Removal of methyl parathion from a chinampa agricultural soil of Xochimilco Mexico: A laboratory study

Large amounts of methyl parathion are used to control pests on crops when cultivated in chinampa soils of Mexico City. The effect of adding methyl parathion on soil characteristics, CO2 emissions, mineral N and 4-nitrophenol, a degradation product of methyl parathion, and the degradation of methyl parathion, was investigated in an aerobic incubation experiment. Treatments were sterilized and non-sterilized soil amended with or without methyl parathion at 280 mg kg(-1), a concentration sometimes found in the top soil. Methyl parathion removal followed a first-order kinetic with a half-life ranging from 16 to 34 days, while small amounts of 4-nitrophenol were detected after three days. No abiotic processes affected the methyl parathion concentration and no 4-nitrophenol was formed in the sterilized soil. It was found that methyl parathion was removed rapidly from soil and less than 35 mu g kg(-1) 4-nitrophenol was found in soil. (C) 2011 Elsevier Masson SAS. All rights reserved.