A 150-year record of heavy metals in the varved sediments of Lake Bolterskardet, Svalbara

Abstract

Laminated sediments from Bolterskardet Lake on Svalbard provide a new 150-year record of heavy metals in the Arctic. Independent data of 137Cs and 210Pb indicate that these laminations are annually deposited varves. The high sedimentation rate and varved sediments make Lake Bolterskardet a good site for studying history of heavy metal pollution in the region. A suite of heavy metals (Pb, As, Cd , Cu, Cr, Co, Ni, and Sn) were studied. The variations of Cu, Cr, Co, and Ni concentrations show an inverse pattern with the median grain size. It suggests that the particle size has a significant role in the accumulation and enrichment of heavy metals in the sediments. In the concentration profiles of studied heavy metals, only Pb concentrations show a significant increase from the lower parts to the upper parts of the core. Profiles of "total," "lithogenic," and "anthropogenic" Pb flux also show an increasing pattern. Anthropogenic Pb flux varies between 0.1 μg cm-2 yr-1 and 12.3 μg cm-2 yr-1, with a mean value of 2.4 μg cm-2 yr-1. The anthropogenic Pb fluxes were relatively low at around 0.7 μg cm-2 yr-1 prior to 1945, slowly increased after 1945, and reached a sidestep (between 1940s and 1970s) with mean value of 1.8 μg cm-2 yr-1. Second high value period was between 1980s and 1990s with mean value of 5.9 μg cm-2 yr-1. The variation of anthropogenic Pb fluxes before 1970 in Bolterskardet Lake coincides with the sulfate record and Pb concentration data from Greenland snow and ice, and the acidity concentration in the Svalbard ice cores. However, the anthropogenic Pb fluxes during the last two decades show a rapidly increasing trend. This regional pattern may suggest that local source is an important factor for heavy metal contamination in Svalbard, and the complex of long-range transport contaminations for regional and global process. © 2006 Regents of the University of Colorado.