HISTORICAL ACCUMULATION OF ATMOSPHERICALLY DERIVED POLLUTANT TRACE-METALS IN THE ARCTIC AS MEASURED IN DATED SEDIMENT CORES

Sediment cores were collected from an undisturbed arctic lake on the Belcher Islands in southeastem Hudson Bay in order to assess the history of trace metal deposition from the atmosphere. Since there is no industry or agriculture on the islands, the only local source of any pollutant trace metals is a native Inuit community established there in 1967. Most of the mass of anthropogenic trace metals found there is carried through the atmosphere from distant sources. Sediment cores collected in 1983 and 1990 were dated using Pb-210 and Cs-137, and analyzed for lead, cadmium, zinc, copper and mercury. Sediment redistribution (focusing) was estimated by measurement of Cs-137 burden in sediment and compared to estimated total atmospheric inputs. Consistent background fluxes for each metal, corrected for redistribution, were found in each core at layers dated-up to World War II. Inputs during the post-War period, emphasized here, have increased apparently from anthropogenic inputs through the atmosphere. The mass of metals input follows the pattern zinc > copper > lead > cadmium > mercury, typical of remote areas. The pattern and values of surface sediment flux enrichment of these metals relative to background is lead, 3.5, mercury, 3.2, cadmium, 1.8, zinc, 1.6, copper, 1.6.