Projekt: Biological/biogeochemical processes and element fluxes at the Black Sea pelagic redoxcline, sedimentation processes and the Late Holocene development of the system

The Black Sea is the largest anoxic basin on earth and provides unique conditions for the study of key processes controlling the biology and biogeochemistry at pelagic redoxclines. By identifying microbiological/biogeochemical agents and assessing rates of the coupled element cycles of carbon, nitrogen, phosphorus, sulphur, manganese, and iron, the functional response of this specific environment upon the change of external conditions will be visible. One task is to map and explain the initial planktological conditions in the surface mixed layer relevant for the vertical particle flux and the redoxcline dynamics. Another task is to study the particle and solute dynamics in the oxic-anoxic transition layer and their natural and anthropogenic components. We postulate authigenic Mn-Fe-P mineral phases at the redoxcline to be important for the phosphorus cycle, upward phosphorus fluxes supporting primary productivity, and the trapping function of trace-metals in anoxic basins and sediments. This task also accounts for the nitrogen and carbon cycles in the redox layer and their modelling. An additional task is to evaluate the fate of anthropogenic organic contaminants and radionuclide tracers in the water column and the sediment. Finally, the sedimentary archive will provide excellent records of the most recent Black Sea environmental history, of past changes in redoxcline dynamics, and of climate signals transported by the large northern rivers of the Black Sea. It will also provide a unique opportunity to systematically study geochemical properties of sediments recovered from oxic, suboxic, and anoxic parts of the Black Sea. The four subprojects of this cooperative Ukrainian-German project in marine sciences will be ! substantiated by joint cruises with the Ukrainian vessel "Prof. Vodyanitsky" and the German "Meteor" and will benefit from mutual presentation and exchange of technological and conceptual approaches.