AEROBIC SOIL METABOLISM OF FLUPYRAZOFOS

To elucidate the fate of flupyrazofos [O,O-diethyl yl-3-trifluoromethy l-5-pyrazoyl)phosphorothionate] in soil, an aerobic soil metabolism st udy was carried out for 60 days with [C-14]flupyrazofos applied at a c oncentration of 0.38 mu g g(-1) to a loamy soil. The material balance ranged from 103.5% to 86.9% and the half-life of [C-14]flupyrazofos wa s calculated to be 13.6 days. The metabolites identified during the st udy were 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole (PTMHP) and O,O- diethyl O-(1-phenyl-3-trifluoromethyl-5-pyrazoyl)phosphate (flupyrazof os oxon), with maximum levels of 9.8% and 1.6% of applied radiocarbon, respectively. Evolved [C-14]carbon dioxide accounted for up to 5.3% o f applied radiocarbon and no volatile products were detected during th e study. Non-extractable C-14-residue reached 31.6% of applied materia l at 60 days after treatment and radiocarbon was distributed almost ev enly in humin, humic acid and fulvic acid fraction. (C) 1998 Society o f Chemical Industry.