link to Recalcitrance and Degradation of Petroleum Biomarkers upon Abiotic and Biotic Natural Weathering of Deepwater Horizon Oil

[Scott Eustis]

As discussed in the chat

Announcement

http://gulfresearchinitiative.org/study-informs-oil-spill-forensics-with-petroleum-biomarkers-degradation-data/

author Dr Aeppli , of the Bigelow Lab at Woods Hole

 on twitter

https://twitter.com/aeppli_lab

*Phone: 207 315 2567. E-mail: cae...@bigelow.org.

pub

pubs.acs.org/doi/abs/10.1021/es500825q

Recalcitrance and Degradation of Petroleum Biomarkers upon Abiotic and Biotic Natural Weathering of Deepwater Horizon Oil

Christoph Aeppli *†, Robert K. Nelson †, Jagoš R. Radović †‡, Catherine A. Carmichael †, David L. Valentine §, and Christopher M. Reddy †

† Department of Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States

‡ Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona, 18, Barcelona 08034, Barcelona,Spain

§ Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, California 93106, United States

Environ. Sci. Technol., 2014, 48 (12), pp 6726–6734

DOI: 10.1021/es500825q

Publication Date (Web): May 15, 2014

Copyright © 2014 American Chemical Society

*Phone: 207 315 2567. E-mail: cae...@bigelow.org.

Tahnks to the authors for this chart!

Petroleum biomarkers such as hopanoids, steranes, and triaromatic steroids (TAS) are commonly used to investigate the source and fate of petroleum hydrocarbons in the environment based on the premise that these compounds are resistant to biotic and abiotic degradation. To test the validity of this premise in the context of the Deepwater Horizondisaster, we investigated changes to these biomarkers as induced by natural weathering of crude oil discharged from the Macondo Well (MW). For surface slicks collected from May to June in 2010, and other oiled samples collected on beaches in the northern Gulf of Mexico from July 2010 until August 2012, hopanoids with up to 31 carbons as well as steranes and diasteranes were not systematically affected by weathering processes. In contrast, TAS and C32- to C35-homohopanes were depleted in all samples relative to 17α(H),21β(H)-hopane (C30-hopane). Compared to MW oil, C35-homohopanes and TAS were depleted by 18 ± 10% and 36 ± 20%, respectively, in surface slicks collected from May to June 2010, and by 37 ± 9% and 67 ± 10%, respectively, in samples collected along beaches from April 2011 through August 2012. Based on patterns of relative losses of individual compounds, we hypothesize biodegradation and photooxidation as main degradation processes for homohopanes and TAS, respectively. This study highlights that (i) TAS and homohopanes can be degraded within several years following an oil spill, (ii) the use of homohopanes and TAS for oil spill forensics must account for degradation, and (iii) these compounds provide a window to parse biodegradation and photooxidation during advanced stages of oil weathering.

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Scott Eustis
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