Hydrocarbons in deep-sea sediments following the 2010 Deepwater Horizon oil spill in the Northeast Gulf of Mexico

High-resolution analyses of sediment cores collected in the aftermath of the Deepwater Horizon (DWH) were conducted to reconstruct the concentration, composition and flux of hydrocarbons to deep-sea (pre-2010, 2010, and 2011) in the DeSoto Canyon, Northeast Gulf of Mexico. Specifically, we analyzed total organic carbon (TOC), aliphatic, polycyclic aromatic hydrocarbon (PAHs), and short-lived radionuclide (234Th, 210Pb) compounds at 2 mm and 5 mm core intervals to elucidate possible hydrocarbon sources and transport pathways to sediments during the time covered in this study. Results showed higher TOC, total aliphatics and PAH fluxes after the DWH blowout (2010-2011) compared to pre-2010 years (up to 46-, 100-, and 50-fold increase; respectively). TOC in 2010-2011 was composed of a mixture of carbon sources including terrestrial, planktonic, weathered oil, and oil. Our results demonstrate that in deep-water oil spills relatively insoluble and dissolved oil hydrocarbons reached the deep-sea. Three distinct transport pathways of hydrocarbons were identified: oil-contaminated marine snow, sinking of burned-oil particles, and advective transport of dissolved-oil from the deep intrusion (at ~1000-1200 m depth). These pathways deposited particulate organic matter, oil-droplets, weathered oil, weathered burned-oil and dissolved hydrocarbon compounds into the deep-sea during 2010-2011. Although high concentrations of PAHs were observed in 2010 (up to 525 ng g-1) compared to pre-2010 years (up to 320 ng g-1), values were lower than urbanized and industrialized areas worldwide. Nevertheless, the large increase of PAH concentrations and large PAH fluxes observed in 2010-2011 may indicate a potential ecological risk to deep-sea environments. This dataset also includes data funded under FIO Y1.x031.000:0005.