Distribution of mercury in unconsolidated sediments from southern Lake Michigan

Abstract

The mercury content of 132 unconsolidated sediment samples from 31 sampling stations in southern Lake Michigan was determined by a radiochemical separation technique. In the deep central portion of the southern part of the lake and in areas west of Benton Harbor, Michigan, and southwest of Grand Haven, Michigan, mercury has accumulated (0.1 to 0.4 part per million) in the uppermost sediment layers. A base level of 0.03 to 0.06 ppm mercury is found at depth in the cores. In sandy areas along the southern and southwestern shores no accumulation of mercury is apparent near the surface of the sediments; an accumulation at a lower interval in these areas is believed to be associated with the presence of metal sulfides. Mercury concentrations in the sediment-water interface samples evidently vary with the organic carbon and total sulfur concentrations of the samples.