Ocean Atmospheric Interactions and the Global Mercury
Cycle: Clear Skies and Should I eat Tuna?
Robert Mason
Chesapeake Biological Laboratory
U Maryland

Methylmercury (MeHg) concentrations in fish are an environmental health concern and have lead to recent and impending federal and state legislation in the USA and elsewhere to control inorganic mercury (Hg) emissions to the atmosphere. However, the link between Hg deposition and MeHg in fish is complex and involves a number of pathways that can enhance or moderate Hg methylation and bioaccumulation. This talk will firstly examine recent evaluations of the global Hg cycle and their implications. Specifically, the role of atmospheric chemistry in the marine boundary layer and air-sea exchange processes play in regulating the relative extent to which the ocean compared to the terrestrial environment acts as the dominant sink for anthropogenic Hg will be discussed. Finally, recent research has been probing the relative importance of direct deposition compared to watershed inputs as a source of bioavailable Hg, in terms of methylation potential, to freshwater systems and the talk will briefly discuss the results of a whole ecosystem Hg experiment that is examining hypotheses concerning the controls over Hg methylation and MeHg bioaccumulation.

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