PESTICIDES IN THE RIVER RHINE

Since 1987 significant decrease of pesticide concentrations in the riv er Rhine has been observed. This is due to the improvement of waste wa ter treatment processes and the closing of some pesticide production s ites in the Rhine basin area. Whereas in the last years point pollutio n from waste water effluents was the dominant source for pesticide inp ut into the river. nowadays the nonpoint pollution (diffuse runoff) be comes more and more important. This leads to seasonal occurrence or to higher concentration peaks after application in agriculture. Only for atrazine and its metabolite desethylatrazine very low ,,background''- levels could regularly be found along the river and all over the year. Furthermore pesticide metabolites and by-products seem to be interest ing for evaluating pesticide pollution in the river Rhine.