Arsenic, Cadmium, Lead, Mercury, and Selenium in Sediments of Riverine and Pothole Wetlands of the North Central United States

Surface sediments (0-10 cm) collected in 1980 and 1981 from 13 wetland areas in Iowa, Montana, Nebraska, North Dakota, and South Dakota were analyzed for total concentrations of arsenic, cadmium, lead, mercury, and selenium. Sediments from pothole-type wetlands had significantly higher concentrations of arsenic, cadmium, lead, and selenium than those from riverine wetlands. Mean (and range) of dry weight concentrations (mg/kg) for pothole and riverine locations, respectively, were arsenic, 4.4 (1.4-9.3) and 2.4 (0.7-6.1); cadmium, 0.52 (0.17-0.87) and 0.26 (0.01-0.55); lead, 13 (7.4-22) and 6.6 (1.1- 14); selenium, 0.89 (0.13-2.1) and 0.52 (0.03-5.1). Mercury concentrations in sediment did not differ significantly between pothole and riverine type wetlands (mean, 0.03, range, 0.01-0.08). A comparison of the concentrations of elements found in this study with values reported in the literature indicated that, with the possible exception of one location, levels were within normal or background ranges.