Decomposition of Methylmercury in Surface Water of the Northwest Atlantic Ocean

Abstract

<p>Biological and photochemical processes can decompose toxic monomethylmercury (MMHg) and render mercury less available for biological uptake. However, and in contrast to freshwater systems, little is known about MMHg decomposition in the marine environment. We are investigating the kinetics and mechanisms of MMHg decomposition in seawater from multiple locations on the continental margin of the northwest Atlantic Ocean. Ship-deck incubation tests were performed during oceanographic cruises in 2009 and 2010. Preliminary results suggest that 1) both biotic and photochemical pathways are important, 2) rate constants of decomposition are similar among locations and comparable to those determined in freshwater lakes, and 3) the mechanism of photochemical destruction in seawater is different from that in lakes. Experiments in 2010 sought to identify alternative photochemical pathways. Quantitative knowledge of the kinetics and mechanisms of MMHg decomposition in seawater will help constrain oceanic budgets and cycling models.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 8, 2011</p>