The atmosphere transport and transformation of mercury was formulated and incorporated into a 3-dimensional regional scale Eulerian air quality model. Three Hg species were considered, elemental (Hg(0)), divalent (Hg(II)) and attachment to particles (Hg(p)). The wet transformation of Hg(0) was fully coupled with cloud processes and concentrations of ozone and soot particles. The interaction between wet transformation of Hg(0) and direct scavenging of other mercury species was also modeled. A mercury air emission inventory for the modeling domain was used for the three Hg species based on Unite State Environmental Protection Agency and Connecticut Department of Environmental Protection databases. The air-surface exchanges of Hg(0), including water surface, plant canopies and soil, were formulated based on theoretical and empirical studies in the literature. Simulations were conducted for the Northeast United State for a summer week and a winter week in 1997. The simulated ambient Hg concentrations and Hg concentrations in precipitation were compared with measurements taking at seven monitoring stations in Connecticut for the same period of time. The analysis of the modeling results also included seasonal variations in Hg concentrations and depositions, and mass balances (emissions and depositions) for various land cover types.
Acknowledgments-- The authors would like to thank Dr. Julius Chang at State University of New York at Albany, for providing SAQM and advising on the model modification, and to Dr. N. L. Seaman and Mr. G. Hunter at Pennsylvania State University for providing the meteorology data.