DOI: 10.7256/2453-8922.2024.1.70079

Abstract: Aufeis is one of the most dangerous natural phenomena. The negative impact of aufeis is determined by the unexpected flooding of the territory and subsequent freezing of water, the formation of ice barriers, the icing of underground structures and communications (mines, tunnels, culverts, and sewer wells), as well as the icing of roads and railways, coastal hydraulic structures, etc. There are cases when explosions of aufeis mounds produce catastrophic disturbances within a few seconds. The aufeis that forms annually in the valley of the Buluus Creek is one of the most famous and studied aufeis of Central Yakutia. The aufeis was sampled from a vertical section. The aufeis is layered, and the thickness of the layers is 3-10 cm. In the upper part of the aufeis, the ice layers are thicker than in the lower. Sampling from the aufeis ice was carried out using a 5.1-cm-diameter steel crown driven by a Bosch electric drill. Measurements of the isotopic composition of oxygen and hydrogen in ice were performed using a Picarro L 2130-i laser isotope analyzer. The isotopic composition of the Buluus ice varies in a narrow range: δ18O values vary from −20.2 to −21.9‰, δ2H values vary from −159.5 to −173.7‰. Generally, the ice is isotopically slightly enriched compared to the surface water of the Ulakhan-Taryn creek, where the δ18O value is −22.18‰ and the δ2H value is −175.1%. Groundwater is isotopically close to the creek water; its isotope composition is also isotopically enriched compared to the ice of the aufeis, with δ18O values varying from −22.17 to −22.25‰ and δ2H values varying from −173.7 to −175.1‰.

DOI: 10.7256/2453-8922.2023.2.40965

Abstract: The subject of the study is the content of iron compounds and their radial differentiation in the profiles of cryogenic soils of the Chara River valley (Transbaikalia). The studied soils belong to post-pyrogenic permafrost gleyzems, the depths of the seasonal active‐layer of these soils are from 34 to 44 cm. Macronutrient concentrations, with the exception of Si, rarely exceed 5.0%, while the silicon content reaches 24.3%. Si is also characterized by removal from the upper part of soil profiles and accumulation in permafrost soil horizons. The highest concentrations are characteristic in the O horizons (Mg – 4.8 and Ca – 1.5 mg/kg) for a significant part of the macroelements. The trace elements, Sr and Zr are distributed vary contrastingly (from 5.0 to 29.7 and from 5.6 to 47.1 mg/kg). Values of the R coefficient from 0.3 to 0.9 indicate the initial stage of post-pyrogenic restoration of soil properties, and the active accumulation of Mg, Ca, Ti, Fe, Sr, and other elements in the upper part of oxidized-gley permafrost gleyzem observed in the profile is a sign of active restoration. The soils contain about 3.4% iron, which more than 60–75% is the silicate group of compounds (Feñ). The moisture content of soils and the prevailing reducing environmental conditions contribute to the formation of monotonous distributions in their profiles, and in soils without signs of stable hydromorphism, permafrost horizons contain almost 2 times more Feox and Feextr.