The purpose of the work is to discuss the main environmental problems of the state of waters in the Sevastopol Bay and to identify the causes affecting their quality. Four seasonal surveys of the Sevastopol Bay water area in 2022 confirmed the prime impact of the Black River runoff, a main source of nutrients, on the hydrochemical composition of the bay waters.

At the same time, it is noted that the hydrochemical parameters of the South Bay waters are predominantly affected by freshwater runoff in the estuarine part of the area rather than by the Black River water. It is assumed that the runoff is permanent, and not emergency, as previously thought. With the winds of the southern directions, the spread of the South Bay water to the central part of the Sevastopol Bay is possible, thus affecting the state of its ecosystem. In summer an additional source of ammonium ions was recorded in the estuarine part of the Artillery Bay, next to which the Crystal city beach is located, with concentrations 80 times higher than the background. Since ammonium is a product of organic matter oxidation, its appearance may indicate the predominance of destructive processes, which affect living conditions of biological organisms and, in general, the ecological state of waters. In the warm season a constant deficiency of oxygen was observed in the bottom waters of an artificial depression under the floating dock, which in some cases leads to the formation of hydrogen sulfide.

All detected threats affect the ecological state of entire ecosystem of the bay, the living conditions of biological organisms and the recreational potential of the bay.

The article provides a multicriterial assessment of urban vacant lands in the city of Astrakhan. Urban vacant lands are defined as undeveloped and unused sites, not attributed to green zones in the city plan. The purpose of the assessment is to recognize the most valuable vacant sites. Their conservation and rehabilitation could enhance the quality and attractiveness of urban environment, while less valuable sites could be recommended for urban development. The work evaluates four landscape functions that correspond to the main problems of the city: 1) runoff regulation function is assessed by the means of morphometric analysis of flow channels and field data on erosion and water logging; 2) climate regulation function is assessed using InVEST urban cooling model; 3) recreational function is evaluated by field and remote sensing data about the current state of vegetation on the vacant sites and by the demand of recreational zones estimated by walking time to the nearest park; 4) air pollution mitigation function is evaluated by the rate of environment child diseases and the density of green spaces in the city districts. Integral assessment of vacant sites helps to provide recommendations on their preferable use. Landscape and ecological potential of vacant lands varies significantly between different parts of the city. Vacant sites of the northeastern outskirts of the city, located within the lower part of the Volga delta, received the highest values, while the small sites in the city center and the industrial zone in the eastern outskirts received the lowest values. As a result, 2570 ha of vacant lands were recommended for greening and rehabilitation, and 327,9 ha for construction.

Positive temperature anomalies called “urban heat islands” (UHI) are formed in cities as a result of progressing urbanization, increasing area and density of buildings, motor transport load and anthropogenic heat emissions. Such UHI reduce the comfort of the urban environment, and affect population health and quality of life. Remote sensing data from the thermal band satellite sensors are widely used to study the UHI intensity and spatial structure. We analyzed Landsat 8 and 9 satellite imageries from 2020 to 2022 representing the Lipetsk urban area in Central Russia. Taking into account the image quality requirements, 5 “winter” and 4 “summer” scenes were selected to examine thermal anomalies. As a result of their processing a map of land surface temperature (LST) excesses over the background values and a map of LST seasonal variations were compiled. The produced maps made it possible to identify 33 principal sources of anthropogenic heat in Lipetsk. 26 of them are located within industrial zones of the left bank side of Lipetsk, including. 23 sources within the territory of the NLMK Group metallurgical combine. LST of the identified heat sources were approximately 4–9°C above the background temperatures in winter and 11–14°C above the background temperatures in summer. The results of the study could become an information-methodical basis for the space monitoring of thermal pollution in Lipetsk.

Using the example of the Moscow region and based on the analysis of various information, including data from cellular operators, we studied a poorly explored phenomenon of absorption of some cities (towns) by others. The objectives of the article included the development of an approach to the study of united cities (towns), including an assessment of the preservation of their self-sufficiency as autonomous centers, as well as the identification of factors and stages of integration.

It is revealed that in the Soviet period the unification of cities (towns) in the Moscow region occurred as a result of the evolutionary development of neighboring centers and their merger. In recent decades the inclusion of cities (towns) into neighboring centers is mainly the result of artificial amalgamation during the current stage of municipal reform. Based on the example of the three largest takeover cases of recent times (Khimki – Skhodnya, Balashikha – Zheleznodorozhny, Podolsk – Klimovsk), and using the data of cellular operators, we analysed the borders, population numbers and the system of external relations of the population. It is shown that all united cities (towns) under consideration continue to be independent centers (in terms of population size and density, and their role as local centers of labor gravity).

The study of the absorbed cities (towns) of the Moscow region made it possible to identify the stages of their integration. It is revealed that after formal administrative subordination, the united center goes through the stages of infrastructural and socio-cultural merger, ending with the stage of complete absorption. It is shown that under the influence of a number of factors (geographical proximity, population size, economic structure, etc.), merger processes can accelerate or slow down.

A methodology proposed in the article is aimed at forming an approach to the study of absorbed cities (towns). The latter disappear from the field of view of official statistics and specialists, despite their continued functioning as independent centers for a long time.

At present the use of organic waste for energy production has become a significant part of the world energy industry. Thereby both the problem of energy supply and waste disposal are solved. In connection with the large volumes of annually formed resource, the ability to provide inexpensive logistics and the demand for energy at the level of local consumption the task of recycling agricultural waste is of particular interest. The paper presents a methodology for assessing the crop waste energy potential, taking into account the type of crops, the energy content and specific features of their processing to produce thermal energy. The regions of the Russian Federation leading in the production of cereals, sunflower and corn, i. e. Stavropol Territory, Krasnodar Territory and Rostov Region, were chosen as study areas, both due to the significant energy potential and the available experience of producing energy from wastes in the South of Russia. The quantities of thermal energy that can be obtained from the waste of these crops are determined (the totals for all crops are 14 600 000, 30 500 000 and 29 100 000 million Gcal/year for the regions, respectively), as well as the share of heat supply coverage in the residential sector of the regions (124, 120 and 160%, respectively). The cluster analysis methods allowed identifying groups of districts that are self-sufficient in terms of the local energy resource, as well as potential “donors” of fuel from waste. The results are displayed on charts and a series of maps.

When studying channel morphodynamics, the processes and forms of meandering and branching are considered independently. However, the development of meanders on large rivers is complicated by the formation of islands on their limbs and in the near-top parts. The most striking manifestation of the process is the branched-winding channels, which develop as a result of the successive formation of islands, creating spurs of meanders if attached to the coastal floodplain. The relief of the floodplains of such rivers is hollow-island in contrast to the ridged relief of typical meandering rivers. Another form of such channels of large rivers is alternating unilateral ramifications, in which the meanders of the main (high-water) branch go around the groups of islands located in a checkerboard pattern, and the channel itself in the floodplain banks remains quasi-rectilinear while in a branched-winding channel it forms segmental meanders. The presence of branches at a meander of the channel disperses the runoff, and decreases the amount of water in the main branch, thus affecting the parameters of the meanders.

Islands are also formed in the near-top parts of meanders, where its dynamic axis shifts towards the convex coast due to the violation of continuous flow around the banks, and erodes it. In the resulting local widening of the channel, a middle center appears and, when it is overgrown, an island is formed. A local widening of the channel is formed on rectilinear «inserts» between adjacent large meanders when the floodplain and channel flows intersect during the flood, and a middle or island is also formed in it. On the upper wings of steep bends, especially forced meanders, the formation of branches is associated with the flow backwater that occurs when it approaches the bedrock bank at the top of the meander at a high angle.

The formation of branchings at the meanders of a channel should be taken into account during river development as a factor that can influence the conditions of navigation and influence the channel reshaping, which is particularly important at the places where linear structures, such as bridges and pipelines, cross the rivers.

To determine the risks for mariculture farms, the intra-annual change of dissolved О₂ concentration was simulated for five zones in the Aniva Bay using the CNPSi model. Zone 1 differed sharply from other zones as the most shallow and freshened. Zone 2 is characterized by a pronounced water exchange with Zone 3 and Zone 4: during spring two layers were formed and stood out in these zones, in the summer the water column was homogeneous. Zone 3 has free water exchange with the open waters of the La Perouse Strait. An outstanding feature of Zone 4, in the deep-water part of the bay, was a distinctive subsidence of waters in the centre of the anticyclonic circulation and the maximum thermocline depth (up to 60–70 m). Zone 5 extends along the western coast of the Tonino-Aniva Peninsula and is characterized by the constant upwelling of waters during the ice-free period, which is clearly expressed by lower water temperatures. The calculation showed that in the areas suitable for mariculture farms coastal waters were provided with oxygen throughout the year. Anaerobic conditions developed in spring only in the deepest parts of the bay. An additional source of oxygen in the Aniva Bay is natural thickets of macrophytes, among which the Japanese saccharin (Saccharina japonica) dominates in terms of biomass and area. Annually, Japanese saccharin itself absorbed at least 1200 tons of C in its biomass and supplied at least 3100 tons of О₂. Unlike the artificially grown biomass, the biomass of all macrophytes would remain in the system and be destroyed during the life cycle, and the oxygen would be consumed for oxidation. The carbon accumulated in the biomass would again return to the rapid cycle, with the exception of the amount transported to the deep central part of the bay, where it would slowly decompose under nearly anaerobic conditions. It would be possible to place additional algae plantations in the bay, which could absorb up to 49 500 tons of C annually, while supplying up to 132 000 tons of О₂. The obtained model estimates could be a starting point for determining the “baseline” of the content of dissolved oxygen and compiling balance equations for gas flows in the ocean-atmosphere system in the Aniva Bay before the development of seaweed plantations, which simultaneously act as carbon farms.

Fluctuations of the residual level of the White Sea in the synoptic range of time scales, including surge fluctuations, are considered on the basis of observation data covering 2004–2020 period. Hourly data on the level at coastal points of Sosnovets, Severodvinsk, Solovki and Kandalaksha were analyzed. The surge run-ups and run-offs are studied based on the analysis of residual sea level (RSL) fluctuations, which is calculated by removing the tidal component from the observation data. The Dvina Bay RSL fluctuations are characterized by the greatest variance. The RSL fluctuations at Sosnovets and Solovki have approximately the same variance, which is significantly lower than in Dvina Bay. The lowest variance is observed in Kandalaksha. According to the data obtained at the Severodvinsk and Solovki stations, a noticeable increase in the variance of RSL fluctuations is observed over the considered period of time, which indicates an increase in their intensity. If five-year periods are compared, the average dispersion in Severodvinsk is 327,3 cm² in 2004–2008, 341,4 cm² in 2009–2013, and 386,8 cm² in 2016–2020. This conclusion is confirmed by the calculations of the probability of positive RSL deviations, as well as by the fact that the number of surge run-ups with a height no less than 100 cm was only two during 12 years from 2004 to 2015, and there were already five such surges in the five-year period 2016–2020. Seven types of synoptic situations are described in which surge run-ups occurred in the White Sea, two of which were not previously considered. Western cyclones of various trajectories account for 73 (74,5%) out of 98 cases of surge run-ups considered in the paper. The largest surge run-ups in Severodvinsk during the period under review reached a height of 130 cm (August 22, 2018) and 153 cm (November 15, 2011). Significant surge run-offs are less frequent than surge run-ups, being, as a rule, lower in their absolute value. The surge run-off on January 31, 2005 was the most pronounced for the entire period 2004–2020. The RSL in Severodvinsk dropped by 123 cm below the monthly average, and by 112 cm in Solovki.

The work presents the results of paleogeographic study, including facies-lithological, malacofaunistic and luminescence analyses, of three boreholes core drilled in the central part of the Manych Depression, which made it possible to determine the time and stages of the existence of the Karangatian ingressive bay in the Manych Depression, and to correlate the latter with phases of the Karangatian transgression identified earlier on the basis of luminescence dating. Based on the results of the study it was found that: 1) the Karangatian Sea penetrated into the Manych Depression during the second phase of transgression in the time interval of ~120–110 ka years ago (MIS 5e–d). The salinity of the bay in the area of the modern Manych-Gudilo Lake reached 20–22‰; 2) the inflow of water of the Hyrcanian transgression of the Caspian into the bay in the central part of the Manych Depression took place 110–105 ka years ago, which corresponds to the third phase of the Karangatian transgression (MIS 5c). The brackish Caspian waters desalinated the Karangatian Bay in the area of the modern Manych-Gudilo Lake down to 14‰ and below; 3) the waters of the Karangatian Sea finally left the Manych Depression about 105 ka years ago (MIS 5c).

The results of palynological analysis allowed climatostratigraphic subdivision of Pleistocene deposits of the Trlica cave, located in the vicinity of Pljevlja town in northern Montenegro. The palynological record confirms significant hiatuses in the sedimentation revealed by the field lithologic-genetic analysis. The changes of landscape and climatic conditions that occurred during the formation of the studied Pleistocene strata are reconstructed. Specific features of flora and vegetation of three stages of the final part of the Early Pleistocene corresponding to MIS 22, MIS 21, MIS 20, as well as three stages of the first half of the Middle Pleistocene correlated to MIS 19, MIS 18 and MIS 15, have been identified. Throughout the entire period of the Pleistocene deposits in Trlica, the mountain landscapes in the vicinity of the cave were covered mainly by forests, that underwent significant transformations of their composition during the change of interglacial conditions by the stages of cooling. The materials of palynological analysis of the Quaternary sediments of Montenegro are very scarce. Therefore, the spore-pollen data of the Trlica section and the revealed climatic-phytocenotic successions of three interglacial and three relatively cold (near-glacial) stages of the Early and Middle Pleistocene presented in the article are an important contribution to the study of the Pleistocene paleoenvironments of the Balkan Peninsula.

Climatic events of the last millennia in the northeastern part of the Norwegian-Greenland basin were reconstructed based on micropaleontological studies of sediments from the AMK-6150 core. New results were obtained from analyses of dinoflagellate cysts, diatoms, and benthic and planktonic foraminifers. These results allow us to infer the time of sediment accumulation and the prevailing natural conditions. According to preliminary data on climatostratigraphy based on the composition of microfossils, the period of sediment formation in the AMK-6150 core does not exceed 7 thousand years. The composition of microfossil assemblages and the results of reconstructions indicate repeated changes in marine environmental conditions during this time. Sediments at the depth of 23–24 cm recorded the beginning of a significant growth of temperature and salinity of surface waters due to a possible increase of the Norwegian Current influence. According to the species and quantitative composition of dinocyst and diatom assemblages, sediments in the short depth range of 14–12 cm accumulated during a period of noticeable decrease in temperature and increased influence of Arctic water masses. The analysis of dinocysts by the method of modern analogues allows reconstruction of the quantitative values of summer paleotemperatures of surface waters and the duration of ice cover. It was found that the cooling episodes and probable formation of seasonal sea ice were possible during the accumulation of sediments at the depths of 29–24, 14–12 and 3–1 cm.

Based on the potentiometric measurements average fluorine concentrations for different phases of the hydrological regime were determined in water samples taken in 2018–2020 in the outlet of the Ob River: 0,103 mg/L in the winter low-water period, 0,079 mg/L in the spring – summer flood, and 0,095 mg/L in the summer – autumn low-water period. The present-day weighted average concentration of fluorine in the Ob River water (0,086 mg/L) closely corresponds to the values measured in 1954–1956 and 1976–1980 (0,090 and 0,084 mg/L, respectively), therefore the fluorine content of 0,08–0,09 mg/L could be taken as a natural background.

The results of studies of river water of the Vladimir city district for the content of heavy metals conducted in August 2022 are presented and the anionic-cationic composition of water is analyzed. It is shown that a number of heavy metals (lead, iron, cadmium, zinc, copper and vanadium) and ions (ammonium, magnesium, sulfates, nitrates, fluorides, phosphates) in water samples of the rivers of the city district exceed hygienic and fishery standards, which is due to both human economic activity and regional specifics of the geochemical composition of water-bearing rocks and features of groundwater functioning and feeding. The potassium concentration in water of the Nerl river, which is a drinking water source for Vladimir, corresponds to the lower threshold of physiological competence, which can affect the health of city residents if they use such water for a long time. It is shown that insufficient extraction of biogenic elements at the treatment facilities of enterprises could lead to their ingress into water bodies in concentrations exceeding hygienic and fishery standards. This in turn could contribute to the accumulation of other elements. Strict requirements for the content of chemical elements in fishery water bodies make it necessary to improve the equipment and technological schemes of purification at treatment facilities. Small rivers of cities are vulnerable and poorly protected; therefore they require special attention of environmental authorities. Being tributaries of larger rivers, small rivers form the quality of their waters. If they are used for the household and drinking purposes, they become a factor determining the health of urban residents.