Intensity Of Water Exchange Research Articles

Numerical simulation of groundwater in hyporheic zone with coupled parameter stochastic scheme

Groundwater numerical modeling is a crucial scientific tool for understanding groundwater circulation and supporting regional water resource planning and management. The effectiveness of these models depends largely on the accuracy of hydrogeological parameters within aquifers, which are often spatially heterogeneous and randomly distributed due to complex geological and tectonic factors. Traditional modeling approaches frequently overlook this randomness, compromising the precision and resolution of groundwater simulations. This study focuses on a section of the Qingshui River in the Huaihe River Basin. Using field and laboratory data, probability distribution functions for key parameters like hydraulic conductivity, specific yield, and specific storage were developed. These functions were integrated into the groundwater model to reflect the inherent stochastic nature of aquifer properties. This integration significantly enhanced model accuracy, reducing the root mean square error of simulated water levels from 0.47–1.43 m to 0.13–0.16 m and improving the Nash-Sutcliffe efficiency coefficients (NSE) from −2.96–0.73 to 0.94–0.98. Additionally, the model facilitated analysis of the interactions between river and groundwater, particularly in the hyporheic zone, under various scenarios. It identified spatial and temporal variations in groundwater recharge dynamics and delay effects at different distances from the river channel. For instance, recharge rates at 50 m and 150 m from the river were 0.295 m/day and 0.015 m/day, respectively, indicating stronger recharge closer to the river. The study also assessed the impact of varying river flows, riverbed permeability, and irrigation practices on water exchanges between the river and groundwater. These factors were found to significantly influence the intensity of water exchange, seepage, and groundwater reserves. This research provides valuable insights for managing river-groundwater interactions and analyzing the ecological environment of surrounding groundwater systems, underscoring the importance of incorporating stochastic characteristics into groundwater modeling.

Numerical study of tidal effect on the water flux across the Korea/Tsushima Strait

Tremendous amounts of materials and energy are transported from the East China Sea (ECS) to the East/Japan Sea (EJS) through the Korea/Tsushima Strait (KTS). Tides undoubtedly play an important role in regulating ocean circulation on the broad continental shelf of the ECS, while the effects of tides on the water exchange between the ECS and EJS remain unclear. Using a three-dimensional Regional Oceanic Modeling System (ROMS) circulation model, we conducted numerical experiments with tides, without tides, and only barotropic tides. The results showed that the water flux across the KTS can increase by up to 13% (in summer) when excluding tides from the numerical simulation. To understand how tidal forcing regulates the KTS water flux, we performed a dynamic diagnostic analysis and revealed that the variation in sea surface height under tidal effect is the main reason for the water flux variation across the KTS. The tidal effect can adjust the sea surface height, weaken the pressure gradient and reduce the water flux across the KTS, which affect the intensity of water exchange between the ECS and EJS. The tidal effect can alter sea level difference between the Taiwan Strait and the KTS, which influences the KTS water flux. Tides can also influence the KTS water flux by altering the sea surface height through interaction with topography and stratification. We also found that tidal effect weakens the northward intrusion of the Yellow Sea Warm Current in winter and in turn enhances the water flux across the KTS according to volume conservation. These modeling results imply that tides must be considered when simulating the ocean environment of the northwestern Pacific Ocean.

Solution to the Unsteady Seepage Model of Phreatic Water with Linear Variation in the Channel Water Level and Its Application

For a semi-infinite aquifer controlled by a river channel boundary, when the Laplace transform is used to solve a one-dimensional unsteady seepage model of phreatic water while considering the influence of the vertical water exchange intensity ε with the change in the river channel water level f(t), a complicated and tedious integral transformation process is required. By replacing f(t) with an operator, this study first derived the analytic formula of the ε term based on the properties of the Laplace transform without the direct participation of f(t) in the transformation. By using f(t) in the form of several types of linear functions, the Laplace transform and inverse transform laws were summarized. The analytical solution to the problem was easily obtained by applying the “integral property” of the transformation to the linear function term with time t. The relative error between the numerical solution and the analytical solution of the example was less than 0.2%, which verified the rationality of the model linearization method and the reliability of the analytical solution. For different boundary conditions, the process of establishing and applying the inflection point method and the curve-fitting method for calculating the model parameters by using dynamic monitoring data for phreatic water is presented with examples.

Formation of waters of tungsten-ore areas under the influence of natural and anthropogenic factors (Eastern Transbaikalia, Russia)

The industrial development of tungsten deposits in Eastern Transbaikalia contributed to a significant deterioration of the environmental situation in the adjacent territories. Heavy-metal water contamination has become a serious problem in the mining areas. The most dangerous are wastes of sulphide ores, the oxidation of which leads to the formation of acidic drains with abnormally high concentrations of heavy metals. The features of the composition of the waters formed in and around the five tungsten deposits were studied and significant differences in their physical and chemical characteristics were shown. The most saline acidic, sulphate waters with the maximum content of heavy metals are recorded in the drainages of the tailings of beneficiation plants and rock dumps and in the ponds of sludge depositories and deposits with an increased ore sulphide content. The groups of elements posing the greatest danger to aquatic ecosystems were identified as Cd, Cu, Zn, Be, Al, Co, Th, Mn in acidic and slightly acidic waters and W, Mo, U, As, Mn in slightly alkaline and alkaline waters. Based on the Eh-pH water parameter ratio, three types of hydrogeochemical environments formed in the mining areas of tungsten deposits were identified. Metal migration in the waters occurs mainly in the form of simple cations, sulphate, fluoride, hydrocarbonate, carbonate and hydroxyl complexes. Geochemical barriers of oxygen, sorption, acidic and alkaline types were studied in the areas around the deposits. The main factors determining the physical and chemical parameters of the waters are shown, including the regional factor, specifically, the ore and host rock composition, the water exchange intensity, and the technogenic factor, which causes a high level of water pollution.

Water exchange unevenness alters the species dominance and community composition of submerged macrophytes in Erhai Lake and the potential mechanisms revealed by laboratory experiment

Water exchange unevenness (WEU) is defined as the coefficient of variation in water exchange intensity over time. Although its influence on aquatic plant characteristics has been recently investigated, there is limited understanding regarding the effects of this hydrodynamic change on submerged vegetation. This study investigated the impacts of WEU on the species dominance and community composition of submerged macrophytes in three bays with different WEU conditions in Erhai Lake, China. Subsequently, a laboratory experiment was conducted to elucidate the mechanisms underlying these effects. The field investigation showed that the dominance values of submerged macrophytes were influenced by WEU. As WEU decreased, the average dominance value decreased for Vallisneria natans (by 34.54 %), Myriophyllum spicatum (16.82 %), and Hydrilla verticillata (12.84 %); showed no significant change for Potamogeton lucens; and increased for Potamogeton maackianus (14.22 %) and Ceratophyllum demersum (17.52 %). The laboratory experiment showed that lower WEU markedly inhibited the growth of V. natans, slightly inhibited that of M. spicatum, and stimulated that of P. maackianus, consistent with the field observations. The inhibitory effect was attributed to a reduced concentration of carbon dioxide in the water; adaptive strategies, i.e., plant height, biomass allocation, and root traits, were more effective for M. spicatum than for V. natans. The stimulated growth of P. maackianus was attributed to increased dissolved oxygen concentration, which promoted root growth and nutrient uptake. Our results indicate that WEU has significant effects on the growth and community characteristics of submerged macrophytes.

Formation of the Layered Circulation in South China Sea With the Mixing Stimulated Exchanging Current Through Luzon Strait

AbstractUsing the layered circulation in the South China Sea (SCS) as an example, a process‐oriented simulation was conducted to explore how the lateral exchanging current and basin circulation responded to the contrasting mixing in the marginal sea‐open ocean system and to the internal modulation over basin slope. Under conditions of intensified turbulent mixing () in the SCS, a crossing Luzon Strait density difference was generated and the net ageostrophic pressure gradient force drove the layered exchanging current with intensified westward deep intrusion into the SCS and an eastward middle outflow. The lateral exchanging current in turn developed a layered basin circulation in the semi‐enclosed middle and deep layers through directly providing external planetary vorticity flux, and releasing the internal potential energy indirectly. The vertical migration of the layered circulation structure over bottom slope owing to flow‐topography interaction is the major intrinsic response to the external exchanging current particularly in the semi‐enclosed deep basin. Although a small was adequate to maintain the basic layered circulation pattern, an intensified was required to extend the deep cyclonic circulation to the bottom. The intrusion of the western boundary current from open ocean not only maintained the strong upper cyclonic circulation but also intensified deep intrusion and modulated the deep layer circulation through vertical coupling. Both the deep density difference between the SCS and open ocean as well as associated vertical coupling should be considered to well understand the intensity of water exchange and the consequent layered circulation in the SCS.

GEOCHEMISTRY AND FORMATION CONDITIONS OF GROUNDWATER COMPOSITION IN THE AREA OF MESOZOIC SEDIMENTARY COVER IN TATARSTAN

Mesozoic sediments cover an area of 2870 km2. Mesozoic sedimentary rocks are located in the southwestern part of the Republic of Tatarstan. A thick sequence (up to 390 m) are composed of clay with thin (up to 1 m) layers of sandstone and marl. Permian polygenic sulfate-carbonate-terrigenous deposits underlie the Mesozoic massif. They are exposed in the north of the Mesozoic sediment area.The studied area (~5000 km2) is used for farming. There are no large settlements or industrial enterprises there. The paper considers the specific features of Mesozoic and Permian groundwater composition. There is a trend to improving the groundwater quality with time. The reason of this positive trend is a decreasing technogenic impact and depopulation of the territory. The lateral and vertical hydrogeochemical stratification is identified and characterized. Clay predominating in the massif appears to be the reason for the decreasing intensity of water exchange. Hydrolysis, cation exchange and leaching of carbonate and sulfate minerals add to this trend.The groundwater composition varies widely due to these processes and control specific mineralogical and geochemical features of Mesozoic massif (the saturation of organic substance, the presence of opoques, the primary marine ionic-salt compositions in local areas). Groundwater is more mineralized, with a large amount of organic substance, silicic acid, iron, boron and other micro-components in the area of Mesozoic sediment. The groundwater mineralization increases non-linearly to 6.1 g/l (mainly due to sulfates, chlorides and sodium), and the hardness increases to 50.6 mmol/l in the geological section of this area (up to a depth of occurrence 300 m) in areas with downward filtration. The water hardness decreasess to 1.5–3.9 mmol/l at depths of 100–150 m (up to 200 m) in large areas. Vertical zonality (up to a depth of 150 m) is determined mainly by the leaching processes of carbonate and sulfate rocks outside the Mesozoic development area. Mineralization increases almost according to the linear law to 3.5 g/l (mainly due to sulfates, calcium and magnesium), and hardness – up to 37.7 mmol/ l here.The balneological properties of water are determined by the increased contents of organic substances, silicic acid, iron, hydrogen sulfide, as well as waters of the group “without specific components and properties”.

Исследование водоудерживающей способности Catalpa speciosa в условиях городов Караганды и Жезказгана

Изучение оводненности и водоудерживающей способности листьев растений имеет важное значение для оценки возможности их культивирования и массового применения в зеленом строительстве в аридных условиях Казахстана. В статье исследованы вопросы оводненности и водоудерживающей способности листьев ценной декоративной культуры Catalpa speciosa в условиях городов Караганды и Жезказгана. Изучены показатели оводненности и потери массы при высушивании в течение 1, 3 и 6 ч листьями растений 1-, 2- и 3-го годов вегетации с мая по август. Установлено, что листья Catalpa speciosa в условиях г. Караганды имели более высокие показатели оводненности и водоудерживающей способности, чем в г. Жезказгане. Максимальные значения потери влаги при высушивании отмечены для растений 1-го года вегетации, минимальные — для 3-их особей. По месяцам вегетационного периода листья максимально теряют свободную воду в условиях г. Караганды в июне, для г. Жезказгана — в июне и июле; минимальные потери влаги отмечены для обоих городов — в августе. Таким образом, критические точки напряженности водного обмена определены в июне и июле, что требуют интенсификации полива в данные месяцы. Более активный полив необходимо организовывать для растений 1-го года развития. В целом, установлены хорошие показатели водоудерживающей способности листьев Catalpa speciosa, что свидетельствует о возможности активного применения данной культуры в зеленом строительстве аридных территорий Центрального Казахстана.

Abiotic features of Sukhyi and Grygorivskyi Estuaries' ecosystems as seaport water areas (northwestern part of the Black Sea)

The article studies the location, origin and abiotic features of the ecosystems of Sukhyi and Grygorivskyi Estuaries that were transformed into water areas of Chornomorsk and Yuzhnyi, the major seaports of Ukraine, in the second half of the 20th century. It also presents a comparison of the abiotic conditions of such ecosystems based on the analysis of published data and additional database materials of the Institute of Marine Biology of the National Academy of Sciences of Ukraine.
 The construction of permanent and deep watercourses in the water areas of the estuaries alongside with large-scale dredging works led to their transformation into narrow sea bays with the depths significantly exceeding those in the adjacent sea. The construction of berths included levelling the coastline, changing the bottom profile and increasing the water volumes by more than three times. Now the volumes amount to 45–55 million m3 in Sukhyi Estuary and 60–70 million m3 in Grygorivskyi Estuary. The current abiotic features of the estuaries' ecosystems are determined by the processes occurring in Odesa sea region of the northwestern part of the Black Sea where such estuaries are located. The estuaries' hydrochemical regime depends on the yearly meteorological features, the intensity of water exchange with the sea, the amount of biogenic matter coming from natural (surface runoff, precipitation) and anthropogenic sources and the intra-aquatic processes of new organic matter production and destruction. Dredging activities resulted in emergence of the conditions for halocline and thermocline formation that hamper vertical water exchange. The formation of zones with extreme values of dissolved oxygen was also noted during the research. The maximum values in the surface layers result from photosynthesis development, while the minimum values in the bottom layers are caused by accumulation and destruction of dead organic matter. This information can be used to forecast the consequences arising from similar anthropogenic interference in the functioning of coastal marine ecosystems.

Application of remote sensing data for monitoring eutrophication of floodplain water bodies

The aim of this article was to investigate the influence of structural features of the floodplain water network on the spatial and temporal dynamics of chlorophyll-a concentration as an indicator of eutrophication. The research was conducted in the waters of the “Dnipro-Orilskiy” Nature Reserve. The geographic information base with polygonal objects which represented water bodies of the reserve was created on the basis of detailed geographical maps and the high resolution space images. The water bodies were characterized using such parameters as the distance of the water body centroid from the nearest shore of the Dnipro River, the area of the water body, the order of the water body and the connectivity of the water body. Chlorophyll-а concentration was estimated based on the surface algal bloom index. The information was obtained about 148 water bodies, 141 of which are water bodies in the floodplain of the Dnipro River. The area of floodplain water bodies within the reserve was 3.28 million m2. The area of floodplain water bodies ranged from 300–232,500 m2. Trophic State Index allows us to estimate the trophic level of Dnipro River waters as mesotrophic, water bodies of first and second order as eutrophic, and water bodies of third and fourth order as hypereutrophic. The dynamics of chlorophyll-a content in water followed the seasonal course of temperatures. The concentration was lowest in the cold period of the year and reached its maximum in the second half of summer. The autumn decrease occurred at the end of September. The seasonal course of air temperature was superimposed on the peculiarities of the temperature regime of a particular water body, which depended on its depth and flow rate. The time, water body area, distance from the Dnipro River channel, connectivity and order of water bodies were the statistically significant predictors of chlorophyll concentration in water and were able to explain 85% of the variation of this indicator. The increase in chlorophyll-a concentration with increasing order of a water body is due to a decrease in the intensity of water exchange and a decrease in the depth of water bodies of higher order. An increase in the order of a water body is accompanied by a branching network of water bodies, the ability of water bodies to clear sediments decreases. Sediment accumulation leads to a decrease in their depth. Warming of shallow ponds and accumulation of organic matter in them are factors of intensive growth of blue-green algae. The evacuation of surplus organic matter, which results from mass vegetation development with excessive nutrient inputs, is a key driver of the eutrophic regime of water bodies. The increasing importance of regulatory processes develops in agreement with an increase in chlorophyll-a concentration in a water body. The importance of the considered factors reaches the highest level in summer time, when simultaneous maximum warming of water bodies and minimum water level in them take place. Accordingly, the differences between deep and relatively cool water bodies and shallow water bodies that warm up quickly, which significantly stimulates the growth of organic mass, reach the greatest contrast. The spatial patterns of variation in chlorophyll-a concentration have a complex multiscale structure, indicating the multiple nature of the acting factors. The spatial variability was represented as a composition of broad-scale and medium-scale spatial processes. The broad-scale process is most dependent on connectivity, whereas for the medium-scale process the leading one is the effect of water body order.

О РАСЧЕТЕ РЕЖИМА ФОСФОРА ПРИ НАЧАЛЬНОМ ЗАПОЛНЕНИИ ВОДОХРАНИЛИЩА

The results of the calculations in changes of the phosphorus concentration in the reservoir during the formation of its ecosystem after the initial filling by river waters are presented. During this period, flooded soils and vegetation represent a significant internal source of nutrients that maintain a high level of ecosystem productivity. Calculations are based on the balance model of phosphorus in a completely mixed water body using the average values of the parameters given in the literature. A modification of the phosphorus balance as presented by Dillon and Rigler was used. Phosphorus leaching from flooded soils is approximated by an exponential relationship. Graphically illustrated is a typical course of change in the phosphorus concentration in the reservoir under the influence of flooded soils, which is a relatively rapid increase in concentrations followed by a gradual decrease. The most important parameter of this process is the time of the onset of the maximum concentration. By calculations have obtained dependences of the time of onset of the maximum phosphorus concentration in the reservoir on the intensity of the leaching process and the parameter of the balance equation. This parameter is the ratio of the water exchange coefficient and the phosphorus retention coefficient. It is shown that the time for the onset of the maximum phosphorus concentrations after flooding decreases sharply with an increase in the intensity of water exchange at its small values, but later the role of this factor becomes insignificant.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ДОННЫХ ОТЛОЖЕНИЙ ЧЕРЕМШАНСКОГО ЗАЛИВА И ПРИПЛОТИННОГО ПЛЕСА КУЙБЫШЕВСКОГО ВОДОХРАНИЛИЩА

Different types of underlying surface of Kuibyshev reservoir watershed, morphometric heterogeneity and active hydrodynamic regime of water area determine also different composition of bottom sediments and content of organic matter in different parts of this water body. Comparative analysis of integral curves of particle-size composition of bottom sediments of Priplotinnyples and Cheremshanskiy bay showed a significant difference in the parameters of these curves. The analysis is based on the soil maps of the catchment area, bathymetric maps, the distribution field of the bottom sediments coarseness and the share of organic matter in them, as well as the velocity fields obtained as a result of hydrodynamic modeling of the water area. Comparable water areas differ fundamentally in the intensity of water exchange. Prilotinnyples is more hydrodynamically active water area, whereas Cheremshansky bay is characterized by extremely slow water exchange. At the same time, the private catchment of the tribe is represented by easily eroded light loams, dolomites and limestones. While the upper part of the private catchment area of the bay is heavily forested, and the lower part of the catchment area is composed of medium and heavy loams. All this determined the formation of bottom sediments (in the form of fine and medium sands) by bedrock and products of channel erosion of the upper and middle sections of the hydrographic network of the Cheremshanka River. Whereas fine-dispersed products of soil erosion in the private watershed of the tribe formed the bottom sediments, represented mainly by silt-silt fractions. Also well warmed extensive shallow water area of the bay creates favorable conditions for mass development of plankton community, its die-off and sedimentation in the form of detritus to the bottom. Whereas greater depth and active hydrodynamics of water masses in the Priplotinnyples determine lower content of organic matter in bottom sediments. The greatest amount of detritus is carried by current from shallow water zones and is deposited in the deep central and right bank part of the tribe.

Dynamics of various forms of manganese in the pond waters

The forms of migration of manganese in pond waters are suspended matter and truly dissolved forms, including free manganese cations, as well as complex compounds formed by manganese with organic substances. The aim of the work was to study the dynamics of the content of various forms of manganese in the water of fish ponds. The content of individual forms of manganese was established according to the method developed by Linnik and Nabivanets. According to the methodology of Alekin, Semenov and Skopintsev determined hydrochemical parameters. It has been established that the dynamics of the content of manganese forms in different seasons depends mainly on the concentration of dissolved oxygen, pH value, inflow from sludge waters and the content of dissolved organic complexing substances in the water. In winter, free uncomplexed ions are the dominant form of migration. In other seasons, the content of complex forms exceeds the concentration of uncomplexed manganese. The dominant form of manganese migration in spring, summer, and autumn is Mn suspended, while in some periods of the same seasons, Mn dissolved predominates, which is explained by the influence of the intensity of water exchange, where suspended particles settle under conditions of slow runoff.

The Effect of Commercial Probiotics on the Phytoplankton Diversity Associated with Biofloc

The intensive aquaculture industry faces two main problems, first, the decrease in the water quality caused by high concentrations of metabolites, and second, the use of low natural food in aquaculture activities with high water exchange intensity. For this reason, efforts are needed to develop biofloc to maximize the contribution of natural food which can increase aquaculture production. The present study aimed to analyze the effect of commercial probiotics on the differences in the phytoplankton diversity associated with biofloc. The fish were divided into three treatment groups. Treatment A involved biofloc formation without using probiotics, treatment B contained biofloc formation using commercial probiotics (Bacillus spp., lactic acid, Lactobacillus spp., Saccharomyces spp. 50/50 feed), and treatment C entailed biofloc formation using commercial probiotics (containing a native microbial consortium, 50/50 feed). The treatment groups were repeated six times so that there were 18 experimental units. The research was conducted from March to April 2015. The results indicated that the administration of probiotics with different types led to insignificant differences among the treatment groups. The highest diversity index value occurred in treatment C on day 34 of the experiment that was equal to 0.49. On the other hand, the highest value of the dominance index (C = 0.99) occurred in treatments A and B on day 21. It can be concluded that the addition of probiotics with different biofloc could result in insignificant phytoplankton diversity. Furthermore, the Nitrogen/Phosphorus (N/P) ratio as a limiting factor for phytoplankton growth indicated different results in each treatment.

Spatial distribution of bottom sediments of the near-dam ples of Kuibyshev Reservoir

The composition of bottom sediments and the patterns of their spatial distribution are determined by external (type of underlying surface of the catchment area, anthropogenic development, intensity of soil erosion) and internal (water regime, intensity of water exchange, morphometry of the basin) factors. The analysis of the granulometric composition of the bottom sediments of the near-dam ples of the Kuibyshev Reservoir showed the relative uniformity of the ples soil in terms of size. At the same time, depending on the location of the sampling points, certain patterns of distribution of the size of bottom sediments in space are traced.

Geomorphometric approach in geoecological assessment of groundwater in the territory of the Arkhangelsk region

It is shown that the Terrain Ruggedness Index, calculated on the digital elevation model, predetermines the chemical composition of groundwater. The high ruggedness of the relief, the small stratum of the overlying bedrocks of Quaternary deposits, the absence of water barriers contribute to the desalination of groundwater due to the penetration of ultra-fresh atmospheric precipitation. The low ruggedness of the relief also causes a low intensity of water exchange and, as a consequence, a higher mineralization of groundwater.

Сезонная динамика и пространственное распределение структурных показателей бактериопланктонного сообщества бухты Севастопольская (Крым, Чёрное море)

Бактериопланктон определяет формирование значительной части вторичной продукции и минерализации новообразованного органического вещества в водных экосистемах и быстро реагирует на любые изменения в окружающей среде. Данные о состоянии микробиального сообщества исключительно важны для понимания процессов переноса вещества и потока энергии в водных экосистемах, что особенно актуально для прибрежных акваторий, где в последние десятилетия произошли существенные негативные трансформации. Целью нашей работы было изучить долговременные изменения структурных показателей бактериопланктона в различных участках бухты Севастопольская (Чёрное море) в период 1992–2005 гг. Численность бактерий определяли прямым микроскопическим методом, используя адсорбционный (эритрозин) или флуоресцентный (акридиновый оранжевый) красители; биомассу рассчитывали с применением коэффициента (2·10−14 г C·кл.−1) или по непосредственным промерам клеток. Для определения морфотипов клеток использовали сканирующую электронную микроскопию. Показано, что диапазон общей численности микроорганизмов составил 0,2·106–10·106 кл.·мл−1; биомассы — 2–201 мг C·м−3. В морфологической структуре бактериопланктона преобладали кокки (диаметр — 0,36–0,86 мкм) объёмом 0,02–0,27 мкм³ и палочковидные клетки (длина — 0,6–1,2 мкм, ширина — 0,2–0,4 мкм) объёмом 0,50–0,65 мкм³. Максимальные значения всех переменных зарегистрированы в летний и осенний периоды года (с июня по октябрь), минимальные приурочены к зимнему и весеннему сезонам. Полученные величи́ны количественных показателей бактериопланктона сопоставимы со значениями для различных акваторий Мирового океана, включая Чёрное море. Динамику структурных показателей бактериопланктона бухты Севастопольская в течение годового цикла определяли абиотические и биотические факторы. Значимо высокая корреляция (86 %, p < 0,01) между гидролого-гидрохимическими и биологическими переменными подтверждает неслучайный характер взаимосвязи между ними. Дискриминантный анализ выявил достоверные различия в структуре бактериопланктонных сообществ между участками бухты с разной интенсивностью водообмена, степенью общей загрязнённости и удалённостью от открытого моря. Достоверно меньший объём клеток бактерий в 2004 г. [(0,16 ± 0,05) мкм³] по сравнению с таковым в 2005 г. [(0,20 ± 0,03) мкм³] (парный t-тест, p < 0,05) был связан, вероятно, с интенсивным выеданием микроорганизмов фаготрофными простейшими. Полученные данные о структуре сообщества бактериопланктона могут быть использованы при прогнозировании состояния экосистемы бухты Севастопольская, а также при разработке и верификации математических моделей функционирования прибрежных экосистем.

ДОННЫЕ ОТЛОЖЕНИЯ ПРИПЛОТИННОГО ПЛЕСА КУЙБЫШЕВСКОГО ВОДОХРАНИЛИЩА (ПО ДАННЫМ ЭКСПЕДИЦИОННЫХ ИССЛЕДОВАНИЙ 2020 г.)

The composition of bottom sediments and the patterns of their spatial distribution are determined by external (type of underlying surface of the catchment area, anthropogenic development, intensity of soil erosion) and internal (water regime, intensity of water exchange, morphometry of the basin) factors. As a result of the expedition studies of the IEVB RAS in the autumn period from September 14 to October 3, 2020, samples of bottom sediments were collected at 21 stations near of Kuibyshev reservoir dam in a 10-centimeter layer. Based on the results of the granulometric analysis and assessment of the organic matter content in the bottom sediment samples, integral granulometric curves were constructed and the spatial distribution of different characteristics of the bottom sediments was analyzed such as the percentage of organic matter in the samples, the interquartile range and the median value of the bottom sediment size at the studied sampling points. The analysis showed that the largest differences in the percentage of particles in the samples of the studied stations (over 60%) are accounted for by particles with a size of about 0,1 mm. Sampling stations located closer to the right bank are characterized by a smaller size of the bottom sediment soil than stations near the left bank. This is due to the fine-grained erosion products of the catchment area is characterized by a relatively uniform granulometric composition of bottom sediments, also mainly by dusty-sand fractions. More uniform in size soil is observed along the right bank – fine products of erosion of sandstones and dolomites of the right bank. The larger interquartile range characterizes the samples taken along the longitudinal profile of the reservoir dam reach and near the left bank in the shallow water zone. In this area of the water area, which is genetically composed of sands and mineral silts, due to the favorable temperature regime and the peculiarities of the circulation of water masses, intensive organic sedimentation processes occur. On average, for the dam reach the content of organic matter in the bottom sediments is 1,1%, which is in good agreement with the data of other researchers.

Пространственно-временная изменчивость концентрации хлорофилла «а» в Краснодарском водохранилище по данным спутниковых снимков

The Krasnodar Reservoir has undergone significant transformations during its operation since 1973. As a result, of active delta formation of the Kuban and Belaya rivers, the reservoir was divided into two autonomous reservoirs, its area decreased by 35 %. The study is aimed at determining the significance of the eutrophication factor in the transformation of the Krasnodar Reservoir. Methods. Based on 51 Sentinel-2 satellite images for 2015–2020 the results of calculations of the concentration of chlorophyll «a» as an indicator of phytoplankton biomass in the reservoir are presented. The MSI sensor calculates the concentration of chlorophyll a (chl «a») based on the normalized chlorophyll difference index. Chl «a» estimates were obtained for a total area of 277 km2; the main bowl of the Krasnodar Reservoir and the Tshchik Reservoir, which was cut off from it. We have built maps reflecting the spatial and intra-annual variability of chl «a». Results The highest average concentrations of chl «a» are characteristic of the shallow upper part of the Krasnodar Reservoir, which is influenced by the runoff of the Kuban and Pshish rivers with an increased nutrient content. Locally high average values of chl «a» were recorded in the areas of the runoff current and in the estuaries of the left-bank tributaries. In the Tshchik water body with a low intensity of water exchange, the relationship between the concentration of chl «a» and hydrodynamic processes is not evident. We have revealed features of the annual cycle of phytoplankton biomass. It has been established that the trophic status of the reservoir is subject to seasonal variability: in spring, 2/3 of the water area correspond to eutrophic waters, 1/3 to mesotrophic waters; in autumn, the entire reservoir has a eutrophic status.

ФОРМЫ МИГРАЦИИ РАДИОНУКЛИДОВ (U и Th) В ПРИРОДНЫХ ВОДАХ В РАЗЛИЧНЫХ ГЕОХИМИЧЕСКИХ УСЛОВИЯХ НА ОСНОВЕ РАСЧЕТНЫХ И ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ

Актуальность исследования обусловлена необходимостью учета разнообразия форм миграцииприродных радионуклидов при смене геохимических условий, а также при прогнозированиирадиоэкологического статуса гидроэкосистем. На территории Семипалатинского испытательного полигона миграция естественных радионуклидов в водных системах слабо изучена, расчет форм миграции урана и тория при смене геохимических обстановок будет информативен для понимания миграции широкого спектра трансурановых радионуклидов. Цель: определить формы миграции урана и тория в природных водах в зависимости от размеров частиц и с учетом широкого спектра компонентов, рассчитать формы их миграции в ручьях и озерах. Объекты: воды ручьев горного массива Дегелен, воды озер экспериментальных площадок Семипалатинского испытательного полигона, модельные гидрогеохимические системы. Методы. Формы нахождения природных радионуклидов исследовали insitu методомкаскадного фракционирования природных вод. рН, Eh вод определяли методом потенциометрии, общую минерализацию – кондуктометрией. Определение основных ионов воды и отдельных элементов произведено методами титриметрии (HCO3–, CO32–, Cl–, Ca2+, Mg2+), оптико-эмиссионной спектрометрии (Na, K, Ca, Mg, Fe, Si), а также ионной хроматографии (Cl–, SO42–). Содержание растворенных органических веществ определяли по перманганатной и бихроматной окисляемости, методом каталитического сжигания, а также по интенсивности UV сигнала. Содержание U и Th определяли методом масс-спектрометрии. Результаты. Определены особенности переноса урана и тория в природных водах различных водных объектов Семипалатинского испытательного полигона,и обозначены определяющие их процессы. Установлено, что сульфат-ион в водах ручьев является индикатором интенсивности водообмена и скорости окисления сульфидных минералов, определяющих выход в раствор значительных концентраций урана. Уран связан с органическими и органоминеральными комплексами и подвержен трансформации форм нахождения в случае изменения геохимических условий среды. Для тория в большей степени, чем для урана, характерен коллоидный транспорт. Доминирующей миграционной формой этих элементов являются взвешенные компоненты природных вод. Отношение Th/U в растворенной форме достаточно стабильно по сравнению с коллоидными и взвешенными формами. Для вод с разным гидродинамическим режимом прослеживается отличие в степени выраженности влияния терригенной составляющей.