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Leaching of Metribuzin Metabolites and the Associated Contamination of a Sandy Danish Aquifer
Environ. Sci. Technol.,39(21), 8374-8381, 2005.,10.1021/es0506758, S0013-936X(05)00675-9
Web Release Date: September 29, 2005
Copyright © 2005 American Chemical Society
Leaching of Metribuzin Metabolites and the Associated Contamination of a Sandy Danish Aquifer
Jeanne Kjær, Preben Olsen, Trine Henriksen, Marlene Ullum
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen, Denmark, and Danish Institute of Agricultural Sciences, Research Centre Foulum, DK-8830 Tjele, Denmark
Received for review April 8, 2005 - Revised manuscript received August 26, 2005 - Accepted August 29, 2005
Abstract: As degradation products of metribuzin have received little attention as potential groundwater contaminants, we evaluated leaching of metribuzin and its primary metabolites desaminometribuzin (DA), desaminodiketometribuzin (DADK), and diketometribuzin (DK) at a sandy test site in Denmark. Soil water and groundwater were sampled monthly over a four-year period. Leaching of metribuzin and DA was negligible. DK and DADK leached from the root zone (1 meter below ground surface (mbgs)) in average concentrations considerably exceeding the EU limit value for drinking water (0.1 μg/L). Both metabolites appear to be relatively stable and persisted in soil water and groundwater several years after application. Past application of metribuzin at the site had contaminated the groundwater with both DK and DADK, which were detected in 99% and 48%, respectively, of the groundwater samples analyzed. Except for three of the groundwater samples, the DADK concentration never exceeded the EU limit value. In contrast, the annual concentration of DK exceeded 0.1 μg/L at 90% of the screens analyzed. The present findings suggest that as the degradation products of metribuzin can leach through sandy soil in high concentrations, they could potentially contaminate the groundwater. In view of this risk DK and DADK should both be included in monitoring programs and their ecotoxicological effects should be further investigated.
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