MP18 Environmental Fate of Mercury
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(YEE-1117-854355) Methylmercury in San Francisco Bay Surface Sediments.

Yee, D¹, Lowe, S¹, Ross, J¹, Conaway, C², Scelfo, G, ¹ San Francisco Estuary Institute, Oakland, CA, USA² University of California Santa Cruz, Santa Cruz, CA, USA

ABSTRACT- Surface sediment samples were collected for the San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP) from sites distributed throughout the estuary in the summers of 2002 to 2004. Trace pollutants including mercury, methylmercury, and a suite of ancillary sediment parameters (TOC, TN, grain size, porewater pH, redox potential) were measured in the field or in the laboratory. Reports in the literature have shown correlations of MeHg to total mercury, TOC, and grain size (%fines) in sediments, relationships examined in samples collected for the RMP. Of the measured ancillary parameters, sediment total nitrogen and surficial redox potential (Eh) were found to be among those most strongly correlated to MeHg concentrations. The activity of sulfate reducing bacteria under anaerobic conditions is expected to produce the majority of MeHg found in estuarine sediments, and the correlation of these parameters with sediment MeHg support this expectation. Implications for future sampling and monitoring and options for ecosystem management will be discussed.

Key words: methylmercury, sediment, redox, mercury