title: Isotope fractionation of toluene: a perspective to characterise microbial in situ degradation.
abstract: A concept to assess in situ biodegradation of organic contaminants in aquifers is presented. The alteration of the carbon isotope composition of contaminants along the groundwater flow path indicates microbial degradation processes and can be used as an indicator for in situ biodegradation. The Rayleigh equation was applied to calculate the percentage of the in situ biodegradation (B[%]) using the change in the isotopic composition of contaminants (Rt/R0) along the ground water flow path and a kinetic carbon isotope fractionation factor (alphaC) derived from defined biodegradation experiments in the laboratory. When the groundwater hydrology is known and a representative source concentration (C0) for a groundwater flow path can be determined, the extent of in situ biodegradation can be quantified.
authors.affiliation: UFZ Centre for Environmental Research Leipzig Halle Ltd., Permoserstr. 15, 04318 Leipzig, Germany. richnow@san.ufz.de
authors.forename: H H
authors.initials: HH
authors.lastname: Richnow
authors.forename: A
authors.initials: A
authors.lastname: Vieth
authors.forename: M
authors.initials: M
authors.lastname: Kastner
authors.forename: M
authors.initials: M
authors.lastname: Gehre
authors.forename: R U
authors.initials: RU
authors.lastname: Meckenstock
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis*; D005591:Chemical Fractionation / Q000379:methods; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D014050:Toluene / Q000737:chemistry*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis
chemical_list: D002247:Carbon Isotopes; D014874:Water Pollutants, Chemical; D014050:Toluene