English 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.
