Abstract

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.

Purpose

The data were collected to asses the concentration, composition and fluxes of hydrocarbons in sediments collected from the DeSoto Canyon located NE of the Deepwater Horizon; to reconstruct the hydrocarbon deposition history in the study area not previously available (pre-2010, 2010, and 2011); and to explain the possible sources and transport pathways of hydrocarbons to deep sediments during the period of the study.

Keywords

Aliphatics, Organic geochemistry, Polycyclic Aromatic Hydrocarbons (PAHs)

UDI

R1.x135.119:0004

Date

3-17-2016 12:00 AM

Point of Contact

Hollander, David
University of South Florida
College of Marine Science
140 7th Ave South
St. Petersburg , FL 33701
USA
davidh@marine.usf.edu

Funding Source

RFP-I

Start of Data Collection

12-1-2010

End of Data Collection

2-28-2011

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