Vol 156, No 4 (2024)

The article is devoted to the problem of small rivers, which make up more than 95% of the total number of rivers in the Chechen Republic (CR). Based on the analysis and systematization of materials on numerous small rivers of the Czech Republic, the quantitative distribution of rivers by their length intervals is given, the relationship between the location of river valleys and settlements, as well as changes in the shape of the valley and turbidity of river water depending on the type of rocks cutting through them are noted. A brief geological and geographical description of individual small rivers of the Chechen Republic, which are of particular interest for the development of scientific, educational, recreational and other types of tourism and recreation, is given. A comparative assessment of the tourist and recreational attractiveness of water bodies according to the point system based on the use of the most significant indicators is also given. According to the results of the assessment, the districts of Chanta–Argun, Sharo–Argun and Hulkhulau were identified as the most attractive in terms of the development of tourist and recreational activities. The main problems of small rivers and ways to solve them are outlined. Measures for greening (prohibition of discharge of untreated waters, household garbage into rivers, monitoring of the state of water protection zones, etc.) and rational use of the potential of small rivers are proposed.

Given the abundance of manifestations of carbonic acid water in Transbaikalia, the information on their physical and chemical characteristics dates mainly to the middle of the last century and is mainly limited to data on macrocomponents. The aim of the study is to obtain modern data on chemical, microcomponent and isotopic composition, content of balneological components in carbonic acid spring, to determine the nature of water and carbon dioxide by isotopic data. Such data were obtained for the carbon dioxide spring Pogrominsky in the Yeravninsky district of the Republic of Buryatia and the first tested borehole located near it in August 2020. The spring water is HCO₃ Ca, the borehole — HCO₃ Na-Ca types with CO₂ content respectively 0.94 and 0.6 g/l and mineralization 0.79 and 0.65 g/l. According to the content of meta-silicic acid H₂SiO₃ (71.3 mg/l) and Fe (34.7 mg/l) the water of the borehole corresponds to the Kuka balneological type, it can be of interest for the organization of bottling. Mass-spectrometric method determined concentrations of 50 trace elements, of which uranium (83 µg/l) is found to be anomalously high in the spring water. According to isotopic data, water of both manifestations has infiltration genesis, carbon dioxide gas is metamorphogenic with the participation of biogenic.

The investigation of cold stress conditions in Kazakhstan is motivated by the lack of generalized studies of thermal comfort for the country, the high social and economic consequences of extreme cold conditions for the region and the observed significant trends in air temperature and precipitation in the region. Basing on 3-hour data for 13 cities of Kazakhstan the seasonal cycle and spatial distribution of thermal comfort over the territory of Kazakhstan were analyzed. The wind-chill index (WCI) was used to assess cold stress, and the physiologically equivalent temperature (PET) was used for the warm period. It was shown that the coldest region of Kazakhstan is the North with the maximum amount of days with cold stress conditions in Astana and Petropavlovsk. The maximum number of days with cold stress occurs in January and February, the minimum is in March, and in October cold stress is not recorded on the territory of the Republic. High heat stress was recorded in all regions of Kazakhstan during all 6 months of the warm half-year. The maximum repeatability of high heat stress (PET index exceeding +35°C) is documented in Almaty and Shymkent. The spatial distribution of thermal comfort is governed mainly by atmosphere circulation in winter and radiation conditions in summer, which is characteristic of continental climate. The interannual variability of cold stress conditions has no pronounced trend and is irregular due to the specific of synoptic processes in a particular year. During the warm period in most cities, the number of days with high thermal stress increases toward the end of the period in accordance with the positive temperature trend.

It was revealed that the most thermally comfortable cities in Kazakhstan are Kokshetau and Kostanay, the most thermally uncomfortable ones are Almaty and Shymkent. It is shown that despite the fact that Kazakhstan is traditionally considered as a country with severe winter conditions, the summer period is the dominant factor for the conditions of thermal discomfort in the Republic.

The article represents development of winter phytoplankton in different areas of Lake Onego in relation to temperature, light conditions, water color, organics and nutrients concentrations. In April 2022 and 2023, right before the ice break-up, low phytoplankton development was observed. The coldwater species of diatoms Aulacoseira islandica was the main representative of winter phytoplankton. The total abundance, phytoplankton biomass and chlorophyll a concentration varied within the range of 0.13–0.71 million cells/l, 0.06–0.44 mg/l and 0.3–0.8 μg/l, respectively. As a result, Petrozavodsk Bay and the central deep-water part of Lake Onego in winter were characterized as low productivity. The low winter phytoplankton abundance in Petrozavodsk Bay is due to a high water color, which determines the shallow depth of the photic zone and, in addition, deep convective mixing of the water column. In the central part of Lake Onego, the limiting factors for the development of winter phytoplankton were unfavorable light conditions due to the large depth of the convectively mixed layer.

The initial results of the search, identification, and analysis of small preserved areas of undisturbed Chernozem soils located in the watershed areas of the Central Russian Upland, outside of protected areas, are presented. To identify the steppe meadow areas that have always been hayfields and/or pastures, i. e. never plowed territories in the old forest-steppe, historical-cartographic analysis of antique maps from the late 18th, mid-19th, mid-20th centuries and modern satellite images was used, supplemented by reconnaissance trips. In total, 45 such areas (with a total area of about 120 hectares) have been identified in the Belgorod oblast, ranging in size from a few dozen to tens of thousands of square meters. It has been shown that hayfields and pastures, preserved in several villages in the southern part of the Central Russian Upland, are of scientific interest for studying the standard properties and functions of native chernozems of the Central Forest-Steppe region. The main indicator of absence of ploughing in the studied areas is the water-resistant granular structure of the top layers of chernozems. The organic carbon stocks in the meter-thick studied soils range from 227 to 319 t/ha — which is in line with the known information about carbon stocks in virgin black soils of the forest-steppe. It has been shown that the diversity of sod variants of native meadow-steppe chernozems is determined by differences in soil-forming rocks: loess-like carbonate medium and heavy loams, thin loess-like loams, red sandy Neogene rocks, and red-brown clays. Differences in the degree of compaction of the upper part of the soil profiles have been discovered, which are caused by varying pressure resulting from livestock grazing, as well as the different ratio of haymaking and grazing depending on local conditions and sites.

Beavers, as mammals that have a unique ability to transform watercourses and their floodplain-channel complexes by building dams and associated ponds, intensively develop streams and, especially, small rivers, as well as small branches of larger rivers in Eastern Europe. During a geodetic survey using GNSS equipment and a field survey of four small rivers in the uplands of the steppe zone of the Volga region, the features of the distribution of beaver dams and associated ponds were identified, and some of their morphometric characteristics (height and length of dams and their ratio; length of ponds) were determined. An analysis of the longitudinal profiles of these rivers showed the significant role of slopes (gradients) in the distribution of these beaver structures: about 90% of them are located on riverbed slopes of less than 2%, including 56% of less than 1%. A weak and statistically insignificant trend of increasing height of beaver dams, as well as a statistically significant trend of decreasing length of beaver dams and associated ponds as riverbed slopes increase, was identified. The highest average heights of beaver dams are confined to those small rivers whose basin soils are comparatively heavily plowed (mainly clayey-loamy Chernozems).