Sulfuric Compounds in the Surface Layer of Bottom Deposits in the Mouth Reach of the Northern Dvina River

The distribution of reduced sulfuric compounds in the surface layer of bottom deposits in the Northern Dvina mouth was examined. The natural biogeochemical processes and anthropogenic pollution are found to cause the formation and accumulation of reduced sulfuric compounds (mostly pyrite and organic forms) in bottom deposits. The concentration of individual forms of sulfur and its total concentration are found to vary widely from year to year. The most intense accumulation of the total reduced sulfur is recorded near the wastewater discharge sites of pulp and paper mills.     

The redox profile of the bottom sediments in the Ob River’s mouth area

By the data of cruise 54 of the R/V Akademik Mstislav Keldysh (September 2007), the results of geochemical studies of the redox processes in the bottom sediments of the Ob River’s near-mouth area as applied to the redox indicator elements such as manganese, iron, and sulfur are presented. The characteristics of the bottom sediments and the distribution of these elements in them testify not only to the significant role of the mixing processes in the formation of the geochemical profile of the bottom sediments in the estuary but also to the role of the postsedimentation (diagenetic) processes.     

Determination of the reduced sulfur species in the anoxic zone of the Black Sea: A comparison of the spectrophotometry and iodometry techniques

The report presents the results of the studies of the reduced sulfur species in the water of the anoxic zone of the Black Sea. The content of hydrogen sulfide was determined by means of spectrophotometry using dilution with oxygen-free distilled water. The detection limit of the H₂S amounted to 0.3 μM with the method’s precision below 3%. The accuracy of the spectrophotometric determination was verified by iodometry after the fixation of the hydrogen sulfide in zinc acetate under the distillation with argon from the acidified seawater sample.