Natural hydrocarbon seepage in the southern Gulf of Mexico: Quantification of emissions and fate of hydrocarbons
Heavy oil and gas bubbles are emitted from the 1200 to 2900 m deep seafloor in the hydrocarbon province Campeche Knoll in the southern Gulf of Mexico. The viscous heavy oil flows across the seafloor, loses volatile compounds, solidifies, and is converted to asphalt with time. Due to the fact that the heavy oil remains at the seafloor, these sites are natural laboratories to study the impact of oil on deep-sea ecosystems, and the time scales of oil and asphalt degradation. These subjects are very timely, and can help understanding effects of deep water oil spills as caused by the 2010 Deepwater Horizon accident in the northern Gulf of Mexico. We propose to study the extent of oil emissions and asphalt deposits using sidescan sonar and to investigate them further employing ROV Quest. A further major topic of the proposed cruise addresses the question whether or not methane can reach the sea surface and may contribute to the pool of greenhouse gases. The fact that seepage of oil-coated gas bubbles leads to oil slicks at the sea surface and enhanced methane concentrations was recently shown in the northern Gulf. It can be assumed that similar efficient transport processes for methane exists in the area of the Campeche Knolls, where oil slicks have been observed in association with about ~30 individual seafloor structures.
Weblog from cruise M114 (in German)
R/V METEOR with Control Station German Research Vessels