Fate and Persistence of exp 14 C Pesticide Residues in Different Soils: Effects of exp 14 C Pesticide Contaminated Run-off Soil Water on Biological Systems. Part of a Coordinated Programme on Isotopic-Tracer-Aided Studies of Agroc

摘要

The interaction of selected fungicides, herbicides and N-fertilizers with microorganisms in cranberry soils and their effects on the degradation of exp 14 C-phenyl-parathion were investigated. Incubation of soils with parathion or p-nitrophenol for 4 days, followed by the addition of exp 14 C-parathion resulted after 24 h in an enhanced degradation of the insecticide to exp 14 CO sub 2 (34-39% of the applied radiocarbon as opposed to 2% in controls) and also in an increased binding of exp 14 C to the soil. The fungicide captafol inhibited the degradation of soil-applied exp 14 C-parathion as evidenced by a reduction of both exp 14 CO sub 2 evolution and exp 14 C-bound residues. Maneb and benomyl suppressed the degradation of exp 14 C-parathion to exp 14 CO sub 2 but not the formation of bound residues. Addition of 2,4-D to exp 14 C-parathion treated soil also resulted in an increased persistence of the insecticide. Studies conducted with the insecticide and (NH sub 4 ) sub 2 SO sub 4 , NH sub 4 NO sub 3 , KNO sub 3 or urea showed that under all experimental conditions the total amounts of exp 14 C recovered were similar, yet the distribution of exp 14 C-compounds into benzene-soluble, water-soluble and bound residues was not. This possibly indicated a change in the pathway of exp 14 C-parathion degradation. The insecticide was most persistent in soils containing (NH sub 4 ) sub 2 SO sub 4 , as demonstrated by a recovery of 29% of the applied radiocarbon in benzene-soluble form. Analyses by TIC of this benzene extraction phase revealed the presence of exp 14 C-parathion, exp 14 C-p-aminophenol and exp 14 C-aminoparathion. (Atomindex citation 14:775835)