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REVIEW OF HISTORICAL AND RECENT MERCURY CONCENTRATIONS IN GREAT LAKES SEDIMENTS
Citation:
Rossmann, R., M. C. MarvinDiPasquale, Marvin, AND Painter. REVIEW OF HISTORICAL AND RECENT MERCURY CONCENTRATIONS IN GREAT LAKES SEDIMENTS. Presented at An Ecosystem Approach to the Health Effects of Mercury in the Great Lakes Basin, Windsor, Ontario, Canada, February 26-27, 2003.
Description:
Sediments of the Great Lakes have been impacted by inputs of mercury to the lakes. The first measurements of mercury concentrations in Great Lakes sediments were for samples collected in 1968 for Lake Ontario, 1969 for Lake Huron, 1969-70 for Lake Michigan, 1970 for Lake St. Clair, 1971 for Lake Erie, 1973 for Lake Superior, the North Channel and Georgian Bay and 1975 for all of Lake Michigan The most recent collection dates for sediments measured for mercury are 1994-6 for Lake Michigan, 1997-8 for Lakes Ontario and Erie, 2000 for Lakes Superior and St. Clair, and 2002 for Lake Huron. Sediments from all lakes were analyzed for total mercury. In addition, Lake Michigan sediments were analyzed for methyl mercury. Total mercury concentrations in most the recently collected surficial sediments increase in the order Lake Michigan (78 ppb, excluding Green Bay) Lake Superior (88 ppb) Lake Erie (190 ppb) Lake St. Clair (200 ppb) Green Baay (360 ppb). For each of these lakes, total mercury concentrations in surficial sediments have decreased during the last 30 years. These decreases in Lakes Superior, Michigan, and Erie are confirmed with cores that document decreasing mercury concentrations toward the sediment surface from a subsurface maximum. This abstract does not nessarily reflect EPA policy.