title: Microbial degradation of alpha-cypermethrin in soil by compound-specific stable isotope analysis.
abstract: To assess microbial degradation of alpha-cypermethrin in soil, attenuation of alpha-cypermethrin was investigated by compound-specific stable isotope analysis. The variations of the residual concentrations and stable carbon isotope ratios of alpha-cypermethrin were detected in unsterilized and sterilized soils spiked with alpha-cypermethrin. After an 80 days' incubation, the concentrations of alpha-cypermethrin decreased to 0.47 and 3.41 mg/kg in the unsterilized soils spiked with 2 and 10 mg/kg, while those decreased to 1.43 and 6.61 mg/kg in the sterilized soils. Meanwhile, the carbon isotope ratios shifted to -29.14 ± 0.22‰ and -29.86 ± 0.33‰ in the unsterilized soils spiked with 2 and 10 mg/kg, respectively. The results revealed that microbial degradation contributed to the attenuation of alpha-cypermethrin and induced the carbon isotope fractionation. In order to quantitatively assess microbial degradation, a relationship between carbon isotope ratios and residual concentrations of alpha-cypermethrin was established according to Rayleigh equation. An enrichment factor, ϵ = -1.87‰ was obtained, which can be employed to assess microbial degradation of alpha-cypermethrin. The significant carbon isotope fractionation during microbial degradation suggests that CSIA is a proper approach to qualitatively detect and quantitatively assess the biodegradation during attenuation process of alpha-cypermethrin in the field.
authors.affiliation: MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Zemin
authors.initials: Z
authors.lastname: Xu
authors.affiliation: MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Department of Environmental Engineering, Quzhou University, Quzhou 324000, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Shen
authors.affiliation: Laboratory for Teaching in Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xi-Chang
authors.initials: XC
authors.lastname: Zhang
authors.affiliation: MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Liu
authors.affiliation: MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Department of Effect-Directed Analysis, Helmholtz Center for Environmental Research - UFZ, Leipzig 04318, Germany. Electronic address: fxyang@zju.edu.cn.
authors.forename: Fangxing
authors.initials: F
authors.lastname: Yang
mesh_terms: D001673:Biodegradation, Environmental; D002247:Carbon Isotopes / Q000032:analysis; D011722:Pyrethrins / Q000032:analysis / Q000378:metabolism*; D012987:Soil / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D011722:Pyrethrins; D012987:Soil; C017160:cypermethrin
keywords: Alpha-cypermethrin; Carbon isotope fractionation; Compound-specific stable isotope analysis; Microbial degradation