Master of Science (MS)
Civil and Environmental Engineering
Six years following the Deepwater Horizon oil spill, buried MC252 oil persists on a beach segment in Fourchon, LA due to the natural anaerobic conditions of tidal groundwater. A field trial of in situ aerobic bioremediation of buried oil began on July 2015. Oxygen was added to the subsurface using Waterloo emitters which deliver O2 through diffusion via pressurized tubing in fixed groundwater wells. The multi-well injection system provided sufficient oxygen concentration in the groundwater in the immediate area of the emitters, resulting in a shift in the composition of the diverse, halophilic, hydrocarbon-degrading microbial population. Stable isotopic and radiocarbon data from dissolved inorganic carbon provided evidence of crude oil mineralization post-aeration, even in areas that had the highest level of contamination. Weathering ratios for 3-ring PAHs were reduced post-aeration, indicating increased rates of degradation of phenanthrenes and dibenzothiophenes. Serum bottle studies were conducted to analyze biodegradation of PAHs and alkanes as a response to adding varying levels of O2 over time. Oxygen amendments were found to stimulate biodegradation of recalcitrant PAHs more effectively in less oily sediments than in sediments with higher oil concentrations. The minimum oxygen amendments in this study were sufficient in shifting the microbial population to a more effectual hydrocarbon degrading community structure.
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Fitch, LeeAnn Renee, "Biodegradation of Buried MC252 Oil in Coastal Beach Sands by PAH Degraders in Response to Oxygen Biostimulation" (2016). LSU Master's Theses. 114.