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(607) Chlorinated Hydrocarbons and Mercury in Two Tributaries of San Francisco Bay .
Leatherbarrow, Jon*,1, Hoenicke, Rainer2, McKee, Lester1, 1 San Francisco Estuary Institute, Oakland, CA, USA2 California Resources Agency, Sacramento, CA, USA
ABSTRACT- The Guadalupe River and Coyote Creek watersheds, which drain into Lower South San Francisco Bay (Lower South Bay), support growing urbanized areas, as well as areas of agricultural and historic mining activities. The San Francisco Estuary Regional Monitoring Program (RMP) conducted seasonal monitoring of water and sediment for organic contaminants and trace elements at two locations near the bottom of these watersheds from March 1996 through July 2001. The objectives of the study were to (1) relate contaminant patterns found in the Estuary with those in the adjacent watersheds to determine if runoff and sediment collected at the lower end of the Coyote Creek and Guadalupe River differ from water and sediment in the Lower South Bay and to (2) determine what kinds of ancillary water and sediment quality parameters should be measured to explain contaminant patterns and improve tributary monitoring design. In Guadalupe River, mercury concentrations were as high as 0.73 g/L in water and 1.08 mg/kg in sediment with probable influences from the inoperative New Almaden mercury mining district in the upper watershed. Wet-season water samples from both stations consistently had higher concentrations of polychlorinated biphenyls (PCBs) (1.1-7.0 ng/L) and the organochlorine (OC) pesticides DDT (2.4-10 ng/L) and chlordane (0.57-5.7 ng/L) compared to RMP stations throughout the Estuary. Because of current and future efforts to develop TMDLs for these contaminants of concern, study findings emphasize the need to characterize contaminant loading from local tributaries and consider effective management solutions in the context of contaminant mass budgets for San Francisco Bay.
Key words: contaminant, river, chlorinated hydrocarbons, mercury
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