||Southern California Coastal Water Research Project Authority, Long Beach. ;Los Angeles County Sanitation District, CA.;Environmental Research Lab.-Narragansett, Newport, OR. Mark O. Hatfield Marine Science Center.;National Oceanic and Atmospheric Administration, Rockville, MD. Ocean Assessments Div.
Despite major reductions in the dominant DDT and polychlorinated biphenyls (PCB) input off Los Angeles (California, U.S.A.) in the early 1970s, the levels of these pollutants decreased only slightly from 1972 to 1975 both in surficial bottom sediments and in a flatfish bioindicator (Dover sole, Microstomus pacificus) collected near the submarine outfall. In contrast, the DDT and PCB concentrations in surficial sediment, Dover sole, and various sportfish species from the outfall area decreased by about an order of magnitude between 1977 and 1981, when the input rate was relatively low and essentially constant. The total DDT:total PCB ration in the fish species collected between 1972 and 1981 more closely resembled those in the bottom sediments than those in the wastewater input. Concentrations of these pollutants in the soft tissues of the mussel Mytilus californianus, collected intertidally well inshore of the highly contaminated bottom sediments, followed much more closely the decreases in the outfall discharges. These observations suggest that contaminated sediments on the seafloor were the principal (although not necessarily direct) cause of the relatively high and persistent concentrations of DDT and PCB residues in tissues of seafood fishes and invertebrates from the study area 5-7 y after control of the dominant wastewater input.