Assessment of the Leaching Potential of 12 Substituted Phenylurea Herbicides in Two Agricultural Soils under Laboratory Conditions

In this study, the potential groundwater pollution of 12 substituted phenylurea herbicides (chlorbromuron, chlorotoluron, diuron, fenuron, fluometuron, isoproturon, linuron, metobromuron, metoxuron, monolinuron, Monuron, and neburon) was investigated under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with two different agricultural soils, one hypercalcic calcisol (HC) and the other endoleptic phaeozem (EP). In the case of the HC, all of the studied herbicides were found in leachates, while for the EP only, chlorbromuron, chlorotoluron, isoproturon, monolinuron, and, especially, fenuron were recovered. For both soils, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t(1/2)) and mobility (as K-OC). The half-lives obtained were markedly higher in the EP (217-518 days) than in the HC (71-178 days). As a consequence, higher values of GUS indexes were observed for EP. The ratio of the GUS between the EP and the HC was about 1.3.