title: Assessment of in situ degradation of chlorinated ethenes and bacterial community structure in a complex contaminated groundwater system.
abstract: The occurrence of in situ degradation of chlorinated ethenes was investigated using an integrated approach in a complex groundwater system consisting of several geological units. The assessment of hydrogeochemistry and chlorinated ethenes distribution using principal component analysis (PCA) in combination with carbon stable isotope analysis revealed that chlorinated ethenes were subjected to substantial biodegradation. Shifts in isotopic values up to 20.4 per thousand, 13.9 per thousand, 20.1 per thousand and 31.4 per thousand were observed between geological units for tetrachloroethene (PCE), trichloroethene (TCE), cis-dichloroethene (cDCE) and vinyl chloride (VC), respectively. The use of specific biomarkers (16S rRNA gene) indicated the presence of Dehalococcoides sp. DNA in 20 of the 33 evaluated samples. In parallel, the analysis of changes in the bacterial community composition in the aquifers using canonical correspondence analysis (CCA) indicated the predominant influence of the chlorinated ethene concentrations (56.3% of the variance, P=0.005). The integrated approach may open new prospects for the assessment of spatial and temporal functioning of bioattenuation in contaminated groundwater systems.
authors.affiliation: Department of Isotope Biogeochemistry, UFZ - Helmholtz Centre for Environmental Research, Leipzig D-04318, Germany. gwenael.imfeld@ufz.de <gwenael.imfeld@ufz.de>
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Imfeld
authors.forename: Ivonne
authors.initials: I
authors.lastname: Nijenhuis
authors.forename: Marcell
authors.initials: M
authors.lastname: Nikolausz
authors.forename: Simone
authors.initials: S
authors.lastname: Zeiger
authors.forename: Heidrun
authors.initials: H
authors.lastname: Paschke
authors.forename: Jörg
authors.initials: J
authors.lastname: Drangmeister
authors.forename: Jochen
authors.initials: J
authors.lastname: Grossmann
authors.forename: Hans H
authors.initials: HH
authors.lastname: Richnow
authors.forename: Stefanie
authors.initials: S
authors.lastname: Weber
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004269:DNA, Bacterial / Q000235:genetics; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*; D014881:Water Supply / Q000032:analysis*
chemical_list: D004269:DNA, Bacterial; D006843:Hydrocarbons, Chlorinated; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical