Aerosol Sci., 1976, 7 , 4 2 5

10 Environmental Chemistry

Analysis of particle size and shape by holography has been further developed by introduction of new systems for automatic analysis of three-dimensional aerosol images, to overcome tedious manual recording

Determination of Atmospheric Turbidity.-Measurement of the integrated aerosol content of the atmosphere has been made for many years by sun photometers and pyrheliometers A new sun photometer is now proposed to improve reliability, and typical errors experienced with current apparatus using 380 nm and 500 nm filters are summarized.112 It is recognized that the pyrheliometric method is the most stable and is best for recording low turbidities at baseline stations."*

Several types of sun photometers were intercalibrated and applied to measure- ment of dust in the Saharan air layer over the N Atlantic ocean: the turbidity data was examined in relation to mineral and sea salt components of particulates collected on air filters at ground l e ~ e 1 l ~ ~ Sahara dust episodes at Monte Cimone and Sestola, Italy, have been measured with Volz sun photometers operated at four wavelength intervals, and related to particle-size spectra at ground level.114 The authors conclude that the large particle mode (radii 0.3-1.2 pm) is mainly responsible for wide variations in optical thickness of the atmosphere

Relationships between the physical properties of the atmosphere and the angular and total scattering of light by haze aerosols are reported by McCa~tney."~ A valuable list of measurements of scattering in the free atmosphere is classified into optical probing, contrast and visibility, and day sky radiance.'I5

Remote Sensing of the Atmosphere.-Satellites have been used to observe the source and trajectories of haze, soil dust, volcanic debris, factory plumes, and smoke from forest fires The geostationary orbiting satellites (SMS/GOES system) operated by the US National Oceanic and Atmospheric Administration provide

visible imagery and infrared data, and Parmenter116 describes results from two satellites operating over the equator at 135 O Wand 75 OW Studies of smoke plumes

by the general purpose LANDSAT-1 satellite can cover a large area of country in great detail, with a resolution of -70 m.117*'18 Differences in absorption by aerosol

in the plumes are detected by a multi-spectral scanner that operates over four wavebands."' LANDSAT images of the UK have been analysed at the University

of East Anglia;Il8 problems of distinguishing plumes from clouds have received special attention

Developments in high-power tunable lasers covering the range -400-40 pm have led to increasing application to optical spectroscopy for monitoring both

' l o R Bexon, J Gibb, and G D Bishop, J Aerosol Sci., 1976, 7, 397

I " J D Trolinger, U.S Environ Prot Agency Rept 600/2-79/005 1979

l I 3 J M Prospero, D L Savoie, T N Carlson, and R T Nees, 'Proc 1 Ith Tech Conf Hurricanes and

'I4 C Tomasi, F Prodi, and F Tampieri, Beit Physik Atmos., 1979, 52, 215

'I6 F C Parmenter, in ref 30, p 254

11' T T Alfoldi, in ref 30, p 258

Interplaner Soc., 1978,

C Frohlich, in ref 9, p 12 and p 89

Tropical Meteorol.', Am Meteorol SOC., Boston, MA., 1978, p 163

York, 1976

Inorganic Particulate Matter in the Atmosphere 1 1

particulate and gaseous pollutants.119 An airborne down-looking lidar (light detection and ranging) is advantageous for research on plume dispersion l Z o Zuev”’ refers to two simultaneously operating lidars, one ground based and the other airborne, to record vertical profiles of the volume backscattering and total scattering co-efficients and their ratio (lidar ratio value) Heighthime cross-sections

of the aerosol over Munich have been recorded by an airborne Nd-glass laser at

1.06 A mobile ground-based ruby laser radar unit has been developed for particulate dispersion measurements lZ3 Basic principles of measurements by lidar and the ‘DIAL’ system (differential absorption lidar), which employs a pulsed tunable laser source to obtain long path absorption data, are discussed by Svanberg lz4

Remote sensing and characterization (complex refractive index and size distribution) of stratospheric aerosols by lidar, by a dustsonde (balloon-borne optical counter), and by satellite-borne photometer have been discussed at a recent Workshop.125 Temporal and spatial variations in the stratospheric aerosol detected

by lidar are shown to respond to meteorological influences and extension of this technique to observe stratospheric-tropospheric interchange of aerosols is proposed 126 With a ground-based ruby lidar system, the backscattering from aerosols is obtained by comparing the total backscattering profile with the expected return from the dominant molecular component in the atmosphere 127.128 Fluc- tuations in the stratospheric aerosol load from 1970- 1977 are discussed with special reference to particles of volcanic and extra-terrestrial origin,lZ9 as observed

by lidar Iwasaka 130 used a two-colour lidar at A 0.6943 pm and 1.06 pm to record the size distribution function and density of stratospheric aerosols with 0.1-1 Fm radii, assuming a refractive index of 1.42; since the measurement time is short, about 100 s, changes in vertical profiles caused by atmospheric processes can be studied In the mesosphere (from -50-60 km altitude), the existence of aerosol layers containing N a and K are confirmed by fluorescence lidar.’31*’32

Microscopy of Dusts and Fibres.-Combinations of scanning electron microscopy

(SEM), transmission electron microscopy (TEM), X-ray fluorescence, and

C K N Patel, Science, 1978, 202, 157

353

I2O J A Eckert and R B Evans, ‘Proc 1 lth Symp Remote Sensing Environ.’, Ann Arbor, MI, 1977, p

I 2 l V E Zuev, Dev Atmos Sci., 1978, 9, 265

12’ R M Hoff and F A Froude, Atmos Environ., 1979, 13,35

l z 4 S Svanberg, ‘Surveillance of Environmental Pollution and Resources by Electromagnetic Waves’

ed T Lund, D Reidel, Dordrecht, Holland, 1978, p 37

1 2 5 A Deepak (ed.), ‘Inversion Methods in Atmospheric Remote Sounding’, Academic Press New York

1977

l z 6 F G Fernald and B G Schuster, J Geophys Res., 1977, 82,433

12’ P B Russell, V Viezee, R D Hake, and R T H Collis, Q J R Meteorol Soc 1976, 102,675

128 R Reiter, H Jaeger, W Carnuth, and M Littfass, Dev Atrnos Sci., 1978, 9, 277

Boston, Mass, 1978, p 197

Y Iwasaka, J Meteorol SOC Jpn., 1977, 55,457

G Megie, F Bos., J E Blamont, and M L Chanin, Planet Space Sci., 1978, 26, 21

R Clemesha, H Kirchoff, and D M Simonich Planet Space Sci., 27,

12 Environmental Chemistry

diffraction analysis have been developed to give valuable information on the depth and surface properties of particles that facilitates identification of sources.133-136 For analysis of fly ash particles, combination of SEM with energy dispersive X-ray analysis (EDXRFA) provides simultaneous colour mapping to show the spatial distribution of Ca, Fe, and K ; some 100 particles can be scanned in 3 min.I3' A similar technique was used to analyse dust particles in pulmonary tissues for Al, Ca,

Fe, Mg, S, Si, and Ti.138 Combination of SEM with X-ray diffraction analysis of Sahara dust enabled distinction between clay and quartz particles of diameter 0.08-7

Other applications of SEM and EDXRFA have been made to analysis of

particulates collected by a piezoelectric cascade impactor, during aircraft sampling

of rocket exhaust87 and volcanic plumes.140 Distinct morphological and chemical differences are related to particle size fractions Thus in volcanic-derived aerosols impure sulphuric acid droplets were seen with some large crystals rich in A1 and Zn, and fragments of basaltic glass and p l a g i o ~ l a s e ' ~ ~

Studies on Antarctic aerosols utilized the resolution obtained by TEM photographs for counting and sizing purposes.141 X-Ray energy spectra showed that over 50% of Aitken particles (d < 0.2 pm) contained A1 and S, 35% contained

Si, but few trace elements which were predominant in larger p a r t i ~ 1 e s I ~ ~ Particulates scavenged by snow and rain and deposited on coniferous trees have been characterized by TEM, SEM, and EDXRFA, with aggregates of small soot particles best observed by TEM.'42 Gonzales and Murr143 developed a TEM

method to examine particulates scavenged by single raindrops, and demonstrated that in New Mexico these particles are mainly polycrystalline aggregates of layer silicates from 0.0 1-3 pm in diameter Quantitative analysis of SO:- in individual particles from 0.01 ,um to a few micrometers diameter is possible by collecting them

on electron microscope screens and coating with BaCI,, after which the growth rings of BaSO, are recorded by TEM.144v145 A similar technique has been used t o analyse non-volatile nitrates in particles >0.2 pm diameter, by reaction with nitron reagent to produce needles surrounding the particles 146

Many improvements have been made to methods for sampling, analysis, and identification of asbestos fibres by TEM, SEM, and X-ray s p e c t r ~ m e t r y ' ~ ~ Fibre counting and size measurements from SEM can be related to analysis of elements,

13' H Malissa and M Grasserbauer, Mikrochim Acta, 1975, No 2,325

134 L D Hulett, H W Dunn, J M Dale, J F Emery, W S Lyon, and P S Murty, 'Measurement

Detection and Control of Environmental Pollutants', I.A.E.A., Vienna, 1976, p 29

R W Linton, P Williams, C A Evans, and D F S Natusch, Anal Chem., 1977, 49, 15 14

1 3 6 F Parungo, E Ackerman, H Proulx and R Pueschel, Atmos Environ., 1978, 12,929

J B Pawley and G L Fisher, J Microsc., 1977, 110, 87

1 3 8 A Brody, N V Vallyathan, and J E Craighead, 'Scanning Electron Microscopy', Pt 3, I.I.T Research Inst., Chicago, IL., 1976, 9,477

F Prodi and G Fea, J Geophys Res., 1979,84,6951

Stoiber, D B Smith, and R A Zielinski, J Geophys Res., 1979,84,6961

I4"R D Cadle, A L Lazrus, B J Huebert, L E Heidt, W 1 Rose, D C Woods, R L Chuan, R E

I 4 l F Parungo, E Ackerman, W Caldwell, and H K Weickmann, Tellus, 1979, 31, 521

14* J Gether, G Lunde, and J Markali, SNSF Project Res Rep FR 7/76, Nisk, Norway, 1976

' 4 3 T W Gonzales and L E Murr, J Geophys Res., 1977, 82, 3161

144 Y Mamane and R G de Pena, Atmos Environ., 1978, 12,69

14' G P Ayers Atmos Environ., 1978, 12, 16 13

146 G P Ayers, Atmos Environ., 1978, 12, 1227

Inorganic Particulate Matter in the A tmosphere 13

e.g., Al, Ca, Fe, Mg, Na, and Si,148,149 and inter-element ratios assist identification

of the main form of asbestos In a recent comprehensive review of SEM and TEM methods applied to fibrous particles that occur in ambient air, an informative series

of scanning electron micrographs is shown which includes ammonium sulphate and gypsum particles in addition to glass and asbestos Nuclepore filters of different pore diameters are preferred for sampling prior to SEM, to partially separate asbestos from larger non-fibrous particles.150 De Nee151 reported improvements in back-scattered electron imagery with SEM that can reveal asbestos microfibres of higher atomic number than organic material in the filter or lung tissue matrix A computerized SEM system combines image analysis of fibres with EDXRFA of their chemical composition, to identify asbestos fibres from other particulate matter.ls2 The detailed particle atlas by McCrone and Delly 153 provides

a unique collection of photomicrographs to assist in characterization of airborne materials from observations with SEM, TEM, and the polarizing microscope Biological Sampling and Monitoring Techniques.-Examination of relative levels of particulate metals in the atmosphere and input to the ground by the use of plants as bioindicators and collectors has continued, often with bioassay of phytotoxic gaseous pollutant^.'^^ Apart from analysis of the indigenous flora such as epiphytic bryophytes,ls5 test plants may be exposed over definite periods (transplant technique) This method is required in many areas where pollution has eliminated the local flora

Lichens are attractive as indicator plants and the value of various species and their identification has been reviewed.lS6 Characteristics of species with respect to selective uptake of metals must be recognized, in addition to the possibility of heavy metal toxicity that could result in threshold levels for metal intake by the thalli.157 Lead concentrations in native lichens (Hypogyrnnia physodes) growing close to a motorway were one third of levels in the substrate which was bark of Pinus

syluestris, and in this case it was concluded that bark sampling was a better indicator of pollution by motor vehicles up to 200 m from the road.lS8 Air pollution from metal industry at Kokkola, Finland was best indicated by accumulation of Fe,

S, and Zn in indigenous epiphytic bark lichens and Zn in pine needles, but

increases in V in lichens were attributed to emissions from fuel oil combustion 159 In

a subsequent study of emissions from wood pulping industry, native lichens were

14* K R Spurny and W Stober, ‘Proc 3rd Int Conf Nuclear Methods Environ Energy Res.’,

149 K R Spurny, W Stober, H Opiela, and G Weiss, Sci Total Environ., 1979, 11, 1

USERDA, Columbia, Missouri, 1977, p 69

1976, 26,496

P B De Nee, ‘Symp Electron Microscopy of Microfibres’, M Asher and P P McGrath (ed.),

U.S.F.D.A., Rockville, MD, 1977, p 68

I5*T Werlefors, C Eskilsson, S Ekelund, S Krantz, and C Tillman, ‘Proc Int Symp Control Air

Pollut Work Environ., Stockholm, 1978, p 255

153 W C McCrone and J G Delly, ‘The Particle Atlas’, 2nd Edn., Ann Arbor, MI, 1973, Vol 1 - 4

154 W A Feder, Environ Health Perspect., 1978, 21, 139

L Rasmussen, Environ Pollut., 1977, 14, 37

D L Hawksworth and F Rose, ‘Lichens as Pollution Monitors’, E Arnold, London, 1976

15’ M R D Seaward, Lichenologist, 1975, 6, 158

l S B K Laaksovirta, H Olkkonen, and P Alakuijala, Environ Pollut 1976, 11,247

Laaksovirta and H Olkkonen, Ann Bot

14 Environmental Chemistry

analysed for seven elements to indicate the distribution of pollutants, in preference

to pine needles.160 Atmospheric heavy metal pollution in the Copenhagen area was examined by analysis of epiphytic lichens (Lecanora conizaeoides), epigeic bryophytes (Brachythecium rutabulum and R hytidiadelphus squarrosus), bulk precipitation, and top regional differences in deposition isopleths found for

Pb, V, and Zn showed good agreement for all media Significant decreases in

concentrations of Ca, F, Li, Se, Sr, and U were found in a terricolous lichen

(Purmelia chlorochroa) along transects radiating up to 64 km from a fossil-fuel power station.16* Hypogymnia physodes is noted as more resistant to SO, than

either Alectoria capillaris or Usnea ~ p p ' ~ ~

The transplant technique for lichens usually involves removal on tree bark or branches, which are then mounted on a suitable base for placement in industrial regions Steinnes and Krog'64 reported order of magnitude increases in Hg (from

0.4 p g g-I background) in Hypogymnia physodes after a month in urban conditions

In North-Rhine Westphalia, FRG, both lichen and rye-grass transplants were analysed 165

Native mosses (Dicranellu heteromalla and Ceratodon purpureus) and grass

(Holcus lunatus) contained 1240 and 130 pg Pb g-', respectively, as a result of

pollution from a battery factory.166 Hypnum cupressiforme growing within 14 km of Consett iron and steel complex in N.E England contained high levels of Cu, Mn,

Pb, and Zn in addition to Fe.I6' In Norway, Hylocomium splendens from rural sites showed 20-fold differences in accumulation of As, Pb, Sb, and Se that were directly related to precipitation,168 and it is noted e l ~ e w h e r e ' ~ ~ that most metals present in moss originate from direct dustfall, precipitation, and stem-flow, since the chemical composition of moss and bark is very different (except for K) Hylocomium splendens from Polish National Parks accumulated more Cd and Cu, but less,Pb and Zn than Pleurozium hylocomium and patterns of regional pollution were e~tablished."~ Emissions from a coal-fired power plant in Fort Union Basin,

Montana led to significant accumulations of As in forage plants of the region

including Agropyron spicatum and Artemisia cana, used as indicators of pollution 1 7 1

The use of small moss bags for regional aerosol monitoring is recently reviewed.I7* These are prepared from specially cleaned moss from rural areas, and the bags are normally exposed for 1-6 weeks at 1.5-2 m above ground After exposure, analysis may be made by atomic absorption following wet ashing in

Ih" K Laaksovirta and H Olkkonen Ann Bof Fenn., 1979, 16, 285

'" A Andersen, M F Hovmand, and I Johnsen, Enuiron Polluf 1978, 17, 133

I b 2 L P Cough and J A Erdman Bryologisl 1977, 80,492

lh4 E Steinnes and H Krog, Oikos, 1977, 28, 160

I h 5 B Prinz and G Schull Schrifl Landes Nordrhein- Wesffalen, 1978, 46, 25

l h 6 J M Ratcliffe".Atrnos Eni!iron., 1975, 9, 623

1 6 7 G Ellison J Newham M J Pinchin and 1 Thompson, Environ Pollut., 1976, 11, 167

I h H E Steinnes, Inst Atomic Energy Rep K R 154, Kjeller, Norway, 1977

l b 9 L Rasmussen and I Johnsen, Oikos 1976, 27,483

K Grodzinska, Water Air Soil Pollut., 1978 9, 83

J J O'Toole T E Wessels, and K L Malaby, Rep IS-M-205 U.S Dept Energy, Office of Health and Environ Res., 1978

K Laaksovirta and J Silvola,Ann Bot Fenn., 1975, 12, 81

Inorganic Particulate Matter in the Atmosphere 15

HNO, 173 Mosses have a high cation-exchange capacity, therefore leaching of metals by rainfall during exposure is minimized.172 Surveys in S.W England for metals in air particulate have been made by moss bags alone,173 or in combination with air filtration and a resin-impregnated material (TAK) to retain air

particulatệ'^^ Moss bag exposure was able to show unsuspected areas of metal pollution, but was difficult to relate to air concentrations from filter analysis.174 A similar conclusion was reached following a combined survey in the Swansea Valley, using moss bags, air filters, and dust and rainwater C 1 0 u g h ’ ~ ~ reported that deposition of particles to moss bags (Hypnurn cupressiforrne) is similar to a flat surface of rye-grass and they are useful dry deposition monitors; because the collection efficiency of moss changes rapidly with particle size and is low for submicron particles, it is less valuable for monitoring concentrations of elements in air particulate than in dry deposition

Methods of Analysis.-Advances in the application of various methods to analysis

of air particulates will only be referred to in brief, since detailed discussion of this topic and methodology is made e1~ewherẹl~~ 178 Several new techniques have been applied to multielement analysis of inorganic particulate material collected from the atmosphere by filters or impactor devices These techniques can analyse specific size fractions or individual particles from such material and provide better chemical characterization to help identify natural and industrial sources of particulates in the ambient atmospherẹ For example, X-ray fluorescence (XRF) analysis of trace elements has been aided by developments in semiconductor detectors This has led

to increasing application of energy dispersive X R F analysis with excitation of photons by X-rays,’79 or by bombardment of air-filter deposits with 3-5 MeV protons (particle-induced X-ray emission: ‘PIXE’) lso>

Proton elastic scattering analysis (‘PESA’), using higher energy protons than PIXE, has been applied where light elements are of main concern ẹg., from F to S,

and reduces problems of attenuation of soft x-ray^.'^*,'^^ The sensitivity of automated energy dispersive X R F permits multielement analysis of filters exposed

on high-volume air samplers for only 10-20 h.ls4 Minimum detectable limits are reported in the range 2.5-8 ng cm-’ filter for As, Br, Cd, Cu, Ga, Hg, Ni, Pb, Rb,

Sb, Se, Sn, Sr, and ZIỊ”~ BirksIs5 concludes that energy dispersion methods are more suited to general element surveys in unfamiliar samples, while wavelength

R Gill, M H Martin, G Nickless, and T L Shaw, Chemosphere, 1975,4, 113

1 7 4 L Ẹ Robson, ‘A Survey of Airborne Metals’, Rept Avon Glos Somerset Environ Monitoring Cteẹ, Bath, 1977

L Ẹ Robson, ‘Rept Collab Study on Certain Elements in Air, Soil, Plants, Animals and Humans in the Swansea-Neath-Port Talbot Area’, Welsh Office, Cardiff, 1975

1 7 6 W S Clough, Atmos Environ., 1975, 9 11 13

”’ H Malissa (ed.), ‘Analysis of Airborne Particles by Physical Methods’, C R C Press, Boca Raton, FL,

1978

M Katz, J Air Pollut ControlAssoc., 1980, 30, 528

J M Jaklevic, R C Gatti, F S Goulding, B W Loo, and Ạ Thompson, in ref 30, p 697

T B Johansson, M Ahlberg, R Akselsson, G Johansson and K Malmqvist, J Radioanal Chem.,

16 Environmental Chemistry

dispersion achieves better resolution of elements and is appropriate for routine analysis of large numbers of samples; it can also distinguish the valence and bonding of elements such as S present as sulphate, sulphite, and sulphide compounds Problems associated with preparation of thin layer standards to calibrate X R F techniques and corrections for attenuation have been reviewed by Dzubaỵlg6

Analysis of individual particles of fly ash has been made by ion microprobe mass spectrometry and auger electron spectrometry to reveal the surface predominance

of Cr, Mn, Pb, and TI, which is explained by a volatilization-condensation mechanism.135 The application of emission spectrographic methods to multielement analysis of air particulates is reviewed by Skogerboẹlg7 With this procedure, porous cup graphite electrodes may be used as air filters and are very suitable for short sampling periods of 4-1 h in urban areas, to follow the time variation of element concentrations I g 7

Neutron-activation analysis has been widely applied to measure some 30 to 40

elements in air p a r t i c ~ l a t e ' ~ ~ - ~ ~ ~ Re cent developments include cyclic activation, using a series of neutron irradiation-transfer-count-return to irradiation system steps to allow detection of short-lived isotopes such as 207mPb (0.8 s half-life), 20F,

and 77mSẹ191.192 Analysis of B in ađition to other elements is achieved by measurement of prompt gamma-ray emission during neutron a ~ t i v a t i 0 n l ~ ~ Some laboratories have used gamma photon activation analysis to include Bi, Sn, Pb, and

Zr in the suite of elements a n a 1 y ~ e d l ~ ~

An X-ray diffraction technique can detect microgram quantities of chrysotile asbestos in respirable Infrared spectrometry has been applied to analysis of quartz dust 196 and asbestos minerals in air particulatệ'^^ Differential thermal analysis offers specific measurement of free crystalline quartz in respirable dust that contains clay minerals, as frequently collected by personal air samplers.198

For characterization of particulates from a polluted atmosphere, the use of raman spectra has been examined between 920 and 1950 ~ m - ' ; ' ~ ~ distinctive spectra are given by (NH,),SO,, NH,HSO,, and H,$O,, and primary particulate carbon from vehicle exhaust However, a large fluorescence background limits general sensitivitỵ Newmanzoo has reviewed current methods for analysis of sulphur compounds in the atmosphere, including laser raman spectroscopỵ

I a 6 T G Dzubay (ed.), 'X-ray Fluorescence Analysis of Environmental Samples', Ann Arbor, MI, 1977

Ia8 L Salmon, AERE Harwell Report R 7859, H.M.S.Ọ, London, 1975

l a 9 J Radioanal Chem 1977, 37, Part 2

1 9 1 N M Spyrou, P Maheswaran, K Nagy, and F Ozek, in ref 134, p 15 Ị

I P 2 N M Spyrou and S A, Kerr, J Radioanal Chem., 1979,48, 169

193 G Ẹ Gordon, D L Anderson, M P Failey, W H Zoller, W B Walters, and R M Lindstrom, in

194 J S Hislop and D R Williams, J Radioanal Chem., 1973, 16, 329

195 B Ạ Lange and J C Haartz, Anal Chem., 1979,51,520

I y 7 J P Coates, A m Lab., 1977, 9, 57

1 9 8 J P Schelz, Thermochirn Acta, 1976, 15, 17

ref 148, p 83

Inorganic Particulate Matter in the Atmosphere 17 Continuous in situ measurement of sulphur aerosols is now possible by flame photometry with separate determination of H,SO, and its ammonium salts.201,202 Many laboratories without extensive analytical facilities require simple methods

of analysis for limited investigations A laboratory manual compiled by SCOPE 203

describes sampling and analysis of several particulate metals in air, avoiding sophisticated techniques Further practical details are available in the book by

K a t ~ ~ ~ ~ Eleven particulate metals collected on polycarbonate membrane filters have been determined by atomic absorption spectroscopy.20s A new colorimetric method for analysis of microgram amounts of SO:- in water extracts from air filters is

reported, using barium-nitrosulphonazo(m) chelate.*06

To establish the accuracy of reported results, intercomparison of trace element analysis by different techniques has been made at 21 laboratories by distribution of simulated (spiked) air filter samples:207 results for Hg and Mo were particularly divergent The NBS standard fly ash reference material (SRM-1633) has now been supplemented by SRM- 1648, urban particulate matter, certified for 9 elements, which was collected from the St Louis, Missouri, urban atmosphere.208 A reference material has recently been prepared by the E.E.C Community Bureau of Reference using air particulates collected from industrial regions of Belgium Intercomparison

of analysis of filter deposits by separate techniques showed that variability was least for As, Co, Pb, and Se, intermediate for Cr, Cu, Fe, Mn, Ni, and Zn, and largest for Cd; problems of incomplete dissolution of Cr, Fe, and Ni by wet ashing were

3 General Physical and Chemical Composition of Particulates

Background Aerosols.-Research on background concentrations of aerosols in the troposphere and their composition has proceeded in several remote regions, where little interference from industrial sources is anticipated Although it is possible to talk in broad terms of continental and maritime background aerosols in addition to rural background measurements that are often used to compare with urban pollution,210 natural sources may cause wide variations in regional backgrounds and make the siting of background stations and assessment of anthropogenic influences difficult.211

The chemical composition of the aerosol near the Amundsen-Scott South Pole Station212 is shown in Table 1, together with concentrations observed at other

J J Huntzicker, R S Hoffman, and C S Ling, Atmos Environ., 1978, 12,83

202 W G Cobourn, R B Husar, and J D Husar, A m o s Enuiron., 1978, 12, 89

203 SCOPE 6, 'Environmental Pollutants, Selected Analytical Methods', Butterworth, London, 1975

204 M Katz (ed.), 'Methods of Air Sampling and Analysis', 2nd Edn Am Publ Health Assoc.,

205 B C Begnoche and T H Risby, Anal Chem., 1975,47, 1041

*06 E M Hoffer, E L Kothny, and B R Appel, A m o s Environ 1979, 13, 303

'07 A Tugsavul, R Dybczynski, and 0 Suschny, Environ Int., 1979, 2, 19

'On Anon, Dimensions, 1979, 63, 19

'09 P A Cawse, AERE Harwell Report R 8191, H.M.S.O., London, 1976

2'o P A Cawse, AERE Harwell Report R 9164, H.M.S.O., London, 1978

2 1 ' E S Selezneva, Sou Meteorol Hydrol., 1978, 1, 3 1

Radioanal Chem., 1977, 37 637

Washington, DC, 1977

42 0.19 1.1

-

0.4

-

5.9 0.037 0.29 0.0 12 0.72 0.024 0.22 0.0008 8.2 1.2 0.24

0.034

2.0 0.24 8.1

S Pole

Remote

sire * *

0.6 7 0.006 1.1 0.40

-

-

2.1 (0.03

-

0.024 0.5 1

-

-

0.068 0.56 0.59

-

21

3 10

* 1 m3 air at 15 O C , 760 mm Hg (Standard Cubic Metre) = 1.226 kg

remote and urban locations Hogan213 found particle concentrations of 50- 100

cm-3 with geometric mean radius from 10-15 nm in the Antarctic during summer, but order of magnitude increases in concentration of very small particles occurred, possibly from subsiding air, when the tropopause height lowered to 380 mb Element concentrations that are recorded in remote polar regions must be accounted for in terms of long-distance transport from crustal weathering, sea salt, volcanic activity, or anthropogenic s o ~ r c e s ~ ~ * * ~ ~ ~

In central Europe, background aerosols have been studied at mountain observatories on the Jungfraujoch * I 5 (Table 1) and Zugspitze peak near

2 1 3 A W Hogan, J Appl Mcteorol 1975, 14 550

R and J Enriron., 1976, 10 1079

R A Duce G L Hoffmann, and W H Zoller Science 1975 187,59

Inorganic Particulate Matter in the Atmosphere 19

Figure 1 Quarterly elemental concentration in air near ground level at Wraymires, Cumbria

(Reproduced by permission from AERE Harwell Report R9484)

( 19 7 1- 1978)

that continental air masses contain 2-3-fold more Al, Ca, Fe, K, Si, N H f , SO:-,

and TSP than do maritime air masses Together, SO:-, NH:, and NO5 can comprise -77% of the continental aerosol and -59% of the maritime aerosol mass.217 Background aerosols in the southern hemisphere are being sampled at

5250 m altitude, on Chacaltaya Mountain, Bolivia."*

At Mauna Loa Observatory, Hawaii (3380 m above sea level), optical characteristics of vertically integrated background aerosol have been measured above the trade wind inversions, where Aitken nuclei counts are only a few hundred per cm3.221 Incursions of aged continental tropospheric aerosol to Mauna Loa from

N America caused an increase of -0.007 in absorbance at 500 nrn above the natural background (-0.0 15) and from the enhancement in spectral extinction under the influence of continental aerosol, the point-mass loading of such particulates in a 5 km column above the Observatory is estimated at - 1 pg m-3.221 Seasonal variations in concentrations of elements in air are reported in non-urban regions of the UK222 and typical results at one station are shown in Figure 1 From

' I b R Reiter, R Sladkovic, and K Potzl, Meteorol Rundsch., 1975, 28, 37

2 ' 7 R Reiter, R Sladkovic, and K Potzl, Ber Bunsenges Phys Chem., 1978, 82, 1188

* 1 8 F Adams, R Dams, L Guzman, and J W Winchester, Atmos Environ., 1977, 11, 57 1

'I9 G McInnes, Rep LR 305 (AP) Warren Spring Lab., Stevenage, 1979

220 N J Pattenden, AERE Harwell Report R 7729, H.M.S.O., London, 1974

2 2 ' G E Shaw, J Atmos Sci., 1979, 36, 862

In Northern Nigeria, under ‘dry season’ conditions of dust-laden Harmattan wind from the Sahara desert, concentrations in air of Al, Br, C1, Co, Fe, Na, Pb, Sc,

V, and Zn at a rural site increased by an order of magnitude above levels in the rainy season, from April to September, when a maritime tropical air mass was dominant.223

Bromine is present in the troposphere in both particulate and gaseous phases, the latter usually at 5-20 times greater concentration, and it is known that gaseous Br may act as a catalyst for recombination of ozone in the s t r a t 0 s p h e 1 - e ~ ~ ~ Particulate

Br levels in non-urban regions of the U K are usually between 10-100 ng mC3 air,3 although a sudden increase from December 1972 to January 1973 was seen to coincide with intense volcanic activity in Iceland.z25

Marine Aerosols.-The importance of marine aerosols, radii <0.2 pm, in the formation of clean air aerosols has encouraged detailed study of their composition.226 Thus the main constituent in pure Atlantic air was S (0.2 pg m-3) and the fact that Ca, C1, and K were at least an order of magnitude lower and Br

was (0.002 pg indicated the absence of sea salt in this particle-size range.226

reported that the mid-latitude oceanic regions of both North and South hemispheres show atmospheric concentrations of 300-500 particles cmP3 mainly

in the size range 20 nm < r < 1 pm Prospero228 found that mineral aerosol levels were highest in the Tropical North Atlantic (14 pg m-3), the Indian Ocean (4.8 pg

m-3), and the Mediterranean (4.3 pg m-3) indicating the influence of arid regions Levels were reduced to 0.35-0.7 pg m P 3 in the central and northern North Atlantic, the South Atlantic and Pacific oceans However, the sea-salt aerosol measured by high-volume air sampling was relatively constant, from 3.3-8.7 pg

Increases in ratios of S 0 4 / N a in marine aerosols relative to bulk seawater are reported over waters off North Brittany229 and in sub-Antarctic areas of the Indian Ocean.230 Oxidation of biogenic gaseous sulphur compounds, mainly dimethyl sulphide to SO, and then to SO:- is believed responsible.230 G r a v e n h ~ r s t ~ ~ l

described both excess SO:- and NH: in submicrometre aerosols over the North

m-3 228

2 2 3 F Beavington and P A Cawse, Sci Total Environ., 1978, 10, 239

2 2 4 S C Wofsy, M B McElroy, and Y L Yung, Geophys R e s Lett., 1975.2,215

2 2 5 P A Cawse, A E R E Harwell Report R 7669 H.M.S.O London, 1974

226 P Winkler, Geophjs Res Lett., 1975 2,45

*” A W Hogan, ‘Proc 9th Int Conf Atmos Aerosols Condensation and Ice Nuclei’, Galway, Ireland,

2 2 x J M Prospero, J Geophys Res 1979, 84 725

2 2 y B Bonsang, B C Nguyen, A Gaudry, and G Lambert in ref 227 p 154

”(’ B Bonsang, B C Nguyen, A Gaudry and G Lambert, ‘Proc Comm Atmos Chern Global Pollut.,

’” G Gravenhorst, Atmos Environ., 1978, 12 707

1977 p 152

Trace Gases and Aerosols,’ 1979

Inorganic Particulate Matter in the Atmosphere 21

Atlantic, probably formed by gas to particle conversion to form SO:- aerosols that

absorb NHZ Concentrations of SO:- and SO, reported in marine and background continental locations are reviewed by M e s z a 1 - 0 ~ : ~ ~ ~ over the oceans the excess SO$-

is about twice the amount contributed by sea-salt aerosol At 40”N in the North Atlantic the SO, concentration is found to increase by an order of magnitude to 2 pg mP3, possibly caused by a reduction in photochemical conversion rate or by

advection of industrial-derived SO, 232 Apart from this exception, which lowers the ratio S 0 4 / S 0 2 to 0.4, the ratio is between 1 and 10 over the oceans and is higher than over continents Marine aerosols from the Gulf of Mexico contained an average of 3030 ng mP3 of particulate and inorganic gaseous C1, with an equivalent amount as organic gaseous Cl.233 The proportion of gaseous to particulate C1 varied

in the range 0.5-100.233

Marine aerosols have been examined in coastal regions to estimate trace-element fluxes to continental areas 234 and to study interactions between sea-salt aerosols, soil and mineral particles, and anthropogenic aerosols.235 Maritime-background aerosol sampled on the coastline of Washington state, for trajectories with at least 3

days of oceanic traverse, contained 25 ,ug Fe m-3 and 1.9 pg Pb m-3: eleven other elements were measured.236 In Central Queensland, Australia, the sea-salt aerosol at cloud-base level only decreased by a factor of 5 up to 1100 km inland, at mean wind

velocities of 5 m s - ~ * ~ ’ Maritime-background aerosols are sampled by the Japanese Meterological Institute at Bonin Is, 27*N, and at Marcus Is, 24ON, as part of a W.M.O network of baseline air monitoring stations.238 Anthropogenic influences are believed to contribute significantly to I, Sb, Se, and Zn in these aerosols.238 Further research on enrichment of elements in marine aerosols is discussed in Section 4

The Stratospheric Background.-The importance of variations in the stratospheric aerosol concentration on solar radiation received by the earth 239 has encouraged investigations using direct sampling techniques in addition to indirect optical methods, to establish the normal background composition and mass, and to record disturbances from volcanic explosions and stratospheric aircraft flights Current knowledge of stratospheric aerosols (and gaseous species) has been reviewed in

1975240 and by several working groups in 1979.241 Cadle and have discussed the optical properties Sulphate aerosols formed in the stratosphere by oxidation of SO, and precursors such as COS and CS,243 at mid-latitudes (in the

233 W W Berg and J W Winchester, J Geophys Res., 1977,82, 5945

235 K Isono and Y Ishizaka, in ref 227, p 82

236 J D Ludwick, T D Fox, and S R Garcia, Atmos Enuiron., 1977, !I, 1083

237 W D King and C T Maher, Tellus, 1976, 28, 11

238 Japanese Meteorol Inst Tech Rep I, Tokyo, 1978, p 6

239 C Junge, Promet Met Fortbild, 1975, 5,9

*‘O CIAP Monograph, ‘The Natural Stratosphere of 1974’, US Dept Commerce, Springfield, VA,

2 4 1 R D Hudson and E 1 Reed (ed.), NASA Ref Publ., 1049, 1979

242 R D Cadle and G W Grams, Rev Geophys Space Phys., 1975, 13, 475

Tallahassee, FL, 1975

1975

22 Environmental Chemistry

absence of volcanic eruptions) are usually in the concentration range 0.3-1.5 ng gg'

of air, and the highest concentrations in this range are found in a 'layer' at 18-20 krn.*,, Nitrate, Br, C1, Na, and Si are generally detected at lower concentrations

than SO,.241 Gas reactions of NO, with SO, or gas-particle reactions between NO, and H,SO, are believed responsible for formation of NOHSO, and NOHS207, tentatively identified in stratospheric aerosols.245 Much information on the global composition of the stratosphere and troposphere between 6-1 3.5 km altitude is being gathered by the NASA aircraft sampling programme for 'GASP' (global measurements of atmospheric species), initiated to study the effects of aircraft exhaust emissions on the upper atmosphere.246 Between 3 0 4 5 ON latitudes, SO:-

levels of 0.2-0.4 pg rn-, are reported in the upper troposphere, increasing to 0.5-1.4 p g rn-, in the lower ~ t r a t o s p h e r e ~ , ~

Theoretical considerations of the formation and growth of H,SO, particles indicate that at normal stratospheric water-vapour concentrations of 1-2 p.p.m., growth of existing particles by vapour condensation is more important than formation of new particles by heteromolecular nucleation reactions for altitudes of 12-2 1 km.247 At altitudes of 18-20 km, general aerosol concentrations are

- 3 particles cm-, ( r 2 0.1 pm) decreasing to - 2 at the North polar region.248 Eruption of the Fuego volcano in Guatemala in October 1974 caused a sudden increase in stratospheric aerosol loading above background, in a layer between 15 and 22 km altitude.249 Volcanic eruptions can result in 1 to 2 orders of magnitude increase in stratospheric SO:-, returning to background 1 to 13 years after the event.250.251 Although the SO:- and NH; inventory of the stratosphere was increased by the Fuego volcano, no increases in particulate C1 or HNO, vapour

were seen and initial injection of S to the stratosphere in the gaseous phase is

likely.251

In the Southern hemisphere at Mildura (34OS, 142OE), G r a ~ , ~ reported that

SO:- was a major constituent of stratospheric particles from 0.03-1 pm radius, with an estimated mass of 1.1 x 10-lo kg H,SO, in a 1 cm2 column between the tropopause (12.9 km) and 30 km altitude In 1977 a major incursion of NH, to 16-28 km was observed, causing a change from a predominant sulphuric acid aerosol to ammonium ~ulphate.,~

Urban Aerosols.-Absolute concentrations of elements in urban atmospheres of the

UK are compared in Table 1 with levels at Collafirth, Shetland Is., a remote background station In many comparative studies the observed concentrations are referred to a single element, selected to represent a natural source material such as soil or marine aerosol Thus the choice of reference elements to indicate the

244 A L Lazrus and B W Gandrud, Geophvs Res Lett., 1977,4, 521

245 N H Farlow, K G Snetsinger, D M Hayes, H Y Lem, and B M Tooper,J Geophys Res., 1978,

246 D J Gauntner, J D Holdeman, D Briehl, and F M Humenik, NASA Tech Mem TM-73781,

247 G M Hidy, J L Katz, and P Mirabel, Atmos Environ., 1978, 12, 887

248 N H Farlow and G V Ferry, J Geophys Res., 1979 84, 1 3 3

249 M P McCormick, T J Swissler, W P Chu, and W H Fuller, J Atmos Sci., 1978, 35, 1296

2 5 0 A W Castleman, H1 R Munkelwitz, and B Manowitz, Tellus, 1974, 26, 222

Lazrus, R D Cadle B Gandrud, and J P Greeberg.J Res 1979,84, 7869

83, 6207

1977