Contributions of global and regional sources to mercury deposition in New York State

A modeling system that includes a global chemical transport model (CTM) and a nested continental CTM (TEAM) was used to simulate the atmospheric transport, transformations and deposition of mercury (Hg). Three scenarios were used: (1) a nominal scenario, (2) a scenario conducive to local deposition and (3) a scenario conducive to long-range transport. Deposition fluxes of Hg were analyzed at three receptor locations in New York State. For the nominal scenario, the anthropogenic emission sources (including re-emission of deposited Hg) in New York State, the rest of the contiguous United States, Asia, Europe, and Canada contributed 11–21, 25–49, 13–19, 5–7, and 2–5%, respectively to total Hg deposition at these three receptors. Natural sources contributed 16–24%. The results from the local deposition and long-range transport scenarios varied only slightly from these results. However, there are still uncertainties in our understanding of the atmospheric chemistry of Hg that are likely to affect these estimates of local, regional and global contributions. Comparison of model simulation results with data from the Mercury Deposition Network suggests that local and regional contributions may currently be overestimated.