Elza Flores Rüegg

Degradation of parathion by soil kept moist with and without repeated applications

Abstract Radiochemical methods were used to show that the persistence of parathion in a gley humic soil, rewetted and kept moist after air-drying, decreased with time. Repeated treatment with parathion (8 μg g −1 ), as an aqueous dilution of Folidol each month for 10 months had no effect on the persistence of parathion. However, the microbial population was modified by repeated treatment with parathion because aqueous suspensions of soil which received parathion degraded it faster than soil, which did not. Also, bacteria, tentatively identified as a Nocardia spp. able to degrade parathion and 4-nitrophenol, were isolated from parathion treated soil but not from untreated soil.