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Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments Across the Laurentian Great Lakes Region
Citation:
DREVNICK, P., D. ENGSTROM, C. DRISCOLL, E. SWAIN, S. BALOGH, N. KAMMAN, D. LONG, D. MUIR, M. PARSONS, K. ROLFHUS, AND R. ROSSMANN. Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments Across the Laurentian Great Lakes Region. ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 161:252-260, (2012).
Impact/Purpose:
To document research results.
Description:
Data from 103 sediment cores from the Great Lakes and inland lakes of the Great Lakes airshed were compiled to examine and provide a synthesis of patterns of historical and recent changes in mercury (Hg) deposition. Limited data from the lower Laurentian Great Lakes shows a legacy of substantial point source Hg contamination followed by marked decreases over the recent half century associated with decreases in industrial use and effluent controls. In contrast, Lake Superior exhibits a more subdued pattern of increasing sediment Hg deposition over a longer period followed by a recent decrease that is suggestive of a largely atmospheric source and is consistent with results from a large number of sediment cores of inland lakes across the Great Lakes airshed. We observed some spatial differences in pre-industrial, peak and modern sediment-Hg flux in the inland lakes, with greater fluxes in eastern lakes compared with those in the central or western portion of the region. In contrast, Hg flux ratios (peak to pre-industrial, modern to pre-industrial and modern to peak) and year of peak Hg flux are remarkably similar across the region, suggesting that elevated sediment Hg deposition in eastern lakes may be due to greater precipitation or greater watershed area to lake area rations in that sub-region. Our analysis suggest that proximity to local/regional urban emisssion sources, watershed area to lake surface area, and pre-industrial (<1850) Hg flux, explain much of the variation in sediment Hg accumulation in inland lakes across the Great Lakes airshed. A consistent region-wide decrease (-20%) of sediment Hg flux since the late 1980s suggests that controls on local and regional Hg emissions have been effective in decreasing the supply of Hg to Lake Superior and inland lakes across the region.
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Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments Across the Laurentian Great Lakes Region