approved December 1997

Steering Group:
Eva Brorström-Lundén, IVL, Sweden
Jan Duyzer, TNO-MEP, The Netherlands
Jozef Pacyna, NILU, Norway
Gerhard Petersen, GKSS, Germany
Addo van Pul, RIVM, The Netherlands

Aims of MEPOP

General objective

Topic 1. Chemical and physical processes (Question number 1)

Topic 2. Air-surface exchange processes (Question number 2)

Topic 3. Regional scale modelling (Question number 3)

Topic 4. Synthesis of regional and global fluxes and trends (Questions number 4 and 5)

Introduction

Atmospheric behaviour of mercury and POPs

Scientific content of MEPOP

Topic 1. Chemical and physical processes (Question no. 1)

Topic 2. Air-surface exchange processes (Question no. 2)

Topic 3. Regional scale modelling (Question no. 3)

Topic 4. Synthesis of regional and global fluxes and trends (Questions no. 4 and 5)

Proposed activities

Activities under Topic 1.

Activities under Topic 2

Activities under Topic 3

Activities under Topic 4

Potential application of MEPOP to policy development

Quality Assurance

Data bases

Operational plan, Time schedule

Collaboration with other sub projects

Plans for assessment and integration

References

Justification of Principal Investigators

Organisation of the subproject

Personnel

Subproject Coordinator:

Steering Group:

List of Principal Investigators

A total number of 22 contributions from potential Principal Investigators (PIs) have been submitted covering a wide range of scientific tasks within the field of atmospheric research on mercury and POPs.

Aims of MEPOP

General objective

The general objective of MEPOP is:

• To quantify the regional atmospheric cycling of semivolatile species such as Hg and POPs.

The following specific questions will be adressed:

• Which chemical and physical processes are important in the atmospheric cycling of Hg and POPs?
• Which air/surface exchange processes are important in the atmospheric cycling of Hg and POPs?
• How can we model the transboundary transport of atmospheric Hg and POPs?
• What are the emission rates from natural and anthropogenic sources and how do they vary across Europe and with time?
• What are the regional and global concentrations and fluxes of Hg and POPs and how do they vary with time?

Executive summary

• To quantify the regional atmospheric cycling of semivolatile species such as Hg and POPs.

The following specific questions will be adressed:

• Which chemical and physical processes are important in the atmospheric cycling of Hg and POPs?
• Which air/surface exchange processes are important in the atmospheric cycling of Hg and POPs?
• How can we model the transboundary transport of atmospheric Hg and POPs?
• What are the emission rates from natural and anthropogenic sources and how do they vary across Europe and with time?
• What are the regional and global concentrations and fluxes of Hg and POPs and how do they vary with time?

To provide answers to these questions, the subproject is organised as 4 different Topics each with one or two specific questions to adress.

Topic 1. Chemical and physical processes (Question number 1)

The main focus in this Topic is laboratory investigations of reaction rates and field measurements of gas-particle interactions. The results will be evaluated using process models.

Topic 2. Air-surface exchange processes (Question number 2)

This topic is focussed on field measurements of dry and wet deposition as well as re-emissions and natural emissions of Hg. Special focus on processes in the interfaces between the atmosphere and water surfaces, soils and vegetation.

Topic 3. Regional scale modelling (Question number 3)

This topic is focussed on the development of modelling tools. This includes testing and intercomparing different modelling approaches, validation of models and the coupling of regional atmospheric models to other environmental compartments and hemispheric or global scales (i.e. setting of boundary conditions for regional scale models).

Topic 4. Synthesis of regional and global fluxes and trends (Questions number 4 and 5)

This Topic is focussed on emission inventories, identification of important fluxes and time trends. Important tasks within this Topic are evaluation of long term measurements and linking spatial and temporal variations in concentrations of Hg and POPs to changes in emissions on regional and global scales.

 In addition to these Topics, a continuous evaluation and assessment of the scientific activities and their relevance to the atmospheric cycling of Hg and POPs will be made.

Project description

Introduction

Figure 1. Saturation vapour pressure of some Hg compounds and POPs.

 The vapour pressures vary considerably within the group of Hg compounds and POPs with Benzo(a)pyrene existing mainly in the condensed (adsorbed) phase and DMHg (dimethylmercury) predominantly in the vapour phase. The intermediate compounds can be classified as semivolatile.

Most of the compounds of Hg and POPs can thus be transported over long distances in the atmosphere. The vapour pressure alone does not determine the atmospheric behaviour and residence time of these compounds since they also have different water solubilities and different reactivity towards atmospheric oxidants.

The POP studies in MEPOP will include compounds that represent both past, present and future use. This includes compounds such as polychlorinated biphenyls (PCBs), hexahlorohexanes (HCHs) and polycyclic aromatic hydrocarbons (PAH) which are frequently present in air. New classes of pesticides that are more readily degraded in the environment will also be included.

Atmospheric behaviour of mercury and POPs

Emissions

Hg is emitted both from combustion activities (mainly coal and waste incineration) and industrial applications where Hg is used in the process (chlorine production). Considerable amounts may also be emitted from diffuse sources due to the volatile nature of elemental mercury wherever the metal is present. A significant contribution is also emitted from natural sources. In Europe, these emissions mainly occur around the mercuriferous belt in the northern Mediterranean region. The natural emissions are difficult to separate from re-emissions of mercury previously deposited. Re-emissions are believed to be of importance mainly from aquatic surfaces.

For POPs, the anthropogenic emissions range from industrial point sources to diffuse area sources such as agriculture. For instance combustion processes lead to emissions of PAHs whereas many of the other persistent compounds are mainly emitted during agricultural and industrial application. Also re-emission of previous deposited POPs such as HCHs and PCBs contribute significantly in the mass balance of these POPs. As for Hg, re-emissions also occur from contaminated industrial sites and other diffuse sources.

For mercury, the chemical form of which it is emitted in will influence the atmospheric behaviour. Elemental mercury, Hg⁰, is volatile and stable with an atmospheric residence time on the order of one year and will be dispersed on a global scale. Particulate (Hg(p)) and vapour phase oxidised forms (Hg(II)) have residence times on the order of days and will be deposited within local to regional scales.

Atmospheric transformations and deposition processes

Generally, the term POPs implies that the substances are persistent and thus unreactive which is also true for most of the compounds in this group. The major removal mechanism for these compounds from the atmosphere is through dry and wet deposition. However, atmospheric processes may change the chemical properties of a compound making it more susceptible to deposition. Also, some modern related compounds produced by man are deliberately made less persistent and thus more reactive. For Hg the chemical and physical conversion between the different species described above will determine the rate of deposition at any given point. Therefore chemical transformations should be taken into account.

.The distribution of semivolatile species such as Hg and POPs between gas and aerosol phases will depend on vapour pressure of the substance, temperature and the concentration and surface properties of the particles. For Hg, the change between different phases is also dependent on the presence of different chemical species capable of transforming the Hg between its different forms.

Air-surface exchange is a process of importance for both Hg and POPs. For Hg, a cycle of deposition of water soluble/particulate phase forms, chemical conversion to volatile Hg⁰ followed by re-emissions can be envisaged for sea and lake water surfaces. For soils and vegetation, similar cycling occurs but the processes involved are more complex.

POPs on the Earth's surface are released back in the atmosphere, and a process of global fractionation may occur in which the organic compounds become fractionated latitudinally. This process, which is dependent on the ambient temperature and the volatility of the organic compounds, results in accumulation of POPs in the polar regions.

The importance of re-emissions of POPs from sea surfaces have been showed both in the Great Lakes in USA as well as in the Arctic sea areas (Hornbucle et al 1994, Bidleman and McConnel 1995). Recently Bidleman et al (1995) showed that the decline in the atmospheric concentration of alpha-HCH in the Arctic had reversed the net direction of air sea exchange. Thus some northern waters are now sources for alpha-HCH.

In terrestrial ecosystems, vegetation and soils acts as an important media for deposition and exchange of POPs and Hg (Kylin, 1994; Munthe et al., 1995). Hg and POPs are dry deposited to plants (leaves, needles) both from the vapour phase and bound to particles. Re-volatilisation can occur during warmer periods but most of the Hg is accumulated and deposited to the ground with the falling litter.

Transboundary transport fluxes

Atmospheric fluxes have been shown to be quantitatively important for the occurrence of POPs in different environments both far away from and near source areas (Eisenreich and Strachan 1992, Barrie et al 1992, North Sea Quality status report, 1993). Warmenhoven et al 1989 calculated the relative contribution of atmospheric deposition to total loading of the North Sea and found that more than 90% of the input of PCBs and HCHs was due to atmospheric deposition. Measurements have shown that substantial amounts of organic toxic compounds are deposited at the west coast of Sweden via atmospheric long range transport and deposition (Brorström-Lundén 1996). Transport of Hg from source areas in central Europe to Scandinavia has been identified from field measurements (Brosset, 1987; Iverfeldt, 1991) and by models (Petersen et al., 1995).

Modelling of transport, transformations and deposition of Hg and POP

The general concept of atmospheric transport models is that concentration of the substance in air is calculated from its emissions and is subsequently transported by the mean wind flow and dispersed by atmospheric turbulence. In the models the removal of the substances from the atmosphere by wet and dry deposition and (photo-)chemical degradation is described. The air-mass transport and dispersion of Hg and POPs in the atmosphere are similar as for other air pollution compounds. Therefore the meteorological framework of models which were originally developed for other air pollution fields (acidification research, smog prediction) are often used to describe the transport and dispersion. However, for POPs and mercury, a considerable difference exists in the processes which determine the removal of these compounds from the atmosphere compared to the other air pollution components. POP and mercury can re-volatilise after it has been deposited which makes the dry deposition process essentially a two-way process. Thus, any model describing the atmospheric cycling of Hg and POPs will have to take into account the atmospheric interfaces with soil and water. This can be done extensively using a multi-compartment approach or using source/sink functions as boundary conditions. The removal of those compounds from the atmosphere largely depends on the gas/particle phase partitioning since the deposition processes of gases and particles are different.

Mercury modelling

Existing models of atmospheric transport and transformation of Hg can roughly be divided into two types; long-range transport models and process models. Process models have been used to develop chemical mechanisms and to simulate local to regional scale transport (Pleijel and Munthe, 1995a,b). The first attempt to model the transboundary transport of Hg was presented in Petersen et al. (1995). The simple chemical parameterisation used in this Lagrangian model has been used in other models in Europe and North America. More advanced parameterisation is currently being developed to be used in a Eulerian modelling approach, see figure 2.

Figure 2. Parameterisation of Hg chemistry in the European ADOM model (Petersen et al., 1997).

This scheme is based on the experience obtained in the development and testing of process models.

POP modelling

POP models have been used for the quantification of the atmospheric input of POP to receptor areas versus the input via other pathways was assessed; North Sea area (Warmenhoven et al., 1989), River Rhine drainage area (Baart and Diederen, 1991). In other studies the deposition of POP on a larger part of Europe has been calculated (Baart et al, 1995, Jacobs and van Pul, 1996, van Jaarsveld et al, 1997). The models used in these studies were originally designed for other air pollutants but have been extended by including the soil and sea water compartments.

In Table 1, an overview of modelled atmospheric residence times is presented. This clearly illustrates the diversity of POP behaviour in the atmosphere and that different model approaches should be used for different compounds.

Table 1. Atmospheric residence times, typical travel scale and dominant removal process of a number of POPs (van Pul, 1997).

1) Calculated with a simple screening model (van Pul et al, 1997).

Scientific content of MEPOP

The scientific objectives of MEPOP are here presented grouped under the headings of 4 different Topics which will for the organisational basis for all participating projects.

Topic 1. Chemical and physical processes (Question no. 1)

This Topic is focused on identifying and quantifying chemical and physical processes of Hg and POPs that influence the deposition of these compounds. For Hg, this includes investigations of oxidation processes of Hg⁰ leading to the formation of water soluble and particulate phase species as well as studies of the atmospheric behaviour of organomercury forms such as dimethyl mercury ((CH₃)₂Hg and CH₃HgCl). For POPs, initial degradation processes of some more reactive gaseous species and model compounds is the main focus. For both Hg and POPs, field measurements of the phase distribution (mainly gas-aerosol partitioning) is an important task. For some of the field based projects in Topic 1, development and refinement of measurement techniques will also be necessary.

The results of the investigations in Topic 1 will serve as input to the modelling activities. Within Topic 1, process modelling will also be performed aimed at designing simplified schemes for the large-scale transport models.

Topic 2. Air-surface exchange processes (Question no. 2)

Focusing on field measurements and process modelling of dry deposition, re-emissions from terrestrial and marine systems and how these processes influence the overall atmospheric cycling of Hg and POPs.

Natural emissions of Hg will also be investigated under this Topic.

Topic 3. Regional scale modelling (Question no. 3)

Topic 3 focuses on the development, validation and application of regional scale models describing emissions, transport and transformations of Hg and POPs in Europe. A main task is to implement information of processes quantified in Topics 1 and 2. Model intercomparisons and validation excersices are also important tasks.

Topic 4. Synthesis of regional and global fluxes and trends (Questions no. 4 and 5)

This Topic will mainly serve as support to the other Topics using a "top-down" approach for identification of important processes and time trends. Important tasks within this Topic are evaluation of long term measurements and linking spatial and temporal variations to changes in emissions on regional and global scales.

In addition to the scientific activities outlined under the Topics above, a continuous evaluation and assessment of the scientific content of the project will be made. This will primarily be the task of the coordinator and the steering group.

Proposed activities

The activities in MEPOP will be diverse and contain laboratory investigations, field measurements, modelling as well as evaluation and assessment. Integration of these activities into a joint research program with a joint goal is the major challenge and the main point of MEPOP. To achieve this, a number of individual research activities have to be linked so that the growing experience within the group can be shared and put to use in a wider context than the individual research project. Already, a number of collaborative programs are involved in MEPOP. As an example, several of the PIs are also participating in projects funded by the EC-DGXII Programme Environment and Climate (Mercury Over Europe (MOE), coordinated by Dr Iverfeldt; and Mediterranean Mercury Cycling System (MAMCS) coordinated by Dr Pirrone).

Individual activities in the different Topics are listed below:

Activities under Topic 1.

• Laboratory investigations of vapour phase reactions of selected pesticides with oxidants (OH, O₃)
• Laboratory investigations of the vapour phase reactions of dimethylmercury and elemental mercury with oxidants including product studies.
• Field measurements of gas-particle partitioning of Hg and POPs including investigations of temporal and spatial variations.
• Process modelling aimed at the development of simplified chemistry schemes.

• Measurements of re-emissions of Hg and POPs from forest soils, lake and sea water.
• Measurements of natural emissions of Hg in the Mediterranean basin.
• Development of remote sensing techniques for measurements of Hg emissions/re-emissions.

• Identification of requirements for regional scale models for Hg and POPs.
• Model intercomparison and initial flux calculations.

• Analysis of time trends of emissions of Hg and POPs
• Identification of large scale temporal and spatial variations in atmospheric concentrations of Hg and POPs. Identification of major atmospheric transport pathways on local and regional sales.
• Compilation of available data on Hg and POPs in the atmosphere and identification of gaps in data.

The on-going activities on preparation of protocols for emission reductions of heavy metals and POPs under the UN-ECE Convention on Long-Range Transboundary Air Pollution (CLRTAP) have put focus on the current state of knowledge on atmospheric transport and deposition of these compounds. The potential environmental hazards of these substances in regional seas and the Arctic region have also led to increasing attention on this topic in international organisations such as HELCOM, MEDPOL, PARCOM and AMAP.

These activities have increased the scientific activity at national and international levels and various programs are under way on emissions, transport modelling and measurements. Significant contributions in summarising the scientific status and identifying knowledge gaps in this area has been made at the UN-ECE/EMEP Workshops held in Durham, USA, 1993 (Pacyna et al., 1993), Beekbergen, the Netherlands, 1994 (de Leeuw, 1997) and Moscow, Russian Federation 1996 (Varygina, M. and Soudine, A., 1997).

Within the UN-ECE/CLRTAP, protocols for limitations of emissions of sulphur, nitrogen and VOCs have been negotiated and have also been updated and strengthened. Within the European Union, a proposed strategy for acidifying pollutants is currently being discussed with even more far-reaching restrictions on emissions of sulphur and nitrogen. For heavy metals and POPs, protocols are expected to be signed within the next few years. The first-phase protocol will be based on available abatement techniques and possible phase out of POPs. The second phase will probably be based on an effect approach such as critical loads as used in acidification. In this approach the actual deposition loads and have to be estimated to be able to assess the exceedances. Source-receptor relationships also need to be quantified in order to device control strategies. A sound scientific understanding of the atmospheric cycling of Hg and POPs is needed to fulfil both these requirements.

In comparison to the efforts made to quantify and model the atmospheric behaviour and transport of acidifying compounds, VOCs and oxidants in recent years, the research conducted on heavy metals and POPs has been limited. In the case of most heavy metals, the atmospheric behaviour is relatively straightforward and quantitative estimates of transport and deposition can be based on relatively simple parameterisations. Mercury and POP, however, have a complex atmospheric cycle involving chemical transformations, transfer between aqueous, gaseous and condensed phases as well as air-surface exchange processes over water, soil and vegetation. Thus, a coordinated research program on Hg and POPs is motivated.

Quality Assurance

Each PI will be responsible for Quality Assurance within the different projects. Joint procedures for QA will be set-up for all projects involving field measurements and analysis of Hg species and POPs. All field measurements will follow the procedures of the guidelines prepared for the Oslo and Paris Commissions for Hg (Munthe, 1997) and POPs (de Leeuw and Brorström-Lundén, 1997), if relevant. Common reference materials in different laboratories involved in MEPOP will be used, if available. The arrangement of measurement and modelling intercomparison excercises will be encouraged within the project.

Data bases

Within MEPOP, systems for making data available to the scientific community will be set up. This will initially be in the form of a joint meta-database with information of availability and location of data. The meta database will include information on:

• Chemical and physical processes (i.e. rate constants, partitioning coefficients etc.)
• Concentrations of Hg and POPs in air and precipitation and other media for model validation (in co-operation with organisations involved in the monitoring of air pollutants e.g. EMEP, OSPARCOM)

Operational plan, Time schedule

The scientific activities of MEPOP project will start in 1998. The subproject will be presented at the EUROTRAC-2 symposium in March, 1998, where also a number of posters will be presented. At least one sub project workshop will be held each year. If possible these workshops will be arranged in conjunction with other activities such as EMEP workshops on heavy metals and POPs.

Collaboration with other sub projects

A number of the scientists participating in MEPOP are already involved in different subprojects of EUROTRAC2. These projects will form the basis for collaboration during the first phase of MEPOP.

Apart from this, collaboration with other EUROTRAC-2 subprojects can be organised via the scientific Topics outlined above.

Plans for assessment and integration

To protect ecosystems from continued pollutant loading, emission reduction strategies need to be developed. Basic scientific knowledge on the atmospheric fate of Hg species and POPs is essential to support the development of these strategies. Atmospheric processes and identification of spatial patterns of deposition are two examples of areas where scientific knowledge is essential for the optimisation of measures to control emissions. For Hg and POPs such information is very limited and urgently needed.

International co-operation on measurements and modelling of mercury and POPs is an important task within organisations focused on agreements on pollution control (e.g. UN-ECE/EMEP). On-going activities include the development of models of atmospheric transport and deposition of heavy metals and POPs as well as agreements on co-ordinated measurements of these species. In many cases, successful modelling and measurements of Hg and POPs is dependent on the generation of basic scientific knowledge that allows the detailed description of the environmental behaviour of these species. The research performed within MEPOP will be entirely devoted to Topics relevant to the development of tools for assessment and evaluation of pollutant transport and deposition in Europe.

Owing to the interdisciplinary nature of MEPOP, assessment and integration will be a crucial part of the subproject. An important task of the participating PIs will be to take part in the assessment process within the subproject. During the initial phase, the assessment and integration will be focused on identifying gaps in our knowledge of Hg and POPs.

One important "end-user" of the results produced within MEPOP will be the organisations involved in modelling the transport of air pollutants from sources. These organisations will be invited to use the model tools developed within this subproject. Within the EMEP domain, the MSC-E in Russia is responsible for the modelling of Hg and POPs. This institute will participate in MEPOP and their involvement will be valuable for ensuring the relevancy of the scientific Topics being investigated.

References

Baart A.C., Diederen H.S.M.A. (1991) Calculation of the atmospheric deposition of 29 contaminants to the Rhine Catchment area. Report no. R 91/219, TNO Division of Technology for Society, P.O. Box 217, 2600AE Delft, The Netherlands

Baart, A.C., J.J.M.Berdowski and J.A. van Jaarsveld (1995) Calculation of atmospheric deposition of contaminants on the North Sea. TNO report R 95/138.

Barrie, L.A., Gregor, D., Lake, R. Muir, D. Shearer, R. Tracey, B. and Bidleman, T. (1992) Arctic Contaminants: Sources, Occurrence and Pathways. Sci. Tot. Environ., 122, 1-74.

Bidleman, T. F. and Mc.Connell, L. L. (1995) A review of field experiments to determine air-water gas exchange of persistentorganic pollutants. Sci. Total Environ., 159, 101-117.

Bidleman, T.F. Jantunen, R.L. Falconer, R.L. Barrie, L.A. and Fellin, P. (1995) Decline of Hexachlorocyclohexane in the Arctic atmosphere and reverse of air-sea exchange Geophysical res. letters 219-222

Brorström-Lundén, E. (1996) Atmospheric Transport and Deposition of Persistent Organic Compounds to the Sea Surface. Journal of Sea Research vol 35 81-90.

Brosset, C. 1987 The behaviour of mercury in the physical environment. Water, Air, Soil Pollution 34, 145.

De Leeuw, F.A.A.M. (1996) Proceedings of EMEP Workshop on European Monitoring, Modelling and Assessment of Heavy Metals and Persistent Organic Pollutants. RIVM-report 722401014.In press.

De Leeuw, F.A.A.M. and Brorström-Lundén, E. 1997. Guidance report on sampling and analyzing of PCB in air and precipitation. Report to the Oslo and Paric Commissions. In press.

Eisenreich, S. and Strachan, W. (1992) Estimating Atmospheric Deposition of Toxic Substances to the Great Lakes -An Update- Proceedings from Workshop held at the Canada centre for Inlands Waters Burlington , Ontario Canada 1992.

Hornbuckle, K. C., Jeremiason, J. D., Sweet, C. W. and Eisenreich, S. J., (1994) Seasonal Variations in Air-Water Exchange of Polychlorinated Biphenyls in Lake Superior. Environ. Sci. Technol., 28, 1491-1501.

Iverfeldt, Å. (1991) Occurrence and Turnover of Atmospheric Mercury over the Nordic Countries, Water, Air, and Soil Pollut. 56, 251-265.

Jacobs, C.M.J. and W.A.J. van Pul.1996 Long-range Transport of Persistent Organic Pollutants: Description of Surface-Atmosphere Echange Modules and Implementation in EUROS. RIVM report 722401013.

Kylin, H. (1994) Airborne Lipophilic air pollutants in pine needles. Thesis Stockholm University.

Munthe, J. 1997. Guidelines for the sampling and analysis of mercury in air and precipitation. Report to the Oslo and Paric Commissions. In press.

NSTF: North sea , Quality Staus report 1993, North sea task force, ISBN1-872349-06-4

Pacyna, J.M., Voldner, E. Keeler, G.J. and Evans G., eds., Proceedings of the First Workshop on Emissions and Modelling of Atmospheric Transport of Persistent Organic Pollutants and Heavy metals, EMEP/CCC-report 7/93, Norwegian Institute for Air Research, P.O. Box 64, N-2001 Lillestrom, Norway.

Petersen G., Iverfeldt A. and Munthe J., 1995. Atmospheric mercury species over central and northern Europe. Model calculations and comparison with observations from the nordic air and precipitation network for 1987 and 1988. Atmos.Environ., Vol. 29, pp. 47-67.

Petersen, G., Munthe, J., Pleijel, K., Bloxam, R. and Vinod Kumar, A. A comprehensive Eulerian modeling framework for airborne mercury species: Development and testing of the Tropospheric Chemistry Module (TCM). Atmospheric Environment In press.

Pleijel, K and Munthe, J. 1995a Modelling the atmospheric mercury cycle - Chemistry in fog droplets. Atmospheric Environment, 29, 1441-1457.

Pleijel, K. and Munthe, J. 1995b Modeling the atmospheric chemistry of mercury- The importance of a detailed description of the chemistry of cloud water. Water, Air, Soil Pollution, 80, 317-324.

Van Jaarsveld J.A., van Pul, W.A.J. and de Leeuw, F.A.A.M. 1997 Modelling transport and deposition of persistent organic pollutants in the European region. Atmospheric Environment, Vol. 31, No.7, pp. 1011-1024.

Van Pul, W.A.J., F.A.A.M. de Leeuw, J.A. van Jaarsveld and C.J. Sliggers, 1997. The atmospheric transport potential of substances. Report 259101005, RIVM, Bilthoven, The Netherlands

Varygina, M. and Soudine, A. 1997. Report and proceedings of the workshop on the ssessment of EMEP activities concerning heavy metals and persistent organic pollutants and their further development. EMEP/MSC-E Report 1/97. Meteorological Synthesizing Center East, Kedrova str. 8-1, Moscow, 117 292 Russia.

Warmenhoven, J.P., Duiser, J.A., de Leu, L.TH and Veldt (1989) The contribution of the input from the atmosphere of the North Sea and the Dutch Wadden Sea TNO R 89/349A

Justification of Principal Investigators

The PIs of MEPOP will all be integrated into the scientific framework with 4 different Topics as outlined above. In the Table below, those PIs who have submitted complete project descriptions have been organised under the specific Topic where their proposed projects fit. A short specification of their scientific area is also given. Some of the PIs have proposed research under more than one Topic in which case they have been placed under the most relevant Topic.

The scientific tasks of these PIs do not overlap. Similarities exist in some cases such as the deposition processes for POPs but the investigations will differ in geographical locations and selection of POPs. Several models will be used for the regional transport of Hg and POPs but this is not judged to be a disadvantage for the development of accurate model tools since the different models use different approaches.

Organisation of the subproject

MEPOP will be coordinated by John Munthe, Ph.D. John Munthe has a scientific background in atmospheric chemistry and his thesis concerned kinetic studies of aqueous phase reactions of Hg relevant to the cycling of Hg in the atmosphere. He has more than 10 years experience on research on air-surface exchange and deposition processes of mercury as well as cycling of Hg in terrestrial ecosystems.

The other steering group members are:

Dr. Eva Brorström-Lundén, IVL

Dr. Jan Duyzer, TNO-MEP

Dr. Jozef Pacyna, NILU

Dr. Gerhard Petersen, GKSS

Dr Addo van Pul, RIVM

The subproject coordinator and the steering group will be responsible for:

• The overall scientific management of MEPOP.
• Reporting of results within the framework of EUROTRAC-2.
• The evaluation of new project proposals to MEPOP.
• Contacts with end-users (specifically EMEP MSC-E).
• Organisation of workshops.
• Initiation of new activities within MEPOP.
• Initiation of cooperation between MEPOP - participants and other EUROTRAC-2 subprojects.

 Time plan for MEPOP

The time plan for different PIs will depend on the availability of funding. Some projects are already on-going and will be integrated into MEPOP as soon as possible. Several projects are expected to start in 1998.

Estimated costs. The costs are somewhat uncertain due to differences in reported duration and starting times of the project