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ESM222Lab4_PCBs_in_SFBay_attachment - Polychlorinated...

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Polychlorinated Biphenyls in San Francisco Bay: Sources and Loadings Report June 30, 2001 California Regional Water Quality Control Board San Francisco Bay Region Prepared by Frederic Hetzel SFB-RWQCB 1515 Clay St., Suite 1400 Oakland, CA 94612 Tel. 510-622-2357 e-mail [email protected]
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DRAFT 1. Introduction Section 303(d) of the Federal Clean Water Act requires the State of California to identify all the water bodies that do not meet applicable water quality standards, and for those impaired water bodies to establish Total Maximum Daily Loads (TMDL). The 303(d) list for San Francisco Bay identified polychlorinated biphenyls (PCBs) as impairing beneficial uses of San Francisco Bay. In 1998, PCBs were placed on the 303(d) list for all San Francisco Bay segments due to an Interim Human Health Advisory caused by elevated fish tissue concentrations of PCBs (OEHHA, 1994). Note that in 2000 the USEPA reported 726 advisories nationwide for the consumption of fish due to PCBs contamination (USEPA, 2001). ). The number of fish consumption advisories due to PCBs is up from 679 in 1998 and 319 in 1993. The criterion continuous concentrations (CCC) are 0.014 and 0.030 µ g/L total PCBs for freshwater and saltwater respectively. The PCBs concentration criterion for the protection of human health from fish or water consumption is 0.00017 µ g/L. In this report, the term PCBs means total PCBs. San Francisco Bay is located on the central coast of California and marks a natural topographic separation between the northern and southern coastal mountain ranges. The Bay functions as the only drainage outlet for waters of the Central Valley. Because of its highly dynamic and complex environmental conditions, the Bay system supports an extraordinarily diverse and productive ecosystem. The basin’s deepwater channels, tidelands, and marshlands provide a wide variety of habitats that have become increasingly vital to the survival of several plant and animal species. The basin sustains communities of crabs, clams, fish, bird and other aquatic life and serves as important wintering sites for migrating waterfowl. PCB Chemical and Physical Properties PCB congeners vary markedly in their chemical and physical properties depending on the degree and position of chlorination. Important properties include non-flammability, low electrical conductivity, high thermal stability, and high boiling point. PCBs are soluble in non-polar organic solvents and biological lipids, an important property leading to their high bioaccumulation potential in biological tissues. PCBs are generally inert, and are strongly resistant to acids and alkalis. PCBs as Aroclors have a low solubility from 0.05 to 0.42 mg/L, small Henry’s Law constant and increasing log K ow from 4.7 to 6.8 with increasing chlorination (Table 3-4). Note that a log K ow greater than 3.5 is generally indicative of a great potential to bioaccumulate.
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