Unexpected Sink for Deepwater Horizon Oil May Influence Future Spill Response

Abstract

A town hall meeting was organized by the Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) inter‐consortia Gulf of Mexico Research Initiative (GoMRI) working group and the Center for Spills in the Environment in conjunction with the Gulf of Mexico Oil Spill and Ecosystem Science Conference. The meeting had the goal of evaluating sedimentation to the seafloor as a significant pathway and fate of oil after the Deepwater Horizon (DwH) well blowout in 2010. About 78,000 cubic meters of crude oil were released into the Gulf of Mexico from a depth of 1500 meters for 86 days, spreading over a large area. Natural and chemically enhanced dispersion, evaporation, dissolution, burning, surface skimming, and direct capture at the wellhead accounted for a significant proportion of the released oil, but the fate of at least 30% of the oil remains unknown. Scientists from different research consortia studying sediments and marine snow in the Gulf began to observe signs of increased sedimentation and hydrocarbon deposition. Sediment mass accumulation rates for the northern Gulf of Mexico increased sixfold to eightfold in 2010, directly following the DwH blowout.