The study is focused on the reconstruction of long-term dynamics of ¹³⁷Cs concentration in water bodies contaminated as a result of Chernobyl and “Fukushima-1” NPP accidents. It was found that the vertical distribution of ¹³⁷Cs in bottom sediments of deep-water sites could be a basis for reconstruction of the dynamics of radionuclide concentration in suspension and in solution. Columns of bottom sediments of reservoirs and experimental values of distribution coefficient Kd are used for reconstruction. The method is applicable in the absence of mixing of the deposited suspension with the underlying layers and at Kd values significantly higher than 104 l/kg. Studies in the Chernobyl and “Fukushima-1” NPP contamination zones have shown that it is possible to reconstruct the long-term changes of ¹³⁷Cs concentration for rivers, lakes and ponds. The obtained data are the first assessment of the time course of ¹³⁷Cs specific activity on suspended sediment in water bodies of the Chernobyl NPP zone, which is important for understanding its behavior in the soil-water system and its migration through food chains. The time dependences of ¹³⁷Cs concentrations are described by the empirical two-exponential and/or semi-empirical diffusion model, applicable for predictive assessments of the long-term dynamics of radioactive contamination in water bodies after nuclear accidents. The results of the study are confirmed by monitoring data for the test water bodies, showing satisfactory agreement with the reconstructed values of ¹³⁷Cs concentrations. The information obtained is important for assessing the environmental consequences of nuclear accidents and developing strategies for the management of contaminated areas. The methodology presented in the study could be adapted to study the behavior of other radionuclides in aquatic ecosystems, contributing to better prediction and management of radioecological risks over a long term horizon.

The gas-aerosol composition of the atmosphere determines specific features of the radiative net irradiance in the atmosphere and the associated climatic changes. The study discusses the anthropogenic variations in the content of the most important greenhouse gases, such as carbon dioxide (CO₂) and ozone (O₃), as well as the atmospheric aerosol. The estimates of their radiative effects (forcing, RF) in various geophysical conditions are given. Based on the modern ECRAD radiation model, the RF values of considered anthropogenic trace gases and aerosols over the past 20 years were estimated for different seasons of the year relative to their preindustrial level for the Moscow region. We determined specific features of the vertical profiles of RF in the shortwave and longwave spectral ranges and their values at the bottom (BOA) and the top of the atmosphere (TOA) depending on solar elevation and surface albedo, both taking seasonal variations into account and without them. The total RF ^Total for the warm period with a low surface albedo is negative (–8,33 W/m² at BOA and –1,35 W/m² at TOA) if seasonal variations of all considering trace gases and aerosols are taken into account. A weakly absorbing aerosol typical of mid-latitudes plays a significant role in the negative RF. The RF ^Total for the cold season is –0,08 W/m² at BOA and +0,38 W/m² at TOA. The positive value of the total RF at the TOA is due to the positive RF of the aerosol with its absorbing properties and the influence of the high albedo of snow surface, as well as due to the positive RF of carbon dioxide. A nonlinear RF dependence of the trace gases and aerosol on the solar elevation and surface albedo was found. The radiative heating rate due to greenhouse gases at TOA is negative in all seasons of the year. At the same time, it is positive at BOA (about 0,45 K/day in the warm season and 0,25 K/day in the cold season), mainly due to the absorption by aerosol in the lower layers of the troposphere. The radiative heating rate due to CO₂ is slightly positive.

Integration associations of different levels are actively developing in all regions of the world. Eight common markets, namely the European Economic Area (EEA), the Eurasian Economic Union (EEU), the Cooperation Council for the Arab States of the Gulf (GCC), the East African Community (EAC), the Economic Community of Central African States (ECCAS), the Southern Common Market (MERCOSUR), the Central American Common Market (CACM) and the Caribbean Single Market and Economy (CSME) are central. These are integration associations based on free trade and free exchange of all factors of production. The purpose of the study was to identify geographic differences in the depth of integration within the world’s common markets. The depth of integration is studied quantitatively using the index of integration depth developed by the authors. It is based on the principle of common approach to assessing integration across four freedoms, i. e. the movement of goods, services, people and capital, represented in the aggregate index by two indicators, namely openness (the ratio of a particular flow within the common market to the size of the country) and importance (the share of flows within the common market in all external flows). This approach allows to assess the country’s participation in both regional and international movement of production factors. The study revealed that common markets formed on similar principles differ significantly in the depth of integration. In contrast to the developed European common market, participants in the Asian, African and Latin American common markets are characterized by a much more intensive exchange of production factors with third countries than with each other. This is facilitated by the regional specific features of the processes of international economic integration. Only the EEA can be classified as a common market with high level of integration; the EEU, CACM, CSME and EAC are characterised by the low level of integration; and it is very low in the GCC, MERCOSUR and ECCAS. There are many centres of diffusion of integration processes in the EEA and CSME; the CACM, EAC, GCC and MERCOSUR have one main centre and one sub-centre; and there is one supercentre in the EEU. In most cases, the centre’s level of integration is one of the lowest within the market.

The paper examines the stable oxygen isotope values for six most abundant ostracod taxa in present-day Caspian Sea bottom sediments from 33 sampling sites. The oxygen isotopic composition of Caspian ostracod shells was found to reflect metabolic effects related to their life cycle. The average δ¹⁸O_ost value (± standard deviation) for each species is as follows: −0,11‰ (±0,7) for Euxinocythere virgata, –0,25‰ (±1,14) for Tyrrhenocythere amnicola donetziensis, +2,94‰ (±0,16) for Candona schweyeri, +1,55‰ (±1,12) for Paracyprideis sp., +1,77‰ (±0,22) for Bakunella dorsoarcuata and +2,45‰ (±0,95) for Camptocypria sp. The results obtained confirmed that Caspian ostracods do not secrete their carapace in equilibrium with the surrounding water. Rather, the studied species showed a positive vital offset – the observed effect averaged about 1‰ (±0,5). The desired isotopic shift for the mixed ostracod assemblage turned out to be equivalent to the average isotopic shift for the studied sample and amounted to +1‰ (±0,5). The work demonstrates that ostracod metabolic processes cause shifts in the expected fractionation of oxygen isotopes between CaCO₃ and water. The resulting isotope offsets must be taken into account in paleogeographic studies for correct interpretation of paleoclimatic changes in the Caspian Sea region using the stable oxygen isotope record.

The changes in annual precipitation, evaporation, river runoff, and potential evapotranspiration for 1946– 1979 and 1980–2021 were considered for 225 catchments located in European Russia (ER) north of 48°N and without large reservoirs within their boundaries,. The ER is generally characterized by higher values of all water balance components in 1980–2021 compared to 1946–1979. A slight increase in river runoff was found for the northern part of the ER, within the Arctic rivers basins and the basins of theUpper and Middle Volga River and the Baltic Sea. A decrease prevailed in the southern part, within the basins of Don, Ural and the Lower Volga rivers. The most notable change was an increase in runoff in the central part of the region. At the same time, its increase for most catchments exceeded the increase in precipitation – the median coefficient of runoff for 225 basins increased from 0,38 to 0,40. The modified Budyko’s equation made it possible to calculate the dependence of the runoff coefficient on the degree of climate aridity for each basin in terms of ω, which shows the part of precipitation spent on evaporation under a given value of the aridity index. The dependence did not change for the northern ER. The transformation of precipitation into runoff has become more effective in the central part, while in the southern part it became less effective. The spatial distribution of parameter ω showed close relationships (determination coefficient more than 0,76) between the degree of synchrony of the maximum potential evapotranspiration and precipitation events, the proportion of forest cover and bare soil in the catchment, air temperatures in January-February, and the fraction of solid precipitation relative to the annual total. However, applying the derived dependence to estimate changes in ω has led to unsatisfactory results, suggesting that the spatial parameters which determine ω values do not control its temporal variability. Based on the estimated ω value for the period of 1980–2021 and climatic scenarios of precipitation and evaporation changes the runoff change for the 21st century was calculated. It is expected that most of the rivers in the ER will increase their runoff in the 21st century regardless of climate change scenarios. On average, 76% of catchments will experience the same direction of river flow changes as in 1946–2021. The forecasted degree of changes will be close to observed during that period.

Predictability and low intra-field variability of yields are the key interest of agriculture. The dependence of productivity on hydrothermal conditions could be determined by the spatial structure of landscape. We used the example of a steppe agricultural landscape in the Orenburg region to study the influence of the areal and qualitative characteristics of the landscape neighborhood on the intra-field variability of phytomass. We used vegetation indices (NDVI) for 92 field sites with a typical area of 100 hectares based on 42 Landsat satellite images over a 30-year period, with an average of 4–6 images per season. The NDVI of field pixels was considered as a dependent variable, while the areas of erosion landforms and live forest belts as well as the total NDVI of forest belts within the distance of 150 m were independent ones. Types of crops and the properties of forest belts and hollows were described during field studies. Cluster analysis was used to recognize crop classes based on the similarity of the annual NDVI variations to those during the years of field observations. Multiple regression equations were compiled to calculate the total contribution of three neighborhood factors to the intra-field variation in phytomass, as well as their individual contributions. We compared the parameters of the equations for June dates with different heat and moisture supply over three years. We found that the intra-field variation in green phytomass could be for more than a half determined by proximity to erosion forms and forest belts. The fields were classified according to the stability of the influence of forest belts and hollows under different hydrothermal conditions. The most stable influence on the green phytomass of crops is correlated with a proximity to erosion landforms, the least – with the state of forest belts. The dependence of green phytomass on landscape neighborhood was stable from year to year and highly significant for 44% of the study area. The proximity to forest belts and their state more strongly influence the June phytomass during hot and dry years, and proximity to erosion forms during years with abundant winter and spring precipitation. The closer to forest belts, the greater is phytomass in almost all fields. The area of adjacent live forest stands is more important than their state. Threshold values have been established for neighborhoods with erosion landforms and live forest belts, which control the green phytomass increase within the interfluves. A significant influence of neighborhood factors on phytomass is manifested regardless of the crop type.

Currently, the qualitative and quantitative hydrological characteristics and the dynamics of their changes are studied mainly for medium and large rivers. The hydrological characteristics of small rivers in Russia are poorly investigated. Considering the increasing deterioration of the ecological state of rivers, affecting primarily the intra-annual water flow distribution of small rivers, the study of flow formation processes, its variability and intra-annual changes is becoming the most important task of hydrology. The article examines changes in the indicators of the intra-annual distribution of runoff of small rivers in the Volga basin based on representative hydrological posts on small rivers in the study area. Water regimes of small rivers before and after the onset of global hydrological changes were analyzed. Spatiotemporal trends of changes in the intra-annual distribution of water flow of small rivers in the Volga River basin were identified. The work presents a first attempt of mapping the trends of changes of the qualitative and quantitative characteristics of water flow of the small rivers.

Within the administrative boundaries of the Rostov region, changes in air temperature and precipitation, as well as flow rates and water levels for 1966–2019 were considered at 6 meteorological stations and 30 river hydrological posts. A statistically significant increase in average annual air temperature was revealed. Over 54 years, the increase in average annual air temperature has averaged 0,38°C/10 years, and it is most significant in January (0,68°C/10 years). No significant changes in the annual amount of precipitation were detected over the entire period; in general, they are not observed in individual months either. However, if we consider the last thirty years, there is a decrease in annual precipitation amounts in the region as a whole (−24,9 mm/10 years), which in turn manifests itself variously in different areas of the region. It is most significant in the southwestern and southern regions: Taganrog (−46,3 mm/10 years), Rostov-on-Don (−35 mm/10 years), Gigant (−47,8 mm/10 years), and less pronounced in the southeastern regions: Remontnoe (−7,6 mm/10 years).

Due to a decrease in humidification of the territory, a decrease in average annual flow rates and water levels is typical to the vast majority of rivers, while there is a redistribution of the Don River flow within the year. It has been shown that the level regime of rivers largely depends on a complex of climatic, hydrological and water management factors, and its change, as a rule, is more pronounced than the changes in water discharge. The analysis of maximum water discharges showed the statistically significant negative trends at most hydrological stations with an average correlation coefficient of −0,33; no significant positive trends were identified. The analysis of the highest water levels showed the statistically significant negative trends also at most posts with an average correlation coefficient of −0,35. The frequency of floods, calculated over a long-term period, ranges from 0 to 26%, the average excess of critical levels is from 7 to 74 cm. Due to the widespread decrease in maximum flow rates and highest water levels, the probability of the dangerous hydrological phenomena associated with the passage of a seasonal flood wave is reduced. On the other hand, a continued increase in air temperature and a decrease in precipitation may cause a significant decrease in water flow of rivers in the future.

The purpose of the study is to identify the main factors, causes, features and nature of the abolishment of rural settlements in the Udmurt Republic, that took place mainly since the late 1930s. The empirical basis of the study is the interactive “Atlas of Disappeared Villages of Udmurtia”, legal documents confirming the fact of abolishment, non-statistical information, as well as information provided by Udmurtstat at the official request of the authors. The collected data are processed using the methods of content analysis, analysis and synthesis, cartographic method and calculation of the Spearman’s correlation coefficient.

A general picture of the abolishment process of rural settlements in Udmurtia is presented. The process is examined in detail for the Votkinsky and Yarsky districts. The former is characterized by a variety of causes and factors of abolishment, and the latter is a typical one in this context.

At least 48 settlements were abolished in the Votkinsky district. During particular historical periods the reasons were different. In the initial period of the USSR, the mass abolishment of individual agricultural farms was caused by the collectivization. In the 1960–1970s the mass abolishment, implemented within the framework of the directive on the abolishment of unpromising villages, was caused by their small population and large migration outflow that took place since the 1950s. Settlements were also abolished due to the confiscation of areas for water reservoirs and hydroelectric power stations, as well as because of the depletion of forest resources.

The main reasons of abolishment were depopulation, recognition of settlements as unpromising and their further exclusion from accounting data.

In addition, the authors pay attention to modern abolishment of rural settlements, when the main factors are their depopulation and economic abandonment. Current trends associated with the formation of new villages replacing once abolished ones are also identified

The paper considers the features of the spatial distribution of litter layers and humus horizons of soils in a forested area. The object of the study was the forest-cultural landscapes on low-productive sandy lands created in the early twentieth century to protect against deflation. The territory is located in the Kamyshin district of the Volgograd region (cadastral quarter No 34:36:000014). The purpose of the research was to determine the distribution of the depth of organogenic layers and humus horizons in relation to the species composition of plantations (coniferous or deciduous species), the total projective cover of the herbage and its dominant associations. The research is topical and aimed at evaluating the effectiveness of forest reclamation measures on sandy lands in the dry-steppe zone. Both terrestrial (soil and geobotanical) and remote (agroforestry much of the territory. The sands were stabilized due to creation of massive plantings and the grass cover formation. The relationship between the composition of a stand, the total projective cover, the dominant herbaceous association and the depth of humus and litter horizons in coniferous plantations has been found. The depth of studied layers increases if hardwoods are admixed which produce leaf litter. The spatial heterogeneity of the indicators for all the studied sites is primarily influenced by the low rate of litter decomposition, as well as the internal re-deposition of organogenic and humus matter by the wind.

The article presents the results of the study of the suspended and bed sediment runoff for the modern period. In addition the features of sediment deposition within a valley bottom section of the Djankuat stream catchment (F = 9,1 km², Q_mean = 1,5 m³/s) with predominance of accumulation are discussed. Field research methods included direct measurements of bed load using the Helly-Smith sampler, determination of the average diameter of bed load and floodplain sediments, channel deformations and accumulation rates on the floodplain within the broader section of the valley floor, including the radiocesium dating method. It has been established that the total sediment runoff of the Djankuat Stream is 10,1·10⁶ kg/year, 13% of which is the bed load. According to the bed load sediment budget observations in 2016 and 2023, as well as the radiocesium dating of floodplain sediments, the accumulation rate on the floodplain within the broader section of the valley floor is 4,8–5,6 ± 1,0 mm/year over the total period since its origination (120 years). During 2016–2023 the volume of annual channel erosion within the same section is 1260 tons/year. The nine-fold difference between the average diameter of the bed load sediments and the median diameter of the floodplain sediments within the broader section of the valley floor indicates that the main deposition events are related to extreme floods with less frequent water discharges.