Pesticide uses and transfers in urbanised catchments.

An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 microg l(-1) due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 microg l(-1)), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water.