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Protocol to Reconstruct Historical Contaminant Loading to Large Lakes: The Lake Michigan Sediment Record of Mercury
Citation:
ROSSMANN, R. Protocol to Reconstruct Historical Contaminant Loading to Large Lakes: The Lake Michigan Sediment Record of Mercury. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 44(3):935-940, (2010).
Impact/Purpose:
To document research results.
Description:
Samples of opportunity from Pb-210 dated sediment cores collected from Lake Michigan between 1994 and 1996 were analyzed for mercury. The storage of both anthropogenic and total (post-1850) mercury in the lake was calculated to be 186 and 228 metric tons, respectively. By setting the sum of mercury stored in a representative core equal to the mercury storage within the entire lake, the time variation of annual mercury fluxes was calculated. The modern (1980-2002) mercury flux to the lake represented by the surface of the core at the time of collection in 1994 was 21.4 µgm-2y-1. This flux was equivalent to that calculated for 1892. The preindustrial flux (=1850) was 3.09 µgm-2y-1, and the peak flux in 1946 was 53.3 µgm-2y-1. These yield modern and peak enrichment factors of 6.92 and 17.2, respectively. Modern fluxes exceed published global atmospheric flux estimates and represent global as well as local fluxes derived from both atmospheric and tributary loads. The modern mercury load to the lake was 1157 kg/y in 1994. The atmosphere was estimated to contribute 91% of the modern load to the lake. Global, regional, and local sources of mercury accounted for 40%, 56%, and 4% of the total load, respectively.
URLs/Downloads:
Protocol to Reconstruct Historical Contaminant Loading to Large Lakes: The Lake Michigan Sediment Record of Mercury