Geophysical Monitoring of Hydrocarbon Biodegradation in Highly Conductive Environments

Natural attenuation is very often the remediation method of necessity, rather than choice, for beach environments impacted by offshore exploration/drilling accidents. Robust methods that can be efficiently utilized in difficult to access and ecologically sensitive areas are needed for the long-term monitoring of such degradation processes. A prime candidate for such a monitoring tool is the spectral induced polarization (SIP) method, a geophysical technique successfully used for characterization and monitoring of hydrocarbon degradation in freshwater environments. In this laboratory experiment the SIP method successfully monitored the natural degradation of beach sediments impacted by the Deepwater Horizon oil spill. Using the SIP, we were able to differentiate between biotic (e.g., microbial driven) and abiotic (e.g., dilution) degradation processes and infer degradation rates. To our knowledge this is the first effort to use the SIP method as a monitoring aid in high salinity environments. Plain Language Summary Offshore drilling/exploration accidents can result in the contamination of remote and ecologically sensitive areas. In most cases the only realistic remediation choice is natural degradation. In this paper we discuss the use of a noninvasive geophysical method, termed spectral induced polarization, as a monitoring tool of oil contamination degradation in brackish environments. The presented laboratory works supports the suitability of the method for monitoring not only the progress of degradation but also any microbial related degradation processes.