Publication Date:
2022-10-26
Description:
Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 46(12), (2019): 6745-6754, doi:10.1029/2019GL082867.
Description:
Although photochemical oxidation is an environmental process that drives organic carbon (OC) cycling, its quantitative detection remains analytically challenging. Here, we use samples from the Deepwater Horizon oil spill to test the hypothesis that the stable oxygen isotope composition of oil (δ18OOil) is a sensitive marker for photochemical oxidation. In less than one‐week, δ18OOil increased from −0.6 to 7.2‰, a shift representing ~25% of the δ18OOC dynamic range observed in nature. By accounting for different oxygen sources (H2O or O2) and kinetic isotopic fractionation of photochemically incorporated O2, which was −9‰ for a wide range of OC sources, a mass balance was established for the surface oil's elemental oxygen content and δ18O. This δ18O‐based approach provides novel insights into the sources and pathways of hydrocarbon photo‐oxidation, thereby improving our understanding of the fate and transport of petroleum hydrocarbons in sunlit waters, and our capacity to respond effectively to future spills.
Description:
We thank Robert Ricker and Greg Baker (NOAA) for helping secure the oil residues, James Payne (Payne Environmental Consultants, Inc.) for collecting many of the surface oil residues, Joy Matthews (UC Davis) for exceptional assistance in preparing and analyzing the oil residues for oxygen content and isotopes, Hank Levi and Art Gatenby at CSC Scientific Company for assistance with the water content measurements, Robyn Comny (US EPA) for providing the Alaska North Slope oil, and Rose Cory (UMich) for discussions about our findings. Special thanks to John Hayes who provided constructive feedback on a preliminary version of this dataset prior to his passing in February of 2017. We thank Alex Sessions (CalTech) for his constructive feedback during the review process. This work was supported, in part, by National Science Foundation grants RAPID OCE‐1043976 (CMR), OCE‐1333148 (CMR), OCE‐1333026 (CMS), OCE‐1333162 (DLV), OCE‐1841092 (CPW), NASA NESSF NNX15AR62H (KMS), the Gulf of Mexico Research Initiative grants ‐ 015, SA 16‐30, and DEEP‐C consortium, a fellowship through the Hansewissenschaftskolleg (Institute for Advanced Studies) to SDW, and assistant scientist salary support from the Frank and Lisina Hoch Endowed Fund (CPW).
Description:
2019-11-30
Keywords:
Petroleum hydrocarbons
;
Photochemical oxidation
;
Deepwater Horizon
;
Stable oxygen isotopes
;
Organic carbon
Repository Name:
Woods Hole Open Access Server
Type:
Article
