Gas hydrates and the global methane cycle
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Investigations at IFM-GEOMARGas hydrates - ice-like, inflamable compounds of water and gas - may exist under high pressure and/or low temperatures in tremendous quantities in arctic regions of permafrost and in marine sediments and are considered to have the potential for a significant impact on global climate and the carbon cycle. Research on marine gas hydrate and the methane cycle has a tradition at IFM-GEOMAR. In summer 1996 during a cruise with RV SONNE offshore Oregon (USA) scientists of the former GEOMAR recovered the largest amount of gas hydrate from the seafloor. By using the large video grab they recovered sediments from 800 m water depth which were interspersed with about 50 kg of whitish gas hydrate. This discovery stimulated research on gas hydrate in Germany and induced funding of scientific programmes with numerous innovative technologies within the special programme GEOTECHNOLOGIEN of BMBF and DFG. The collaborative programme COMET is coordinated by IFM-GEOMAR and scientists of the research unit marine geosystems are leaders of the 5 subprojects. Within this programme we study in detail the complex transport processes and biogeochemical reactions in hydrate-bearing surface sediments to better understand the working and efficiency of the benthic filter. We use advanced lander technology, numerical modelling, and isotopic analysis of fluids and authigenic precipitates to quantify rates of hydrate turnover. Mechanisms of hydrate dissolution and gas bubble transport are further investigated in a newly designed pressure laboratory. Authigenic carbonates and their isotopic composition are analyzed to reconstruct the changing rates of hydrate turnover on geological time scales. Fluxes of methane into the water column and the atmosphere are studied using hydroacoustic techniques and the stable isotopic composition of dissolved methane.
Other gas hydrate projects with participation of IFM-GEOMAR:
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