Survey of organochlorines in Finnish watercourses by caged mussel method.

Monitoring organochlorine compounds with caged common lake mussels (Anodonta piscinalis) in the pulp and paper mill recipient watercourses of Finland annually from 1984 produced many statistically significant time trends. A decrease of chlorophenols and chloroguaiacols originating from chlorobleaching were observed in all recipients in parallel with the decreasing discharges from the mills. Metabolites of chlorophenols, chloroanisoles and chloroveratroles were constant. Significantly elevated PCB concentrations were measured in four watercourses. At two of these areas, the PCB concentrations were constant. In contrast, a statistically significant increase of PCB (and DDE) was found at one recipient lake from mill producing recyclic paper and in a lake downstream of an industrialised city. Overall decreases were observed for other chlorohydrocarbons. Material flows of chlorohydrocarbons were, in some cases, positively correlated with waterflows (Q). [Copyright &y& Elsevier]