Oil spill fingerprinting method for oily matrices used in the Deepwater Horizon NRDA

ABSTRACT

The circumstances of the Deepwater Horizon oil spill and the resulting multiyear natural resources damage assessment (NRDA) investigation presented challenges to conventional oil spill fingerprinting protocols that included rapid weathering of the spilled oil, the practical aspects of intra-laboratory reproducibilty in analyses conducted over multiple years, and the fact that spilled Macondo well oil was geochemically similar to other spilled and naturally seeped crude oils from the northern Gulf of Mexico. This article describes a three-tiered oil spill fingerprinting method, based largely upon modification of existing quantitative methodology, that was used to compare nearly 1,600 oily matrix NRDA samples to the spilled Macondo oil. The method was also used to compare fresh Macondo oil to genetically related crude oils from the northern Gulf of Mexico, and in most cases could distinguish Macondo oil from closely related oils from the region.

KEYWORDS:

• Biomarkers
• weathering
• reproducibility
• diagnostic ratio
• Macondo

Acknowledgment

The author wishes to thank the efforts of numerous NRDA field teams that collected the samples used in this analysis. The author also wishes to thank Nancy Rothman (New Horizons), William B. Driskell (Driskell Consultants), Ann Jones (Industrial Economics, Corp.), and Greg Baker (NOAA) for coordinating the large analytical program; Wendy Wong and Eric Litman (NewFields), who managed the chemical analysis at Alpha Analytical; and George Desreuisseau and Gang Hu (NewFields) for organizing the data used for chemical fingerprinting analysis. This study was conducted within the Deepwater Horizon NRDA investigation, which was cooperatively conducted by NOAA, other Federal and State Trustees, and BP. The scientific results and conclusion of this publication, as well as any views or opinions expressed herein, are those of the author only. The author declares no competing financial interest in the publication of this study.

Funding

Funding for the study was provided by NOAA through Industrial Economics, Corp. (Cambridge, MA) as part of the NRDA process.