Following the Deepwater Horizon oil spill in April, 2010, hard structures were constructed to deter oil migration into sensitive marsh areas behind Fourchon Beach, LA These hard structures created conditions for accumulation and burial of oil across an 8 foot deep beach vertical profile. Buried oil persists in these areas due to anaerobic conditions of beach groundwater. The objectives of this thesis are to compare the rate and extent of biodegradation of 3-ring PAHs in crude oil deposits from the surface and subsurface, and to investigate effects on beach groundwater after introduction of O2. Field samples were removed from 2011-2016 from the area including oil samples from depth with a Geoprobe, oil-sand aggregates distributed over the surface of the beach, free oil floating on the groundwater surface and oil recovered during excavations used as part of response in 2013 and 2015. Weathering of PAHs was estimated based on ratios of alkylated phenanthrenes and dibenzothiophenes to poorly biodegradable chrysenes. The average weathering ratio was 0.731±0.22 for phenanthrenes and 0.48±0.22 for dibenzothiophenes. Results indicate that oil weathers significantly differently based on location in the beach vertical profile. Oil above the groundwater table was significantly more than buried oil below groundwater level. Oil above the groundwater table weathers up to 2 orders of magnitude faster than buried oil below groundwater level. A field trial of in situ biostimulation demonstrated the ability to amend groundwater with oxygen. Weathering of oil buried below the groundwater surface was seen. Terminal electron acceptors and nutrients were evaluated based on repetitive (pre and post oxygen introduction) groundwater analysis of O2, nitrate, nitrite, ferrous and ferric iron, sulfate, sulfide, ammonium, orthophosphate, pH and alkalinity. Results suggest that oxygenated groundwater is confined locally to emitter wells due to slow groundwater movement. Nutrient concentrations pH and temperature are sufficient for microbial function; however the hypersaline nature of the groundwater may limit microbe population.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11112016-102721 |
| Date | 09 December 2016 |
| Creators | Romaine, Zachary Joseph |
| Contributors | Pardue, John, White, John, Willson, Clinton |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11112016-102721/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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