Permafrost-affected gleyzems of the Subpolar Urals: morphological and cryogenic structure, temperature regime and physical-chemical properties

The article studies the structure and properties of permafrost-affected gleyzems and peat-gleyzems in the tundra landscapes of the Subpolar Urals, the southernmost mineral soils with insular permafrost that is particularly sensitive to present-day climate change. The study examines in detail the morphological and cryogenic structure, temperature regime, mineralogical composition, and physical-chemical properties of active layer and underlying permafrost. The thin active layer is characterized by the predominance of peat horizons and significant gleyization of mineral horizons; a high-ice transition layer is localized in the upper permafrost. Massive cryogenic textures were revealed in the active layer, and schlieren and ataxic textures were found in the underlying permafrost. Peat-gleyzem, in contrast to the colder gleyzem, is characterized by a relatively mild temperature regime, which is explained by the increased thickness of the heat-insulating peat horizon and a greater depth of snow cover. Permafrost-affected soils of the Subpolar Urals are confined to climate-driven ecosystem-modified permafrost. It was revealed that the predominance of the coarse silt fraction in soils with close underlying permafrost contributes to the significant thixotropy of gleyed active layer. Cryogenic-lithological heterogeneity of profiles in the conditions of the subarctic humid climate of the mountainous country determines the specific structure and properties of gley permafrost-affected soils of the Subpolar Urals.