Investigation of a wood treatment facility: Impact on an aquatic ecosystem in the San Joaquin River, Stockton, California

Abstract

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and metals were monitored in the river sediments near the McCormick and Baxter (MCB) wood treatment facility, Stockton, CA. Transplanted clams and resident fish species were used to assess bioavailability. The highest PCDD and PCDF contamination in sediments were confined to an area next to the facility and an area in the nearby Stockton harbor (DK location). Pentachlorophenol (PCP) wood treatment at MCB was the most probable source of the contamination. PCBs contaminated a wider area of the Stockton Ship Channel and harbor. Metal concentrations were uniformly low except for the metalloid arsenic in the Old Mormon Slough and lead and zinc near boat docks in the Stockton harbor. Despite high mortality rates, clams (Corbicula fluminea) bioaccumulated PCBs, PCDDs, and PCDFs. In clams, PCBs and 2,3,7,8 TCDD were much closer to equilibrium with the sediments than were higher chlorinated PCDDs and PCDFs. All fish were at background levels for 2,3,7,8 TCDD. All fish had lower lipid adjusted PCDD/F and PCB concentrations in the skinned muscle than in the whole fish. PCBs in fish were above background levels for United States river systems. Although high contamination exists in the river near this superfund site, adverse effects on the aquatic community could not be demonstrated.