Orekhova N. The distribution and fluxes of oxygen and sulfide at the surface of sediments in the Black Sea

In this work, observational data were collected and a database was formed to incorporate information on the distribution of oxygen, sulfide and other key redox species in pore waters of the upper layer of sediments in the Black sea, retrieved from voltammetric profiling with a glass Au/Hg microelectrode, as well as information on organic carbon, iron, porosity, and other geochemical characteristics of the upper layer of sediments, retrieved from standard geochemical analyses.The obtained data have allowed estimation of variability in the vertical profile of sulfide in the investigated area and they have revealed that the concentration of sulfide in pore water increases from the western to the eastern part of the Black sea.The influence of fluxes of oxygen and sulfide at the surface and within the upper layer of sediments at bottom water chemistry has revealed that sediments are the source of sulfides for the bottom waters in the northern part of the sea and in the area of the continental slope. Yet, sediments often consume sulfide from water in the southern part of the sea. The highest fluxes of sulfide have been detected near the shelf break resulting in the shortest residence time of sulfide in the bottom waters. It has been also demonstrated that oxygen is consumed more actively in the region of the eastern shelf, as compared to the western shelf of the Black sea.