The Deepwater Horizon offshore platform well blowout, which occurred on 20 April 2010 off the coast of Louisiana, has released large amounts of crude oil and methane into the Gulf of Mexico. As a result, petroleum-based surface films (accompanied by elevated levels of subsurface methane and other dissolved gases) have spread over an unprecedented large area, raising the possibility that air-sea transfer of momentum, heat and gaseous constituents may be modified sufficiently so as to have significant impacts on regional meteorology and ocean/atmospheric chemistry. Prior research, conducted primarily in laboratory settings, has demonstrated that air-sea fluxes of momentum, energy and gases are sharply reduced by the presence of such surface active agents (termed 'surfactants'). This RAPID-type effort will allow a combination of moored and episodic ship-based transect type measurements of the above-mentioned air-sea fluxes (as well as some subsurface quantities) to be conducted over a month-long period near National Data Buoy Center site #42012 off Mobile Bay, Alabama. This work will be done in conjunction with efforts already being conducted by the Dauphin Island Sea Lab operated by the University of South Alabama, and will make use of their 25' research vessel. Supported research activities will address four themes: (1) in situ characterization of surfactant concentrations associated with the oil spill; (2) measurements of air-sea exchanges of momentum, water vapor, heat, carbon dioxide and methane; (3) quantification of impacts of these fluxes on the surface ocean heat budget and biogeochemistry; and (4) investigation of the spill's impact in reducing thermal coupling between the atmosphere and underlying ocean surface.
The Intellectual Merit of this work rests in collection of high-quality flux measurements in conjunction with an oil spill of unprecedented scale, as needed to better assess impacts on ocean/atmosphere chemistry and regional meteorology through potential modification of land-/sea-breeze systems and possibly on the behavior or more intense tropical storms.
Broader Impacts of the research will include improved understanding of influences of widespread petroleum spills (or other surfactant sources) on regional meteorology and atmospheric/oceanic chemistry, the dissemination of these findings via conference presentations and formal publication, and enhanced training/career development for a supported postdoctoral research associate.
The 2010 Deepwater Horizon Oil blowout leaked one of the largest amount of oil and natural gas into the environment in the history of fossil fuel extraction. This study investigated several questions regarding the fate of the oil and what kind of interaction it was having with the environment. Two of the questions examined here were whether methane from the leak, contained in the natural gas, was escaping into the atmosphere and if oil from the spill was changing the rate in which it escaped to the atmosphere. We are interested in these questions because the methane concentration has an impact in both the atmosphere and the ocean. In the atmosphere, methane is a potent greenhouse gas, which leads to changes in the planet's heat balance and can influence wind speed and rainfall. In the ocean, methane serves as a food source for microbes. Under the right conditions, the microbes will flourish, consequently deplete an area of its oxygen, and lead to fish kills, which would have a major impact on the survival of local economies. Our study found that the methane and carbon dioxide emissions to the atmosphere were small. The amounts were similar to the amounts in the environment caused by river inputs and coastal processing. This implies that the gases had escaped into the atmosphere before our arrival (mid August after the leak had stopped) or that the gases were trapped in the water column. Because of the ecological implications of methane in ocean waters, ongoing methane and oxygen monitoring is recommended, in concert with an engineered remediation plan.
