Pedogenic carbonates in automorphic soils of the subtaiga zone of the southeastern part of Western Siberia

   Pedogenic carbonates are the main source of soil inorganic carbon, which plays an important role in the exchange of carbon between the soil and the atmosphere. Thus, it has an impact on global climate processes. In addition, this process further arouses interest in the study of carbonates because climate change is considered one of the urgent problems of our time [18]. The article presents the results of a study of pedogenic carbonates in automorphic soils of the subtaiga zone of the southeastern part of Western Siberia. The research was conducted in the south-east of Western Siberia (Tom-Yayskoye interfluve) in the subtaiga natural zone. The processes related to the distribution of carbonate horizons in the soil profile have been studied. Morphological features of carbonate neoplasms, including chemogenic (hypocutanes) and biogenic formations (biofilms with needle-like calcite crystals), have been studied using optical methods and scanning electron microscopy (SEM), and the influence of microrelief factors on the formation of carbonate horizons in the conditions of the subtaiga zone of the southeastern part of Western Siberia has been assessed. A significant diversity in the distribution of inorganic carbons in soils with a thickness of two meters was established. Regional differences in CaO content were identified: in the Tomsk region, the average CaO content in carbonate horizons is 3.0 – 4.0 %, and in the Kemerovo region – 6 %. This indicates less intensive leaching of carbonates in the southern part of the region. The main form of carbonate neoplasms is hypocutans, which form near the upper line of the carbonate horizon around the root canals. It was shown that the formation of hypocutanes is linked to both the movement of carbonates from deeper layers (perdescendum model) and the stretching of capillary solutions as they dry out (perascendum model). The results obtained are important for understanding the current state of soil carbonate horizons and predicting their changes in a changing climate.

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