Biological/biogeochemical processes and element fluxes at the Black Sea pelagic redoxcline, sedimentation processes and the late holocene development of the system - Cruise MSM33 - November 2 - December 6, 2013 - Cádiz (Spain) - Varna (Bulgaria) (English)

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 cycles of carbon, nitrogen, phosphorus, sulfur, manganese and iron at the redox boundary the functional response of this specific environment upon the change of external conditions will be visible. Geochemical and textural investigation of authigenic mineral phases at the redoxcline will be also important to assess the importance of the so-called "Mn-Fe-P shuttle" for the phosphorus cycle and primary productivity, and to clarify the trapping function of trace-metals in anoxic systems. To meet the various water column sampling demands, on more than 40 stations CTD and P-CTD profiles as well as multi-nets and in-situ pumps were deployed along several slope transects in the northwestern and northeastern Black Sea. Additionally, a permanent sediment trap mooring has been deployed in the central western basin. The sedimentary archive has been extensively sampled during the cruise by means of multicorer, gravity corer and piston corer. The upper parts of the cores consists of finely laminated late Holocene units providing excellent records of the Black Sea environmental history, of past changes in redoxcline dynamics, and of climate signals transported by rivers from the northern drainage basins of the Black Sea. Presite multibeam and Parasound surveys of about 400 nm were concluded. The research cruise was integral part of the implementation plan of the bilateral scientific cooperation between Germany and Ukraine in the field of marine sciences supported by the German and Ukrainian Ministries of Education and Science.