PT03 Persistent Organic Pollutants (POPs)
Exhibit Hall
8:00 AM - Tuesday
(PT033) Organic contaminants in sediments from Stege Marsh, San Francisco Bay, CA.
Hwang, H-M1, Young, TM1, 1 Civil & Environmental Engineering, University of California, Davis
ABSTRACT- Surface sediment samples from Stege Marsh, San Francisco Bay, CA were analyzed to investigate the levels and sources of persistent organic pollutants. Total PAH (polycyclic aromatic hydrocarbon) concentrations ranged from 2,590 to 10,700 ng/g (dry wt.). PAH distribution patterns and selected PAH ratios indicated that emission from fuel combustion is likely a major source of PAHs. Stormwater runoff from adjacent urban area entering via Carson Creek may be a major pathway transporting PAHs into Stege Marsh. Total PCB (polychlorinated biphenyl) concentrations ranged from 148 to 698 ng/g. PCB congener distribution patterns were similar to Aroclor 1240. Concentrations of total DDTs and chlordanes ranged from 41.4 to 176 ng/g and 10.8 to 85.1 ng/g, respectively, and were much higher than those in ambient San Francisco Bay sediments. 4,4′-DDT accounted less than 5% of total DDTs. In all samples, PEL (probable effects level) quotients of PAHs were above 1. PCBs, DDTs and chlordanes exceeded PEL up to 18 times, indicating that higher incidence of adverse effects on aquatic organisms are expected. Estimated body residues of PCBs, DDTs and chlordanes in fish tissue using theoretical bioaccumulation potential (TBP) were above EAP human health risk threshold and California screening values. The results from this study indicate that Stege Marsh is highly contaminated by organic chemicals and likely to impact human health and aquatic life. When SM sediments need to be dredged, it is important to note that they are not available for beneficial uses, such as habitat restoration.
Key words: PCBs, PAHs, DDTs, Sediment