The radiation indicators of rock dumps, ground and surface water, atmospheric air and residential air, as well as alluvial soils of technogenic landscapes of the South Elkon uranium-ore region in the territory of South Yakutia were studied. It has been shown that the most active dumps in their radiation parameters are close to radioactive ores, while the exposure dose rate here is 1600-2150 µkR/h, the effective specific activity of natural radionuclides is 20441-23640 Bq/kg, and the uranium content is 1637-1888 mg /kg. Ranking of the studied dumps according to the degree of radiation hazard showed that only 2 dumps out of 31 (6,4 %) belong to the category of safe, 13 (41,9 %) - to the category of potentially hazardous, and 7 and 9 (22,6 % and 29,0 %) - respectively categories of dangerous and especially dangerous. In the mountainous terrain, cold and humid climate of the study area, these rock dumps, unevenly distributed over an area of about 500 km2 of mountain-taiga landscapes, are the main source of radioactive contamination of air, ground and surface water, and soil cover. At the same time, the maximum values of uranium and radon content in the studied surface and groundwater, respectively, were 8,0 and 32,2·10-5 g/l, as well as 112 and 3090 Bq/l. In the studied technogenic zones, there is a direct relationship between the intensity of pollution of surface waters and alluvial soils drained by them, formed in the floodplains of these watercourses. Key words: rocks, soils, surface and underground waters, air, radiation parameters, technogenic pollution.

The radioecological situation of the mothballed geological survey site at the Elkon Plateau deposit in the Aldan Highlands was assessed by field radiometry. It was found that the extraction of a huge mass of radioactive rocks to the surface from underground mine workings (adits, mines) has significantly increased the area with an elevated background radiation of 1.0–12.0 µSv/h and more. The studies have shown that under conditions of anthropogenic contamination, the determining factors of migration, distribution, and accumulation of natural radionuclides in soils, besides their chemical properties, are humid climate, genetic features of radioactive ore, presence of permafrost rocks, soil-forming processes, and organic matter content. In the existing conditions of mountain taiga landscapes, the intensity of wind dispersion of radionuclides from dumps is significantly lower than that of hydrogenic dispersion. Active leaching of uranium from the dump rocks led to a dramatic disturbance of the radioactive equilibrium between radium and the parent radionuclide towards its excess in the soils of the Akin Creek Valley. Prolonged uncontrolled environmental impact of radioactive dumps contributed to the accumulation of uranium and radium in soils to levels of low- (14 252–66 836 Bq/kg) and medium-activity (102 294–601 987 Bq/kg) solid radioactive waste. At present, the problem of environmental contamination with natural radionuclides in the Elkon uranium ore mining district remains extremely urgent and requires close attention of nature conservation specialists.

The aim of the study. The aim of this article was to identify the geographical and genetic features of soil formation in the cryolithozone of Central Yakutia and to assess the diversity of all types of permafrost soils of this territory. Location and time of the study. Soil-geographical and soil-genetic studies were carried out near the Middle Lena, on the territory of Central Yakutia within various geomorphological tiers of the Central Yakut Plain at different times, starting from the 1990s. Methodology. In carrying out these works, widely used methods of soil research were used, such as comparative geographical, profile genetic and comparative analytical in combination with well-known and commonly used analytical methods. At the same time, all the main results of soil studies conducted on this territory by our predecessor permafrost soil scientists were taken into account in a comparative aspect. Main results. According to the obtained results, it is necessary to state that this region of the cryolithozone is characterized by extremely peculiar landscape and climatic conditions of soil formation, the formation of the cryogenic soils occurring in a cryoarid climate, mainly on loose alluvial deposits of various ages, under forest and meadow-steppe vegetation and continuous permafrost. In the studied territory, the cryogenic soil-forming processes are crucial for the development of properties, composition and regimes of these permafrost soils, causing their high diversity and diversity of the soil cover of Central Yakutia. The systematic list of permafrost soils of the studied territory includes 17 types and 21 subtypes of soils and is forecasted to expand as the study of the soil cover of this unique region of the cryolithozone deepens. At the same time, the diversity of soils there is formed by the six types of zonal and azonal forest, five types of meadow-steppe and five intrazonal types of the permafrost soils. A broader concept of "permafrost soils" is proposed, in contrast to that interpreted in the current classification of soils of Russia and WRB, the essence of which is that regardless of the depth of seasonal thawing, all soils underlain by the permafrost are called permafrost soils. In these soils, the interlocking of seasonally and permanently frozen layers is observed in winter. These soils may differ in pronounced cryomorphic features (cryozems, fawn) or not have them (podburs, podzols, chernozems), being characterized by a permafrost type of temperature regime. Conclusion. In the cryolithozone environment of Central Yakutia, elementary soil-forming processes occur under cryogenesis conditions, which in the general hierarchy of soil-forming factors is considered at the subfactorial level; minor variations of the soil-forming factors can change the directions and rates of the soil-forming processes and, ultimately, lead to a high degree of diversity and contrast in the soil cover of the studied territory.

For the first time, the phosphate state of permafrost forest post-pyrogenic polycyclic soils of Central and Southern Yakutia, formed respectively in arid and humid climates, was studied and evaluated. These soils with a polycyclic profile, formed in the transaccumulative facies of this regions of the permafrost zone, contain, in addition to the modern one, 2–3 buried humus horizons with abundant inclusion of black charcoal. These pyrogenic humus horizons are characterized by an increased content of humus, total nitrogen and phosphorus soluble in iron oxalates, exchange bases, as well as fractions of physical clay and silt compared to neighboring mineral horizons of the soil profile. At the same time, the brown soil of Southern Yakutia, formed under less severe and humid climatic conditions, compared with those of the pale soil developed under cryoarid conditions of Central Yakutia, was more biogenic, and the total content of phosphorus here was 98.0–427.2, whereas in the second soil – only 11.0–257.1 mg P2O5/100 g of soil. Organophosphates predominated in the composition of the total phosphorus of burozem, amounting to 51.8–81.3%, and in pale soil – mineral forms of phosphorus, which accounted for 52.2–78.8%. The fractional composition of mineral phosphates of both types of permafrost soils was mainly dominated by phosphates of one and a half oxides (Al-P and Fe-P), totaling 43.3–94.3%, and among the latter – Fe-P, which accounted for 34.8–87.4% of the total amount of all fractions of mineral phosphates. It is assumed that the high content of iron phosphates, and in some cases occluded aluminum-iron phosphates in the studied permafrost soils, is due to the manifestation of both cryogenic and biogenic pyrogenic ferruginization in their genesis.

An assessment of the radioecological situation of the preserved geological exploration site at the Elkon Plateau field in the Aldan Highlands was carried out using field radiometry. It was found that the removal of a huge mass of radioactive rocks to the surface from underground mine workings (tunnels, mines) significantly increased the area with an increased radiation background - 1,0-12,0 mSv/h or more. Studies have shown that in conditions of man-made pollution, the determining factors of migration, distribution and accumulation of natural radionuclides in soils, in addition to their chemical properties, are: a humid climate, genetic features of radioactive ore, the presence of permafrost rocks, soil formation processes and the content of organic matter. Under the prevailing conditions of mountain-taiga landscapes, the intensity of wind scattering of waste from dumps is significantly lower than that of hydrogenic. The active leaching of uranium from the rocks of the dumps led to a sharp disturbance in the soils of the Akin Creek valley of the radioactive equilibrium between radium and the parent radionuclide towards its excess. Prolonged uncontrolled exposure of radioactive dumps to the environment contributed to the accumulation of uranium and radium activities in soils to levels of low (14252-66836 Bq/kg) and medium-active (102294-601987 Bq/kg) solid radioactive waste.

Fire rates have increased in the Arctic during the last decades. This requires thorough investigations on how the Arctic ecosystem responses to pyrogenic damage since melt frozen grounds release enormous amounts of methane and carbon dioxide contributing to global climate changes. In the paper we discuss the current state of knowledge on this topic, problems that impede further studies and possible ways to solve them.

Radiometric surveys of mining dumps on spent placers of gold, monazite and the exploited gold-uranium ore deposit in South Yakutia were carried out. It is established that the dumps of alluvial, overburden and waste rocks in terms of the effective specific activity of radionuclides when used in construction work are characterized by different degrees of tolerance. It is shown that stacked radioactive ore dumps at the “Lunnoye” deposit after heap leaching of gold become powerful uncontrolled sources of radioactive pollution of the environment. It is recommended to conduct periodic monitoring of their radioactivity levels by express methods of field radiometry for the safe use of mining dumps as building materials.

The phosphate state of six types of frozen soil in Central Yakutia (forest podzolic, pale brown and pale, meadowsteppe chernozems, meadow-chernozem, and chernozem-meadow) was studied for the first time. We estimated the total phosphorus content and intra-profile distribution, and calculated the forms of mineral phosphates using the Chang-Jackson method and mobile phosphates according to Ginzburg-Artamonova. The weighted average total phosphorus content in these types of soils was low (174–376 mg/kg). The highest amount of total phosphorus was observed in permafrost meadow-chernozem (376 mg/kg), chernozems (358 mg/kg), and pale (344 mg/kg), slightly lower in chernozem-meadow (302 mg/kg), and the lowest was in pale-brown (214 mg/kg) and podzolic soils (174 mg/kg). Under cryolithozone conditions in Central Yakutia, which is characterized by a cryoarid climate and continuous permafrost, cryogenic soils are characterized by low biological activity and, consequently, a low amount of phosphates available to plants. The mobile phosphate content in the studied frozen soils (1,3–7,4 mg Р2О5/100 g soil) was low and very low according to Ginzburg-Artamonova (not exceeding 1–2% of the gross content). The upper horizons of frozen chernozems, which are the warmest and most fertile soils in Central Yakutia, have the amount of phosphates (18,3– 42,1 mg Р2О5/100 g soil), which makes 8–1 % of the gross content and is estimated as medium and high. In various genetic horizons of frozen soils in Central Yakutia, the total amount of all forms of mineral phosphates estimated accrording to Chang-Jackson varies widely and ranges from 11,4 to 188,0 mg Р2О5/100 g soil. The studied frozen soils also differ in the minimum content of the most loosely bound phosphates available to plants, amounting to 2,7–6,0 mg Р2О5/100g soil, which usually does not exceed 10 % of the total amount. We conclude that the fractional composition of mineral phosphates in the frozen forest soils of Central Yakutia is dominated by phosphates that are difficult for plants to reach. The maximum content of iron phosphates reaches 63,1–92,6 % of the total amount of all fractions. A relative increase in calcium phosphates to 56,5–58,0 % of the total content is observed in the frozen meadow-steppe soils of this region.

A radiological and medical-biological study of the population of Aldan and Tommot of the Aldan region of South Yakutia, located in the zone of increased natural radiation, was carried out. The annual individual effective exposure dose to the population turned out to be 2 times higher in the city of Aldan (6.22 mSv). The contribution of radon and its decay products in the city of Aldan was 59.5%, in the city of Tommot -48.3%. Assessment of the adaptive potential (AP) of the circulatory system of the population showed a high percentage of the occurrence of functional stress of adaptation mechanisms, especially among residents of the city of Aldan (86.5%). The correlation showed a negative role of an increase in the level of triglycerides, urea, the activity of LDH, CK, and a decrease in the activity of alkaline phosphatase on AP. The presence of GBL dys-function and, especially, fatty hepatosis was also associated with a decrease in AP.

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.

Впервые проведена комплексная оценка радиационной и экологической обстановки на 9-ти золоторудных месторождениях Куранахского рудного поля (КРП), а именно «Северное», «Порфировое», «Центральное», «Южное», «Первухинское», «Боковое», «Дорожное», «Дэлбэ» и «Канавное». При проведении исследований использовался комплексный подход, основанный на применении геоэкологических, радиоэкологических и геохимических методов исследования в сочетании с экспрессными и точными методиками полевых и лабораторных работ. Показано, что гамма-фон на исследуемой территории изменяется в пределах от 7 до 26 мкР/ч и не превышает фоновые величины, характерные для карбонатных и терригенных осадочных пород. В мелкоземе пород отвалов и карьеров концентрации 40К варьируют в пределах 0.6-10.1 мг/кг, 238U – 0.8-12.3, а 232Th – 0.5-10.8 мг/кг и в целом соответствуют таковым, характерным для осадочных горных пород. Эффективная удельная активность радионуклидов в мелкоземе горных пород изменяется от 38 до 386 Бк/кг. Помимо оценки радиоэкологической обстановки на исследуемой территории, нами также изучалось общее экологическое состояние природной среды в районе КРП. Здесь также отмечается многофакторное антропогенное и техногенное воздействие на природные ландшафты. В частности показано, что в данном районе 47 % общей площади территории природных ландшафтов нарушено геолого-разведочными и добычными работами. В общем по результатам проведенных исследований радиоэкологическая обстановка в исследуемом районе в настоящее время оценивается как благоприятная, а эколого-геологическая может быть охарактеризована как напряженная, а в отдельных случаях даже как кризисная.

In this article, the soils of experimental beds of arable land with potatoes of the Tittyakh plot are studied. A general microbiological analysis of the selected soils–determination of the main ecological and trophic groups of microorganisms, as well as identification of the presence of phytopathogenic fungi contributing to potato spoilage - was carried out. It has been established that the used pesticides (herbicides) reduce the total number of microorganisms in the arable land with potatoes by 3 times and have different effectiveness against pathogenic fungi for potatoes. It was revealed that the soil at the Tittyakh site is infected with the most dangerous fungi for potatoes from the genera Fusarium, Trichoderma, Alternaria.

This paper examines the effect of planted spruce (Picea obovata Ledeb.) stands on changes in the morphological characteristics, composition, and properties of cryogenic meadow–chernozem soils that formed in a cryoarid climate under meadow–steppe vegetation in the vicinity of the City of Yakutsk, the central part of the Sakha (Yakutia) Republic. It is shown that the initial morphological profile of the virgin soil (Wca–AUca–ABca–BCA–BCca–Cca) has been transformed over a 45-year exposure period into the profile of a forest humus–calcareous soil (O–OH–AJ–ABca–BCA–BC–Cca). The morphological structure of the virgin soil underwent the following changes: the forest litter (O) and litter–humus (OH) horizons formed; the thickness of the seasonally thawing layer decreased from 123 to 102 cm; and the 10% HCl effervescence depth, which indicates the presence of mobile carbonates (CaCO3 and MgCO3) in the soil, increased to 26 cm from the surface. In addition to the morphology, the composition and properties of the humus–calcareous soil have also changed significantly in comparison with the initial meadow–chernozem soil. The pH values of soil–water extracts from the AJ and ABca horizons of the humus–calcareous soil decreased by 1.0–0.7, respectively. The total amount of exchangeable bases (Ca+2 and Mg+2) increased in the 0-to 100-cm layer of the forest soil by 1.2 times in comparison with the meadow–steppe soil; the total salt content increased by 1.5 times; and the total N content and organic C content increased by 3.2 and 1.7 times, respectively. Concurrently, the amount of mobile carbonates in the secondary soil decreased by 2.9 times. The magnetic and salt profiles of the studied soils, as well as their salinization degrees and chemistry, have also changed, and the initial cryogenic–exudational water regime has been transformed into a permafrost, periodically-percolative regime due to the change in the vegetation growing on the studied soils.

— The results of the field radiometric survey of the mined monazite Vasil’evka placer in southern Yakutia are presented. It is shown that the natural background radioactivity of soils of the surveyed area mainly depends on the features of its geological structure and, to some extent, on landscape-geocryological conditions. The rate of equivalent dose of gamma radiation on the soil surface of the studied plot varies in a wide range (from 0.04 to 0.50 µSv/h or more), depending on changes in the concentrations of 40 K, 238 U, and 232 Th in soils. Radiogeochemical features of soils in the studied area are well displayed on radiometric maps by isolines of the dose rate and radionuclide contents. The concentrations of 40 K, 238 U, and 232 Th are minimal in a peat-bog soil and a high moor on the interfluves composed of crystalline schists and gneisses and are maximal in podburs and alluvial soils formed on the products of weathering of granitoid rocks and monazite-bearing alluvial deposits in the Vasil’evka River valley. The studied soils are characterized by low mean concentrations of 40 K and 238 U, corresponding to their background values in soils of Yakutia. The mean concentration of 232 Th in the studied soils is increased as compared to the geochemical background. In addition to the composition of soil-forming rocks, the content and distribution of radionuclides in soils are significantly affected by soil-forming processes, chemical properties of elements, and technogenic impact. According to the effective specific activity of radionuclides, the studied soils correspond to the first, second, and third classes of building materials. Soils and enriched sands in some parts of technogenic landscapes are assigned to low-radioactive industrial waste according to the specific activity of thorium and require disposal. Their use as building materials from the identified areas of natural thorium concentration in alluvial deposits has serious limitations.

For the first time, a study of the microflora of permafrost forest soils of the Yakutsk Botanical Garden was implemented. It was found that in 2019 in the studied permafrost soils the number of microorganisms ranged from 103 to 106 CFU/g soil. Of all types of permafrost soils, humic calcareous soil (Rendzic Leptosols Eutric) appeared to be the most saturated with microorganisms, while solod soil (Stagnosols/Planosols) was the poorest. In the microflora of the studied permafrost soils, mycelial microorganisms predominated. Although this can not be said about solod, where ammonifying bacteria prevailed. Changes in the number of microorganisms mainly depended on soil temperature, humus and nitrogen content. Humidity and pH value in these soils turned out to be less significant in changing the composition of the microflora of these soils. Number of microorganisms and pH showed negative correlation. The study of the distribution of microorganisms along the profile of the studied forest soils showed that an increase in the number of bacteria and fungi was observed in the upper organogenic horizons, and their number decreased with depth.

The magnetic susceptibility (MS) of three types of permafrost forest soils (pale-yellow, pale-brown, and podzolic) formed on permafrost soil-forming rocks in the cryoarid climate of Central Yakutia for the first time was studied. It is noted that the studied permafrost soils develop within various high-altitude geomorphological levels of the ancient alluvial Central Yakut plain and form a regular zonal series from bottom to top, that is, with an increase in the absolute height of the terrain: pale-yellow gray ‒ pale-yellow typical and solodic ‒ pale-yellow leached ‒ pale-brown typical ‒ pale-brown podzolized and podzolic soils. At the same time, in this series of zonal soils, the values of their volume (VMS) and specific (SMS) magnetic susceptibilities also naturally decrease, due to the increased intensity of eluvial soil processes, such as solodization and podzolization in the genesis of these soils. The weighted average values of the specific magnetic susceptibility calculated for 9 sections of the studied permafrost forest soils, taking into account individual values of SMS and the thickness of their genetic horizons, changed for pale-yellow soils in the range of 21.6–42.1, pale-brown – 3.9–12.4, podzolic – 1.8–5.7 × 10–8 m3/kg. It is also established that based on certain values of the VMS of these soils, all the studied types of permafrost forest soils in Central Yakutia belong to the group of low-magnetic ones and differ in the values of volumetric magnetic susceptibility that do not exceed 100 × 10–5 Si units. Among the studied pedons of zonal forest soils of Central Yakutia, various types of their magnetic profiles are noted, which are determined by the geographical and genetic features of these soils.

This article describes the features and migration patterns of natural long-lived heavy radionuclides 238U and 226Ra in the major components of the environment including rocks, river waters, soils, and vegetation of permafrost taiga landscapes of Southern Yakutia, which helped us to understand the scale and levels of their radioactive contamination. Different methods have been used in this study to determine the content of 238U and 226Ra in various samples, including gamma-ray spectrometry, X-ray spectroscopy, laser excited luminescence, and emanation method. It was determined that the main source of radioactive pollution of soil and vegetation cover, as well as surface waters in these technogenic landscapes, are the dumps of radioactive rock that were formed here as the result of geological exploration carried out in this area during the last third of the 20th century. The rocks studied were initially characterized by a coarse, mainly stony gravelly composition and contrasting radiation parameters, where the gamma radiation exposure rate varied between 1.71 and 16.7 µSv/h, and the contents of 238U and 226Ra were within the range 126–1620 mg/kg and 428–5508 × 10−7 mg/kg, respectively, and the 226Ra: 238U ratio was 1.0. This ratio shifted later on from the equilibrium state towards the excess of either 238U or 226Ra, due to the processes of air, water, and biogenic migration. Two types of 238U and 226Ra radionuclides migration were observed in studied soils, namely aerotechnogenic and hydrotechnogenic, each of which results in a different intraprofile radionuclide distribution and different levels of radioactive contamination. In this study, we also identified plants capable of selective accumulation of certain radionuclides, including Siberian mountain ash (Sorbus sibiricus), which selectively absorbs 226Ra, and terrestrial green and aquatic mosses, which accumulate significant amounts of 238U.