Marine Geochemistry
Surface sediments of the ocean and other aquatic environments are very dynamic systems. They are shaped by particle fluxes of minerals, plankton, or organic matter as well as by the dissolution and microbial degradation of these components. Furthermore, the formation of authigenic minerals (including clays, pyrite or gas hydrates) or of trace gases as methane takes place.
At the sediment-water interface (SWI) steep gradients and high densities of micro- and macro-organisms are observed. The processes acting at this interface are controlling the preservation of organic and inorganic matter as well as of other proxies used for geological reconstructions.
The degradation of organic matter or biogenic silica within surface sediments causes fluxes of nutrients, oxygen, CO2, or methane through the sediment water interface back into coastal water or the ocean. The quantification of these fluxes is relevant for considerations of the “benthic habitat” as well as for biogeochemical cycles. The effects of fluid flow through sediments for hydrological cycles or the release of methane, nutrients or xenobiotics are studied at mud volcanoes or at sites of submarine groundwater discharge (SGD).
For these objectives we are applying in situ techniques (allowing measurements at up to 6000m water depth), analyze natural radio nuclides, determine the age of biomarkers by e.g. 14C analysis, and measure isotopes to decipher the formation and fate of methane.
Together with partners from other research institutes and SME´s (Small and Medium Enterprises) we are developing sampling techniques and sensor systems for in situ observations. For data visualization and analysis Geo-Information-Systems are applied supporting the identification of biogeochemical provinces at the seafloor or the calculation of spatial budgets.
Our main research areas are the Southern Ocean, the Northern North Atlantic (e.g. Spitzbergen or the Haakon Mosby Mud Volcano) as well as coastal regions in the North Sea.
We consider our investigations as a contribution to an improved understanding of biogeochemical cycles, land-ocean interaction related to nutrient budgets and submarine groundwater discharge, or coastal zone management issues supported by GIS techniques