ABSTRACT
Soluble and solid phase geochemical profiles as well as microbiological rate experiments were used to evaluate the dominant terminal electron accepting processes occurring in an aquifer polluted by complex mixtures of hydrocarbons. Sulfate reduction and methanogenesis were identified as dominant processes influencing the biodegradation of aquifer contaminants. Sedimentary microorganisms were able to biodegrade complex hydrocarbon mixtures most readily under sulfate reducing conditions. Sulfate depletion could be correlated with the loss of distinct hydrocarbon components. Evidence for the anaerobic microbial destruction of whole oils, gas condensate, mono- and polynuclear aromatic hydrocarbons, as well as straight and branched chain alkanes could be obtained. Collectively, the anaerobic biodegradation patterns observed in our experiments help explain the in-situ hydrocarbon profiles measured in petroleum-contaminated sediments and help illustrate the importance of intrinsic remediation activity in governing the transport and fate of these materials in complex environments.
