Novel Biological Exposures Following the Deepwater Horizon Oil Spill Revealed by Chemical Fingerprinting

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Coastal Sciences, Gulf Coast Research Laboratory


The diverse biological resources in the northern Gulf of Mexico were variably exposed to oil released from the failed Macondo well during the Deepwater Horizon oil spill. In this study, chemical fingerprinting via gas chromatography/flame ionization detection and GC/mass spectrometry [including total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs), and petroleum biomarkers] were used to demonstrate novel exposures of four specific resources—Sargassum, deep-sea corals, osprey nests, and dolphin lung tissue. Pelagic Sargassum collected 80 and 170 km from the wellhead during the active spill contained weathered Macondo oil, whereas Sargassum collected 3 to 4 months after the spill showed no chemical evidence of exposure. Deep-sea coral 11 km from the wellhead in late 2010 contained Macondo-derived “oily” floc on its exterior, consistent with its exposure to severely weathered Macondo oil transported as dispersed droplets within the deep-sea plume—and inconsistent with local Biloxi Dome seep oil in the area. Osprey nest materials collected from three nests on Horn Island (Mississippi) in early 2011 contained weathered Macondo oil indicating direct exposure of the occupying adults, and potentially of their eggs or chicks. Finally, lung tissue from a stranded dolphin carcass collected during the spill, which had Macondo oil on its exterior, contained 0.046 μg/g (wet) of decalins and 0.162 μg/g (wet) of PAHs, mostly alkyl-naphthalenes, generally consistent with those predicted (using equilibrium partitioning theory) for the breathing zone vapor phase above moderately evaporated Macondo oil, suggesting inhalation of Macondo oil vapors occurred prior to death.

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Oil Spill Environmental Forensics Case Studies

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