000K utf8 1100 $c2005 1500 eng 2050 urn:nbn:de:gbv:8-diss-12941 3000 Mau, Susan 4000 Methane output from cold seep structures along the Central American continental margin$hChristian-Albrechts-Universität zu Kiel [Mau, Susan] 4030 Kiel$nChristian-Albrechts-Universität zu Kiel 4209 Methane seepage from different geological structures was investigated along the convergent margin off the Pacific coast of Costa Rica in order to identify the fate and the amount of methane discharging into the ocean. Thus, the water column above four mud extrusions and one of several embayments caused by the subduction of seamounts (scarps) was examined by means of methane concentration analyses, carbon isotopic characterization of the methane and current measurements. It was discovered, that most of the vent derived methane is dispersed and diluted by mixing with seawater having background methane-concentrations whereas only a part of the methane is oxidized. Besides, repeated measurements indicate long-term variations in methane seepage, which might be related to earthquake activity. The amount of methane released from mud extrusions and scarps offshore Costa Rica was estimated to be ~0.2‰ of the global methane output from the seafloor, which is reported to be in the order of 20 Tg yr-1. The estimated methane outputs present the first ones from an erosive convergent margin and are of great significance for assessments of the global methane output in general and of specific geological structures, e.g. mud extrusions, in particular. 4950 https://nbn-resolving.org/urn:nbn:de:gbv:8-diss-12941$xR$3Volltext$534 4961 https://macau.uni-kiel.de/receive/diss_mods_00001294 5051 550 5550 carbon cycle 5550 continental slope 5550 Costa Rica 5550 greenhouse gas 5550 Kontinentalrand 5550 marine biogeochemistry 5550 Methan 5550 Pacific ocean 5550 seismic activity