Cadmium, lead, mercury, arsenic, and selenium concentrations in freshwater fish, 1976-77--National Pesticide Monitoring Program.

As part of the National Pesticide Monitoring Program, the Fish and Wildlife Service, U.S. Department of the Interior, collected freshwater fish during 1976--77 from 98 monitoring stations and analyzed them for residues of cadmium, lead, mercury, arsenic, and selenium. Range and geometric mean values in mg/kg wet weight follow: Cd, 0.01--1.04, 0.07; Pb, 0.10--4.92, 0.32; Hg, 0.01--0.84, 0.11; As. 0.05--2.92, 0.27; Se, 0.05--2.87, 0.56. An arbitrary 85th percentile was calculated for concentrations of each element in fish to identify monitoring stations having fish with higher-than-normal concentrations: Cd, 0.11 mg/kg; Pb, 0.44; Hg, 0.19: As, 0.38; Se, 0.82. Log-transformed mean concentrations in fish from 1976--77 monitoring stations are compared with means from the same stations in 1972 (Cd, Hg, Pb, As, Se) and 1973 (Se) to depict temporal trends in whole-body concentrations: Cd, significant decline; Pb, no significant difference; Hg, significant decline; As, significant increase; Se, no significant difference. Because of changes in laboratories and analytical procedures, these conclusions should be used cautiously as trend information. Production, consumption, and disposal of cadmium, lead, mercury, arsenic, and selenium are discussed as potential environmental sources of the elements to the aquatic environment. Specific environmental sources are suggested for monitoring stations having trace element levels exceeding calculated 85th percentiles.