title: Macondo oil in deep-sea sediments: Part 1 - sub-sea weathering of oil deposited on the seafloor.
abstract: Chemical analysis of sediment cores collected up to 8km from the Macondo well in 2010/2011 demonstrates the extent of weathering of the Macondo oil deposited in deep-sea sediments following the Deepwater Horizon disaster. On average, dissolution and biodegradation of the oil on the seafloor increased with distance from the well indicating that weathering occurred rapidly and overwhelmingly during the oil's transport as dispersed oil droplets within the deep-sea plume. Beyond about 5km from the well, the oil deposited on the seafloor had lost most mass below C25, was relatively enriched in n-C25+ n-alkanes and C3- and C4-alkylated benz[a]anthracenes/chrysenes, the latter owing to 95% depletion of total PAHs. Biodegradation of C28 and C29 tricyclic terpanes, C34 and C35 17α(H),21β(H)-homohopanes, C27 13β(H),17α(H)-dia and C27 14β(H),17β(H)-steranes and dissolution of C26 to C28 triaromatic steroids occurred. The results provide a means to distinguish Macondo oil in deep-sea sediments from naturally-occurring seep oils and pervasive ambient background hydrocarbons.
authors.affiliation: NewFields Environmental Forensics Practice, LLC, 300 Ledgewood Pl., Suite 305, Rockland, MA, United States. Electronic address: sstout@newfields.com.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Stout
authors.affiliation: Payne Environmental Consultants, Inc., 1651 Linda Sue Ln., Encinitas, CA, United States.
authors.forename: James R
authors.initials: JR
authors.lastname: Payne
mesh_terms: D000473:Alkanes / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D006838:Hydrocarbons / Q000032:analysis / Q000737:chemistry; D061329:Oil and Gas Fields; D010578:Petroleum / Q000032:analysis; D059392:Petroleum Pollution / Q000032:analysis; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000473:Alkanes; D006838:Hydrocarbons; D010578:Petroleum; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical
keywords: Biodegradation; Biomarkers; Deep-sea plume; Deepwater Horizon; Dissolution; PAH