Department of Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States.
Environ Sci Technol. 2012 Aug 21;46(16):8799-807. doi: 10.1021/es3015138. Epub 2012 Aug 2.
Following the Deepwater Horizon disaster, the effect of weathering on surface slicks, oil-soaked sands, and oil-covered rocks and boulders was studied for 18 months. With time, oxygen content increased in the hydrocarbon residues. Furthermore, a weathering-dependent increase of an operationally defined oxygenated fraction relative to the saturated and aromatic fractions was observed. This oxygenated fraction made up >50% of the mass of weathered samples, had an average carbon oxidation state of -1.0, and an average molecular formula of (C(5)H(7)O)(n). These oxygenated hydrocarbon residues were devoid of natural radiocarbon, confirming a fossil source and excluding contributions from recent photosynthate. The incorporation of oxygen into the oil's hydrocarbons, which we refer to as oxyhydrocarbons, was confirmed from the detection of hydroxyl and carbonyl functional groups and the identification of long chain (C(10)-C(32)) carboxylic acids as well as alcohols. On the basis of the diagnostic ratios of alkanes and polycyclic aromatic hydrocarbons, and the context within which these samples were collected, we hypothesize that biodegradation and photooxidation share responsibility for the accumulation of oxygen in the oil residues. These results reveal that molecular-level transformations of petroleum hydrocarbons lead to increasing amounts of, apparently recalcitrant, oxyhydrocarbons that dominate the solvent-extractable material from oiled samples.
在“深水地平线”灾难之后，对浮油、油浸沙和油覆盖的岩石和巨石进行了 18 个月的风化作用研究。随着时间的推移，烃残留物中的含氧量增加。此外，还观察到相对于饱和和芳香族馏分，风化作用导致含氧馏分的增加。该含氧馏分占风化样品质量的>50%，平均碳氧化态为-1.0，平均分子式为(C(5)H(7)O)(n)。这些含氧烃残留物不含天然放射性碳，证实了其化石来源，并排除了近期光合作用产物的贡献。我们将油中碳氢化合物的氧合作用称为含氧碳氢化合物，这是通过检测羟基和羰基官能团以及鉴定长链（C(10)-C(32)）羧酸和醇来证实的。根据烷烃和多环芳烃的诊断比，以及这些样品的采集背景，我们假设生物降解和光氧化共同导致了油残留物中氧的积累。这些结果表明，石油碳氢化合物的分子水平转化导致了越来越多的、显然难以生物降解的含氧碳氢化合物的积累，这些含氧碳氢化合物在油污染样品的可溶剂萃取物质中占主导地位。
