Resolving polychlorinated biphenyl source fingerprints in suspended particulate matter of San Francisco Bay

The presence of PCB contamination in San Francisco Bay has been documented, but the number of sources, their chemical composition, and their geographi c/temporal distribution are poorly understood. A self-training pattern reco gnition technique, polytopic vector analysis is used to determine those par ameters from PCBs adsorbed on the particulate fraction of surface waters. F ive chemical fingerprints (end-members) were resolved. Four were consistent with published Aroclor patterns. Aroclor 1260 was observed throughout the estuary, in all cruises, with highest proportions observed in Coyote Creek, a tributary of the South Bay. A pattern that matches typical Aroclor 1254 was observed in all cruises but was in generally higher abundance in spring 1995. A second Aroclor 1254 pattern, consistent with an atypical Aroclor 1 254 batch described in the literature, was observed in moderate proportions in the three 1996 cruises. Aroclor 1248 was present in significant proport ions in only one cruise (cruise 12. July 1996) but was the dominant fingerp rint in the Central Bay samples collected at that time. End-member 5 did no t match published Aroclor source patterns. Its composition exhibits high pr o portions of the metabolism-resistant congeners PCB-138 and PCB-153. The s ource of this pattern is not known, but we hypothesize that it may be due t o sewage inputs in the Bay or from atmospheric inputs.