Secondary carbonates in edaphic components of ecosystems

The paper considers some examples of secondary carbonates in edaphic ecosystem components (soils, river and lake bottom sediments, suspensions). In addition to calcite, more soluble and less stable polymorphic modifications of calcite vaterite and aragonite, which are important precursors of carbonate-forming systems, are diagnosed. Microforms of vaterite are formed in presence of low molecular weight amino acids. In turn, microforms of aragonite are associated with extremely high salinity of water. According to the nonclassical mesocrystal concept, stability of vaterite and aragonite in situ is explained by the formation of mesocrystals – hierarchically organized superstructures from nanocrystals. The mesocrystal concept may be an important key to understanding the micro-and macroaggregates in soils.