Riedel, G. S.. The Academy of Natural Sciences Estuarine Res. Ctr, griedel@acnatsci.org
Benoit, J. S.. The Academy of Natural Sciences Estuarine Res. Ctr., benoit@acnatsci.org
Mason, R. P.. University of Maryland, Chesapeake Biological Lab., mason@cbl.umces.edu
Gilmour, C. C.. The Academy of Natural Sciences Estuarine Res. Ctr., gilmour@acnatsci.org

The coastal zone plays an integral role in the global mercury (Hg) cycle, as a sink for terrestrial Hg and a potential source of methylmercury (MeHg) to the oceans. We have compiled our studies of atmospheric deposition, fluvial sources, and the behavior and fate to construct total Hg and MeHg budgets for the Patuxent River, a subestuary of Chesapeake Bay. Roughly 40% of both total Hg (Hg-T) and MeHg deposited to the upper watershed is exported. A relatively low MeHg yield from the upper Patuxent watershed is consistent with the few wetland areas, and high urbanization. Freshwater flow is a major source of Hg-T but not MeHg to the river. Fluvial inputs of Hg-T, but not MeHg, are strongly correlated with flow. De novo production in sediments appears to be the main source of MeHg, although MeHg concentrations in estuarine Patuxent sediments are low relative to freshwater sediments. Tidal exchanges with the main Bay are important terms for Hg and MeHg budgets. Sediment burial is the major sink for Hg, exceeding loss to the Bay. However, export of MeHg to Chesapeake Bay appears to exceed burial, supporting the hypothesis that estuaries are net exporters of MeHg to the oceans.
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
Code: SS28WE0885S