title: Comparison of bacterial and archaeal communities in depth-resolved zones in an LNAPL body.
abstract: Advances in our understanding of the microbial ecology at sites impacted by light non-aqueous phase liquids (LNAPLs) are needed to drive development of optimized bioremediation technologies, support longevity models, and develop culture-independent molecular tools. In this study, depth-resolved characterization of geochemical parameters and microbial communities was conducted for a shallow hydrocarbon-impacted aquifer. Four distinct zones were identified based on microbial community structure and geochemical data: (i) an aerobic, low-contaminant mass zone at the top of the vadose zone; (ii) a moderate to high-contaminant mass, low-oxygen to anaerobic transition zone in the middle of the vadose zone; (iii) an anaerobic, high-contaminant mass zone spanning the bottom of the vadose zone and saturated zone; and (iv) an anaerobic, low-contaminant mass zone below the LNAPL body. Evidence suggested that hydrocarbon degradation is mediated by syntrophic fermenters and methanogens in zone III. Upward flux of methane likely contributes to promoting anaerobic conditions in zone II by limiting downward flux of oxygen as methane and oxygen fronts converge at the top of this zone. Observed sulfate gradients and microbial communities suggested that sulfate reduction and methanogenesis both contribute to hydrocarbon degradation in zone IV. Pyrosequencing revealed that Syntrophus- and Methanosaeta-related species dominate bacterial and archaeal communities, respectively, in the LNAPL body below the water table. Observed phylotypes were linked with in situ anaerobic hydrocarbon degradation in LNAPL-impacted soils.
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Irianni-Renno
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.|Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, 78712, USA.
authors.forename: Daria
authors.initials: D
authors.lastname: Akhbari
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.|Trihydro Corporation, Fort Collins, CO, 80524, USA.
authors.forename: Mitchell R
authors.initials: MR
authors.lastname: Olson
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.|Department of Civil and Environmental Engineering, University of California, 209 O'Brien Hall, Berkeley, CA, 94720, USA.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Byrne
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.|Department of Civil and Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, NC, 27708, USA.
authors.forename: Emilie
authors.initials: E
authors.lastname: Lefèvre
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.
authors.forename: Julio
authors.initials: J
authors.lastname: Zimbron
authors.affiliation: Chevron Energy Technology Company, 6001 Bollinger Canyon Road, Bldg. C1206, San Ramon, CA, 94583, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Lyverse
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO, 80523, USA.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Sale
authors.affiliation: Department of Civil and Environmental Engineering, Colorado State University, 1301 Campus Delivery, Fort Collins, CO, 80523, USA. susan.de_long@colostate.edu.
authors.forename: Susan K
authors.initials: SK
authors.lastname: De Long
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D020564:Deltaproteobacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D060587:Groundwater / Q000382:microbiology*; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D006838:Hydrocarbons / Q000378:metabolism*; D008697:Methane / Q000096:biosynthesis; D059013:Microbial Consortia / Q000235:genetics; D000066388:Oil and Gas Industry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013431:Sulfates / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D006838:Hydrocarbons; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D014874:Water Pollutants, Chemical; D008697:Methane; D010100:Oxygen
keywords: Biodegradation; LNAPL; Microbial communities; Petroleum hydrocarbons; Pyrosequencing