Gas chemistry and carbon cycling at hydrothermal systems along the Mid-Atlantic Ridge: time- and space-referenced biogeochemical and isotopic investigations

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... Main goal is to obtain insight into the essential geochemical and biological processes. Thus, the study stands in the frame of a close interdisciplinary co-operation between working groups rooted in the fields of mineralisation - petrology, geochemistry of vent fluids - gas chemistry, biogeochemistry - organic geochemistry, and microbiology-zoology. This study aims to elucidate the transformation of carbon species and reduced gases brought along by hydrothermal fluids. Three goals are in its focus (i) to understand formation processes and the respective composition of fluids (ii) to describe the biogeochemical transformation processes of carbon species and hydrogen (iii) characterisation of extend and relevance of hydrothermal cyclicity by charting the variability of vent fluids in time and space. For this purpose, concentrations and isotope signatures (C, H) of the main reactive gases methane and hydrogen as well as of other components of the carbon cycle namely C2-C5 hydrocarbons, dissolved organic matter (DOC), CO2, and biomass are determined. It is aspired to compile a comprehensive data set for geographically apart hydrothermal systems including information on temporal variation that allows to combine the identified geochemical and biological processes in model description of the total system.