A survey of aerosol research in European community programmes

J. Aerosol Sci., Vol. 23, Suppl. I, pp. S9--SI3, 1992 Printed in Great Britain.

0021-8502/92 $5.00 + 0.00 Pergamon Press Ltd

A SURVEY OF AEROSOL RESEARCH IN EUROPEAN COMMUNITY PROGRAMMES J. VAN GEEL, J. MAGILL, H.E. SCHMIDT Commission of the European Communities, Joint Research Centre, Institute for Transuranium Elements, Posffach 2340, D-7500 Karlsruhe, Federal Republic of Germany

ABSTRACT

In the European Commission's 3rd Framework Programme (1990-1994) of community research and technological development, aerosol problems are of particular importance in the specific programmes Environment, Nuclear Fission Safety (with emphasis on Reactor Safety and on the Decommissioning of Nuclear Installations), Industrial and Materials Technologies, and Measurement and Testing. Under Environment, significant efforts are directed towards monitoring natural and anthropogenic aerosols in the atmosphere, understanding the role played by aerosols in ecosystem regulation, and the development of techniques to reduce aerosol emission from industrial plants. To ensure Nuclear Fission Safety, investigations are necessary to identify the mechanisms and determine the quantities of fission product aerosols released in the event of an accident and to develop measures for aerosol retention in such cases. The release of radioactive aerosols from nuclear installations in case of fire has been studied, and methods of aerosol abatement by acoustic techniques are under investigation. In decommissioning of nuclear installations the problem of aerosol formation and dispersion arises during dismantling operations. Industrial and Materials Technologies require information on aerosols ranging from welding fumes, asbestos fibres, lead compounds and quartz particles to aerosol/vapour mixtures of toxic products, aerosols from biotechnology industries and airborne micro-organisms. Finally, for Measurement and Testing, reference aerosols are needed for calibration purposes and to improve and harmonize particle counting and characterisation. A brief summary of examples for each of the above activities, carried out in the form of EC cost shared actions or at the Commission's Joint Research Centre, will be given, together with a description of some aerosol problems still to be solved. KEYWORDS

European Community, Joint Research Centre, Framework Programme, Nuclear Aerosols, Atmospheric Aerosols, Safety at the Workplace, Acoustic Aerosol Scavenging

INTRODUCTION

The legal basis for the European Commission's policy in promoting scientificresearch and technological development in E C member states is the multiannual Framework Programme, which has to be proposed every three or four years by the Commission, approved by the European Parliament and agreed upon by the Council of Ministers. The present 1990-1994 Framework Programme foresees, over a period of 5 years, an expenditure totalling 5.7 billion ECU. In this programme, there is,no specific reference to aerosol research. But it plays an important role in environmental research as well as under the headings bio-sciences, energy research and industrial and materials technologies. The majority of the funds foreseen by the framework programme are spent in national and industrial laboratories with, as a rule, a 50% participation of the executing partner(s).Universities and hospitals can opt for funding of 100% of the additional cost made for the project when the real cost or the value of their own input is at least 50% of the real totalcost of the project. $9

SI0

J. VANGEELet al.

Due to the interlinkage of aerosol work within several of the framework programmes, it is impossible to give precise budget figures for the different aerosol projects. But rough estimates indicate, that funding of Commission sponsored aerosol research in the present Framework Programme period is approximately 20 M E C U . SHARED-COST AEROSOL RESEARCH As far as shared-cost actions are concerned, the data bank on Community supported research under the 3rd Framework Programme lists 103 entries of activities which deal, to a larger or lesser extent, with aerosol problems. The principal headings are nuclear safety, where the detection and measurement of airborne radioactivity from natural sources (radon), as well as radioactivity generated during fuel cycle processing, during dismantling operations of nuclear installations, and in reactor accidents is being investigated, non-nuclear environmental protection against atmospheric pollutants, airborne toxicity in medicine and health, the climatic impact of cloud formation, the preparation of polydisperse aerosol reference materials, and the standardisation of aerosol samples over a wide range of particle sizes - A large Community sponsored programme concernes aerosol sampling in workplace air in which some 30 industrial and academic laboratories participate and which deals with topics like the analysis of welding fumes, with aerosol sampler testing and with low level asbestos fiber sampling. In studies related to the safety of nuclear fission aerosol research is undoubtedly one of the most important items, since inhalation of radioactive aerosol particles is by far the most dangerous procedure of uptake of radioactivity by man. A good example for a shared-cost action in reactor safety is the PHEBUS PF project, for which experiments are to be carried out in the laboratories of the French Commissariat i~ rEnergie Atomique in Cadarache in collaboration with Institutes of the Joint Research Centre in Ispra and Karlsruhe and with the participation of an important number of institutions in Community member states and even in non-EC countries. The principal objectives of the PHEBUS PF project is to identify and to quanitify the amount of fission products released to the primary cooling circuit and to the containment of a nuclear power reactor in case of a severe accident. These aerosol deposits will then be analysed, and the results of these analyses will be compared with model predictions (Jones et al., 1990). E X A M P L E S FOR A E R O S O L R E S E A R C H C A R R I E D OUT AT T H E J O I N T R E S E A R C H CENTRE 10% of the Framework programnme funding have been laid aside for the Commission's Joint Research Centre (JRC), which runs laboratories in Ispra (Italy), Geel (Belgium), Petten (The Netherlands) and Karlsruhe (Germany) with a total staff of some 2000. The main contributors to aerosol research within the JRC are the European Institute for Transuranium Elements in Karlsruhe, the Community Bureau for Nuclear Measurements in Geel, and the Institute for Environmental Research, the Institute for Safety Technology, and the Institute for Remote Sensing Applications, all in Ispra.

Correction of Remote Sensing Data for the Presence of Atmospheric Aerosols At the Institute for Remote Sensing Applications in lspra; data obtained from the Coastal Zone Colour Scanner (CZCS) on board satellites are used for quantitative estimates of (chlorophyll-like) phytoplankton pigment in coastal water analysis. The data, however, must be corrected for the presence of aerosol in the atmosphere. The evaluation of the CZCS data consists of computing from the measured spectral radiance at the satellite altitude (at channel wavelengths of 443, 520, 550, and 670 nm) the spectral radiance leaving the water after having interacted with water molecules and suspended matter. To do this, all radiation scattered from the air molecules and aerosol particles as well as light reflected from the water surface has to be substracted from the total radiance. Data correction is also necessary for agricultural land cover classification by satellite, using the so-called Thematic Mapper (Sturm, 1992;Hill and Sturm, 1991).

Global Change and the Environmental Sulphur Cycle In a new project, launched at the Institute for Environmental Research in lspra, the role of aerosols in the environmental sulphur cycle is being investigated. It has been proposed that the gas dimethyl sulphide (DMS) rather than hydrogen sulphide is responsible for returning sulphur to the land to replenish losses of the large quantities washed into the sea each year (in the form of sulphate ions). Marine organisms emit large quantities of DMS over the large open areas of the oceans which are

A survey of aerosol research

SII

carried inland by wind. The gas DMS reacts with other atmospheric gases to produce a n o n - s e a s a l t (NSS) sulphate aerosol consisting of sulphate and methane sulphonate which is precipitated to the ground.DMS apparently also plays an important role in climate regulation. Rapid oxidation of DMS emitted from algae over the oceans leads to the formation of droplets of sulphuric acid. These droplets are very effective nucleation centres for water vapour condensation and lead to cloud formation. This results in increased radiation scattered back into space and thereby acts to keep the planet cool. Laboratory, field and modelling studies are performed to study the mechanisms of aerosol formation from the gas phase, their interaction with other trace gases and their role as cloud condensation nuclei (Notholt et al., 1992; van Dingenen and Raes, 1991; Raes et al., 1992; Raes and van Dingenen, 1992).

Atmospheric Oxydation of Biogenic Emissions (Monoterpenes) - Formation of Acidic Compounds In another project of the Environment Institute in Ispra, formation and deposition of acidic compounds over forest areas are being investigated. Monoterpenes are the principal volatiles emanating in large quantities from conifers. These appear to play a significant role in tree growth regulation through insect attraction and disease resistance. In addition, due to their reactivity, monoterpenes take part in the global carbon cycle.Terpenes react with ozone to form highly reactive perexy radicals. These in turn react with atmospheric pollutants (SO2, NOx) to produce reaction products in aerosol form which are then precipitated out over forest areas. The mechanisms of the aerosol formation processes involved are of interest here (Kotzias et al., 1992a, 1992b, 1990). Elemental Analysis of Single Aerosol Particles The Central Bureau of Nuclear Measurements of the Joint Research Centre in Geel/Belgium has started to work on the elemental analysis of single aerosol particles using the PIXE (proton-induced x-ray emission) microprobe. So far, the feasibility of the method has been demonstrated. Generation of Nuclear Aerosols in Fires When surfaces which are contaminated with radioactive deposits are exposed to fire, particles can be set free to form a radioactive aerosol. Deposits of this type are found inside glove boxes which are used in our laboratory as in many others and in fuel fabrication facilities. An accidental fire in such a facility can thus release radioactive aerosol to the atmosphere.To asses the potential hazard resulting from such an accident, and to optimize the safe design of such installations, information is required on the factors affecting the degree of dispersion of aerosol particles. At the European Institute for Transuranium Elements in Karlsruhe, fire experiments have been carried out with deposits of uranium-plutonium oxides on a variety of substrates. Both, combustible and non-combustible substrates have been investigated. Of particular interest here is the interaction with other smoke particles and how the degree of resuspension depends on the particle size. The work has yielded some very interesting results. It was found, that only about 1% of the radioactivity is transported away from the site of the fire in the form of aerosol particles; and that the very fine carbonaceous smoke particles do not contain heavy metals, which, for their part, are present rather as big carbon-free particles. (Buijs et al., 1988, 1989, 1992}.

Acoustic Aerosol Scavenging The aim of the Acoustic Aerosol Scavenging project is to investigate the feasibility of using high intensity sound waves to scavenge particulate material from the air. The basic idea is to agglomerate the fine particles by the use of a sound field, to a size large enough that they precipitate out either due to sedimentation in the gravitational field or by the action of an externally applied field such as the electric field in an electrostatic precipitator. These agglomeration and precipitation steps form the basis of the scavenging process. First tests carried out in Karlsruhe with a newly constructed dynamic test rig to increase the separation efficiency of an electrostatic filter by acoustic preconditioning the aerosol, are presented in this conference (Magill et al., at this conference).In the future we will carry out tests on different aerosol systems using sound generators which work at 20, 10, and 5 kHz.The main application is the routine treatment of industrial off-gases to improve the efficiency of current gas-cleaning technology, such as electrostatic filters, cyclones, Venturi scrubbers, bag filters and so on. Potential applications to large-scale aerosol hazards are being considered. Examples for such applications are dust explosions, tunnel fires, fog clearance in restricted areas, smoldering fires in underground rubbish dumps and others (Magill et al., 1989a, 1989b, 1990). Of particular interest in this context is how these aggregates behave in thermal, gravitational, electrical and acoustic fields, and how this behaviour is related to the primary particle diameter, material density, and fractal dimension (e.g. for diffusion limited aggregation). This is why we have started to pay particular attention to the fractal properties of solid particle aggregates (Magill, 1991)

S12

J. VAN (}EELet

al.

TOPICS THAT MERIT INCREASED ATTENTION At the Community level,standard[sat[on of aerosol samplers, the definitionand production of reference materials for calibration purposes, and intercomparisons for the analysis of industrial aerosols, are in high demand. Another interestingsubject is stillthe understanding of the agglomeration process of aerosol particles.It has been observed, that soot agglomerates better in an acoustic field than does TiO2, but the reasons are not clear. Is this due to the fact that the aerodynamic distributions of condensation aerosols and of mechanically generated aerosols are different,is itdue to the electrostaticrepulsion between particlesof the mechanically produced TiO2 aerosol,or is itdue to differencesin the stickingcoefficient? A great challenge to aerosol technology will be to develop new techniques to further reduce industrial emissions. At present, the legal limit for particle emissions depends on toxicity,but is generally less than 50 rag/m3. Future legislation will not only reduce this value but will also limit the number concentration of particles in a given size range, particuilarlyfor those below I pro.For highly toxic materials, such as dioxins and furanes, where emission levels must be less than 2mg/m3, new agglomeration techniques might thereforefind immediate applications. The fractal properties of solid aggregates need further investigation. Questions which still have to be answered are, how much charge can a fractal aggregate hold? How is this charge distributed? How does the charging affect the aggregate structure? If the aggregate is sufficiently large, can a micro-explosion of the aggregate occur through electrostatic repulsion of the charge? Such information is required to understand not only practical questions of how charged aggregates behave in electrostatic filters, but also to resolve fundamental issues, such as the sudden combustion of aerosol structures. In our Karlsruhe laboratories we are presently studying the transmission and detection of large particles (> 10 pro) in ducts and channels with turbulent flow (Project TRABI). If we understood the underlying physics better, we would be in a position to solve a problem of considerable technical importance (Buijset al.,1992b). HOW TO G E T I N V O L V E D IN EC S P O N S O R E D A E R O S O L R E S E A R C H It has been recognized a long time ago, that an essentialasset for a flourishingand competitive c o m m o n market isa "trans-national" research structure which underlies the different national economies. The promotion of such a structure is the main objectiveof the Commission's programme on H u m a n Capital and Mobility which aims, parallel to and in support of similar national efforts,at the development of talents and abilities of young people and at the establishment of interrelations and collaborations between existing national research institutions, by fully respecting grown national cultures and scientifictraditions.A way of reaching this goal is the setting-up of research networks, in which several laboratories (the optimum target number would be five) from different member countries (at least 3) collaborate in a c o m m o n project.Under certain conditions,and ifthe subject to be treated fallsunder the themes of the Framework Programme, the Commission helps to finance the exchange of scientistsand may contribute to the overall cost of the activityover a limited period of time.More information on ECsupported research programmes in general and on conditions for participationin the E C H u m a n Capital and Mobility Programme can be obtained from the Directorate General for Science, Research and Development of the Commission of the European Communities, 200 rue de la Loi, B-1049 Brussels .(Krickan-Richter et al. 1991)

Acknowledgements The authors would like to thank A.V.Jones, D.Kotzias, F.Raes, and B.Sturm for their assistance in preparing the manuscript.

REFERENCES Buijs, K., B. Chavane de Dalmassy (1988). Contaminated Smoke: A Simulation of the Heavy Metal Containing Aerosols from Fires in Plutonium Glove Boxes, E U R Report 11089 EAr.

A survey of aerosol research

S13

Buijs, K., B. Chavane de Dalmassy, S.Pickering (1989). The Dispersion of Radioactive Aerosols in Fires, J.Nucl.Mater. 166,199-207.

Buijs, K., B. Chavane de Dalmassy, (1992a). Fire Experiments under Realistic Laboratory Conditions. Annual Report 1991 of the Institute for Transuranium Elements, EUR Report 14493 EN, p. 60 - 61.

Buijs, K., B. Chavane de Dalmassy, (1992b). Duct Transport of Big Particles. Annual Report 199I of the Institute for Transuranium Elements, E U R Report 14493 EN, p. 61 - 63.

Hill, J., and B. Sturm (1991). Radiornetric Correction of Multitemporal Thematic Mapper Data for Use in Agricultural Land Cover Classification and Vegetation Monitoring. Int. J. Remote Sensing 12, I4721491.

Jones, A.V., E. Bonnani, A. Markovina (1990). Principal Results of the Phase B Verification Studies in Support of the PHEBUS-PF Project. C S N I Workshop on Aerosol Behaviour and Thermal Hydraulics in the Containment, Fontenay-aux-Roses.

Kotzias, D., K. Fytianos and F. Gels (1990). Reaction of Monoterpenes with Ozone, Sulphur Dioxide and Nitrogen Dioxide - Gas-Phase Oxidation of SO2 and Formation of Sulphuric Acid. Atmospheric Environment 24A, 2127-2132.

Kotzias, D., C. Sparta and M. Duane (1992a). Distribution of Optical Isomers of Monoterpenes in the Leaf Oil of Conifers. Naturwissenschaften 79, 24-26. Kotzias, D., M. Duane and B. Nicollin (1992b). Atmospheric Oxidation of Biogenic Emissions (Monoterpenes). Fresenius Envir. Bull. 1, 79-82. Krickan-Richter, L., and O. v. Schwerin (1991). EC Research Funding - A Guide for Applicants, 3rd Edition, Commission of the European Communities, Office for Official Publications, Luxembourg. and Human Capital and Mobility 1992-1994 - Information Package (1992), Commission of the European Communities, Directorate General XII for Science, Research and Development. Magill, J., S. Picketing S. Fourcaudot, J.A. Gallego-Juarez, E. Riera-Franco de Sarabia, G. RodriguezCorral (1989a). Acoustic Aerosol Scavenging. J.Acoust. Soc. Amer. (JASA) 85, 2678 - 2680 Magill, J., S. Picketing S. Fourcaudot, J.A. Gallego-Juarez, E. Riera-Franco de Sarabia, G. RodriguezCorral (1989b). Acoustic Aerosol Scavenging. J.N ucl. Mater. 166, 208 - 213 Magill, J., K. Richter, S. Fourcaudot, P. Barraux, J.A. Gallego-Juarez, E.Riera-Franco de Sarabia, G. Rodriguez-Corral (1990). Agglomeration of Aerosol and Aerosol Mixtures in a Sound Field, Frontiers of Nonlinear Acoustics, Proc. of the 12th International Symposium on Non-Linear Acoustics, pp. 615 - 620, Edited by M.F.Hamilton and D.T.Blackstock, Elsevier Science Publishers Ltd., London

Magill J. (1991) Fractal Dimension and Aerosol Particle Dynamics. J. Aerosol Sci. 22 (1), I65-168. Notholt, J., J. Hjorth and F. Raes (1992). Formation of HNO2 on Aerosol Surfaces during Foggy Periods in the Presence of NO and NO2. Atmospheric Environment, 26A, 2II - 2I 7. Raes F., A. Saltelli and R. Van Dingenen (1992a). Modelling Formation and Growth of H2SOa-H20 Aerosols: Uncertainty Analysis and Experimental Validation. J. Aerosol Sci. in press. Raes F., and R. Van Dingenen (1992b). Simulation of Condensation and Cloud Condensation Nuclei from Biogenic SO2 in the Remote Marine Boundary Layer. J. Geophys. Res. in press. Sturm, B. (1992). In Imaging Spectroscopy: Fundamentals and Prospective Applications (F. Toselli and J. Bodechtel eds.) pp. 47-60, Brussels and Luxembourg. Van Dingenen, R., and F. Raes (1991). Determination of the Condensation Accommodation Coefficient of Sulphuric Acid on Water-Sulphuric Acid Aerosol. Aerosol Science and Technology 15, 93 - 106.