Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

Methaneseeps were investigated in Hudson Canyon, the largest shelf-break canyonon the northern US Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathratehydrate stability. The acoustic identification of bubble streams was used to guide water columnsampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methaneconcentration with methaneoxidation rates and current velocity into a steady-state box model, the total emission of methaneto the water columnin this region was estimated to be 12 kmol methaneper day (range: 6 – 24 kmol methaneper day). These analyses suggest this methaneis largely retained inside the canyonwalls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissionsand measured oxidation rates, the oxidation of this methaneto dissolved CO2 is expected to have minimal influences on seawater pH. This article is protected by copyright. All rights reserved.