Home – Home – Jornals – Advanced Search

This paper presents the results of 3D inversion of magnetovariational tippers obtained at the Cape Schmidt observatory via digital processing of geomagnetic variation records performed by the MAGDAS-I magnetometer. 3D tipper frequency inversion is carried out using the ModEM software. The result is horizontal and vertical sections in the coastal strip of the Chukchi Sea in a spatial region with a dimension of 300 × 300 × 200 km along the X , Y , and Z axes, respectively. The geoelectric section of the investigated region contains both surface and deep conductive blocks located at different azimuths relative to a measurement point. The surface conductive anomaly near the observatory with a resistivity of ≈3 Ohm·m is located in the southeast direction at depths of a few hundred meters. The other conducting inhomogeneity is larger and located in the same direction, but at a distance of about 25-30 km and depths of 4-16 km. The resistivity of its central region at a depth of 8 km is equal to 1 Ohm·m. From the side of the South Chukchi Depression, there is an inclined conductive block in the Chukchi Sea, located closer to the coast to the bottom of the Earth’s crust, and the maximum resistivity of this block in the central part at a depth of 20 km is equal to ≈7 Ohm·m. The most noticeable feature of the section is a massive upper-mantle conductive block under the continent at depths of 50-120 km with a resistivity of 3-4 Ohm·m in the central part at depths of 70-85 km. Deeper into the continent, the block is slightly inclined to the southeast. There are visible conductive regions that connect this block with upstream conductive formations. The epicenters of weak crustal earthquakes recorded in the region are located above the northwestern marginal part of the upper-mantle block, including its central region. Possible mechanisms of high electrical conductivity of anomalous blocks are discussed.

In accordance with regulatory documents, the organization and conduct of logging operations should be carried out by methods and techniques that ensure maximum conservation of forest environment, contribute to the reproduction of valuable forests in the shortest possible time, and strentength their protective and protective functions. This is especially true for the coniferous-broad-leaved forests of the Far East, which are a unique formation that includes cedar and black-fir-broad-leaved, spruce-broad-leaved, hard and soft-leaved subformations. These forests are characterized by a very complex canopy structure. The composition includes, as a rule, 10-20 tree species, differing in their biology and growth, which creates a clearly expressed vertical density of the forest stand. The presence in plantations of endemic and forbidden species, as well as lianas and shrubs listed in the Red Book (2008) require a special approach to the methods and technologies of wood harvesting. Studies have shown that in the formation of coniferous-broad-leaved forests, selective felling methods and logging technologies should be predominantly used, allowing not only to preserve undergrowth and fine-grained valuable species, but also to ensure the formation of a post-cutting stands close to the original forest type. This leads to very important conclusions on the organization of wood harvesting only by certain types of machines and mechanisms using narrow stripe technology, which is confirmed by our research.

The total area of protective forests in Amur Oblast in 2022 was 2.51 million ha, of which 1.72 million ha (68.5 %) was forested, 0.18 million ha (7.2 %) was unforested land, and 0.61 million ha (24.3 %) was non-forest land. The share of protective forests in the forest fund of Amur Oblast is 5.6 % for forested lands and 8.2 % for all lands. For most of the post-Soviet period, the area of protective forests in Amur Oblast was characterized by a constant area: in the period 1998-2022, the total area of protective forests was in the range of 2.50-2.52 million ha. According to the contribution, the forbidden strips of forests located along water bodies are the most represented (47.9 % of the forested lands and 49.6 % of all protective forest lands). Spawning belts of forests are in second place in terms of representation (29.0 % of forested lands, 27.2 % of all lands). The third place in terms of contribution is occupied by protective forest belts located along public railways, federal public roads, public roads owned by the constituent entities of the Russian Federation (20.7 % of forested lands, 20.9 % of all lands). The prevailing categories of protective forests quite logically correspond to the economic specifics of the regions of Amur Oblast. The water protection services of the protective forests of Amur Oblast need to be strengthened. Under the conditions of climate warming, it is recommended that the regulatory recognition of forest services to prevent the degradation of permafrost is recommended.

For the first time a study of microbial communities of permafrost forest soils of the Yakut Botanical Garden of the Institute of Biological Problems of Cryolithozone, Russian Academy of Sciences, Siberian branch was conducted. The studied area is characterized by high soil diversity, almost all types of forest soils found in Central Yakutia are common here. It was found that in the studied permafrost soils in 2019, the number of cultivated microorganisms ranged from 5.2 ± 0.5 × 10² to 2.5 ± 0.1 × 10⁶ CFU/g of soil. Humus-carbonate soil turned out to be the most saturated with microorganisms of all types of permafrost soils, and malt was the poorest. According to the total number of microorganisms, humus-carbonate and pale gray soils formed as a result of the turf soil formation process were distinguished. It was noted that microorganisms were concentrated in the upper organogenic horizons and their number decreased with depth. Mycelial microorganisms dominated in the microbocenoses of the studied four out of five types of soils formed on loose light alluvial deposits, and ammonifying bacteria prevailed in the microbocenoses of malt developing on loess-like alluvial loams. It was found that the predominance of certain groups of microorganisms depended on the chemical composition of soils, as well as on the characteristics of their formation. Mycelial fungi were mainly represented by representatives of the genera Aspergillus sp . and Penicillium sp . Aerobic cellulolytic microorganisms were found in the amount of 5.2 ± 0.5 × 10² - 8.3 ± 4.1 × 10⁴ CFU/g, most of them were found in humus-carbonate soil. Nitrogen fixators were found only in humus-carbonate soil (98 %). It has been studied that the number of microorganisms with physicochemical parameters (C, N, pH, humidity) correlates in different types of soils in different ways. The change in the number of microorganisms mainly depended on the soil temperature, humus and nitrogen content.

The article notes the main sources of phytodetritus in undisturbed cryolithic larch forests of Central Evenkia. The features of the distribution of phytodetritus stocks and its individual components depending on the age of forest stands (young, mature and overmature) and forest types are considered. All these stands were formed on the territory of a small drainage basin in Central Evenkia after intensive ground fires in the early and last decades of the 20^th century. An uneven distribution of litter stocks was revealed both in age groups and forest types. Significant annual fluctuations in litter stocks over 7-year observation period were also noted. The composition of the litter is dominated by needles - 84.8-93.2% of the total mass, while the branches and bark of larch ( Larix Mill.) and birch ( Betula L.) leaves account for only 3.0-3.2, 4.5-2.6, and 7.7-< 1 %, respectively. It was established that according to the degree of accumulation of phytodetritus in the main types of larch forests of the basin under consideration, they are arranged in the following descending order: ledum green moss, red berry green moss, shrub green moss. Litter stocks in them vary from 2.4 to 76.3 t/ha. The total stock of litter in the territory of the basin is 133038 tons, of which 103916 tons fall on larch forests, with a predominance of mature and overmature - 4966 and 61188 tons, respectively. In larch forests of the permafrost zone, phytodetritus is formed mainly due to the litter of the moss-lichen cover. The role of litter from aboveground organs and root mortmass is insignificant. In all cases, with an increase in the age of forest stands, an increase in the mass of the litter is observed. The role of individual components of phytodetritus in the deposition of biogenic elements was revealed, with a significant predominance of carbon and nitrogen in them and an insignificant content of phosphorus and potassium as additional sources of mineral nutrition in forest biogeocenoses of the permafrost zone, and a low rate of their entry into the soil in the process of detritus mineralization was noted.

The results of microscopic analysis of 118 samples of solid precipitation (snow) collected during the cold season of 2019-2020 at three key points in the neighboring Altai-Sayan and Tobol-Irtysh glaciological regions and on their border are presented. In 45 samples (38 %), advective pollen grains of trees (Betula sp., Pinus sp.) and herbs (Artemisia sp., families Asteraceae, Amranthaceae s.l. (incl. Chenopodiaceae), Fabaceae, Poaceae) were identified. Territories from which pollen grains arrived with air masses causing precipitation during the cold season were determined. Advective pollen of wormwood (Artemisia sp.) was brought from the territory of the Kazakh Upland and was determined in the snow of both glaciological regions and on their border. Pollen grains of Amaranthaceae s.l. (incl. Chenopodiaceae) were introduced from the plains of Kazakhstan and, partially, from the snow-free slopes of the Altai Mountains and from the Middle Ob Lowland. Pollen of Fabaceae family was only identified in the precipitation of the Altai-Sayan glaciological region, while pollen grains of Poaceae family were found in the precipitation of the Tobol-Irtysh region; in the border zone of the two glaciological regions, pollen grains of these taxa were not found.

The construction of heated buildings in the Arctic is considered. To increase the bearing capacity of the foundations via their preservation in the frozen state, an environmentally friendly heat-insulating material obtained from the Arctic raw materials (opal-cristobalite and zeolite rocks) has been proposed. The aim of this work is to evaluate the efficiency of insulation layer made of granular foam-glass ceramic on the basis of numerical modeling of the thermal interaction between the heated building and the frozen base. We have investigated the influence of protective screens, construction parameters of a dome-shaped building, and the thickness of insulation layer on the thermal regime of a frozen base over 30 years in comparison with the option without the use of special engineering measures. Calculations indicate that the safe exploitation of a heated building without traditional seasonal cooling devices and a ventilated underground is only possible with the use of protective screens. The building can have the shape of not only a dome but also an elongated ellipsoid of unlimited length. In this case, for building width of 6-8 m, the thickness of insulation layer should be 1.0-1.4 m. The proposed technology is promising to reduce the cost of low-rise Arctic construction, rational use of mineral resources, and preservation of the permafrost and Arctic landscapes.

Glaciation of the northern Baikal region is associated with mountain ranges surrounding Lake Baikal. The underlying rocks are in the frozen state. The existing glaciers are remnants of a larger Pleistocene glaciation, and their area is subjected to continuous shrinking. The analysis of tree cores allowed us to reconstruct the climatic background of the glaciation changes in the recent past. A dendroclimatic curve is divided into two parts: the first part lasted until about 1860-1865, when the summer air temperature was almost always below the mean summer temperature for the entire considered period (~16 °С); the second part (until now) is characterized by higher (above-average) temperatures. During the field work, the current state of the regional glaciation was described for the areas of the Baikal, Barguzin, and Verkhneangarsk ranges. The areas of glaciation were determined from the Landsat 7 and Sentinel-2 satellite images for 2000 and 2021 and were controlled by orthophotoplans based on the UAV survey in August 2021. The maximum reduction of glaciated area over 21 years is generally typical for small forms of glaciation and reaches 10-30 % for the main glaciers. Data on temperature regime of air and rock surface along an altitudinal profile in the Verkhneangarsk Range were obtained for the first time.

This paper presents a retrospective analysis of the geometric electromagnetic induction (EMI) sounding data. The data were acquired in the 1990s in the city of Neryungri to determine probabilistic relationships between unconfined compressive strength of saturated sandstone samples and the attenuation coefficient of the harmonic field induced by a high-frequency vertical magnetic dipole at 1.125 MHz in frozen sandstone rock mass. The results indicate that the consistent increase in the attenuation coefficient with decreasing strength of sandstone rock mass is correctly described by a logistic function equation. The inverse regression relationship is adequately described by a power function equation which can be used as a probabilistic model for predicting mean values of unconfined compressive strength of saturated sandstone rock mass (but not only sandstone rock samples) from the attenuation coefficient. The relative error of model predictions at the 70-80 % confidence level is ±(27.7-32) %, which is close to the limit of allowable error (±20.0 %) for laboratory measurements of mean strength of rock samples. This provides favorable conditions for applying the geometric EMI method in rock strength mapping for geotechnical engineering in Neryungri, as well as in areas of similar geology in southern Yakutia with sporadic permafrost.

A recently published book by L.N. Khrustalev, a leading specialist in engineering geocryology, professor of the Department of Geocryology, Faculty of Geology, Lomonosov Moscow State University is devoted to methods for solving a wide range of problems of engineering geocryology: thermal and mechanical interaction of engineering constructions with bearing rocks, land reclamation measures, methods for assessing the reliability of design solutions for construction in the permafrost zone, as well as methods of predictive calculations for monitoring of objects built on permafrost. This monograph contains a wide range of recommendatory and standard calculations, as well as some previously unpublished author’s works. In essence, it is a desk reference for specialists involved in the design and calculations of engineering constructions on permafrost. Another highlight of the book is its electronic component: all the calculations proposed in the book are implemented in Microsoft Excel macros and are available for download and processing. This practically eliminates the possibility of errors (the user only needs to enter the correct input data).