ETBC: Global 3-D Modeling of Atmospheric Mercury and its Coupling to the Ocean and Land: Impacts of Past and Future Anthropogenic Emissions

Harvard University, Cambridge MA

Investigators

Abstract

This project will improve understanding of the global biogeochemical mercury cycle and its link to oceanic methylmercury, which bioaccumulates through the food chain and causes human health risks. It will use a global three-dimensional model (GEOS-Chem) driven by assimilated meteorological data and will include mechanistic representations of mercury speciation and transfer between the atmosphere and terrestrial and oceanic reservoirs. The model will improve on the existing version of GEOS-Chem, most notably through the incorporation of a detailed process-based terrestrial model. Although many processes are still uncertain, the work will develop a first capability to model how rapidly changes in anthropogenic mercury emissions are reflected by terrestrial inorganic mercury concentrations. The coupled land-atmosphere-ocean modeling framework will be evaluated and constrained using a large body of observational mercury data from the atmosphere (ships, aircraft, land sites), oceans (air-sea exchange, mercury speciation, correlations with environmental variables), and soils. This research will provide a platform for future work examining (1) the potentially large impacts of climate change on the global mercury cycle, (2) the link between the global cycle of mercury and that of methylmercury, which is the bioavailable species that accumulates in food-webs. This will lead to a unique resource for the development of national and international policies targeted at reducing environmental mercury levels through control of anthropogenic emissions. The multiphase, three-dimensional modeling framework will have application to future modeling of other contaminants such as persistent organic pollutants. The project will train a graduate student in interdisciplinary environmental modeling.