Bioconcentration of trace metals in rainbow trout: a field study.

Caged rainbow trout were exposed for a month at two sites in the river Po, one upstream and the other downstream of the river Lambro inlet. Gills, spleen, kidney, muscle, and vertebral bone were examined for metal content after 7, 15, and 30 days of exposure. Cd accumulated mostly in spleen and muscle; Hg in muscle and kidney; Pb in bone, spleen, and kidney; Cr in spleen, muscle, and gills; and Cu in kidney. The highest Zn levels were measured in gills, but no consistent variations were observed. Trends of accumulation, target organs, and estimated whole body contents are discussed. Although the metal content of most organs was low and variations in concentrations were relatively contained, differences between the two stations were observed for Cd, Hg, Pb, and Cr.