Antigoni Voudouri

Dynamic processes of mercury over the Mediterranean region: results from the Mediterranean Atmospheric Mercury Cycle System (MAMCS) project

The Mediterranean Atmospheric Mercury Cycle System (MAMCS) project was performed between 1998 and 2000 and involved the collaboration of universities and research institutes from Europe, Israel and Turkey. The main goal of MAMCS was to investigate dynamic processes affecting the cycle of mercury in the Mediterranean atmosphere by combining ad hoc field measurements and modelling tasks. To study the fate of Hg in the Mediterranean Basin an updated emission inventory was compiled for Europe and the countries bordering the Mediterranean Sea. Models were developed to describe the individual atmospheric processes which influence the chemical and physical characteristics of atmospheric Hg, and these were coupled to meteorological models to examine the dispersion and deposition of Hg species in the Mediterranean Basin. One intercomparison and four two-week measurement campaigns were carried out over a three-year period. The work presented here describes the results in general terms but focuses on the areas where definite conclusions were unforthcoming and thus highlights those aspects where, in spite of advances made in the understanding of Hg cycling, further work is necessary in order to be able to predict confidently Hg and Hg compound concentration fields and deposition patterns.

Modelling Framework for Atmospheric Mercury over the Mediterranean Region: Model Development and Applications

The atmospheric part of the mercury cycle is considered as very complicated because of the various physicochemical processes involved. The temporal and spatial scales of various processes are varying according to mercury species. While Hg 0 is considered as long-range transport pollutant, Hg II is fast reacting and deposits quickly (wet and dry). Hg P has behaviour similar to the other particulate in the atmosphere. There is enough evidence now about the various disturbances in what are considered as background quantities. The most important reasons are (i) the increase of emissions from sources like coal burning, waste incinerators, cement production, mining etc, (ii) the lack of understanding of important physicochemical processes like fluxes, transport, transformation and deposition. Because of these verified disturbances, during the last years, a considerable effort has been devoted to reduce the mercury emissions. At the framework of the EU/DG-XII project MAMCS a significant effort has been devoted at the development of appropriate models for studying the mercury cycle in the atmosphere. The model development is performed within the atmospheric models RAMS and SKIRON/Eta. In this development we tried to transfer and utilize the modeling techniques applied in conventional air pollution modelling studies. In addition, we had to develop new methodologies for processes like re-emissions from soil and water bodies and gas to particle formation. The developed modeling systems have been applied in the Mediterranean Region where the multi-scale atmospheric processes (thermal and mechanical circulations at regional and mesoscale) are considered as important, according to a number of past air pollution studies. Seasonal-type of simulation has been performed and annual deposition patterns have been estimated. As it was found, the regional-scale pattern and the trade wind systems (from North to South) and the photochemistry are the key factors for controlling the mercury deposition, especially the Hg P .

Chapter 4.11 Validation of the integrated RAMS-Hg modelling system

Abstract RAMS-Hg and CMAQ-Hg are two state-of-the-science integrated modelling systems developed to study the complex chemical transformation, transport and deposition of atmospheric mercury. In the present study model results using RAMS-Hg are both compared with observations from the Hg deposition network (MDN) and wet deposition of Hg results using CMAQ-Hg. A preliminary validation of the RAMS-Hg model as well as quantitative estimation of the advantages of the proposed approach on coupling mercury processes to an atmospheric modelling system is presented. Model validation indicated that the comprehensive model simulated reasonably well the wet deposition measurements of Hg at the MDN sites.

Modeling of the Mercury Cycle in the Atmosphere

The physical and chemical processes involved in the mercury cycle in the atmosphere are very complicated and need special treatment. At the framework of the EU/DG-XII project MAMCS a significant effort has been devoted for the development of appropriate models for studying the mercury cycle in the atmosphere. In addition, an improved emission inventory is created while monitoring data in various locations in Europe are selected and used for model calibration and inter-comparison. Our model development includes the incorporation of almost any type of source (point or area), gas and aqueous phase chemistry, gas-to-particle conversion, wet and dry deposition, air-water exchange processes etc. The development was performed within two well-known atmospheric modeling systems: the Regional Atmospheric Modeling System (RAMS) and the SKIRON/Eta. There are several reasons for performing the development of the mercury cycle modeling within these two models: The main reason for using RAMS is its unique capability of two-way interactive nesting of any number of grids which is considered as absolutely necessary for studying near-source dispersion of mercury species. Additional capabilities are the full microphysical parameterization for wet processes, the detailed parameterization of surface processes and the non-hydrostatic formulation. The main reason for using the SKIRON/Eta model for development is its unique capability of describing the dust cycle (uptake, transport, deposition) and the existence of a viscous sub-layer formulation which is necessary for description of mercury fluxes from the sea surface. In both models the mercury cycle formulation is called simultaneously at each time-step in order

Some Preliminary Results Concerning the Hg Budget Estimates for the State of New York

In this paper an attempt was made to identify the in/out of state contributions of mercury sources to the total deposited mercury over the State of New York. The transport, transformation and deposition of mercury in New York State are also discussed.