Mercury Contamination of Birds from a Polluted Watershed

From 1878 until 1970, Homestake Mining Company discharged metallic mercury (effluent from the mercury amalgamation process of gold recovery) into the Cheyenne River watershed. Total mercury concentrations in the muscle, liver, and kidney were determined for 22 species of birds collected from this contaminated western South Dakota watershed. Elevated mercury levels were found in the fish-eating birds, with especially high levels in double-crested cormorants (Phalacrocorax auritus). Levels in nonfish-eating birds were lower, but the mean residues were significantly higher than the mean levels of control birds. In general, greater mercury accumulations occurred in the livers of fish-eating birds and the kidneys of nonfish-eaters. Mercury residues were compared in muscle-liver, muscle-kidney, and liver-kidney tissue combinations. A significant correlation (P < 0.01) was found to exist for these three combinations in the five species examined.