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Sulfur isotope fractionation during sulfate reduction by archaea and in hydrothermal sediments

Objective



Research objectives and content The chemistry of the Earth surface has changed through time from a chemically reducing stage to the oxidized stage we know to day. Important aspects of the evolution of the chemical conditions at the Earth's surface can be read from stable isotopic compositions of sulfide deposited in ancient sediments. During dissimilatory sulfate reduction by Eubacteria sulfide is produced depleted in 34S. Deposits of sedimentary sulfide depleted in 34S are therefore an indication of bacterial sulfate reduction, and further indicate a sulfate-rich ocean. To adequately interpret the ancient record, isotope fractionation by the relevant bacterial species must be understood. It has been proposed that life on Earth originated at high temperature in hydrothermal vent environments, and that the early oceans were warmer than today. The thermophilic Archaea, Archaeoglobus sp., represents the oldest lineage of sulfate reducing bacteria, and is the closest relative known to the earliest sulfate reducers Isotope fractionation during sulfate redution by Archaeoglobus has never been measured and will be a focus of this study. Furthermore isotopic fractionation during sulfate reduction by natural populations from hydrothermal sediments will be measured. Together, these measurements will constrain the range of expected fractionations from ancient ocean sediments and hydrothermal areas, considerably constraining our interpretation of the isotope record of sedimentary sulfides. Training content (objective, benefit and expected impact) Training: 1. Gain a broader understanding of the chemical and biological evolution of the Earth's surface. 2. Advance my skills in the isolation and culturing of bacteria 3. Work in close contact with scientist connected to the Earth System Science Center at Odense University. 4. Obtain a more ecological understanding of the biogeochemical sulfur cycle. 5. Work together with students and obtain teaching experience. Links with industry / industrial relevance (22)

Funding Scheme

RGI - Research grants (individual fellowships)

Coordinator

Odense Universitet
Address
55,Campusvej
5230 Odense M
Denmark