ABSTRACT
Information on mercury residues in field collections of living organisms is especially abundant. Elevated concentrations of mercury occur in aquatic biota from areas receiving high atmospheric depositions of mercury, or when mercury concentrations in the diet or water are elevated (Sorensen et al., 1990; Wiener et al., 1990a; Fjeld and Rognerud, 1993). Mercury levels are comparatively elevated in fish-eating fishes, birds, and mammals (Langlois et al., 1995). In general, mercury concentrations in biota were usually less than 1.0 mg/kg FW tissue in organisms collected from locations not directly affected by human use of the element. However, concentrations exceed 1.0 mg/kg — and are sometimes markedly higher — in animals and vegetation from the vicinity of chloralkali plants; agricultural users of mercury; smelters; mining operations; pulp and paper mills; factories producing mercury-containing paints, fertilizers, and insecticides; sewer outfalls; sludge disposal areas; and other anthropogenic point sources of mercury (Schmitt and Brumbaugh, 1990). In some Minnesota lakes, mercury concentrations in fish are sufficiently elevated to be potentially hazardous when ingested by mink, otters, loons, and raptors (Swain and Helwig, 1989).
