Methane Concentrations in Gas Plumes from Mississippi and Green Canyon Seeps, July 2014

We collected water samples from gas plumes and measured dissolved methane concentrations shipboard during a 2014 cruise to Green Canyon (GC185) and Mississippi Canyon (MC118) methane seeps to improve our understanding of bubble dissolution. Samples were collected by remotely operated vehicle in vertical profiles following bubble streams from the seafloor up to 200 m above bottom. Samples were also collected at constant depth, 100 m above bottom, in horizontal transects across a bubble plume. Water samples were analyzed shipboard for dissolved methane gas concentrations reported here. Gas phase samples were returned to shore for gas composition analysis. These samples were co-located with measurements of bubble physical properties derived from high-speed videography reported elsewhere.