Oxygenation of petroleum hydrocarbons after the Deepwater Horizon disaster
Abstract
The release of petroleum hydrocarbons after the Deepwater Horizon incident served as a model to study petroleum oxygenation in marine systems. While such processes are well established to remove select hydrocarbons from the ocean, little attention has been given to the formed product of oil weathering: oxygenated hydrocarbons (OxHC). As they are outside the analytical windows of most commonly used method for oil spill research, OxHC have mostly been overlooked so far. However, we found that OxHC were rapidly formed during the first 100 days after the onset of the Deepwater Horizon spill, and made up 50-90% of the weathered oil mass thereafter. The OxHC fraction had an oxygen content of >10% by mass, contained carboxylic acids and alcohols, and was petroleum-derived, as confirmed by radiocarbon analysis (Aeppli et al, 2012). To investigate the oxygen incorporation processes and products, we used two strategies. First, we employed selective chemical modification of OxHC that preserved their carbon backbones while making the compounds amenable to gas chromatography for structural elucidation. This strategy allowed us to identify saturated and aromatic compounds as parent compounds of OxHC. Second, we used stable oxygen isotopes as a proxy for oxygenation, and observed O-18 enrichment with increasing degree of weathering. Overall, this study sheds light on how oil hydrocarbons are oxygenated via microbial and photochemical transformation, leading to recalcitrant products of oil weathering. Reference: Aeppli et al., (2012). Environ Sci Technol, doi:10.1021/es3015138
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B21A0341A
- Keywords:
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- 4251 OCEANOGRAPHY: GENERAL / Marine pollution;
- 4850 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Marine organic chemistry;
- 4851 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Oxidation/reduction reactions