Pesticide contamination of groundwater in western Europe

Abstract

In recent years, many measurements have been made of residues of pesticides in shallow and deep groundwater in western Europe. Some triazine herbicides and their transformation products have been detected most frequently. The average concentration in measuring series for deep groundwater was usually below 0.1 μg l −1, and the highest values were usually below 0.5 μg l −1. The concentrations of mecoprop in deep groundwater ranged up to 0.6 μg l −1 and those of bentazone to almost 1.0 μg l −1. Some other herbicides were found at comparatively high concentrations and the highest values were found for TBA and TCA in tile-drain water. The soil fumigant 1,3-dichloropropene was mainly found in shallow groundwater, but its admixture 1,2-dichloropropane was also found in deep groundwater (range up to 10 μg l −1, sometimes even higher). Residues of the nematicides aldicarb and oxamyl have been measured in shallow and intermediate groundwater, but measurements for deep groundwater are still lacking. Some carbamoyl-oximes were incubated in subsoil materials to study their transformation and their rate of transformation in anaerobic subsoils was surprisingly high. The maximum admissible concentration of 0.1 μg l −1 in a Directive of the European Communities of 1980 is the subject of much debate, because a toxicological basis is lacking.