Investigating the chemical and isotopic kinetics of aerobic methane oxidation in the Northern US Atlantic Margin, Hudson Canyon

Wednesday, 16 December 2015
Poster Hall (Moscone South)
Eric W Chan1, John D Kessler1, Alan M Shiller2, Molly C Redmond3, Eleanor C Arrington1 and David L Valentine4, (1)University of Rochester, Rochester, NY, United States, (2)University of Southern Mississippi, Dept. of Marine Science, Stennis Space Center, MS, United States, (3)University of North Carolina at Charlotte, Charlotte, NC, United States, (4)University of California Santa Barbara, Santa Barbara, CA, United States
Recent discoveries of methane seepage along the US Atlantic margin have led to speculation on the fate of the released methane. Here we examine the kinetics of aerobic methane oxidation to gain a fundamental understanding of this methane sink. In order to look at this process in its entirety, a unique mesocosm incubation system was developed with a Dissolved Gas Analyzer System (DGAS) to monitor in real time the chemical and isotopic changes involved with aerobic methane oxidation. This system measures changes in methane, carbon dioxide, and oxygen concentrations as well as the stable carbon isotopes of methane and carbon dioxide with time. In addition samples are strategically removed to characterize trace metals, nutrients, cell counts, and microbial community genetics. This presentation will detail the results obtained from samples collected inside the Hudson Canyon at the edge of the methane clathrate stability zone and outside the Hudson Canyon, not influenced by the methane seepage. These results show that in both environments along the Atlantic margin, methane was consumed aggressively but the timing of consumption varied based on location. In addition, these results are leading to insights into the chemical requirements needed for aerobic methane oxidation and the resulting isotopic fractionation.