Assessment of heavy metals in red king crabs following offshore placer gold mining

Red king crabs, Paralithodes camtschaticus, with commercial and subsistence importance, seasonally occur nearshore in Norton Sound, north-eastern Beri ng Sea, Arctic Alaska. Since the end of the nineteenth century, the coastal area in the northern Sound has been intensively mined for placer gold. Min ing was extended offshore in 1986-1990. Heavy metal concentrations in the c rabs were monitored during 1987-1990 to assess the impact of offshore minin g. Crabs were only present in the study area during ice-covered months when mining was seasonally suspended, Arsenic, Cd, Cr, Cu, Ph, Ni, Zn and Hg co ncentrations in muscle and hepatopancreas tissues were generally not differ ent between mined and unmined reference (control) areas. Furthermore, conce ntrations of these metals were not different in similar surficial sediments upcurrent and downcurrent of mining. The concentrations of most metals in both tissues fluctuated over the study period, with no temporal trend. Exce ptions were for Hg in muscle tissue and As in hepatopancreas tissue which s howed progressive significant increases each year. Also, there was a fracti onation of selected metals between the two tissues; Cr, Pb and Zn were grea ter in muscles, whereas Cd, Cu and Ni were greater in hepatopancreas. Arsen ic and Hg had similar concentrations in both tissues. All elemental concent rations in the crab muscles from Norton Sound were below or within the rang e of concentrations observed in red king crabs from five other locations in the North Pacific, including a mined area. In Norton Sound, all metals, ex cept Cd, were at least an order of magnitude below the US Food and Drug Adm inistration guidance levels for contamination or human consumption. This in vestigation demonstrated that mining activities did not affect the concentr ations of the heavy metals measured in red king crabs, (C) 2000 Elsevier Sc ience Ltd. All rights reserved.