title: Multi-isotope (carbon and chlorine) analysis for fingerprinting and site characterization at a fractured bedrock aquifer contaminated by chlorinated ethenes.
abstract: The use of compound specific multi-isotope approach (C and Cl) in the characterization of a chlorinated ethenes contaminated fractured aquifer allows the identification of several sources and contaminant plumes, as well as the occurrence of biodegradation and mixing processes. The study site is located in Spain with contamination resulting in groundwater concentrations of up to 50mg/L of trichloroethene (TCE), the most abundant chlorinated ethene, and 7 mg/L of tetrachloroethene (PCE). The potential sources of contamination including abandoned barrels, an underground tank, and a disposal lagoon, showed a wide range in δ(13)C values from -15.6 to -40.5‰ for TCE and from -18.5 to -32.4‰ for PCE, allowing the use of isotope fingerprinting for tracing of the origin and migration of these contaminants in the aquifer. In contrast, there is no difference between the δ(37)Cl values for TCE in the contaminant sources, ranging from +0.53 to +0.66‰. Variations of δ(37)Cl and δ(13)C in the different contaminant plumes were used to investigate the role of biodegradation in groundwater. Moreover, the isotopic data were incorporated into a reactive transport model for determination of whether the isotope pattern observed downstream from the tank's source could be explained by the simultaneous effect of mixing and biodegradation. The results demonstrate that a multi-isotope approach is a valuable tool for characterization of complex sites such as fractured bedrock aquifer contaminated by multiple sources, providing important information which can be used by consultants and site managers to prioritize and design more successful remediation strategies.
authors.affiliation: Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona, Spain. Electronic address: jordi.palau@unine.ch.
authors.forename: Jordi
authors.initials: J
authors.lastname: Palau
authors.affiliation: Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona, Spain; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Massimo
authors.initials: M
authors.lastname: Marchesi
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Julie C C
authors.initials: JC
authors.lastname: Chambon
authors.affiliation: Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Ramon
authors.initials: R
authors.lastname: Aravena
authors.affiliation: Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona, Spain.
authors.forename: Àngels
authors.initials: À
authors.lastname: Canals
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Binning
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Poul L
authors.initials: PL
authors.lastname: Bjerg
authors.affiliation: Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona, Spain.
authors.forename: Neus
authors.initials: N
authors.lastname: Otero
authors.affiliation: Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Soler
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis; D002713:Chlorine / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater / Q000737:chemistry*; D007554:Isotopes / Q000032:analysis; D013750:Tetrachloroethylene / Q000032:analysis*; D014241:Trichloroethylene / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002247:Carbon Isotopes; D007554:Isotopes; D014874:Water Pollutants, Chemical; D014241:Trichloroethylene; D002713:Chlorine; D013750:Tetrachloroethylene
keywords: Chlorinated solvents; Compound-specific isotope analysis; Environmental forensics; Groundwater contamination