Oxygen absorption in the oxidation of organic compounds in the coastal sediments of Sevastopol (the Black Sea)
The formation of the oxygen regime of water bodies is closely related to the intensity of the biological processes in the bottom sediments. The aim of this work was the defining the role of different groups of bacteria in the utilization of oxygen in the oxidation of organic compounds in the sediments of the coastal areas of Sevastopol, including using original methodological approaches. The total oxygen absorption of the bacterial community is considered as set of processes of aerobic utilization and oxidation of the reduced products of anaerobiosis. Oxygen absorbed in 0.01-cm surface layer is about 40 %. The values of oxygen flux through a unit surface of various mechanical composition of bottom sediments were quite comparable due to differences in the bacterial density and the depth of penetration of oxygen. The values of aerobic oxygen absorption changed from the mouth to the inner part of Sevastopol Bay from 2.69 to 1.82 mkgO<sub>2</sub>·sm<sup>-2</sup>·h<sup>-1</sup>. Utilization rate of organic carbon in the surface layer of Sevastopol Bay sediments was evaluated within 1.57-2.76 mkgC·sm<sup>-2</sup>·h<sup>-1</sup> and reached 1.13 and 0.34 in paleoriverbeds of Chernaya and Belbek. The production of reduced compounds in recalculation on H<sub>2</sub>S ranged from 0.096 to 0.65 mkg·sm<sup>-2</sup>·h<sup>-1</sup>. The share of active anaerobic microflora of the maximum possible in conditions of real temperature was 7.5-87.5 % and oxyphilic - 0.2-31 %. Thus, the ratio of aerobic oxygen demand and, through metabolism products oxidation, anaerobic microbiota determines their potential contribution to processes of decomposition of organic matter. However, realization of this possibility is limited by the factors of actual oxygen content and temperature.