Composition and fate of gas and oil released to the water column during the Deepwater Horizon oil spill

Reddy, C.M. et al. (2012) Composition and fate of gas and oil released to the water column during the Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America, 109(50), pp. 20229-20234. (doi:10.1073/pnas.1101242108) (PMID:21768331) (PMCID:PMC3528605)

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Abstract

Quantitative information regarding the endmember composition of the gas and oil that flowed from the Macondo well during the Deepwater Horizon oil spill is essential for determining the oil flow rate, total oil volume released, and trajectories and fates of hydrocarbon components in the marine environment. Using isobaric gas-tight samplers, we collected discrete samples directly above the Macondo well on June 21, 2010, and analyzed the gas and oil. We found that the fluids flowing from the Macondo well had a gas-to-oil ratio of 1,600 standard cubic feet per petroleum barrel. Based on the measured endmember gas-to-oil ratio and the Federally estimated net liquid oil release of 4.1 million barrels, the total amount of C1-C5 hydrocarbons released to the water column was 1.7 × 1011 g. The endmember gas and oil compositions then enabled us to study the fractionation of petroleum hydrocarbons in discrete water samples collected in June 2010 within a southwest trending hydrocarbon-enriched plume of neutrally buoyant water at a water depth of 1,100 m. The most abundant petroleum hydrocarbons larger than C1-C5 were benzene, toluene, ethylbenzene, and total xylenes at concentrations up to 78 μg L-1. Comparison of the endmember gas and oil composition with the composition of water column samples showed that the plume was preferentially enriched with water-soluble components, indicating that aqueous dissolution played a major role in plume formation, whereas the fates of relatively insoluble petroleum components were initially controlled by other processes.

Item Type:Articles
Additional Information:This research was supported by National Science Foundation Grants OCE-1043976 to C.M.R., OCE-1045025 to R.C., and OCE-1045670 to B.A.S.V.M; US Coast Guard Grant HSCG3210CR0020 to R.C.; and Department of Energy Grant DE-FG02-06ER15775 to C.M.R.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Mcintyre, Dr Cameron
Authors: Reddy, C.M., Arey, J.S., Seewald, J.S., Sylva, S.P., Lemkau, K.L., Nelson, R.K., Carmichael, C.A., Mcintyre, C.P., Fenwick, J., Ventura, G.T., Van Mooy, B.A.S., and Camilli, R.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Proceedings of the National Academy of Sciences of the United States of America
Publisher:National Academy of Sciences
ISSN:0027-8424
ISSN (Online):1091-6490

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