Persistence and metabolic fate of fenitrothion in northern Ontario forest soils and leaf litter under laboratory conditions

Abstract

Abstract Sandy and clay loam forest soils and leaf litter were fortified with 14C‐fenitrothion (10 μg/g) and incubated in an environmental chamber (20°C, 80% RH, 16 h light and 8 h dark) for a period of 75 d. Fenitrothion loss, metabolites and bound residues formed and 14CO2 produced, were measured at intervals of time by TLC, and radiochemical methods. The radioactivity decreased exponentially in sandy and clay loam soils, and in litter. Dissipation was slower in forest litter than in soils, and the corresponding DT50 values (d) were: 6.34, 7.98 and 16.42. The residual amounts (%) of fenitrothion on the 75th day were respectively 1.5, 1.1 and 10.2. The peak concentrations of the major metabolite (4‐nitrocresol) and the corresponding periods (d) found in sandy and clay loam soils and leaf litter were respectively 25.1%, 10; 16.6%, 15 and 6.9%, 15. The metabolite dissipated more rapidly in the soils than in litter. Aminofenitrothion vas detected sporadically in sandy loam soil at low concentrations compare...