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The X-ray fluorescence, atomic absorption and step-by-step extraction methods were used to obtain novel data on chemical composition of soils as well as on the forms of the heavy metals Cu, Pb and Zn residing in them. The key areas in the surroundings of the village of Utulik (southern shore of Lake Baikal) were surveyed. It was found that the contents of trace elements in these soils varied mainly within the regional background. However, the soils experiencing anthropogenic load are contaminated with Cu, Pb and Zn. The calculated coefficients of radial differentiation of elements in the soils of the conditionally background area showed an accumulation of lead (R > 1) in the O and E horizons, zirconium in the E horizon as well as chromium and iron in the B horizon. These soils are characterized by the removal of elements Cu, Ni, Co, Zn and Mn (R < 1). In samples soil from the conditionally background area, Cu, Pb and Zn occur mostly in forms poorly absorbed by plants. Furthermore, Zn is weakly fixed in polluted soils and basically occurs in exchange forms, and the role of amorphous hydroxides increases substantially in the fixation of Pb. Because of light granulometric soil composition and low sorption capacity of geochemical barriers, the presence of abundant amounts of Zn and Pb in exchange forms presents a potential threat to their migration to contiguous environments. An assessment of the buffer capacity of soils was made, indicating that the buffer capacity is medium (20.5-24.5 numerical points) or low (<20) with respect to heavy metals. These characteristics should be taken into account when monitoring the soil state and planning any economic activity.

A wide-scale investigation providing insights into the spatial and temporal distribution of sanitary and microbiological indicators of water quality was undertaken in the shallow nearshore zone of Lake Baikal. Water samples were collected along the entire lake perimeter during several years, from 2012 to 2016, and in 2020 (total number, n = 450). Comparison of the abundance of fecal indicator bacteria in the bottom and surface waters at a total depth of 1 m showed that the concentration of sanitary indicator bacteria was generally higher in the surface water layers. The dynamics of water quality indicators as determined from May to November at the monitoring stations in the villages of Listvyanka and Bol’shie Koty did not reveal, according to statistical calculations, any substantial differences in the number of fecal indicator bacteria in most cases for different months of this study. Results of four circum-Baikal surveys at the same stations in June and September 2015 and 2016 also showed no notable differences in terms of the period of sampling. The concentration gradient of the fecal indicator bacteria 100 m from the water edge exhibited an consistent decrease of these microorganisms with distance from the shore towards deeper parts of the lake. An area of sampling was revealed, in which the concentrations of fecal indicator bacteria exceeded considerably the regulatory standards (SanPiN 2.1.5.980-00). The village of Khuzhir was such a site. In the shallow water at the villages of Sakhyurta and Kultuk, the concentrations of fecal indicator bacteria were on the verge of maximum permissible concentration. These data provided evidence of constant and significant water pollution in the nearshore zone adjacent to settlements characterized largely by touristic activities (the recreational activity is increased)

An analysis is made of the long-term data sets on the annual and seasonal water flow and the major ions flux of the Northern Dvina river at the village of Ust’-Pinega where hydrological and hydrometric observations were begun in 1882 and 1947, respectively. Long-term phases of their increased/decreased values were revealed, and their main characteristics were determined. It is established that the difference in the mean annual water flow between the long-term phases of increased and decreased values relative to the values characteristic of the lower flow were 17 % for the annual flow, 16 % for the flood flow, 32 % for the winter flow, and 38 % for the summer-autumn flow. It is concluded that changes in chemical flux during the shift from the phase of increased to decreased water flow was less clearly pronouced. The largest differences in the ion flux in the contrasting phases of water discharge were characteristic for the summer-autumn hydrological season and winter low-water season. During these periods the ion flux increased by 14-17 % and 10-11 %, respectively, whereas during the snow-melt flood period and the whole year, the ion flux was only 5-8 % higher. A relative dynamic constancy of the geochemical load on the White Sea by the Northern Dvina, regardless of its water discharge, is caused by the inverse relationship between water discharge and the concentration of chemicals. In addition, the anthropogenic influence on the ionic composition in the catchment area of the river is insignificant, which makes it possible to maintain established relationships under climate change.

For the first time in the scientific literature, an analysis is made of the channel formation conditions and of the morphology and channel regime of the Lower Ob (within Khanty-Mansi Autonomous Okrug - Yugra) which in this context, in spite of its important economic and water transport significance, remains largely unexplored. The geomorphological structure of the valley determines downstream of the confluence of the river with the Irtysh the concentration of the river at the right valley side in a common channel producing single branches divided by straight unbranched sections shaped by river flow concentration along the right valley side and formation single branches, divided by straight unbranched sections. It is found that at the village of Pogrebennoe the broadening of the floodplain to 60 km is accompanied by the formation of a bifurcated channel (Malaya and Gornaya Ob), the distribution of water discharge in the main channels (up to four) and by numerous floodplain channels connected with one another and with the tributary, the Severnaya Sos’va river. In this connection, the water discharge of the main branches downstream decreases (by as much as 5 % of the total discharge in the Malaya Ob), there occur changes in the morphology of the channels of the branches of the bifurcated channel and in the parameters of their forms and in the intensity of reconfigurations and caving; the number and shallowness of river bars increase. It is established that the morphodynamic types are different in the common channel and in the branches of the bifurcated channel. The common channel is represented by one morphodynamically homogeneous section, with an absolute predominance of single bifurcations; the branches of the bifurcated channel are mainly meandering, and only the Gornaya Ob in the section along the valley side forms single bifurcations. On the boundary of the Khanty-Mansi Autonomous Okrug - Yugra and Yamalo-Nenets Auonomous Okrug the river is concentred in two main branches (Malaya and Bol’shaya Ob). We obtained hydrological and morphological relationships between the parameters of channel bends of the channel of the branches of the bifurcated channel and the branches of single bifurcations and their discharge during floods. However, the relationships are unstable, because they are disturbed due to the variability in water discharge within one form and local conditions.

This paper considers periglacial sediments of the high accumulative Abalakh plain located in the interfluve of the Lena and Amga rivers (Central Yakutia). The genesis of loose deposits is determined, and the role of various sedimentation processes in their formation is revealed. Results were obtained on the basis of the cryolithological description of 94,5-meter borehole drilled in 2018. An analysis was made of the degree of roundedness and frosting of the surface of quartz grains. Diagnostic elements on the particle surface characteristic for different sedimentation processes are identified. An assessment of the relationship in the composition of quartz and feldspar grains was made. It was established that the layer under consideration has an alluvial (Tobolsk and Samara-Taz horizon) and lacustrine-alluvial genesis (Zyryanka horizon). It is pointed out that aeolian processes were also involved in sedimentation of the Tobolsk horizon. The source for deposits in the profile of the Abalakh plain was provided by loose deposits of short-range transport which were processed in the fluvial environment. Evidence for post-sedimentation processes of frost weathering was discover in deposits of the Zyryanka Samara-Taz horizons. It was established that loamy deposits of the ice complex were produced as a result of a complicated set of processes including frost weathering, aeolian transportation in a suspended state, and accumulation in stagnant basin conditions.

This paper presents the results of studies aimed at identifying statistical relationships between the landscape structure and the variability in Siberian stone pine (Pinus sibirica) increments in the permafrost-hillocky northern-taiga landscapes of Western Siberia (Nadym river basin). Dendrochronologies of Siberian stone pine growing on frost mounds of different types were compiled. Principal component analysis was applied to obtain independent variables that describe the site and landscape structure of the territory. Cores from 512 trees growing on 23 frost mounds were analyzed. The methods used were as follows: crossdating, dendrochronological standardization, and elimination of monotonic trends for each tree. Results of the classification of Sentinel satellite images were used to calculate the proportions of lakes, forests, sparse forests, floating bogs and flat-hillocky peat bogs, with the radius of the vicinity of a frost mound of 100-2000 m. Correlation, dispersion and regression analyses were used in the analysis of the dependence of the median increment on the characteristic of the mound site and landscape neighborhoods. It is established that on high mounds the variability in increments is higher on tops than on slopes, whereas the situation is often the contrary on low mounds. It is also found that the tops and slopes of the frost mounds respond differently to climatic fluctuations depending on the landscape structure and the height of the mound: the close proximity of lakes reduces the variability of phytoproductive functioning on the summit surfaces. It was revealed that the sensitivity of Siberian stone pine growth to temperature fluctuations increases with an increase in the diversity of the facies structure caused by the development of thermokarst subsidence and cryogenic cracks.

In order to identify the features in the dynamics of the soil temperature regime during the post-fire reforestation of the subtaiga light-coniferous geosystems of the Tunka depression, a study was made of the demutation processes in the pine forests of the Badary urochishche the fires that occurred in 2010. As part of monitoring observations in 2011-2020, the specificity of rehabilitation of understory trees as well as of the shrub layer and live ground cover was determined. The period of appearance of the first shoots of undergrowth was noted; the projective cover of species of all forest-growing layers was estimated. By comparing the dominant composition of secondary succession biocenoses with natural plant communities, indicators of the prospects for successful reforestation were identified. An analysis was made of 10-year-long observation data on the soil temperature regime from the surface to a depth of 3.2 m was carried out at the selected sites. Measurements were made all year round in an automatic mode using atmospheric-soil measuring systems. The differences between the soil temperatures on the disturbed and natural sites, which vary over a year, were revealed. Open soils on the site affected by fire are warmer in the summer and colder in the winter. Snow cover acting as a heat insulator on both sites reduces the differences. However, with late snow onset, the contrasts increase. During the observation period, a decrease in microclimatic differences was observed with the regeneration of vegetation cover, which indicates the reforestation of the temperature regime in the pyrogenically disturbed area. The results obtained at this stage, and also the continuation of the monitoring are applicable to the analysis of pyrogenic transformation of subtaiga light-coniferous geosystems in the south of Eastern Siberia and the forecast of post-fire reforestation of light-coniferous forests of the Tunka depression, taking into account regional specifics. The continuation of comprehensive monitoring will allow for a more detailed assessment of the regeneration of the landscape and climatic conditions of the territory in the future.

This article presents a comparative description of the thermal springs occurring on the coast of the Sea of Okhotsk, in the Priokhotye region. In the northern segment of Priokhotye, their groundwater is salty and brackish, mainly of the chloride class. Only one thermal spring (Khiimskii) is a freshwater spring. The water temperature varies from 22 to 63 °C. In the western segment, the water of the thermal springs is fresh, of the bicarbonate class. It is established that the thermal springs are associated with Quaternary dikes of alkaline basalts. The composition of thermal waters is governed by changes in climatic and permafrost conditions, and by fluctuations in the level of the Sea of Okhotsk in the Late Pleistocene-Holocene time. A consequence of these processes in the northern segment of Priokhotye was the introduction of thalassogenic waters to the bowels of the earth 18-9 thousand years ago. In the zone of their contact with the heated dikes of basalts, ascending jets of thermal chloride water appeared. In the western Priokhotye, the conditions in the Late Pleistocene-Holocene period were favorable for the formation of an extensive zone of fresh groundwater. Its contact with high-temperature dikes gives rise to thermal waters, the composition of which is close to the cold waters of the zone of active water exchange. The process of formation of thermal water springs in the valleys of watercourses takes place in two stages. First, the rising thermal jets are dispersed in the zone of active water exchange. Newly formed minerals colmate cracks and pores, forming a heat-removing vent. In the second stage, this vent contributes to the emergence and functioning of the thermal spring.

The need to seek new ideas and approaches in studying the cyclic nature of planetary and regional water exchange is substantiated. Based on systematizing available data and results obtained by this author, an analysis is made of the role of interphase transfers of natural waters in the formation of water exchange cycles. It is stated that the effect of phase mixing is inherent in natural waters. This effect is responsible for the unity of natural waters, and for a high intensity of their interphase transfer. Such a methodological approach was used to specify the scheme of climatic (hydrological) cycle of natural waters. In addition to the known atmospheric (atmogenic) cycle, cryohydrogenic, atmolithogenic, glaciogenic and cryolitogenic cycles have been identified as well as estimating the mass of water annually involved in these cycles, the intensity of water exchange in each cycle and the output of energy liberated or spent. Implementation of this scheme would provide an opportunity to more purpusefuly study water resources and various water exchange cycles.

Using instrumental observation data from meteorological stations located in the Southern Urals, a comprehensive fire hazard index and a forest fire hazard index for the 1978 to 2020 warm season (May-September) were calculated. The analysis was based on the daily values of surface air temperature, amount of precipitation, dew point deficit, average wind speed, as well as gain and number of days after the last rain. A correlation analysis between critical values of fire hazard indices and the forest fire actual data was carried out, revealing a close relationship between the extreme values of fire hazard indices and abnormally hot years. Fire hazard indices reflect the set of meteorological conditions conducive to the occurrence of fires in different ways. The forest fire hazard index, in contrast to the fire hazard complex indicator, in addition to the meteorological index, takes into account environmental factors. The calculated values of fire hazard indices were structured in the form of a database that can be used in meteorological forecasts to assess and predict fire conditions based on weather conditions. Comparison of the present data with results of wildfire space monitoring from the Terra-MODIS satellite are presented. An increase in dangerous meteorological conditions from 1995 to 2000 and a decrease in the number of days with critical values of fire hazard indices from 2000 to 2005 were established.