Quantifying the flux and fate of methane into the Hudson Canyon at the edge of methane clathrate hydrate stability

Wednesday, 16 December 2015: 09:15
3009 (Moscone West)
John D Kessler1, Mihai Leonte1, Fenix Garcia-Tigreros Kodovska1, Eric W Chan1, David L Valentine2, Matthias Y Kellermann2, Eleanor C Arrington1, Luis C. Navarrete1, Alexander Weinstein1, Alexandre Chepigin1, Tom Weber3, Carolyn D Ruppel4 and Mary I Scranton5, (1)University of Rochester, Rochester, NY, United States, (2)University of California Santa Barbara, Santa Barbara, CA, United States, (3)Center for Coastal & Ocean Mapping, School of Marine Science and Ocean Engineering/Joint Hydrographic Center, University of New Hampshire, Durham, NH, United States, (4)USGS Coastal and Marine Science Center Woods Hole, Woods Hole, MA, United States, (5)Stony Brook University, School of Marine & Atmospheric Sciences, Stony Brook, NY, United States
Methane seeps were investigated in the Hudson Canyon, along the northern US Atlantic Margin on the R/V Endeavor in July 2014. These seeps are located along the upper feather-edge of the methane clathrate hydrate stability zone. Water column samples were collected guided by the acoustic identification of bubble streams in a 32 km2 region. This presentation details the measurements of dissolved methane concentration, natural stable isotopes, potential methane oxidation rates, and current velocity which were used in chemical and isotopic models to quantify (1) the total emission of methane to the water column in this region and (2) the extent of aerobic methane oxidation. In addition, the timing, efficiency, and kinetics of aerobic methane oxidation were investigated with mesocosm incubations of seawater in a unique experimental design that enabled high temporal resolution data acquisition. Finally, the ultimate fate of methane carbon was assessed with high precision measurements of pH.