| Abstrakt: |
The composition of bottom sediment in the estuarine part of the Simmi River, a small tributary of the Amur River (Bolon State Nature Reserve, Russian Far East), was studied using X-ray fluorescence, electron microscopy, sedimentation analysis, and laser diffractometry. It is established that the formation of labile components in the bottom sediments (vivianite–clay microaggregates, gypsum microcrystals, and vaterite mesocrystals) is linked with effects of the pyrogenous factor in the Simmi River basin and the level regime of the main river. The formations are mobile due to their small size (<100 μm). The bottom deposits are primarily formed by such suspended sediments (particle size <100 μm), which is consistent with the lacustrine–alluvial genesis of the area. Two vivianite formation mechanisms have been identified in the bottom sediments in periods following fires, when the concentration of phosphate ions in the river water is elevated. Vivianite is formed on the surface of ferruginous–clay microaggregates, due to the reduction of Fe (III) in the presence of organic matter and on biological templates (organic residues and single-celled microorganisms). [ABSTRACT FROM AUTHOR] |
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