EFFECTS OF LOCAL AND DISTANT CONTAMINANT SOURCES - POLYCHLORINATED-BIPHENYLS AND OTHER ORGANOCHLORINES IN BOTTOM-DWELLING ANIMALS FROM AN ARCTIC ESTUARY

Elevated concentrations of organochlorines in the tissues of large mar ine predators in the Canadian Arctic are well documented. This paper p resents some of the first data on the composition and distribution of chlorinated organic compounds in some arctic coastal animals found at lower levels of the marine food chain. Organisms include bottom-dwelli ng invertebrates: clams (Mya truncata), mussels (Mytilus edulis), sea urchins (Strongylocentrotus droebachiensis) and fish: sculpins (Myoxoc ephalus quadricornis). The majority of samples were collected in the v icinity of Cambridge Bay, Northwest Territories (NWT), Canada; however , samples were also collected near another inhabited area (Hall Beach, NWT) and at a reference site (Wellington Bay, NWT). PCBs and other or ganochlorines typically originate in more industrialized parts of the northern hemisphere, enter the Arctic, and are subsequently biomagnifi ed. In this study, differences in the PCB congener compositions and co ncentrations, as well as the relative concentrations of a larger suite of organochlorines in biota, allowed the discrimination between local and distant PCB sources. Terrestrial runoff from southern Victoria Is land, NWT, has resulted in localized elevation of PCBs and chlorinated pesticides in marine sediment and bottom-dwelling animals. The major inputs of PCBs to coastal waters within Cambridge Bay were derived fro m local sources (the hamlet dump and DEW Line site). In addition, tran sport from more distant sources via riverine input accounts for locall y elevated concentrations of other organochlorines in upper Cambridge Bay. This process may also account for concentrations of all measured organochlorines that are higher in Wellington Bay than in Queen Maud G ulf. The high PCB concentrations in the whole tissue (excluding liver) or livers of four-horned sculpins in Cambridge Bay (up to 220 ng/g an d 1950 ng/g, respectively) and, to a lesser extent, Wellington Bay (3. 8 ng/g and 47 ng/g, respectively) reflect a strong tendency for biomag nification of PCBs in coastal benthic communities.