Potential impact of soil microbial heterogeneity on the persistence of hydrocarbons in contaminated subsurface soils

• Published in: Journal of environmental management 2014-04, Vol.136, p.27-36
• Main Authors: Aleer, Sam, Adetutu, Eric M., Weber, John, Ball, Andrew S., Juhasz, Albert L.
• Format: Article
• Language: English
• Subjects: 14C-benzene mineralisation; Animal, plant and microbial ecology; Applied ecology; Benzene - chemistry; Biodegradation of pollutants; Biodegradation, Environmental; Biodiversity; Biological and medical sciences; Biomass; Bioremediation; Biotechnology; Chemical Phenomena; Cluster analysis; Conservation, protection and management of environment and wildlife; DNA, Bacterial - isolation & purification; Ecotoxicology, biological effects of pollution; Enterobacteriaceae - isolation & purification; Enterobacteriaceae - metabolism; Environment and pollution; Environmental Pollution - analysis; Fundamental and applied biological sciences. Psychology; Gammaproteobacteria - isolation & purification; Gammaproteobacteria - metabolism; General aspects; Hydrocarbons; Hydrocarbons - chemistry; Impact analysis; In situ bioremediation; Industrial applications and implications. Economical aspects; Nitrates - chemistry; Petroleum - analysis; Polymerase Chain Reaction; Pseudomonas - isolation & purification; Pseudomonas - metabolism; Soil - chemistry; Soil contamination; Soil Microbiology; Soil microorganisms; Soil Pollutants - chemistry; Spatial heterogeneity; Sulfates - chemistry; Terrestrial environment, soil, air; Xanthomonas - isolation & purification; Xanthomonas - metabolism
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2014.01.031

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 14C-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. •Bacterial spatial heterogeneity in subsurface environments was assessed at a site.•Soil from different locations had similar total petroleum hydrocarbon levels.•But differences in bacterial diversity and hydrocarbon removal potential observed.•Microbial heterogeneity led to different contaminant removal rates in soil samples.•Aerobic conditions were found to lead to better contaminant removal.