Abstract

In 1991 the monitoring program on pesticide residues occuring in the uppermost groundwater was continued. Several permanent wells, placed below agricultural land used for potatoe-, maize- and flowerbulb culture, as well as wells placed below uncropped land, have been sampled and analysed for pesticides residues. The sampling took place on vulnerable soil types as well as soil types that were expected to be less vulnerable to leaching of pesticides. Below both vulnerable and less vulnerable soils pesticide residues have been found. Since the start of this sampling program in 1988, 26 different organic compounds have been detected in the wells. In 1991 21 compounds were found. The compounds are residues of pestivides allowed as well as forbidden for use in groundwater protection areas. Some of the highest concentrations were found for transformation products and admixtures.