title: Kinetics of biotransformation of chlorpyrifos in aqueous and soil slurry environments.
abstract: The attenuation of chlorpyrifos (CPF) by the enriched indigenous soil microorganism was studied in 15 d aerobic and 60 d anaerobic batch experiments in aqueous and soil slurry (1:3 w/w) media. At the end of the batch experiments, 2.78 ± 0.11 μM of CPF was degraded by 82% in aerobic and 66% in anaerobic aqueous environments, while 12.4 ± 0.5 μM of CPF was degraded by 48% in aerobic and 31% in anaerobic soil slurries. The reduced degradation in the soil slurries was due to the significantly (2-10 times) slower rate of degradation of soil phase CPF compared with its degradation rate in water. The pathways of degradation of CPF were identified, including a partial anaerobic degradation pathway that is constructed for the first time. The simulation of the various conversions in the degradation pathways using first order kinetics was used to analyze relative persistence of metabolites. The common metabolite 3,5,6-trichloro-2-pyridinol (TCP) accumulated (increased monotonically during the period of experiments) in aerobic soil slurry and in anaerobic aqueous as well as soil slurry systems but did not accumulate in aerobic aqueous system. The most toxic compound in the pathway, chlorpyrifos oxon (CPFO) was not detected in anaerobic environment. In aerobic environment, CPFO was short lived in aqueous medium, but accumulated slowly in the soils.
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India; School of Water Resources, Indian Institute of Technology Kharagpur, Kharagpur 721302, India. Electronic address: mktiwari@iitk.ac.in.
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Tiwari
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
authors.forename: Saumyen
authors.initials: S
authors.lastname: Guha
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D004390:Chlorpyrifos / Q000378:metabolism*; D002849:Chromatography, Gas; D004785:Environmental Pollutants / Q000378:metabolism*; D007306:Insecticides / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D012988:Soil Microbiology; D014871:Water Microbiology
chemical_list: D004785:Environmental Pollutants; D007306:Insecticides; D004390:Chlorpyrifos
keywords: Aerobic and anaerobic medium; Biodegradation pathway; Chlorpyrifos; Kinetics; Metabolites; Soil slurry