Resolving Biodegradation Patterns of Persistent Saturated Hydrocarbons in Weathered Oil Samples from the Deepwater Horizon Disaster

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• 作者：Jonas Gros ; Christopher M. Reddy ; Christoph Aeppli ; Robert K. Nelson ; Catherine A. Carmichael ; J. Samuel Arey
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：February 4, 2014
• 年：2014
• 卷：48
• 期：3
• 页码：1628-1637
• 全文大小：554K
• ISSN：1520-5851

文摘

Biodegradation plays a major role in the natural attenuation of oil spills. However, limited information is available about biodegradation of different saturated hydrocarbon classes in surface environments, despite that oils are composed mostly of saturates, due to the limited ability of conventional gas chromatography (GC) to resolve this compound group. We studied eight weathered oil samples collected from four Gulf of Mexico beaches 12鈥?9 months after the Deepwater Horizon disaster. Using comprehensive two-dimensional gas chromatography (GC脳GC), we successfully separated, identified, and quantified several distinct saturates classes in these samples. We find that saturated hydrocarbons eluting after n-C22 dominate the GC-amenable fraction of these weathered samples. This compound group represented 8鈥?0%, or 38鈥?8 thousand metric tons, of the oil originally released from Macondo well. Saturates in the n-C₂₂ to n-C₂₉ elution range were found to be partly biodegraded, but to different relative extents, with ease of biodegradation decreasing in the following order: n-alkanes > methylalkanes and alkylcyclopentanes+alkylcyclohexanes > cyclic and acyclic isoprenoids. We developed a new quantitative index designed to characterize biodegradation of >n-C₂₂ saturates. These results shed new light onto the environmental fate of these persistent, hydrophobic, and mostly overlooked compounds in the unresolved complex mixtures (UCM) of weathered oils.