DEGRADATION OF [C-14] TEBUPIRIMPHOS UNDER ANAEROBIC AQUATIC CONDITIONS

An anaerobic aquatic metabolism study with [pyrimidinyl-2-C-14]tebupir imphos at a concentration of 2 ppm Was conducted using a sandy loam fl ooded with pond water at a constant 22 degrees C. Over the course of t he study, extractable residues from water decreased from 56.9% at day 0 to 42.6% of the applied radioactivity at day 127. Extractable residu es from soil decreased from 38.3% at day 0 to 30.7% at day 127. Nonext ractable residues in water cmd soil at the end of day 127 were 22.3% a nd 7.4%, respectively. Volatile residues never exceeded 0.1% of the ap plied radioactivity during the entire period of incubation. The parent concentration declined from 93.5% at day 0 to 51.1% at day 127. The h alf-life of tebupirimphos under anaerobic aquatic conditions was calcu lated to be 194 days. The degradates formed were desisopropyltebupirim phos, desethyltebupirimphos, tert-butylhydroxypyrimidine, and the S-et hyl isomer of isopropyltebupirimphos. Desisopropyltebupirimphos and te rt-butylhydroxypyrimidine were the major products (>10%), whereas dese thyltebupirimphos and the S-ethyl isomer of isopropyltebupirimphos nev er exceeded 3% of the applied radioactivity during the entire period o f incubation.