Non-invasive monitoring of microbial induced oil degradation in beach sediment under high conductivity conditions using the spectral induced polarization method
Massive oil spills, such as the Deepwater Horizon oil spill in April 2010, have prompted increased research and attention on the techniques available to monitor oil spills, including degradation processes, and have highlighted the limitations of existing monitoring methods. Previous research has shown the spectral induced polarization method (SIP) to be sensitive to the biogeochemical changes that occur as a result of microbial oil degradation; however, there is no research on the applicability of the SIP method under high conductivity conditions typical of coastal environments. The purpose of this study is to monitor natural attenuation of microbial oil degradation in brackish coastal sediment. Natural attenuation is of primary importance since in many instances, such as for remote and inaccessible areas, it is the only option available for remediation. This research is based on the hypothesis that biogeochemical changes due to microbially-induced processes can generate detectable SIP signals, even under high conductivity environments. Five different treatments of heavy oil contaminated sediment were run for 143 days. Results indicated that geophysical signals were more pronounced in the columns with conductivities close to the actual field conditions from where the sediments were collected. Gas Chromatography/Mass Spectrometry analysis showed decreased peaks in the chromatograms of active columns compared to control columns, as well as the appearance of metabolites, indicating degradation of the substrate (contaminant oil). The results show that SIP is sensitive to the biogeochemical changes occurring as a result of microbial oil degradation even under high conductivity conditions, indicating that it could be a useful tool to non-invasively monitor natural attenuation within brackish environments.M.S.Includes bibliographical referencesby Christine M. Kima
