Collaborative Research: Mercury in the Atmosphere Over the Eastern United States

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This project comprises the first large-scale airborne experiment focused on mercury over North America. The project has two primary objectives: 1) Constrain emissions of mercury from major source regions in the eastern United States, 2) Quantify the distribution and chemical transformations of mercury in the lower troposphere. To address these goals the NSF/National Center for Atmsopheric Research C-130 aircraft will be equipped with a suite of state-of-the-art instrumentation to measure gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particle-bound Hg (pHg) and a suite of other compounds for air mass characterization. Flight plans will be designed to study industrial mercury sources over the Ohio River Valley, outflow of North American mercury to the Atlantic, and the impact of convective precipitation on surface wet deposition of mercury over the Southeast U.S. Operational planning will utilize regional and global forecast models to optimize the use of flight time. The C-130 observations will be integrated and analyzed after the mission with several chemical transport and Lagrangian models. These models will be used to examine the consistency between observations and emission inventories, allow the integration of ground-based observations with aircraft observations in a unified framework, constrain source-receptor relationships, and test different hypotheses about the chemical transformations and global cycling of mercury.Human exposure to mercury is a significant health risk and a problem of national and global significance. Project results will reduce the uncertainties concerning source-receptor relationships and the relative contributions of domestic, foreign and natural sources to the inventory of atmospheric mercury over the eastern U.S. The research will involve a number of graduate and undergraduate students from several different U.S. institutions and thus will expose these students to working on high-level scientific problems of great national significance. In addition to a core group of scientists from the U.S., mercury scientists from Canada, Italy, Germany and Russia will also collaborate in the work, thus strengthening international scientific cooperation on global environmental problems.