Redistribution of mercury from contaminated lake sediments of Clear Lake, California

Abstract

Mining operations conducted at the Sulfur Bank Mercury at Clear Lake, California, from 1872-1957, together with acid mine drainage since abandonment, deposited ca. 100 metric tons of Hg in the sediments of Clear Lake. However, the ratio of methyl:total Hg in sediments increased with distance from the mine. Water exhibited an even more gradual decline in total Hg concentrations with distance from the mine, in both unfiltered bottom water and filtered surface water. The present pattern of Hg distribution in Clear Lake shows that water column transport plays some role in the lake-wide contamination of methyl Hg, but high methylation at relatively low inorganic Hg concentrations cannot be ruled out.