Pollution of surface waters with pesticides in Germany: modeling non-pointsource inputs

Pesticide pollution of surface waters represents a considerable hazard for the aquatic environment. However, the mean amount of pesticides reaching th e water resources vanes considerably between regions and depends highly upo n application rates, chemical characteristics of pesticides and natural con ditions during application. In this study a model was developed which estim ates loss of 42 active ingredients applied to 11 field crops, vineyards and orchards along each non-point source path of entry (subsurface drains, run off and spray drift). A spatially and temporally differentiated data set of application rates and periods was compiled for each active ingredient and target culture to enable the modeling of pesticide transport. The model res ults are provided in digital raster format (100 mx 100 m) within a geograph ic information system (GIS). The calculated pesticide loads in surface wate rs were compared with measured loads from different catchments in Germany. Both data sets agreed as to the order of magnitude, nevertheless due to the scale of the study the estimated loads cannot be interpreted as absolute v alues and only differences between active ingredients, regions and applicat ion periods should be assessed. (C) 2000 Elsevier Science B.V. All rights r eserved.