TRANSPORT AND TRANSFORMATION OF C-14 TERBUTHYLAZINE IN SUBSURFACE GRAVEL UNDER SATURATED AND UNSATURATED WATER FLOWING CONDITIONS

C-14-Terbuthylazine was applied to subsurface gravel in laboratory col umns at a rate corresponding to 0.67 kg/ha, and in an outdoor lysimete r at a rate corresponding to 0.30 kg/ha. In the columns, the transport was investigated both under saturated and unsaturated water flowing c onditions, and in the lysimeter, under unsaturated conditions only. Th e retardation factor was smaller under saturated (R-f = 2.4) than unde r unsaturated (R-f = 5.1) conditions whereas recoveries decreased in t he order saturated column (W = 59.7 %) > unsaturated column (W = 31.7 %) > lysimeter (W = 15.4 %). Deethylterbuthylazine was formed during t he transport and exhibited a lower retardation factor than terbuthylaz ine. (C) 1997 Elsevier Science Ltd.