Department of Environmental Sciences

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Seminar Abstracts
Environmental Sciences Seminar Abstract            

  Mercury in the Atmosphere, Biosphere, and Policy Sphere: Insights from Global Modeling
Noelle Eckley Selin
Massachusetts Institute of Tech.
Cambridge, MA

Concern about the toxicity of mercury depositing to ecosystems has prompted efforts to regulate its emissions in both national and international policy arenas. Current concentrations of atmosphericmercury have increased three-fold since pre-industrial times, and the main source of anthropogenic mercury emissions is coal-fired power generation. Despite increasing attention to mercury as an environmental problem, the global budget of mercury and its chemistry and cycling in the atmosphere are not well understood. Our research uses a global, 3D chemical transport model (GEOS-Chem) in conjunction with worldwide atmospheric observations to constrain the redox chemistry, biogeochemical cycling and deposition of mercury. Our global budget analysis of mercury shows that anthropogenic emissionswill continue to affect the atmosphere-ocean-biosphere system for centuries to millennia. Over the U.S., the Midwest is affected by deposition of regional emissions, but areas such as the Southeast experience high levels of wet deposition resulting from convective scavenging of reactive mercury from higher altitudes. We then conduct a policy-focused analysis combining atmospheric, ocean and ecosystem models to explore the influence of domestic and international mercury controls on exposure to fish methylmercury. Results show that regional and ecosystem variation has a strong effect on the ability of domestic controls to address excess exposures. Research results will bediscussed in the context of existing and proposed national and international policy actions on mercury.

Last updated: 02/20/2009