Mercury dynamics in terrestrial ecosystems in response to global change

Terrestrial carbon pools play an important role in uptake, deposition, sequestration, and emission of atmospheric mercury (Hg). Biomass and soil C pools are highly sensitive to climate and land use changes with potentially serious consequences for the fate of an estimated 50,000 Mg of atmospheric Hg associated within carbon pools. Our proejct is to assess how global change during the next 100 years is likely to affect Hg cycling processes (i.e., atmospheric Hg uptake, sequestration, and emission) associated with vegetation and soil carbon pools. We assess how global change affects plant-derived atmospheric Hg inputs to ecosystems via changes in plant productivity, plant senescence, and litterfall; and how global change impacts on plant, litter, and soil carbon pools will affect sequestered Hg within these pools and feedback on the future atmospheric Hg burden. This proposed study includes a systematic determination of Hg in vegetation and soil C pools in terrestrial ecosystems, field and laboratory experimental studies, and modeling components. Systematic quantification of Hg levels in major ecosystems will provide the first comprehensive database on Hg pools, plant Hg uptake, sequestration, and Hg turnover associated with terrestrial C pools in the U.S. Fate processes of Hg sequestered in C pools are fundamental to the prediction of how anticipated C pool changes in the future will feed back on the future atmospheric Hg burden. Integration of Hg data into an existing global change C model will enable prediction on how various global change senarios will affect C-related Hg cycling. Our results will support the formulation of strategies by land managers, policy makers, and stakeholders to mitigate atmospheric Hg and stabilize Hg sequestered in terrestrial C pools.