Due to its depth under the sea surface, the Deepwater Horizon oil plume in the Gulf of Mexico represents a new category of oil spill and a scientific opportunity to study the behavior of hydrocarbons in the ocean. Conventional oil spill models are unlikely to predict accurately the magnitude of the dissolved hydrocarbon load to the water column from a rising oil plume. Hence, resulting environmental assessments may underestimate the extent of risks and damage to aquatic wildlife and ecological resources in the subsurface.
With funding through this Grant for Rapid Response Research (RAPID), scientists at the Woods Hole Oceanographic Institution will develop unprecedented estimates of hydrocarbon dissolution fluxes arising from the sea floor oil seep and upwelling oil plume emitting from the Deepwater Horizon wellhead. This effort will be the result of laboratory, comprehensive two-dimensional gas chromatography (GC×GC), and modeling tools that are unsurpassed in their collective ability to address these questions. In addition, the Woods Hole investigators will collaborate with several other RAPID-funded research teams, who will be studying other aspects of the fate and behavior of the spill on samples collected at the same time.
Broader Impacts: Results from this research will contribute broadly to an understanding of petroleum fate and carbon cycling in the Earth system. Knowledge gained from this research will also be translated directly to state and federal agencies involved in the damage assessment and restoration of the spill. The PI has and will continue to provide interviews to the press as well as inform other parties on the chemistry of this spill.
The proposed work will provide the concepts, processes, and parameters necessary for existing industry oil spill models to be adapted to the unprecedented situation of a major oil release on the deep sea floor. The anticipated expansion of offshore drilling operations into deeper waters may lead inevitably to the risk of more spills in the future. The Deepwater Horizon incident provides an invaluable opportunity to assess properly the subsurface hydrocarbon content resulting from this type of oil release.
This study provided numerous key insights into the science of the Deepwater Horizon blowout and the subsequent release of oil and gas from the Macondo well. The initial goal was to study the petroleum hydrocarbons found in subsurface plumes. We identified one plume in late June 2010 at 1100 meters and observed that it was composed of only a select few compounds. That is, of the 1000s of compounds in oil, only six compounds were in the majority. These compounds were benzene, toluene, ethyl benzene, and the three xylenes (collected called BTEX) at a total of 75 micrograms per liter (Fig 1). We noted that these compounds have properties that allow them to dissolve in water at levels higher than the other compounds in the oil. In order to achieve these results, we also had to collect a pristine sample of oil leaking from the well, which we did by using a specialized sampler and an underwater remotely operated vehicle (Fig 2 and Fig 3). These findings were published in two high profile manuscripts in the journals Science and the Proceedings of the National Academy of Sciences. We also estimated the amount of hydrocarbons biodegraded at the sea surface and calculate the amount of total oil released. Overall, this was a successful effort that allowed us to respond quickly to perform science in the time of crisis.
