FATE OF MONOCROTOPHOS IN THE ENVIRONMENT

The fate of monocrotophos in the aqueous and soil environment was examined. Hydrolysis rates for monocrotophos are pH-dependent and follow first-order kinetics. The half-lives of monocrotophos in pH 3 and 9 buffer solution at 25 °C are 131 and 26 days, respectively. N-Methylacetoacetamide and O-desmethylmonocrotophos were the major hydrolytic degradation products detected. There was no observable qualitative or quantitative difference when the aqueous and soil experiments were conducted in the dark or with exposure to sunlight. Soil metabolism studies showed rapid and extensive decomposition of monocrotophos and its soil metabolites to14CO2and unextractable residues. N-Methylacetoacetamide, N-(hydroxymethyl)monocrotophos, and 3-hydroxy-N-methylbutyramide were detected as soil degradation products. Soil TLC data indicated that monocrotophos was mobile under test conditions. Rotational crops planted at various time intervals after soil treatment contained low, if any, significant residue levels of monocrotophos or its metabolites. © 1990, American Chemical Society. All rights reserved.