| Abstract
| - The mobility and degradation of imazosulfuron, labeled with carbon-14 at the imidazole ([imi-14C]imazo) or pyrimidine ring ([pyr-14C]imazo), in lysimeters with 1 m2 surface and 110 cm depth wereinvestigated for three years. One lysimeter was treated with [imi-14C]imazo in two successive yearsat the rate of 50 g of active ingredient (ai)/ha each. The other two lysimeters were treated once with[pyr-14C]imazo and a mixture (1:1, w/w) of the two labeled imazosulfurons, respectively (50 g of ai/ha). In the first and second years of monitoring, the yearly mean concentration of 14C in the leachatewater was <0.10 μg/L in each lysimeter. Although in the third year the concentration of 14C in theleachate water was 0.17 μg/L for the lysimeter treated twice with [imi-14C]imazo, the concentration ofimazosulfuron and its degradation products in the leachate water ranged from 0.01 to 0.06 μg/L. Atthe study termination, the main portion of 14C recovered was found in the upper 30 cm soil layer ineach lysimeter, and no 14C was detected below a depth of 50 cm. These findings indicated thatimazosulfuron and its degradation products in soils translocated into groundwater only slightly. Keywords: Imazosulfuron; mobility; degradation; soil
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