Oxidation As A Sink For Seep And Hydrate Methane In The Coastal Ocean The major objective of this research is to measure the removal rates of CH4 and non-methane hydrocarbons (NMHC) released from hydrocarbon seeps, saline seeps, brine pools and hydrate outcrops in the Gulf of Mexico.While invertebrate internal organs containing symbiotic methane oxidizers have been previously shown to be intense sites of CH4 oxidation in these environments, this study will concentrate on CH4 and NMHC oxidation occurring in the water column, in sediments and on invertebrate external surfaces at such sites. CH4 and NMHC oxidation rates will be determined by measuring 14CH4 and 14C2H6 uptake. The role of CH4 and NMHC oxidation in carbon cycling and local productivity will also be investigated. Specifically, the contribution of oxidation to the production of utilizable organic carbon, in the form of methanotrophic biomass, which is available to the benthic community in the immediate vicinity of these sites will be estimated by measuring the fraction of labelled CH4 or C2H6 which is incorporated into cell carbon. This study will allow a better assessment of the role of oxidation in removing CH4 and NMHC released from seeps and hydrates into the coastal ocean and identify the major sites where oxidation occurs.
