Stable carbon isotope fractionation during the biodegradation of lambda-cyhalothrin

In this study, themicrobial degradation of lambda-cyhalothrin in soil was investigated using compound-specific stable isotope analysis. The results revealed that lambda-cyhalothrin was biodegraded in soil under laboratory conditions. The half-lives of lambda-cyhalothrinwere determined to be 49 and 161 days in non-sterile and sterile soils spiked with 2 mg/kg lambda-cyhalothrin and 84 and 154 days in non-sterile and sterile soils spiked with 10 mg/kg lambda-cyhalothrin, respectively. The biodegradation of lambda-cyhalothrin resulted in carbon isotope fractionation, which shifted from -29.0 parts per thousand to -26.5 parts per thousand in soil spiked with 2 mg/kg lambda-cyhalothrin, and to -27.5 parts per thousand with 10 mg/kg lambda-cyhalothrin. A relationship was established between the stable carbon isotope fraction and the residual concentrations of lambda-cyhalothrin by the Rayleigh equation in which the carbon isotope enrichment factor epsilon of the microbial degradation of lambda-cyhalothrin in the soil was calculated as -2.53 parts per thousand This study provides an approach to quantitatively evaluate the biodegradation of lambda-cyhalothrin in soil in field studies. (c) 2015 Elsevier B.V. All rights reserved.