Owing to the importance of drinking water in human nutrition, in this study, we performed a comparative analysis of the chemical composition of drinking water from settlements endemic to Kashin–Beck disease and from territories that are not endemic to Kashin–Beck disease. Our analysis showed that all drinking water samples were weakly alkaline and had a hydrocarbonate–calcium–magnesium composition. There were no considerable differences in mineralization, pH, or concentrations of Mg, Si, F, Se Zn, K, and Na. All waters had weak hardness specific for the waters from the northern territories. The mineral waters from the Urov biogeochemical subregion of the biosphere have elevated concentrations of Ca, Mg, Sr, Si, and Li and lower concentrations of I, Se, and Cu. The maximum Sr content was found in mineral water from the Bazanovo village, i.e., 20 mg/L, with a Ca/Sr ratio of 8 units. Owing to the inconsistency of data on the chemical composition of drinking water from the territories endemic for Kashin–Beck disease, we suggest an indirect role of biogeochemical factors in the disease pathogenesis. Previous pathologies may be important, which have arisen because of hypothermia, common cold, hormonal imbalance, and alimentary factors.

The questions of heterogeneity, organised character and optimum condition of the biosphere, its functioning and transformation always were and remain central scientific problems, for they are directly bound up with cognition of nature of life as a planetary and cosmic phenomenon, with a historical estimation of a role of the living matter in the past, present and future, with definition of a place and role of the person in evolution of the Earth and with forecasting assessment of biogeocenosis development.In this article attention is paid on importance of a biogeochemistry in development of ecological researches, questions of geochemical ecology and concept of biogeochemical provinces directly bound up with the analysis of a present condition and evolution of the biosphere.

The paper discusses the core ideas and the development of biogeochemistry as an integrated research avenue in geochemistry and biology created by V.I. Vernadsky. Much attention is paid to the key concepts of biogeochemistry: living matter, the biogenic migration of chemical elements, and the chemical elemental composition of organisms and its ecological significance. The development of the various functions of the biosphere is analyzed: ecological, concentrational, and informational. The differentiation of the chemical elemental composition of organisms is analyzed under conditions when the biosphere is impacted by anthropogenic activities (the development of industries). The role of biogeochemistry is demonstrated with reference to the development of biotechnologies and the elaboration of a biogeochemical indication of the ecological state of biospheric taxons. The progress in biogeochemistry and its current problems are briefly analyzed.

In the Urov sub-region of the biosphere (Eastern Transbaikalia), a local increased content of Sr in soils and plants was found due to high concentrations of Sr in soil-forming rocks (carbonated granites). The purpose of this study is to assess the concentrations of Ca and Sr in the technozem of dumps and quarries of seven developed deposits (W-Mo, Mo-Cu, Pb-Zn, Au). The fraction of technozem (< 1 mm) was ground to a grain size of 150-200 mesh and analyzed by XRF. The content of Ca and Sr in plant mowing was determined by the flame variant of AAS. It was found that the content of Ca and Sr in 25 samples of technozem varied between 4970-37200 mg/kg (Ca) and 100-620 mg/kg (Sr). The average content of Sr is 308 ± 122 mg/kg. The increased Sr content was characteristic of carbonate technozems with an increased level of Ca (Mo-Cu ore occurrence). Increased accumulation of Ca and Sr in mowing plants was found in the technozems of the Zhireken Mo-Cu deposit: 35100 mg/kg (Ca) and 397 mg/kg (Sr). In general, the concentrations of Ca and Sr in technozem approach to their content in conditionally background soils and do not significantly contribute to the pollution of natural landscapes within the Urov-region of the biosphere.

The purpose of this study is to estimate the migration of heavy metals (HMs) and As into the water of the Ardon river, and their content in the soils of the areas adjacent to the Unal Tailings Pond (UTP) caused due to the industrial waste of the Mizur Ore Mining and Processing Enterprise (OMPE) (North Ossetia). The main survey loops for experimental research and collection of biogeochemical materials are located in the Ardon river basin where the major abandoned polymetallic fields of the Republic are located. Soil samples were taken from 20 sites throughout the Ardon river and within the UTP. HMs and As levels in the water, alluvium, soils samples were determined using the atomic-absorption spectroscopy (AAS) in its flame version and/or electrothermal atomisation. We have determined that UTP wastewater discharge into the Ardon river along with Me introduction with waters of the Unaldon river, as well as the dust/pulp coming from UTP followed by the formation of bottom polymetallic anomalies provide a significant contribution to the Me pollution of the Ardon. High Me content in soil and slurry as a result of its deflation and in UTP effluents may lead to Me absorption by plants and other organisms. The data obtained reflect the processes of modern transformation of mountain taxa of the biosphere with a technogenic component and can be used for remediation of contaminated areas.

Biogeochemical studies were carried out in two territories of the Northern Caucasus, including the Unal depression (which is enriched in Zn, Pb, Cu, and Cd) in the basin of the Ardon River in the Republic of North Ossetia–Alania and a profile down the Baksan River (which is characterized by elevated W and Mo concentrations) in the Kabardino–Balkarian Republic. The accumulation of metals was studied in both individual plants and ecogroups and in a lateral profile and a profile across altitudinal belts in the basin of the Ardon River. Selective Zn enrichment was found in the leaves of the birch Betula platyphylla Sukacz., whereas Cd and Zn were detected to be accumulated in the leaves of various willow and aspen types. Correlations were evaluated between the activity of soil enzymes (dehydrogenases, invertase, peroxidase, and catalase) and the concentration levels metals in soils at base-metal and W–Mo of biogeochemical provinces. It was determined that an increase in the totals of the concentrations of all metals in the soils of both areas is inhibited the activity of dehydrogenase. According to the degree of their inhibition by metals, the soil enzymes define the following sequence: dehydrogenases > invertase > (catalase and peroxidase). A change in the activity of soil enzymes at anthropogenic pollution can serve as an additional biogeochemical indicator for exploration operations and in ecological studies.

The review presents summarized information on a new research avenue in biogeochemistry and geochemical ecology: relationships between the microcosm (viruses) and manifestations of animal and human pathologies. Some aspects of the biological action of selenium, zinc, copper and iodine, their influence on the manifestation and course of viral infections are considered. Attention is focused on the antioxidant, membrane-protective, boosting immunity, hormonal functions of trace elements, and on the antibacterial and antiviral properties of metallic copper and its compounds. The criteria currently applied in assessing the Se status of territories are compared with the incidence of COVID-19 and HIV in the population of the Russian Federation. In some cases, selenium deficiency in the environment is shown to be associated with a higher susceptibility to RNA viral infections. Emphasis is put on the necessity of improving the criteria for assessing the trace element status of territories and further studies in the geochemical ecology of viruses and their role in the biosphere.

Fluorine environmental emissions are often associated with the activities of metallurgical industries. It is common knowledge that fluoride excess negatively affects the state of vegetation, health of animals and human who often suffer from pathologies that are named with the general term “fluorosis”. Soil, water, leaves and fruits of agricultural crops were sampled in the area of aluminum production (Tursunzade, Tajikistan) and the content of fluoride in them was determined as well. Also, the clinical condition of local cattle was evaluated. The X-ray examination was performed for animals of 1–12 months and adult cows. The phosphorus content in the surface water bodies was found to be 1.1–31.5 mg/l, in soils – from 220 to 1000 mg/kg, depending on the distance from the aluminum plant. As for the fruit samples, phosphorus was detected in the amount of 8–122 mg/kg of, as for the cultivated plants leaves – 70–180 mg/kg. The highest concentration of fluoride was determined in the mowing of herbage plants (growing in the southwest direction from the plant, at a distance of 2–3 km from it) – 610 mg/kg. The development of fluorosis was diagnosed in cattle, young animals aged 2.5–3 years also suffered from the wear and blackening of the teeth enamel. At the same time animals of different ages demonstrated the tail vertebrae softening and anomalies of bone development. This study revealed the presence of total pollution of all the environmental objects and the need for measures in order to correct the fluoride content in biogeocenoses.

The assessment of opportunities of various methods of complex ecologo-biogeochemical monitoring of objects of the accumulated environmental damage (tailings dams) in modern biospheric conditions is very significant. Organisms of different levels of the organization are applied: from infusorians to the highest mammals and the human body. In addition to direct determination of levels of toxicants in organism researchers often use their morphometric parameters, in particular - the fluctuating asymmetry. Calculation of this parameter for sheet plate of the birch growing near the Unalsky tailings dam (North Ossetia) was compared to determination of biologically active sulfur-containing components (metallotioneins, glutathione, cysteine) and pigments (a-chlorophyll, b-chlorophyll, carotene). In the technogenic horizons of urbozem and natural soils, leaves and hay crops of plants the content of microelements is found. In soils and urbozem it is revealed: Pb - 10.5-589, Cu - 7.0-891, Zn - 23-4156, Cd - 0.2-91, As - 5-18.8, Se - 0.05-4.6 mg/kg. High positive correlation between the content of Pb in soils and asymmetry of birch leaves (r = 0.89) is established. On other metals correlation was low (r = 0.18-0.21). Floristic inspection found noticeable decrease in phytovariety and biomass on technogenic platforms. Value of the fluctuating asymmetry is moderately correlated with amount of metals in soils and leaves. The same relation is found between its value and content of glutathione and metallotionein in extracts of birch leaves. Correlation with levels of pigments (a-chlorophyll and carotinoids) was not observed. Comparison of the fluctuating asymmetry of leaves of white birch with the total content of metals and the concentration in water extract confirms certain correlation between these parameters. Higher concentration of the sum of metals and sulfur-containing biologically active agents is followed by increase in value of asymmetry.

RedOx processes determine the resistance of the organism to pollutants. The aim of the study was to establish a possible relationship between copper and zinc concentration in the blood of calves and the enzyme activity of superoxide dismutase. The study was conducted in 2019 on 50 calves with a weight of 201-250 kg. The samples of venous blood were taken to estimate the level of hemoglobin, glutathione, metallothioneins, as well as zinc, copper, and superoxide dismutase activity. The obtained average values of these substances concentration were compared between each other. A positive correlation between the activity of superoxide dismutase and the concentration of zinc (r = 0.64) and copper (r = 0.87) in the blood of calves has been established. It may be because both metals are obligatory components of superoxide dismutase. There is also a positive relationship between the levels of copper and zinc (r = 0.68). For the other parameters, no reliable relationship was found. The data obtained indicate a positive relationship between the activity of superoxide dismutase and metal concentrations of copper and zinc in the blood of calves. At the same time, a more significant positive relationship is established for copper.

The article deals with the assessment of biogenic migration of molybdenum and other trace elements in ore and background conditions. The purpose of this study was to determine the specific features of copper and/or molybdenum accumulation rates in animals against the background of various tungsten and rhenium content levels in the environment and animal feeds, as well as possible metals incorporation into XO-XDH of cow milk. The field biogeochemical studies were performed in summer 2009, 2012, and 2018 in ore landscapes of W-Mo deposits (Tyrnyauz) and background areas of the North Caucasus with the selection of breeds, soils, natural water, plants, animal blood, and dairy products. For comparison, dairy products from the Moscow region were also examined. It was established that metals accumulated not only in soils but also in pasture plants. High content of molybdenum in the blood of cows in ore regions accompanied by a sharp decrease in the concentration of copper was noted. The concentration of studied metals in buttermilk in ore regions increased by 5–10 times in comparison with the control zone. When studying W-Mo ore landscapes of the North Caucasus (Tyrnyauz), the tungsten and rhenium were found to be capable of incorporation into the xanthine enzyme fractions (oxidase) in animals. This fact was discovered for the first time. In the case of an increase in the content of molybdenum and/or tungsten (rhenium) in the environment, the migration of the latter metals is significantly enhanced in ore conditions.

The comparative assessment of the levels of content and migration parameters of biologically active chemical elements in the biogeochemical food chains of the main localities of the Urov endemic disease in the Eastern Transbaikalia: rocks-soils-plants-animal hair, milk was conducted. The differentiated polyelement microelementosis with an excess of Sr [1], Mn, Cr, Ni, in some cases – P, Ba, As, Zn and deficiency of Se, J, Cu, and Mo is typical in Urov biogeochemical provinces of Eastern Transbaikalia against the background territories. Soil landscapes are not much different in content of selenium, but its migration in plants was reduced in places of spread of Urov disease. Parameters of migration of chemical elements in the soil-plant complex reflected on their content in wheat, hair cover of animals and milk cows. The sources of this imbalance are soil-forming rocks, specific conditions of soil formation (accumulation of organic matter in freezing soils of narrow valleys with a high degree of moisture and low flow, and selective concentration by plants). For floodplain soils with a high level of organic matter is characterized by a high content of micromycetes of the genus Fusarium as their species composition and abundance. The data obtained are consistent with the results of research by Chinese scientists on the assessment of the chemical elemental composition of hair in healthy children and with Urov Kashin-Beck pathology [2] and considered as risk factors in the genesis of this endemic disease. Funding This study was supported by the Russian Foundation for Basic Research, project No. 19-05-00054 References 1. Ermakov V.V., U. A. Gulyaeva, S. F. Tyutikov, T. G. Kuz’mina, and V. A. Safonov. Biogeochemistry of Calcium and Strontium in the Landscapes of Eastern Transbaikalia. Geochemistry International, 2017, 55 (12). P. 1105–1117. https://link.springer.com/article/10.1134%2FS0016702917090026 2. Wang X., Ning Y., Zhang P., Li C., Zhou R., Guo X. Hair multi-bioelement profile of Kashin-Beck disease in the endemic regions of China. J Trace Elem Med Biol., 2019. 54 (July 2019). P. 79-97. https://rareomics.healx.io/disease/kashin-beck-disease.

This study was aimed at assessment of Re migration and its accumulation by organisms within the Zhireken ore field and neighboring territories (Eastern Transbaikalia). To measure the concentrations of Re in biogeochemical objects, the ISP-mass spectrometry method and solutions with known metal content were used. Other metal were determined by AAS. The hyperaccumulation of rhenium by plants growing around Zhireken quarry (up to 60 mg/kg) at a background level of 5-10 ng/g of dry matter was established. The Re content in the reservoir of the bottom part of the quarry (74 mu g/l) and the duct (63 mu g/l) exceeds the background concentrations by 1,000-5,000 times. The coefficient of water migration Re in the ore anomaly reaches 914 units, which indicates its high migration ability. Re concentrations in soils and ground correlate with Mo, Cu and Fe ones. In plants, this relationship is not established. The Re hyperaccumulation by plants is the basis for the development of technologies for extracting metal from ore materials and reconndissance of rhenium anomalies.

The higher accumulation of Mo, W, Cu and Re by soils and organisms in the Baksan River basin owing to the anthropogenic contamination by the former Tyrnyauz W–Mo industrial complex and migration of the metals with natural waters are discovered during biogeochemical studies of W–Mo mining landscapes of the North Caucasus and background territories. The man-made transformed soils of the Baksan River valley and natural waters are enriched in moderately mobile compounds of Mo and other metals. The competitive relationships are found not only between Mo and Cu, but also between Mo and W while assessing the biogenic migration of metals. An increased content of Mo and W is found in the hair coat, blood and milk of farm animals, which is accompanied by changes in the activity of some enzymes.

The paper presents analysis of the accumulation of toxic and vital chemical elements in discrete links of the food chain under conditions of a biogeochemical province in relation to the accumulation of phytochelatins and metallothioneins in the leaves of white birch (Betula pubescens). Gradients of metal concentrations are determined in the soils with increasing distance from the Unal tailing dump and the effects of these gradients on the concentrations of the elements in birch leaves. Correlations are determined between the concentrations of toxic elements in the pulp and leaves separately for the native sample and water washout. A strong correlation was found between the total dissolved concentration of all metals and the total metallothionein and glutathione concentrations. It is hypothesized that the biochemical system of glutathione is more closely related to the accumulation of metals by plants than the system of metallothioneins. Estimates are made whether it is possible to apply the method of bioindication of the ecological state of a territory by determining the fluctuating asymmetry of birch leaves. This bioindication parameter was evaluated separately for each of the cardinal points. It is demonstrated that a high total concentrations of the metals in soils and birch leaves is correlated with an increase in the fluctuating asymmetry of the leaves and the concentration level of sulfur-bearing biological active compounds. The bioindication technique is however still far from perfect and is difficult to apply and, hence, requires further studies.