Methano- and Sulfidogenesis in the Lakes of the Abrau Peninsula (Krasnodar Territory)

The geographical position, tectonic and geological-hydrogeological structure of the basin of the Malyy Liman and Abrau lakes, their landscape features as natural monuments of regional importance located on the territory of the Abrau peninsula of the Krasnodar Territory are described. Using the example of the aquatic landscapes of the Malyy Liman and Abrau lakes and the river of the same name, water and bottom sediments were studied. Hydrochemical parameters, the content of methane and sulfide sulfur in bottom sediments and methane in water as components of aquatic landscapes were studied. The results of the determination of sulfides, as well as the characteristic odor and color of bottom sediments, indicate the presence of free H2S and hydrotroilite (FeS ∙ nH2O) in them. Electron microscopy revealed the presence of hollow spheres in the bottom sediments, which indicates their possible gas saturation. Microinclusions of biogenic pyrite (FeS2), which was formed on fragments of plant and organism residues, were found under an electron microscope. In aerobic-anaerobic conditions of the upper layer of bottom sediments of lakes, pyrite formation occurs both directly through a one-stage process of pyritization of reactive iron, but also through a multi-stage process of pyrite formation from iron monosulfide. It has been established that lakes are exposed to anthropogenic influences, which can increase many times during the holiday season. This leads to their eutrophication and increased meanogenesis, which in turn contributes to the activation of methane emissions into the atmosphere. Specific methane fluxes from the water surface of the Malyy Liman and Abrau lakes have been determined.