After the Deepwater Horizon (DWH) blowout, MC252 crude oil was washed onto the shores of the northeastern Gulf of Mexico. Weathered oil was buried in sandy Florida beaches in the form of sands covered by oil films, small oil particles, large agglomerates and oiled sand layers. While oil films and oil particles were observed to degrade relatively quickly, larger buried sand and oil agglomerates (SOA) can persist in the dry beach sand, where they are protected from photodegradation and mechanical stress. To determine the degradation of such large agglomerates, a time series study was initiated that quantified the weight loss and compositional changes of MC252 standardized sand and oil agglomerates (sSOAs) buried at 5, 15, 25, 35, and 45 cm depths in dry beach sand at Pensacola Beach, Florida. Sets of 10 experimental, standardized SOAs were removed at 2 - 6 month intervals over a time period of 3 years. Analysis of the sSOAs revealed a total weight loss of 10.85% or 3.66 g per sSOA volume and a loss in petroleum hydrocarbons of 59% or 2.85 g per sSOA/ over the three-year burial period. Decay rate constants for saturated hydrocarbons (C15-C40) of the surface layer of the sSOAs averaged 0.0043 d-1 (SE = 0.0017) for initial 181-day period, and 0.0027 d-1 (SE = 0.0004) for the thee-year observation period (C15-C40). PAH initial decay was 0.022 d-1 (SE = 0.004) for the initial (181-day) decay and 0.005 d-1 (SE = 0.001) for three-year period for the compounds that could be detected in the sSOA surface layer (biphenyl, acenaphthylene, acenaphthene, fluorine, dibenzothiopene, phenanthrene, pyrene, benzo(c)phenanthrene, chrysene, 7,12-dimethylbenz(a)anthracene, benzo(b,j,k)fluoranthene, benzo(a)pyrene, and benzo(g,h,i)perylene) in the surface lay. The results indicate that buried larger SOAs persist in the dry beach sands for years despite access to oxygen in contrast to oil films on sand grains and buried small oil particles that at Pensacola Beach disappeared within a year. Causes for the slow degradation of larger SOAs in the beach include the lack of photodegradation, the protection from mechanical disintegration, as well as low nutrient and moisture concentrations in the sand. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester 2018. / May 14, 2018. / BP Oil, degradation, oil decay, polycyclic aromatic hydrocarbons, saturated hydrocarbons, sediment / Includes bibliographical references. / Markus H. Huettel, Professor Directing Thesis; Ian R. MacDonald, Committee Member; Yang Wang, Committee Member; Olivia U. Mason, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_650266 |
| Contributors | Bociu, Ioana (author), Huettel, Markus (professor directing thesis), MacDonald, Ian R. (committee member), Wang, Yang (committee member), Mason, Olivia Underwood (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Earth, Ocean and Atmospheric Science (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, master thesis |
| Format | 1 online resource (55 pages), computer, application/pdf |
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