Trends of organochlorine compounds in Finnish inland waters - Results of mussel incubation monitoring 1984-1998

Caged common lake mussels (Anodonta piscinalis) have been used in the monit oring of organochlorine compounds in pulp and paper mill recipient watercou rses of Finland annually from 1984 to 1998. Statistically significant decre asing trends of chlorophenols and chloroguaiacols originating from chlorobl eaching were observed in all recipients in parallel with the decreasing dis charges from the mills. Metabolites of chlorophenols, chloroanisoles and ch loroveratroles had no or slightly increasing trends. Elevated PCB concentra tions were measured in four watercourses. In two areas, PCBs were found to be significantly increasing, in two other cases they showed no trend. A mil l producing recycled paper was apparently responsible for an increase of PC Bs and DDE in recipient water-courses. Overall decreases were observed for other chlorohydrocarbons except for DDT. Material flows of chlorohydrocarbo ns were positively correlated with waterflows (Q) in some cases.