Pesticides in groundwater in the Netherlands

Onderzoek naar het voorkomen van bestrijdingsmiddelen in het grondwater in Nederland


Groundwater in the Netherlands has been investigated for residues of pesticides. Aim of this investigation was to get more information about the threat to groundwater quality as a consequence of application of pesticides, in order to consider possible measures for protection of groundwater quality in the future. A total of 59 groundwater samples have been taken in regions where pesticides are applied and where the soil is relatively vulnerable for leaching of pesticide residues to groundwater. In contract for two provinces (Zuid-Holland and Noord- Brabant) some extra samples have been taken. Most of the samples have been taken from a depth of 5 or 10 m below soil surface. From the results can be concluded that in 36 cases groundwater contained residues of pesticides at concentrations higher than the EC-guideline for drinking water, where a maximum concentration of 0.1 mug/l is mentioned for one pesticide and 0.5 mug/l for the total of several compounds. In 42 samples residues of pesticides have been found. In groundwater below potato cultured land residues of 1,2-dichloropropane, 1,2,3-trichloropropane, MITC and aldicarbsulfon have been found. Below maize cultured land residues of atrazine, bentazone and metolachlor were present. In flower bulb culture ETU, 1,2- dichloropropane, 1,3-dichloropropane, aldicarbsulfon and chloroallylalcohol have been found in the groundwater samples ; all the samples contained at least one pesticide. Furthermore residues of gamma-HCH, bromacil, metalaxyl and mecoprop have been found in one or more samples. As a consequence of these results monitoring of some selected pesticides in selected areas is suggested. Further investigation for the presence of residues of 1,2-dichloropropane is recommended in order to judge the extent of threat to quality of deeper groundwater and possible threats for drinking water supply.

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