Abstract
Degradation of salithion (2-methoxy-4H-1, 3, 2-benzodioxa-phosphorin-2-sulfide) in two types of Japanese soils was studied by using a 14C preparation labeled at the phenyl ring. Salithion disappeared rapidly with a half-life of less than 3 days under aerobic upland conditions, finally degrading to 14CO2 and unextractable bound residues. The degradation pathways included cleavages of P-O-aryl and P-O-aralkyl linkages, demethylation, and oxidative desulfuration of the thiophosphoryl moiety. The degradation rate retarded under sterilized conditions, suggesting microbial degradation in the soils. Non-biological formation of the bound residues also caused the disappearance of salithion in the Ushiku soil (Andosol).
