Bioconcentration of organochlorine pesticides in rainbow trout caged in the River Po

Two groups of rainbow trout were caged in the River Po upstream and downstream of the confluence with the River Lambro, a relatively small tributary which drains the most industrialized and urbanized area of the entire basin. Fish were analyzed for organochlorine pesticide concentration at the start of the experiment and after 7, 15 and 30 days of exposure. The results demonstrate that the emission of the River Lambro represent an important point source of αHCH, γ-HCH and HCB to the River Po and to a smaller extent of DDT and its metabolites. On the basis of levels measured in downstream trout, the steady-state concentration of HCB and DDT metabolites were predicted by means of a computer program and compared to data referring to River Po water analysis, using the relationship between bioconcentration and Kow,.