ORGANOTINS IN FRESH-WATER HARBORS AND RIVERS - TEMPORAL DISTRIBUTION,ANNUAL TRENDS AND FATE

The occurrence of butyltin and phenyltin compounds in water, mussels, and sediment of freshwater boat harbors of Lake Lucerne, Switzerland, and six Swiss river systems was determined between 1991 and 1993 follo wing the sales ban of organotin-containing antifouling paints. In harb or waters, average levels of tributyltin (TBT) were between 40 and 50 ng/L in 1993, which was one order of magnitude lower than in 1988. Res idues of up to 9.2 mu g/g TBT and 0.7 mu g/g triphenyltin (TPT) occurr ed in zebra mussels (Dreissena polymorpha) and were related to the wat er concentrations. In a sediment core, high levels of TBT and TPT occu rred in the upper 7 cm and 5.5 cm, respectively, with significant decr eases below. Estimated sedimentation rates and the fact that transform ation products did not increase with depth indicate that TBT and TPT a re persistent in these sediments. In all rivers, di- and/or monobutylt in of up to 46 ng/L occurred consistently, and occasionally TBT and TP T of up to 26 and 11 ng/L, respectively. This study indicates that eve n though regulations were effective in reducing TBT and TPT levels in boat harbor water, contamination of surface fresh waters including riv ers by organotin compounds is still widespread and has ecotoxicologica l consequences. Moreover, harbor sediments represent long-term reservo irs of these compounds.