Influence of a heavy rainfall event on the leaching of [14C]isoproturon and its degradation products in outdoor lysimeters.
In four different agricultural soils the long-term leaching behaviour of [14C]isoproturon was studied in outdoor lysimeters (2 m length, 1 m2 surface area). The herbicide was applied in spring 1997 and spring 2001. At the end of the first 4-year-investigation period between 0.13% and 0.31% of the applied radioactivity was leached. Isoproturon or known metabolites could not be detected in the leachate. However, shortly after the second application isoproturon and its degradation products 2-hydroxy-isoproturon and monodemethyl-isoproturon were leached via preferential flow in one of the lysimeters (Mollic gleysol) in concentrations of 4.5 microg L-1, 3.1 microg L-1 and 0.9 microg L-1, respectively, thus considerably exceeding the EU threshold limit of 0.1 microg L-1 for ground and drinking water. The results indicate that in soils where mass flow transfer dominates, leaching of isoproturon to groundwater is of low probability whereas in highly structured soils which have the tendency to form macropores, isoproturon can be transported via preferential flow to the groundwater.
Dörfler
Ulrike
U
GSF-National Research Centre for Environment and Health, Institute of Soil Ecology, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany. doerfler@gsf.de
Cao
Guoyin
G
Grundmann
Sabine
S
Schroll
Reiner
R
D000327:Adsorption; D000383:Agriculture; D002250:Carbon Radioisotopes / Q000032:analysis; D004463:Ecology; D004784:Environmental Monitoring / Q000379:methods; D005858:Germany; D006540:Herbicides / Q000032:analysis*; D010671:Phenylurea Compounds / Q000032:analysis*; D011891:Rain; D014874:Water Pollutants, Chemical / Q000032:analysis
D002250:Carbon Radioisotopes; D006540:Herbicides; D010671:Phenylurea Compounds; D014874:Water Pollutants, Chemical; C028904:isoproturon