Water pollution by pesticides in three watersheds

摘要

Measurements were carried out in autumn 1996 in 3 rural sewage plants in Hesse, central Germany. Results showed that in the outflow, residues of agricultural pesticides (isoproturon, metazachlor and trifluralin) increased with increasing pesticide use, and residues of non-agricultural pesticides (diuron, simazine and chlorotoluron) increased as a function of the number of urbanized areas. The average dissipation into surface water of isoproturon and metazachlor was 0.5-1.1 litres/application. The chronological sequence of daily number of applications, number of sprayer cleanings and pesticide load showed that most of the emission occurred during the cleaning of sprayers. The outflow of sewage plants in 2 areas contributed approximately 65 and 75%to the overall pesticide load in local streams. Comparison with results of similar studies implied that almost the whole remaining pesticide load originated from point sources (farms).