Persistence and Degradation of Pesticide Residues in Different Agricultural Soils, Related to Biological Activity. Part of a Coordinated Programme on Isotopic-Tracer-Aided Studies of Agrochemical Residue - Soil Biota Interactions.

摘要

Laboratory studies and small-scale field experiments were conducted involving pesticides extensively used in agricultural practice in Brazil (the insecticides aldrin, carbaryl and parathion, and the fungicides carbendazim and metalaxyl) with emphasis on biological activity and soil organic matter content. The ability of fungi isolated from soils of southern, centre and northern regions of Brazil to degrade exp 14 C-aldrin and its metabolites was assayed in culture growth medium. Results showed that the microorganism Penicilium sp. was able to metabolize the parent compound or one of its metabolites added to the medium. Field studies performed with soils packed into PVC tubes showed that added exp 14 C-aldrin leached fastest in the soil poor in organic matter. exp 14 C-carbaryl was used to evaluate the effects of addition of carbon sources on its persistence and degradation in soils rich and poor in organic matter. It was found that cellulose can influence the behaviour of carbaryl in soil low in organic matter by interfering with microorganismal population. Studies on the degradation of exp 14 C-parathion by soil kept moist with and without repeated applications demonstrated that microbial population was modified by the repeated treatment. The adsorption, movement and persistence of the fungicide exp 14 C-carbendazim was examined in Brazilian soils differing in organic matter content. Soils with highest levels. (Atomindex citation 14:727872)