title: Potential impact of soil microbial heterogeneity on the persistence of hydrocarbons in contaminated subsurface soils.
abstract: In situ bioremediation is potentially a cost effective treatment strategy for subsurface soils contaminated with petroleum hydrocarbons, however, limited information is available regarding the impact of soil spatial heterogeneity on bioremediation efficacy. In this study, we assessed issues associated with hydrocarbon biodegradation and soil spatial heterogeneity (samples designated as FTF 1, 5 and 8) from a site in which in situ bioremediation was proposed for hydrocarbon removal. Test pit activities showed similarities in FTF soil profiles with elevated hydrocarbon concentrations detected in all soils at 2 m below ground surface. However, PCR-DGGE-based cluster analysis showed that the bacterial community in FTF 5 (at 2 m) was substantially different (53% dissimilar) and 2-3 fold more diverse than communities in FTF 1 and 8 (with 80% similarity). When hydrocarbon degrading potential was assessed, differences were observed in the extent of (14)C-benzene mineralisation under aerobic conditions with FTF 5 exhibiting the highest hydrocarbon removal potential compared to FTF 1 and 8. Further analysis indicated that the FTF 5 microbial community was substantially different from other FTF samples and dominated by putative hydrocarbon degraders belonging to Pseudomonads, Xanthomonads and Enterobacteria. However, hydrocarbon removal in FTF 5 under anaerobic conditions with nitrate and sulphate electron acceptors was limited suggesting that aerobic conditions were crucial for hydrocarbon removal. This study highlights the importance of assessing available microbial capacity prior to bioremediation and shows that the site's spatial heterogeneity can adversely affect the success of in situ bioremediation unless area-specific optimizations are performed.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Mawson Lakes, Adelaide, South Australia 5095, Australia.
authors.forename: Sam
authors.initials: S
authors.lastname: Aleer
authors.affiliation: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Mawson Lakes, Adelaide, South Australia 5095, Australia; School of Biological Sciences, Flinders University, Adelaide, South Australia 5001, Australia.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Adetutu
authors.affiliation: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Mawson Lakes, Adelaide, South Australia 5095, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Weber
authors.affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia 5001, Australia.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Ball
authors.affiliation: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Mawson Lakes, Adelaide, South Australia 5095, Australia. Electronic address: Albert.Juhasz@unisa.edu.au.
authors.forename: Albert L
authors.initials: AL
authors.lastname: Juhasz
mesh_terms: D001554:Benzene / Q000737:chemistry; D001673:Biodegradation, Environmental; D044822:Biodiversity; D018533:Biomass; D055598:Chemical Phenomena; D004269:DNA, Bacterial / Q000302:isolation & purification; D004755:Enterobacteriaceae / Q000302:isolation & purification / Q000378:metabolism; D004787:Environmental Pollution / Q000032:analysis*; D020563:Gammaproteobacteria / Q000302:isolation & purification / Q000378:metabolism; D006838:Hydrocarbons / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry; D010578:Petroleum / Q000032:analysis; D016133:Polymerase Chain Reaction; D011549:Pseudomonas / Q000302:isolation & purification / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry; D014974:Xanthomonas / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D006838:Hydrocarbons; D009566:Nitrates; D010578:Petroleum; D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D001554:Benzene
keywords: (14)C-benzene mineralisation; In situ bioremediation; Spatial heterogeneity