Master of Science (MS)


Environmental Sciences

Document Type



Use of bioremedial technologies has gained popularity in recent decades for application at oil spill sites. While much research has been done on specific case studies along marine shores, such as with the spill of the Exxon Valdez, there still remain questions as to the advantage of active biological treatment vs. natural attenuation in freshwater environments. To examine this question, a comparative study of allochthonous and autochthonous microbial communities ability to degrade weathered oil residuals was implemented at the CITGO Petroleum Refinery in Lake Charles, Louisiana following a spill of approximately 40,000 barrels of slop oil on June 19th, 2006 into a freshwater drainage canal and wetland area. Three treatments were tested including bioaugmentation, or the addition of a cultured allochthonous microbial community, biostimulation, utilizing the addition of nutrient amendments to aid the growth of autochthonous microbial populations, and finally an experimental control or a natural attenuation treatment. After completion of treatment applications for 74 days, sampling and analysis at three sampling intervals (0, 43, and 74 days), and statistical analysis performed in two manners (including day 0 data as sampling points, and correcting for initial variability with day 0 data) research has shown that there was no statistical difference between the effects of either active treatment type and that of the experimental control. Biological remedial activity of a freshwater spill site in a warm climate was observed to be more influenced by the natural environment and climate conditions than by that of anthropogenic inputs such as nutrient supplement or selective allochthonous bacterial communities. Furthermore, autochthonous microbial communities exhibited similar bacterial activity as well as the ability to successfully reduce petroleum hydrocarbon concentrations within the freshwater canal to below that of Louisiana Department of Environmental Quality RECAP screening levels for continued industrial use based on oil Total Petroleum Hydrocarbon fraction analysis (LDEQ, 2003).



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Ralph J. Portier