Degradation of [C-14]tebupirimphos under anaerobic aquatic conditions

An anaerobic aquatic metabolism study with [pyrimidinyl-2-C-14]tebupirimphos at a concentration of 2 ppm Was conducted using a sandy loam flooded with pond water at a constant 22 degrees C. Over the course of the study, extractable residues from water decreased from 56.9% at day 0 to 42.6% of the applied radioactivity at day 127. Extractable residues from soil decreased from 38.3% at day 0 to 30.7% at day 127. Nonextractable residues in water cmd soil at the end of day 127 were 22.3% and 7.4%, respectively. Volatile residues never exceeded 0.1% of the applied radioactivity during the entire period of incubation. The parent concentration declined from 93.5% at day 0 to 51.1% at day 127. The half-life of tebupirimphos under anaerobic aquatic conditions was calculated to be 194 days. The degradates formed were desisopropyltebupirimphos, desethyltebupirimphos, tert-butylhydroxypyrimidine, and the S-ethyl isomer of isopropyltebupirimphos. Desisopropyltebupirimphos and tert-butylhydroxypyrimidine were the major products (>10%), whereas desethyltebupirimphos and the S-ethyl isomer of isopropyltebupirimphos never exceeded 3% of the applied radioactivity during the entire period of incubation.