Studying anaerobiosis in a model experiment with kaolin

A stagnant moisture regime was modeled in kaolin containing a wide range of ferric minerals from the Prosyanovskoe site. The dynamics of growth of the main physiological groups of microorganisms and changes in the physicochemical properties of kaolin were studied. Experiments proved the ability of the FeRed iron-reducing bacterium strain found in the developing cenosis to reduce iron and synthesize magnetite; however, biogenic magnetite was not registered in the treated kaolin. Anaerobiosis resulted in formation of the thermodynamically unstable ferric hydroxides: ferrihydrite 5F e2 O 3 . 9H 2 O, akaganeite βFeOOH, and a new ferric hydroxide modification that caused an increase in the oxalate-soluble iron from 1 to 10% of the total iron. A low-ordered protolepidocrocite crystallized to a regular lepidocrocite. A decrease in the chemogenic forms of goethite and hematite and an increase in the biogenic forms of these minerals developing over the ferrihydrite were noted.