Field metabolomics and laboratory assessments of anaerobic intrinsic bioremediation of hydrocarbons at a petroleum-contaminated site.
Bottom Line: Benzene, ethylbenzene, 2-methylnaphthalene, 1,2,4- and 1,3,5-trimethylbenzene were targeted as contaminants of greatest regulatory concern (COC) whose intrinsic remediation has been previously reported.We could find no in situ benzene intermediates (phenol or benzoate), the parent molecule proved recalcitrant in laboratory assays and low copy numbers of Desulfobacterium were found, a genus previously implicated in anaerobic benzene biodegradation.Thus, while the intrinsic anaerobic bioremediation was clearly evident at the site, non-COC hydrocarbons were preferentially metabolized, even though there was ample literature precedence for the biodegradation of the target molecules.
Affiliation: Department of Botany and Microbiology and Institute for Energy and Environment, University of Oklahoma, Norman, Oklahoma 73019, USA.Show MeSH
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Mentions: Sulfate reduction could be measured in all aquifer material incubations regardless of COC amendment (Fig. 2). As replicate incubations varied, the rates were averaged with extremes (highest and lowest values) indicated. Given that hydrocarbon metabolism can sometimes require long incubation periods (Caldwell and Suflita, 2000), sulfate was replenished (134 days) when the concentration of this anion fell to approximately 100 µM. The sulfate reduction rates in the COC‐amended incubations were not significantly different before or after the sulfate replenishment or from the substrate‐unamended control. Thus, the hydrocarbon addition did not inhibit background microbial activity. The average rate of sulfate loss for all incubations (excluding toluene) was 55.0 ± 8.0 µM day−1 (Fig. 2). Toluene, the positive control, stimulated sulfate reduction above the substrate‐unamended control (Fig. 2).
Affiliation: Department of Botany and Microbiology and Institute for Energy and Environment, University of Oklahoma, Norman, Oklahoma 73019, USA.