ALKOR AL543

In the coming decades, sedientary source and sink fluxes of nutrients, metals and greenhouse gasses will be altered by global environmental change and the associated trends of ocean deoxygenation and acidification. Due to the broad range of sedimentary redox conditions in close vicinity and well-characterized seasonal cycles of temperature, salinity and oxygen, the western Baltic Sea is an ideal location to investigate those trends under well-defined boundary conditions. On the proposed research cruise, we intend to investigate the impact of changing redox conditions on the sedimentary release or fixation of bio-essential metals (nickel, zinc, and their isotopes) as well as radium and radon (tracers for submarine groundwater discharge and sedimentary efflux in general). Furthermore, we would like to investigate the impact of diffusive sedimentary fluxes versus ground water discharge on the distribution of greenhouse gases (methane and nitrous oxide) in the water column.