Limnology and Freshwater Biology

The distribution of biogenic elements in the vertical section of bottom sediments of Lake Kotokel (Eastern Baikal region)

2025-04-30T11:23:01+08:00

Chemical composition of organic-mineral sediments (sapropel) of Lake Kotokel (Eastern Baikal region) based on 14.5 m and 16.5 m long drilling cores and distribution of the major biogenic elements (TOC, H, TN, S) and TP along the depth of bottom sediments have been studied. . A reduction type of diagenesis has been established, during which destruction of organic matter occurs. The major role in diagenetic transformations of organic matter belongs to different physiological groups of microorganisms, primarily heterotrophic, ammonifying and sulfate-reducing bacteria. The lightening of the isotopic composition of carbon confirms active microbial processes that change the initial composition of organic matter as a result of its anaerobic decomposition. The weighting of the TN isotopic composition in the upper sediment intervals indicates a rather intense nitrogen cycle and its ‘high’ loss from organic matter composition, which leads to the growth of δ¹⁵N.

Features of the ichthyofauna of freshwater bodies in 22 river basins of the northeastern Fennoscandia (Barents and White Sea basins, 1972-2024 studies)

2025-03-07T17:22:14+08:00

The data on the distribution of fish species in 128 different types of freshwater bodies of northeastern Fennoscandia (Murmansk region, northern Karelia, northeastern Finland and Norway) (hereinafter referred NEF), belonging to 22 river basins (Barents and White Sea basins) for the time period from 1972 to 2024 are summarized. The factors determining the presence/ absence of fish species were analyzed. The trends of changes in the structure of fish communities of freshwater bodies under conditions of environmental changes were studied. The data are presented on the distribution and biological characteristics of the European whitefish Coregonus lavaretus, which remains a widespread species in various freshwater bodies of the NEF and often forms the “core” of their ichthyocenoses. In total, 20 species of fish live in the freshwater bodies of the study area, of which 16 are native and 4 are introduced. The basis of the native ichthyofauna of water bodies is the cold-water adapted group of fish. The number of fish species in a water bodies varies from 1 to 18. The distribution of fish species is determined by a number of factors, including geography, catchment area size, and water body morphometry. The number of species in the basins of medium-sized rivers of the Murmansk region increases in the direction from northwest to southeast due to taxa of higher rank (families and genera). The large and deep-water lakes and lake reservoirs of the White Sea basin are home to virtually the entire spectrum of species in this study area. The most common fish species are the Eurasian minnow, nine-spined stickleback, northern pike, burbot, European perch and European whitefish. It was established that in the studied water bodies the European whitefish is represented by various sympatric ecological morphs. The studied morphs of whitefish in the water bodies of 8 river basins of the NEF differ not only in the structure of the branchial apparatus and nutrition, but also in the age, growth and maturation of the fish. Differences in the structure of whitefish populations are observed both between water bodies of different river basins and within the basins of these rivers. In the studied water bodies of the NEF, a general tendency of transition of whitefish-salmon water bodies to whitefish-perch or whitefish-smelt water bodies is observed. These successional processes are associated with changes in fish habitat conditions under the influence of global and regional factors: climate change, hydropower, anthropogenic pollution, eutrophication, and invasive species.

Phosphate Minerals in the Bottom Sediments of Lake Onega from the Upper Neopleistocene to the Holocene

2025-05-26T13:37:18+08:00

This study investigates phosphorus-bearing minerals in the bottom sediments of Lake Onego and its proglacial precursor. The composition of phosphorus mineral phases differs in the Late Neopleistocene glaciolacustrine and Holocene lacustrine deposits. The former are dominated by fluorapatite, monazite, and xenotime, whereas the Holocene sediments,represented by fine-grained lacustrine muds,contain significant amounts of vivianite and Fe–Mn hydroxides. These differences revealed changes in phosphorus sources and conditions of its accumulation, which is important for assessing the trophic state of Lake Onega at all stages of its development under climatic and anthropogenic changes.

Parasite fauna of common bream Abramis brama (Linnaeus, 1758) (Cypriniformes: Leuciscinae) from the Irkutsk Reservoir

2025-02-20T16:22:43+08:00

The first data on the parasite fauna of the common bream (<i>Abramis brama</i>), acclimatized to the Irkutsk Reservoir, are presented. The study reveals that the parasitic community of these fish comprises six eurytopic species: myxosporidians (2), cestodes (1), trematodes (2), and nematodes (1). It is suggested that the bream and other fish species in the reservoirs of the Angara River host a significantly greater diversity of parasites than currently recorded. Given the near-total lack of data on fish parasites in the Irkutsk Reservoir, the urgency of comprehensive parasitological and molecular genetic studies is emphasized.

Hydrochemical conditions and trophic status of the freshwater Curonian Lagoon

2025-07-22T04:02:30+08:00

The Curonian Lagoon is the largest lagoon in Europe with freshwater conditions. For a long period, a large amount of nutrients was supplied with the flow of the Neman River, which led to significant eutrophication of the lagoon. The consequence of this was a summer peak increase in phosphorus phosphates, associated with the intensive development of cyanobacteria and water “hyperblooming”. Comparison of data obtained in the southern part of the lagoon in 2019-2024 with an earlier period of water “blooming” (2007-2016) showed a 2-3-fold decrease in summer concentrations of phosphate phosphorus and a change in the N:P ratio (from <16 to ~30-50). As a result, the intensive development of cyanobacteria (water “hyperblooming”) ceased. During the period of water “hyperblooming” (2007-2016), chlorophyll a concentrations during the growing season and in summer exceeded 100 µg/l and characterized the Curonian Lagoon as a hypertrophic water body. In the modern period (2019-2024), chlorophyll a concentrations have decreased by 3-4 times (~40 µg/l). The decrease in chlorophyll and phosphorus concentrations in recent years can be characterized as significant de-eutrophication of the Curonian Lagoon.

Biotesting of a freshwater (river) ecosystem water quality by genetic markers of Tradescantia model test system

2025-06-03T17:50:58+08:00

In the field of assessing the quality of the aquatic environment, the use of biotesting methods is a mandatory element of environmental monitoring. Plant model test systems, such as Tradescantia clones, are used for biotesting of water quality in freshwater river ecosystems. To study the level of clastogenicity of the water samples of the Akhuryan River (Armenia), collected at five sampling points along the river in the summer, a test for micronuclei in the pollen mother cells of Tradescantia clone 02 (micronucleus assay – Trad-MCN) is used. The following two marker test-criteria were taken into account: the frequency of tetrads with micronuclei (Tetr/MCN) and the frequency of micronuclei in tetrads (MCN/tetr). The study of clastogenic effects in the sporogenic cells of Tradescantia showed increase in the frequency of occurrence of both test criteria in all studied water samples compared to the background with maximum manifestation in the Akhurik sample (p < 0,01). A reliable positive correlation was shown between the marker criteria of the micronucleus assay and the chemical elements: HCO₃, CO₃, B, Mg, Ca, As, Se (p < 0.01).

The first results of DNA barcoding of freshwater Oligochaeta (Annelida) of the European North-East of Russia

2025-07-23T19:00:27+08:00

Oligochaetes inhabiting freshwater ecosystems are considered promising indicators of ecological status due to their sensitivity to environmental changes. However, traditional identification based on morphological characteristics is often challenging. The application of molecular techniques, particularly DNA barcoding of the mitochondrial cytochrome c oxidase subunit I (cox1) gene, improves the accuracy of species identification and enhances our understanding of oligochaete genetic diversity. This study presents new data on taxonomic and genetic diversity of aquatic oligochaetes (Annelida, Clitellata) from various freshwater bodies in the European North-East of Russia. A discrepancy was revealed between morphological (17 species) and molecular (26 genetic lineages) differentiation of taxa. Significant cryptic diversity was recorded in Tubifex tubifex (Müller, 1774) and Limnodrilus hoffmeisteri Claparède, 1862, which were subdivided into 11 genetic lineages, with maximum intraspecific cox1 distances reaching up to 26.1%. The presence of Tasserkidrilus kessleri (Hrabě, 1962), identified through molecular data, was recorded for the first time in the Vychegda River basin. The results confirm the high effectiveness of molecular approaches for studying biodiversity in northern freshwater ecosystems and provide a foundation for the development of a regional reference library of DNA barcodes.

Ecological and biogeochemical studies of the Bureya Reservoir in the area of a giant landslide

2025-06-07T14:23:10+08:00

For the first time in the Russian Far East, , a temperature of, a giant landslide with a volume of 24.5 million m³ occurred in December 2018 at 32 °C. The landslide was accompanied by a massive rock movements that collapsed directly into the Bureya Reservoir. It completely blocked the access of water to the Bureya Hydroelectric Power Station and provoked a tsunami. According to geomorphologists’ research, the Bureya landslide is one of the largest in the world in terms of tsunami wave height and is a unique natural phenomenon in an ice-covered reservoir. To assess the ecological and biogeochemical state of the Bureya Reservoir in winter and summer (2019-2022), comprehensive studies of water composition in the landslide influence zone, using gas chromatography, spectrography and microbiology, were carried out . The obtained results support the idea on complex biogeochemical processes during cyclic thawing-freezing of rocks and explosive emission of methane accumulated in the pore space.

Microbial transformation of hydrophobic polyaromatic hydrocarbons with the emergence of hazardous benzene derivatives

2025-06-07T14:09:11+08:00

Microbial transformation of phenanthrene in the groundwater of the riverbank filtration zone is the aim of this study. Seasonal monitoring of the groundwater, conducted by the Institute of the Water and Ecology Problems FEB RAS, confirmed the presence of phenanthrene in the water samples. The results of the experimental modeling showed that phenanthrene transformation was significantly affected bytemperature and adaptive potential of microbial communities. The degradation of phenanthrene by microbial consortia is accompanied by methylated transformation byproducts (benzene derivatives) impairing water quality and water treatment.

Evidence of Tunguska 1908 Event in the sediments of two lakes in Evenkia (Siberia, Russia)

2025-07-24T17:16:16+08:00

The Tunguska catastrophe of 1908 (the “Tunguska meteorite”) was the most powerful atmospheric explosion of unknown origin in human memory that occurred over the territory of the Evenki district of the Krasnoyarsk region. Traces of any cosmic body have not yet been found. Lakes Zapovednoye and Peyungda are located at a distance of 50-60 km from the supposed epicenter of the Tunguska catastrophe of 1908. In the bottom sediments of lakes Zapovednoye and Peyungda, heterogeneities in the species composition of chironomids and Сladocera were found, probably reflecting changes in ecosystems due to the Tunguska catastrophe of 1908. No significant changes in the diatom composition were detected. The new information may be useful as evidence of the reaction of lake ecosystems after a strong impact, and therefore provide new information to the knowledge about the Tunguska catastrophe of 1908.

The Schmeilsche lobus in Diaptomidae (Crustacea: Calanoida): comparative morphology and diagnostic potential

2025-07-16T15:03:16+08:00

The Schmeil’s (Schmeilsche lobus) organ is a specific cuticular outgrowth on the dorsal surface of the second pair of swimming legs. Using a scanning electron microscope, its shape was studied and described in 40 representatives of the Diaptomidae family. The Schmeil’s organ has a characteristic shape, similar in females and males of the same species, resembling a triangle or a fold. A triangle, unlike a fold, has a more elongated shape tapering to the top, it can be with a sharp, rounded or curved angle. The Schmeil’s organ may look like a longitudinal or transverse fold, more or less deep. The presence of a Schmeilsche lobus was first established in a representative of the Paradiaptominae subfamily Metadiaptomus asiaticus (Uljanin, 1875), as well as in 10 species of Diaptominae. The species differentiation based on the Schmeil’s organ structure is useful at the case of the great similarity of the key diagnostic structures, for example, it is differ between the genera Leptodiaptomus and Acanthodiaptomus, which have the similar morphology of the fifth pair of legs in females, as well as in subgenera within the genus Arctodiaptomus and species of the genus Eudiaptomus, with great similarity in males’s fifth pair of legs structure. The considered examples confirm that the presence and shape of the Schmeil’s organ can be used as an additional diagnostic feature.

Results of measurements of trace gaseous concentrations at the Boyarsky reference station for monitoring the atmosphere of the Baikal natural territory in 2024

2025-07-26T10:09:02+08:00

The paper presents the results of measurements of ground-level ozone, nitrogen oxide and dioxide, and sulfur dioxide concentrations in the atmosphere of the southeastern coast of Lake Baikal at the Boyarsky research station of the Institute of Physical Material Science Siberian Branch of the Russian Academy of Sciences (IPMS SB RAS). The features of the daily variation of small gaseous impurities in different seasons of the year are revealed. Seasonal variations of ground-level ozone, nitrogen oxide and dioxide, and sulfur dioxide concentrations were obtained. Periods with increased ground-level ozone concentrations were noted. It has been shown that high ozone levels may be associated with long-range transport from polluted areas of Mongolia and China.

Monitoring of hydrochemical parameters of Lake Pit’evoe on Bolshoy Solovetsky Island

2025-05-06T19:42:31+08:00

We conducted five-year hydrological studies (from 2020 to 2024) of a small freshwater lake on Bolshoy Solovetsky Island during the summer low water period, obtained hydrochemical data and compiled a bathymetric mapparameters of . This glaciotectonic body of water was classified as a small deep lake receiving waters of the western lake-canal system. It does not experience direct anthropogenic impact, with the exception of recreational load. Air temperature and precipitation fluctuations led to changes in temperature and water level in the water body studied . The combination of these variations influenced the hydrochemical parameters. Color, electrical conductivity, increase of dissolved iron and pH, lower mineralization (sum of main ions) largely depended on the amount of precipitation. Water temperature affected the concentration of oxygen and anoxic conditions were created in the bottom layers of the lake. The occurrence of anaerobic processes in the bottom layers of the lake was accompanied by an increase in the products of organic matter destruction, in particular, hydrocarbonates. At the same time, no increase in the content of hydrogen sulfide was noted, its concentrations did not exceed 5 μg/l over the period of research. The results obtained indicate the need to conduct annual monitoring of drinking water sources, even though present fluctuations in the hydrochemical indicators are mainly associated with climatic changes.

The impact of cloudiness on the plankton biomass in Lake Dolgoe (Belarus) during the spring thermal bar

2025-06-30T14:42:39+08:00

Mathematical modeling was used to study the impact of cloudiness on the plankton dynamics in Lake Dolgoe (Belarus) during the spring thermal bar. Three computational experiments, involving different cloudiness values, were caried out, and in which the other meteorological parameters (air temperature, relative humidity, atmospheric pressure, wind speed, and wind direction) were set on the grounds of the data sourced from the weather station located in the urban settlement of Sharkovshchina, for March 2024. The computation outcome revealed that the extent of the sky cover with the clouds contributes to the non-uniform distribution of the phyto- and zooplankton in Lake Dolgoe in early spring.

Fluxes and composition of sediment particles in the water column of Southern Lake Baikal between 1999 and 2021

2025-07-25T12:49:27+08:00

This study investigates in detail natural processes of modern sedimentation in South Baikal. The article presents data on the total flux of sedimentary matter, collected between March 1999 and March 2021. The quantity and composition of the recovered material is largely determined by SiO_2bio, which is directly dependent on annual blooms of diatoms in the lake. Since 2010, particle fluxes have generally increased. At the same time, there was a change in the dominant diatom species. So called “Melosira years” were replaced by years with increased productivity of species of the genus Synedra. Presumably, this happened due to climate change.

The state of aquatic ecosystem according to hydrochemical and hydrobiological indicators of the Kizhi skerries area of Lake Onego during the ice period

2025-06-14T06:01:11+08:00

For the first time during theice-сovered period, comprehensive hydrochemical and hydrobiological studies were conducted in the area of Kizhi Island on Lake Onego. During winter, average concentration of total phosphorus was 7 μg/l, which corresponds to oligotrophic water types. The concentrations of iron, manganese and pollutants (including petroleum products and synthetic surfactants) did not exceed the maximum permitted levels for fishery water bodies. The results of hydrochemical analysis suggest that the water quality in the Kizhi skerries is satisfactory. The study area is characterized as oligotrophic with elements of β-mesotrophy determined by hydrobiological indicators (bacteria, phytoplankton, zooplankton and macrozoobenthos).

Water temperature and dissolved oxygen content in a small lake in Karelia over an annual cycle against the background of regional climate variability

2025-07-26T20:46:42+08:00

The article analyzes the results of water temperature and dissolved oxygen content measurements taken at a mooring in a small lake in southern Karelia from October 2022 to October 2024 and compares them with records from the previous 15-year period (2007-2022). The measurements were carried out using RBR Ltd. temperature and dissolved oxygen sensors at 14 depths with 1 min resolution over an annual cycle. The study aims to identify changes in the thermal, oxygen, and the mixing regimes of a small lake in southern Karelia under regional climatic variability. The fall and winter seasons of 2022/23 and 2023/24 were characterized by contrasting weather conditions – the former was warmer than the baseline and the latter was colder and snowier (precipitation in some months exceeded the baseline by 2-3 times). The open water period of 2024 was noticeably warmer than the baseline, and the precipitation amounts in individual months were 2-4 times lower than the baseline. During both cold seasons, anoxic conditions in the bottom layers of the lake lasted for about four months (from mid-January until ice breakup in early May), and during the open water periods of 2023 and 2024 their duration was about three weeks and 1.5 months, respectively. Stratification (the period with a more than 1 °C temperature difference in the water column) in 2024 lasted 119 days, which is 20-60 days more than in previous years of measurements. Due to the calm and warm weather in the summer and early fall, the lake mixing regime in 2024 was dimictic, while in previous years the polymictic regime prevailed (excluding 2022). The biological summer (the period with water temperature above 10 °C) lasted more than 140 days in 2023 and 2024. Based on the 2008-2024 data, we determined the relationship between the duration of the biological summer and the mean monthly air temperatures in May and September, with September temperatures making a greater contribution. The identified changes in the thermal, oxygen and mixing regimes may have an adverse effect on the lake ecosystem, necessitating continuing monitoring.

Persistent organic pollutants in hydrobionts in river ecosystems of Crimea

2025-07-13T23:59:02+08:00

For the first time, the content of persistent organic pollutants (DDT, its metabolites DDE and DDD, and six indicator congeners of polychlorinated biphenyls) was determined in several fish species (Alburnoides maculatus, Squalius cephalus, Neogobius fluviatilis) and shrimp (Palaemon adspersus) in three small Crimean rivers: the Alma, Belbek, and Chernaya. It was revealed that hydrobionts accumulated these substances, the composition and concentration levels of which varied significantly in different areas. In the Crimean spirlin (Alburnoides maculatus) in the Belbek River and the silver prussian carp (Carassius gibelio) in a lake located in the lower catchment area of the Alma River, the highest concentrations of DDE, exceeding maximum permissible concentrations, as well as a high environmental risk from its impact, were determined. PCBs were either not detected or detected at low concentrations in fish tissue in rivers Alma and Belbek, indicating the absence of industrial sources of pollution, while agricultural pollution remains significant. A difference in the accumulation of persistent organic pollutants was revealed in the organs of the shrimp from the Chernaya River: the concentration of DDE and PCBs in the caviar was 10 to 20 times higher than in the muscle tissue. In the Chernaya River, a high environmental risk associated with the impact of congeners PCB 138 and 153 on the shrimp population was identified.

Bacteriophages of Lake Baikal in the structure of the new international classification ICTV (analytical overview)

2025-07-17T10:04:40+08:00

We analyzed the first research results from the literature concerning autochthonous bacteriophages, a new link of a microbial loop in the ecosystem of Lake Baikal. In a short time, the cutting-edge study methods revealed a significant taxonomic diversity of phages in various biotopes of the lake in all seasons of the year and at all depths. For the first time, we examined a size structure and abundance of Baikal bacteriophages as well as the genetic diversity of T4-like phages in the surface microlayer and biofilms from biogenic and abiogenic substrates of the lake. The whole genome of the new Baikal bacteriophage, PaBG, was determined. The International Committee on Taxonomy of Viruses (ICTV) ratified it as a novel genus Baikalvirus.

Accumulations of Cr, Cu, Zn and Pb in sediments under cage trout farms of Lake Ladoga

2025-06-06T16:38:18+08:00

This study presents an environmental assessment of the accumulation levels of trace metals (Cr, Cu, Zn, and Pb) in the sediments of Lake Ladoga near three cage trout farms. Samples were collected at the end of an intensive fish feeding period from both the cage and reference sites. Using ICP-MS, acid-soluble and labile metal forms were analyzed. The results show that Zn had highest accumulation levels, which can be attributed to organic waste from the farms. The labile forms of Zn (up to 53%) pose serious risks of secondary pollution in the water column. However, no significant input of Cu and Pb from the trout farms was found. Elevated Cr concentrations (up to 133 mg/kg) were observed in both the cage and reference sites, mainly due to natural factors such as geochemical features of the surrounding bedrocks. The integrated Pollution Load Index (PLI) indicated moderate pollution levels, ranging from 1.0 to 1.2. These results highlight the need for monitoring Zn content under cage farms, development of sediment quality guidelines, and assessment of hydrological and geochemical conditions in aquaculture planning.

Systematization of Organic-Mineral Bottom Sediments in Small Lakes of the Southern Western Siberia: A Landscape Zonation Context

2025-07-31T17:32:27+08:00

The systematization of organic-mineral bottom sediments of 38 small lakes in the south of Western Siberia has been carried out, taking into account landscape and sapropelation zones. The study covers the subtaiga, forest-steppe, steppe and subzones of ribbon forests, where 494 samples of bottom sediments were taken. The analytical work was performed at the Analytical Center for multi-elemental and isotope research SB RAS (Novosibirsk) using a set of modern analytical methods: determination of ash content, elemental composition (AAS, ICP-AES, and X-ray fluorescence), mineralogy (X-ray Diffraction, SEM). To systematize bottom sediments, the classification of bottom sediments developed by the authors was applied based on ash content (types), Si/Ca ratio (classes) and the type of dominant primary production (genetic species). The relationship between the distribution of bottom sediment types and landscapes, as well as sapropelation zones, has been identified. Organic-mineral and mineral-organogenic types prevail in the subtaiga/forest-steppe (intensive zone of sapropelation). Mineralized sapropels and mineral silts dominate the steppe/ribbon forests landscape (a zone of weak sapropel formation). Organogenic bottom sediments are extremely rare in all landscapes and sapropelation zones. The distribution of sediment classes among all the lakes considered is uneven, with the predominance of lakes with a silicon sediment class. Planktonic-macrophytic and macrophytic-planktonic genetic species are predominant regardless of the landscape and sapropelation zone. Local features of the geochemical and mineral composition in nearby lakes have been established using the example of Lakes Peschanoe and Chistoe (forest-steppe landscape), which is due to differences in the genetic species of sapropel. The proposed systematization makes it possible to assess the resource potential of sapropels for agriculture and reclamation, and serves as a basis for monitoring anthropogenic and climatic impacts. The unique composition of the bottom sediments of each individual lake underscores the need for detailed geochemical analysis when planning environmental management.

Formation features of Lake Baikal hydrometeorological regime in the modern period

2025-07-31T15:06:47+08:00

We analyzed the main features of climate fluctuations near Lake Baikal and water regime components between 1980 and 2023. The analysis indicated climate warming with the highest rates of air temperature rise during the cold season of the year and an increase in climate aridity or a decrease in annual and monthly atmospheric precipitation. During the Southern Hemisphere cyclones and the development of convective or orographic clouds, the spatial heterogeneity of summer atmospheric precipitation increased. In winter, under the dominant influence of the Asian monsoon anticyclone, these differences were minimal. Correlating with climate change, the ratio between the lake’s water balance components transformed, determining the features of seasonal and interannual fluctuations in its water level. The inflow of surface waters to the lake and the runoff from it decreased, while the evaporation from the surface of the water body, on the contrary, increased. The heating of the lake’s water masses increased, especially at its northern end distinguished by the lower wind activity. Due to the later freezing of the lake and earlier ice breakup (up to 20 days), the ice cover period reduced. We observed climate change in circulation factors at Lake Baikal, including an increase in the activity of migratory cyclogenesis in the cold season of the year and upper-level anticyclogenesis in the warm season, where the frequency of blocking processes also increased. Keywords: air temperature, precipitation, inflow, evaporation, water level.

Silica in sapropel sediments of small lakes across different landscape zones in the south of Western Siberia

2025-06-24T11:50:57+08:00

Using IR-spectroscopy, the ratio of biogenic to silicate (terrigenous) silica was determined in small lakes of the Baraba Lowland, located in different landscape zones of the south of Western Siberia. These lakes exhibit substantially differing hydrochemical water parameters and sapropel composition. It was established that in sapropel deposits across all landscape zones, regardless of sapropel type, class, or genetic kind, the content of biogenic SiO₂ (SiO₂bio) ranges from 12% to 29% of the total silica content (siliceous sapropel: 12–29%; calcareous sapropel: 13–25%; mixed sapropel: 12–29%).

Persistent organochlorine pollutants in the water ecosystems on the coast of the Kandalaksha Gulf of the White Sea

2025-06-02T19:09:46+08:00

The paper presents the results of studying selected persistent organochlorine pollutants (hexachlorobenzene, pentachlorobenzene, pentachlorophenol, and pentachloroanisole) from bottom sediments of small stratified lakes at different stages of isolation from the White Sea, unaffected by anthropogenic impact.The sediment samples were collected at deep-sea stations by employees of the N. Laverov Federal Center for Integrated Arctic Research, Ural Branch of the Russian Academy of Sciences (Arkhangelsk) during complex expeditionary work in March 2019. Persistent organochlorine pollutants were extracted from air-dry samples by accelerated liquid flow extraction with a hot mixture of organic solvents with further preparation according to RD 52.24.417-2011 (RF) and ISO 14154:2005. Identification and quantitative determination of individual compounds were performed using capillary gas chromatography with electron capture detection. The presence of selected persistent organochlorine pollutants in the sediments was revealed. Their total content ranged from 9.7 to 63.6 ng g^-1, with hexachlorobenzene and pentachlorophenol being found in the highest concentrations. The concentrations of the pollutants were generally assessed as not high by the Norwegian Quality Standards. The input of persistent organochlorine pollutants into the bottom sediments of the studied lakes is presumably associated with long-range transport from various sources located in low/temperate latitudes and nearby regions.

Assessment of the toxic effects of the herbicides atrazine and glyphosate on the phytoplankton community of the Black Sea

2025-07-31T21:38:28+08:00

The impact of glyphosate and atrazine herbicides on the growth and photosynthetic activity of the Black Sea phytoplankton community in spring was assessed. It has been shown that atrazine is more toxic to phytoplankton than glyphosate. The size structure of the phytoplankton community is an important factor determining its sensitivity to herbicide exposure. Pico-phytoplankton is more sensitive to pollutants than micro-nano-phytoplankton. Atrazine inhibits phytoplankton growth after 24 hours of exposure, with the greatest negative impact on pico-phytoplankton (EC₅₀=16 μg/L). Micro-nano-phytoplankton exhibits high resistance to atrazine (EC₅₀=22-32 μg/L). Unlike atrazine, glyphosate has a delayed effect on microalgae. For micro-nano-phytoplankton, the effect of glyphosate exposure is observed after 4 days. Pico-phytoplankton reacts quickly to glyphosate: on the 3 day at 50 μg/L, a twofold decrease in abundance was recorded. The use of pico-phytoplankton as a bioindicator for monitoring aquatic ecosystems and fluorescence parameters as early stress markers is recommended. Safe concentrations of atrazine and glyphosate for aquatic ecosystems do not exceed 5 and 10 μg/L, respectively.

Spatial distribution of zooplankton communities in the littoral zone in small lakes of Nizhny Novgorod Region (European Russia)

2025-07-29T02:37:06+08:00

Aquatic macrophytes in the littoral zone of lakes act as a powerful environmental factor, shaping the spatial distribution of aquatic organisms. The study examined the distribution patterns of zooplankton communities across the transverse profile of macrophyte beds in the littoral zone of small lakes in the Nizhny Novgorod region. It was found that in the studied biotopes, macrophyte beds altered several water parameters and created their gradient. The analysis revealed that, from the shoreline helophyte and mixed vegetation toward the open water, zooplankton communities exhibited a gradual shift in dominant and subdominant species, a decrease in the proportion of cladocerans, and an increase in rotifers. The type of biotope had the greatest influence on the species structure of zooplankton communities. The study also analyzed the preference of certain zooplankton species for macrophyte beds of different life forms. A decline in species richness and zooplankton biomass was observed at the edge of vegetation near the open water. It was concluded that the succession of plants from different ecological groups along the transverse profile of the macrophyte zone drives changes in environmental factors and planktonic invertebrate communities in an ecocline-like manner.

Genetic structure of an amphipod species Eulimnogammarus (Philolimnogammarus) marituji Bazikalova, 1945 in the Lake Baikal basin

2025-07-18T10:58:33+08:00

Hundreds of Baikal amphipod species form a so-called species flock, and Eulimnogammarus (Philolimnogammarus) marituji Bazikalova, 1945 is one of the most widespread representatives of this group in the southern part of Lake Baikal. Despite this, nothing is known about the genetic structure of this species. In this study, we identified three genetic lineages of E. marituji based on the sequences of a mitochondrial gene cytochrome c oxidase subunit I (COI) and a nuclear gene 18S rRNA. We designated these lineages as the southern (S), western (W) and central (C) lineages. While the three lineages are geographically separated in Baikal, they are mixed in the Angara and Yenisey rivers. The age of the last common ancestor is estimated at 3.6 million years ago. We also observed first-and second-generation hybrids, which at the moment prevents us from considering these lineages as separate biological species. In addition, based on the literature and our observations, we hypothesise that the previous findings of a distinct species Eulimnogammarus (Philolimnogammarus) viridis (Dybowsky, 1874) in the Yenisey River should be attributed to E. marituji.

The role of extreme environmental factors in mass fish mortality: a case study of reservoirs in Belarus

2025-07-31T14:57:24+08:00

The article examines the cases of mass death of fish in the reservoirs of Belarus, occurring without an obvious reason. Possible abiotic and biotic factors are analyzed, including oxygen deficiency, the “blooming” of water by blue-green algae, parasitic and infectious diseases, as well as the hydrochemical characteristics of the aquatic environment. The need for comprehensive and long-term monitoring is emphasized in order to identify the true causes of death and develop effective measures to reduce the negative impact on the ichthyofauna. Based on the collected data, an approach is proposed for assessing and minimizing environmental risks for fish populations.

The effect of short-term exposure to water extract of phycobiliproteins on adult Pacific oysters (Magallana gigas)

2025-07-30T20:19:57+08:00

In the context of the rapid development of Russian aquaculture for bivalve mollusks in the 21st century, it has become crucial to develop technologies that aim to minimize stress levels and enhance the resistance of oysters against diseases and parasitic infections in hatcheries. This research investigated the effect of an aqueous extract of phycobiliproteins (CBP), derived from the blue-green alga Spirulina platensis, at concentrations ranging from 2 to 200 μg/mL on adult Pacific oysters (Magallana gigas) for 24-48 hours. Using flow cytometry, we assessed the cellular composition of oyster hemolymph, apoptosis induction in hemocytes, and their metabolic activity. Furthermore, oyster mortality and respiratory activity have been evaluated throughout the experiment. The findings revealed that the highest extract concentration (200 μg/ml) decreased hemocyte metabolic activity and reduced the relative proportion of granulocytes within the oyster hemolymph. At the same time, there was no significant difference in the proportion of apoptotic hemocytes between the experimental and control groups. The survival rate of mollusks in the experiment was 100%, indicating that the extract may be relatively safe for these organisms. These findings suggest that the extract could be used as a basis for the development of functional feeds based on spirulina derivatives, which could increase resistance and reduce stress in oysters during cultivation in aquaculture nurseries.

Structure and seasonal dynamics of phytoplankton of the Kizhi Island area of Lake Onego

2025-02-11T21:15:19+08:00

An investigation into the phytoplankton condition in the area of Kizhi skerries of Lake Onego during the spring, summer and autumn of 2023 revealed a high level of microalgae development. The quantitative indicators of the phytocenosis characterise this area of Lake Onego as mesotrophic. The classification of the water type in the Kizhi skerries area of Lake Onego is determined by the indicator values of phytoplankton found during the study period and their quantitative development. The water type is thus classified as a β-mesosaprobic pollution zone with water quality class 3, i.e. satisfactorily clean. The most significant increase in quantitative development was observed during the spring and autumn periods, with diatoms and cyanobacteria being the dominant phytoplankton species. In contrast, during the summer months, cyanobacteria, along with golden and green algae, were the primary components of the phytoplankton community. Furthermore, silicon concentrations was decreased from spring to autumn that was caused by increasing ofabudance and biomass of diatom algae. At the same time, lower values in the ratio of общal nitrogen to total phosphorus can be applied as indicator of active production of cyanobacteria. The intensive vegetation of phytoplankton in the Kizhi Island area is related to the area’s natural conditions.

Correlation between body length and habitat depth in endemic amphipods of Lake Baikal

2025-04-07T23:34:29+08:00

Amphipods (Crustacea, Amphipoda) are among the most ancient and taxonomically diverse invertebrate groups in Lake Baikal, comprising over 350 morphological species and subspecies. This group of Baikal endemics has remarkably divergent morphological features and occupies various biotopes and depths of the lake (from shallow waters to the deepest zones). This study examines the relationship between maximum body length and habitat depth in Baikal amphipods. The analysis of the literature data has shown that most species have a body length that does not exceed 40 mm. Amphipod species are unevenly distributed by depth, with most of them inhabiting the littoral (0 – 20 m) and sublittoral (20 – 70 m) zones. We show that both dwarf forms of Baikal amphipods (body length < 5 mm) and giant forms (body length > 50 mm) occupy deep-water zones of Lake Baikal, but the dwarf forms mainly inhabit the littoral and sublittoral zones. Statistical analysis revealed a moderate positive correlation between amphipod body length and habitat depth. The removal of the parasitic genus Pachyschesis (Bazikalova, 1945) from the dataset led to an increase in the correlation strength.

Accumulation of microplastics and anthropogenic fibers in natural populations of blood-sucking mosquitoes of the genus Aedes in the environs of Tomsk (Western Siberia, Russia)

2025-08-03T23:56:00+08:00

The content of microplastics (MPs) was monitored in natural populations of blood-sucking mosquitoes of the genus Aedes (Meigen, 1818) at different mosquito life cycle stages in the environs of Tomsk (Western Siberia, Russia) across various biotopes (meadow swamps, forest bogs, sphagnum bogs) for three years (2021–2023). A total of 990 mosquitoes were analyzed for MP content. The detected MPs varied in shape and size, ranging from 0.1 to 1 mm. The average number of MPs per mosquito individual increased from 0.012 ± 0.003 in 2021 to 0.191 ± 0.087 in 2023. The MP content increased from larval stage I to larval stage III, decreased at stage IV, and then decreased at pupal and imago stages. The highest MP content was recorded in mosquitoes from sphagnum bogs, while the lowest one was found in insects from meadow swamps. No statistically significant differences were revealed across biotopes. Black fragments and fibers <0.5 mm in size were predominant. The analysis revealed a general trend in which the number of MPs increases annually, particularly small black fragments (tire and road wear particles). This increase may be attributed to the proximity of roads that contribute to MP pollution in nearby water bodies, as well as degradation of synthetic textiles resulting in the release of MPs and anthropogenic fibers via sewage effluents. The obtained data indicate a wide distribution of MPs in natural populations of Aedes mosquitoes and confirm the urgent need for further research into the effect of MPs on their biology and the role of these insects as pollution indicators.

Features of sulfate reduction by groundwater microbial complexes

2025-06-27T10:26:54+08:00

Sulfate reduction is an important biogeochemical process in underground aquifers. The presence of hydrogen sulfide in the environment is a marker of the destruction of organic matter in anoxic conditions and the activation of microbiological processes. Research into the nature of interaction between surface and groundwater is relevant for assessing the sanitary and hygienic indicators of drinking water. The paper describes the results of determining the content of organic matter, hydrogen sulfide and the abundance of sulfate-reducing bacteria in groundwater of the riverbank filtration zone. It has been established that the activity of sulfate reduction processes in groundwater varies significantly in space and time. The maximum number of sulfate-reducing bacteria was accompanied by active formation of hydrogen sulfide in the aquifer after spring snowmelt at a depth of 45 m in wells located at a distance of 1500 m from the riverbank. At a distance of 50 m from the riverbank, the quality of groundwater changes significantly in the upper aquifer in the summer-autumn period, especially after floods.

Diatom from the Late Holocene bottom sediments of Peyungda and Zapovednoye Lakes (Evenkia, Russia)

2025-08-02T15:21:11+08:00

As part of a biostratigraphic study in the taiga zone of southern Evenkia (Krasnoyarsk Territory, Russia) within the territory of the state nature reserve “Tungussky,” aimed at reconstructing paleoecological conditions of the region and as a continuation of comprehensive research on diatoms communities in the bottom sediments of various water bodies across the country initiated by diatomologists back in the first half of the last century in the USSR, an analysis was conducted of Late Holocene bottom sediments of Peyungda and Zapovednoye lakes. In total, 248 taxa below genus rank were identified belonging to 66 genera and 27 families. Similarities and differences in the composition of the diatom community in lake-bottom sediments of Lake Zapovednoye and Lake Peyungda have been revealed. The degree of similarity in species composition turned out to be high — 69%. Common trends in the development of these lakes corresponding to identical time frames have also been observed. In Lake Peyungda, which spans nearly 4,500 years, evidence has been found for the beginning of the Meghalayan stage of the Holocene epoch associated with the onset of prolonged drought approximately in 2250 BP through sustained increases in the abundance of thermophilous species such as stagnant-streaming waters Aulacoseira ambigua (Grunow) Simonsen and stagnant water specie Discostella stelligera (Cleve & Grunow) Houk & Klee.

Polyunsaturated long-chain alkenones in bottom sediments of the meromictic Lake Shira (southern Siberia) as a paleo-indicator of climate change

2025-07-31T19:57:23+08:00

To understand long-term climate variability and its connection with modern global warming, this study analyzed the composition of long-chain alkenones in the bottom sediments of Lake Shira (North-Minusinsk valley) over the past 3000 years. In the ICE2023, Shira-I-21 and Shira-II-21 cores, gas chromatography-mass spectrometry revealed methyl- and ethyl-alkenones, predominantly C₃₇ and C₃₈, with double bonds ranging from two to four. The vertical profiles show substantial fluctuations in total concentration (1-355 µg/g), likely associated with changes in water level, salinity, and organic matter preservation conditions. Alkenone peaks coincide with light (carbonate-rich) layers, reflecting phases of lake level decline and increased salinity. Elevated alkenone concentrations in the clay-rich sections of the core may indicate enhanced adsorption and preservation. The results confirm the potential of long-chain alkenones as a proxy for paleo-salinity and, consequently, paleo-humidity in arid regions of Siberia.

Heavy metal-driven changes in the exometabolite profile of Bacillus velezensis S18

2025-08-01T22:43:40+08:00

Anthropogenic heavy metal contamination of aquatic ecosystems results in the toxic effects on microorganisms and the disruption of microbial community structures. To adapt to toxic stress, microorganisms employ various detoxification mechanisms, one of which is the biosynthesis of siderophores. In this study, we analyzed the changes in the exometabolite profile of the Bacillus velezensis S18 strain grown in the presence of different concentrations of heavy metals. It was demonstrated that salts of CoCl₂×6H₂O, AlCl₃, ZnSO₄, MnSO₄, NiSO₄×7H₂O, FeCl₃×6H₂O, CuSO₄×5H₂O and GaBr₃ significantly reduced the production of catecholate and hydroxamate-type siderophores, with complete inhibition observed in the presence of Ni²⁺, Fe³⁺, and Cu²⁺. HPLC profiling of exometabolites was performed, and their iron-chelating activity was evaluated using the CAS assay. These findings highlight the potential application of the B. velezensis S18 strain in bioremediation processes and the synthesis of broad-spectrum biochelators.

Coastal-aquatic vegetation of the freshwater Curonian Lagoon and opportunities for its economic use

2025-08-01T22:59:10+08:00

The Curonian Lagoon is a large lagoon with predominantly freshwater conditions, where coastal-aquatic vegetation develops intensively. Phragmites australis dominates in the coastal zone, forming a biomass exceeding 1000 g/m², as well as Scirpus lacustris. Maximum of biomass is in August-September. Its potential use should be balanced with environmental measures. Negative impact on bird nesting, fish spawning can be minimized by harvesting during the winter season. After the completion of the growing season, the dry mass of aboveground shoots of Ph. australis, unlike other species, exhibits minimal reduction, allowing it to be used as a useful renewable resource (building material, fuel, etc.). Appropriate harvesting techniques during the winter period (e.g., cluster mowing) and the utilization of reeds forming dense stands in the coastal zone, beyond addressing economic objectives, will facilitate the preservation of biotopes and enhance habitat conditions in coastal areas (e.g., fishery amelioration).

Population characteristics of freshwater bream Abramis brama in the Novosibirsk reservoir (Western Siberia) 60 years after introduction

2025-07-02T17:44:18+08:00

Freshwater bream Abramis brama is the most successful alien fish species in the Ob basin. It was introduced into the Novosibirsk Reservoir immediately after the formation of the reservoir, in the late 1950s. It quickly became numerous, and since the 1990s it has accounted for up to 90% of fish catches. Over the 60 years since the introduction of the species, its population characteristics have changed. The lifespan of fish has increased to 16 years, while their size characteristics have decreased, especially in older individuals (weight by an average of 19%), which may be due to the increased number of the alien mollusk Viviparus viviparus, which worsens feeding conditions. The largest bream recorded in the Novosibirsk Reservoir had a commercial length of 57 cm and a weight of 5540 g. Compared to the first years, bream began to reach sexual maturity at an older age, but with a similar standard length and weight of individuals. The onset of spawning is noted at a water temperature of 8 ° C and, compared to previous periods, has shifted to an earlier date (the first ten days of May), which is obviously caused by an increase in the temperature background in the region. Bream fecundity has significantly decreased, which may be due to the known effect of fish density on their fecundity, and at present individual absolute fecundity ranges from 76.8 to 385.1 thousand eggs (an average of 187.85 thousand), and relative - from 103 to 269 eggs (an average of 166). Absolute fecundity is closely related to the body weight of females (r = 0.852). At present, the population characteristics of bream, reflecting the life strategies of fish, are generally close to the parameters of the populations of this species from the central part of its native range.

Methods of hydrophysical measurements at autonomous stations in shallow lakes during the ice-covered period

2025-07-31T21:02:07+08:00

The article provides a brief description of some methods of hydrophysical measurements at autonomous stations in shallow lakes during the ice-covered period. These methods were designed based on 30 years of experience. Long-term records of solar radiation fluxes on the lake surface and at several depths inside the water column help identify patterns in the evolution of the snow-and-ice cover optical properties and water such as the albedo, and extinction coefficient (weakening) of the solar radiation fluxes in snow, white and black ice and water. Long-term measurements of water temperature by sensors distributed throughout the water column can be used to determine the start dates and duration of the annual thermal cycle stages, calculate the stability parameters of the water column, and characterize the mixing regime of lakes. Long-term measurements with dissolved oxygen sensors allow studying the daily, synoptic, seasonal and interannual variability of oxygen conditions in lakes in order to estimate the duration and severity of oxygen deficiency periods. Temperature measurements by sensors frozen into ice or positioned in water under ice allow estimating the heat flux at the water-ice interface and calculating the rate of black ice growth. An “Autonomous device for measuring the temperature profile in the bottom layers of water and soil” is used to study the dynamics of the heat flux at the water-sediment interface during the winter, including the poorly studied periods of ice formation and destruction. Measurements with current profilers are used to estimate the turbulence parameters of the mixed/stratified layers of ice-covered lakes in diurnal and synoptic cycles. The results of calculating the energy parameters (basic potential energy, buoyancy flux) of the water column of a small ice-covered lake are given to showcase the application of methods for measuring water temperature and solar radiation fluxes and assessing the mixing efficiency in the study of radiation-driven convection in ice-covered lakes.

Influence of anthropogenic activity on the quality of rivers in Listvyanka settlement (South Baikal)

2025-08-12T16:24:01+08:00

This paper presents the results of microbiological studies of the water quality of four tributaries of Southern Baikal, Listvenichny Bay. Monthly monitoring from October 2022 to July 2025 showed a decline in the water quality and an increase in the number of sanitary-indicative groups of microorganisms in the estuary part of rivers relative to the reference area above the influence of Listvyanka settlement. Thus, the number of coliform bacteria (CB) on average in rivers increases by 17 times, E. coli – by 55 times, and enterococci – by 11 times. In recent years, the water quality in the Malaya and Bolshaya Cheremshanka Rivers remains low. Thus, in comparison to the study of 2015-2016, the maximum values of enterococci abundance increased by 3 times, the number of E. coli - by 2 times and 23 times, respectively.

Studying the Genetic Potential of Cytobacillus pseudoceanisediminis from a Deep Subsurface Mineral Spring for the Synthesis of Biologically Active Substances

2025-07-29T14:29:52+08:00

Microorganisms are fundamental to global ecosystem functioning, playing crucial roles in biogeochemical cycles and producing diverse bioactive secondary metabolites. Extremophiles are promising sources of novel metabolites due to their adaptations to harsh environments. This study investigated the biosynthetic potential of the thermophilic, heavy metal-resistant bacterium Cytobacillus pseudoceanisediminis BNOᵀ, isolated from a deep subsurface mineral spring. Genomic analysis identified six biosynthetic gene clusters (BGCs): terpene-precursor, type III polyketide synthase (T3PKS), azole-containing RiPP-terpene, terpene, nonribosomal peptide synthetase (NRPS), and NRPS-independent (NI) siderophore. Comparative analysis revealed high homology (>95% identity) for five BGCs (T3PKS, RiPP-terpene, terpene, NRPS, NI-siderophore) with the marine sediment strain C. pseudoceanisediminis 2691 and related Cytobacillus species, indicating evolutionary conservation within the genus. The terpene-precursor cluster showed low homology (52.3% identity for core genes) and matched non-Cytobacillus species, suggesting potential horizontal gene transfer. Transcriptomic analysis under standard laboratory conditions (LB medium, 37°C) revealed constitutive expression (>90% of genes) for all BGCs except the NI-siderophore cluster (51.7% genes expressed). This constitutive expression suggests the basal importance of these metabolites for physiology or pre-adaptation to the native stressful environment and facilitates potential biotechnological exploitation. The presence of NRPS and siderophore clusters correlates with the strain’s exceptional heavy metal resistance. This study highlights C. pseudoceanisediminis BNOᵀ as a source of conserved and potentially novel BGCs, with significant biotechnological potential, particularly for bioremediation. Future work should characterize the metabolites produced and investigate BGC expression under stress conditions.

Hydrochemical and hydrobiological investigations of the Upper Angara R. and of its tributaries

2025-08-11T23:04:51+08:00

We have presented the results of hydrochemical and hydrobiological investigations performed in the Upper Angara R. basin and at North Baikal tributaries. A 4-fold increase of mineralization in the Upper Angara R. water from sources to inflow was found out due to income of tributaries waters with a high mineralization. Compared to previous investigations, we registered enrichment of waters in the investigated water flows with trace elements. Increase of normative by copper, molybdenum, iron and manganese was registered in water of some rivers. Determination of microorganisms sanitary groups showed a trend to improvement of riverine waters quality.

Decapod fauna of the Chernaya River basin (Crimea)

2025-07-31T20:30:23+08:00

The results of hydrobiological studies of the Chernaya River basin are presented. The checklist of decapod crustaceans comprises 15 species from 12 families, with the majority (approximately 87 %) recorded in the estuarine section. A brief characterization of each species is provided. The decapod fauna is predominantly marine in origin (13 species), which is typical for estuarine zones. The native fauna of the Chernaya River is represented by only one species – the narrow-clawed crayfish Pontastacus leptodactylus. The current structure of the river system’s decapod fauna is shaped by the diversity and dynamics of environmental factors and human activities. One driver of increased species diversity is the introduction of non-native species. Four alien species were reliably documented, including two first records for the Chernaya River basin: the oriental shrimp Palaemon macrodactylus and marbled crayfish Procambarus fallax. The biological traits of these species suggest a high likelihood of successful naturalization in the region.

Possibilities of assessing the state of Lake Baikal surface water using Google Earth Engine

2025-08-01T07:28:21+08:00

The use of remote sensing (RS) data is associated with many difficulties that lead to high labor and computer resource costs. The use of cloud computing greatly simplifies this work. The aim of this study was to demonstrate the possibilities of Google Earth Engine (GEE) for assessing the state of Lake Baikal surface water. An overview of the datasets on the GEE platform was made. The available data processing algorithms were reviewed. It was noted that, in addition to standard methods of stationary processing of satellite images, the GEE platform offers quite complex machine learning methods. For example, Random Forest method significantly improves the accuracy of the results. In addition, the possibilities of constructing a composite from Sentinel-2, Landsat-8, MODIS satellite images, calculating spectral indices to determine the boundaries of water bodies, estimating surface temperature, chlorophyll-a concentration, Secchi disk transparency in selected areas of the water body are shown. It is necessary to control the accuracy of the data and compare it with field research data. The results of RS data processing can be used as additional material during monitoring the state of water bodies. Processing is carried out in the cloud using the JavaScript programming language. It is possible to create applications for interactive use. It is advisable to use GEE possibilities for operational monitoring and analysis of changes in water bodies based on large data sets available on the platform.

Chemical composition of various fractions of atmospheric aerosol in Southern Baikal region in 2024

2025-08-06T18:45:51+08:00

For the first time, comprehensive seasonal studies of the chemical composition of aerosol particles across size fractions of 0.8, 2.0, 5.0, and 10 μm were conducted at three atmospheric monitoring stations: in the industrial center of Southern Baikal region in Irkutsk and in the Central Ecological Zone of the western coast of Southern Baikal – at the Listvyanka and Bolshiye Koty stations. The research included analysis of particle morphology, size distribution, ionic and trace element composition, polycyclic aromatic hydrocarbons (PAHs), and soot content. Spatial and seasonal variations in atmospheric aerosol composition across the three stations were shown to result from combined anthropogenic and natural factors: industrial activity, meteorological conditions, forest fires, and transportation. Elevated concentrations of pollutants across various particle size fractions were detected during the arrival of air masses from northwestern and northern directions, regions characterized by the presence of industrial centers in Irkutsk Oblast and Krasnoyarsk Krai. The summer periods featured transport of impurities via air masses from the southern directions (Buryatia, Mongolia, Tuva and Kazakhstan).

Response of the Baikal littoral amphipod Eulimnogammarus cyaneus (Dybowsky, 1874) to warm and cold LED light of low intensities

2025-07-28T13:55:29+08:00

Light pollution is currently becoming widespread throughout the world and affects both individual organisms and ecosystems. It was shown that light with different spectral characteristics affects organisms differently. Lake Baikal is also subject to light pollution. Light pollution on the lake tends to increase due to the growth of tourist flow and infrastructure development. Therefore, in this work we decided to evaluate the reaction of the amphipod Eulimnogammarus cyaneus, which is widespread in the littoral of Lake Baikal, to artificial light of different spectral characteristics and intensities. In a series of experiments, individuals were given a choice between warm (with a color temperature of 3200 K) and cold (5600 K) lighting or darkness. In the experiments, the illumination level was set at 2 lx or 10 lx. As a result, we found that warm and cold light had an effect on the behavior of individuals compared to the control. However, we did not find any difference in the behavior of amphipods when comparing warm and cold lighting. Furthermore, no differences were found between the response of individuals under cold light with 2 lx and 10 lx. However, the intensity of warm light is important for amphipods. A weak light avoidance response (demonstrated by E. cyaneus) may increase the frequency of detection of individuals of this species by predators in areas of the littoral of Lake Baikal subject to light pollution.

Greenhouse gas fluxes (CH₄, CO₂) from the Kuibyshev Reservoir: an eddy covariance study

2025-08-02T03:14:27+08:00

The study presents the results of evaluating greenhouse gas fluxes (methane and carbon dioxide) from the surface of the Kuibyshev Reservoir (Russia) using the eddy covariance method along with the LI-7700 (CH₄) and LI-7200RS (CO₂/H₂O) gas analyzers. Measurements were conducted from August to December 2024 in a shallow section (2–4 m) of the reservoir within the water cluster of the Volga Carbon Polygon (Republic of Tatarstan, Russia). The results showed that the reservoir is a source of methane and carbon dioxide, with maximum emissions observed in August–September (52.84 ± 22.49 and 47.53 ± 27.06 mg CH₄ m^–2·day^–1; 2.32 ± 1.70 and 2.54 ± 1.75 g CO₂ m^–2·day^–1, respectively). At the same time, significant daily CO₂ uptake was also recorded in August–September, driven by the photosynthetic activity of phytoplankton. In autumn, alongside emission, occasional methane flux from the atmosphere into the water column was recorded. During winter, gas exchange was minimized due to the ice cover. Seasonal variability of the fluxes is determined by a combination of biological processes (methane production and oxidation, photosynthesis), physical factors (water temperature, concentration gradients, turbulent mixing), and meteorological conditions (wind impact, ice cover formation). The eddy covariance method enables continuous data collection with high temporal resolution and accounts for the spatial heterogeneity of the water surface. The obtained data are important for refining the contribution of reservoirs to the regional carbon balance and global carbon cycle and demonstrate the advantages of using the eddy covariance method in such studies.

Accumulation and release of elements during the decomposition of Myriophyllum spicatum L. biomass in the Yenisei River stretch subjected to human impacts

2025-07-30T15:02:02+08:00

An in-situ experiment was conducted within the limits of the city of Krasnoyarsk, at the dammed part of the Yenisei River, which is affected by the activities of a fish farm and water discharged by the thermal power plant. The aim of the experiment was to study possible secondary contamination of the aquatic ecosystem by heavy metals (HMs) and nutrients during decomposition of a submerged macrophyte – Myriophyllum spicatum L. The rate of decomposition of M. spicatum biomass was determined. Release and accumulation of macro elements and trace elements, including HMs, were studied using inductively coupled plasma atomic emission spectrometry (ICP–AES), and nitrogen and carbon were determined using high-temperature catalytic combustion. Throughout the experiment, Al, Be, Cu, Fe, Ga, Li, Mo, Ti, and V were accumulated in the decaying M. spicatum biomass, and In, K, Mg, Mn, Na, P, Pb, S, Tl, N, and C were released from it. The study showed that decomposition of M. spicatum biomass is a probable source of the secondary contamination of the ecosystem by HMs and nutrients (C, N, P).

Analysis of water surface changes in Arga Island (the Lena Delta), based on remote sensing data

2025-07-31T17:33:12+08:00

Recent climate change has led to an acceleration of permafrost melting in Arctic regions, causing significant landscape transformations through thermokarst processes. This study focuses on water surface dynamics in Arga Island (the Lena Delta), by analyzing satellite imagery from Sentinel-2 (2019-2024) and topographical data. We used a multi-method approach that combined median composite generation, spectral indices (MNDWI, NDVI, and Tasseled Cap), and supervised classification to quantify changes in water bodies and soil moisture. We also used the topographic position index (TPI), derived from the ArcticDEM data, to contextualize these changes within areas prone to thermokarst processes. The results indicate stable areas of water bodies over a six-year period with no significant changes in size (e.g., an area of 388 km² in depressions in 2019 versus 390 km² in 2024). However, an analysis of the MNDWI values between 2019 and 2024 has revealed localized moisture increases in upland areas, suggesting the emergence of thermokarst hotspots. These areas, which are characterized by positive TPI values and rising wetness indices, may represent early stages of degradation. Methodologically, the study demonstrates the effectiveness of cloud-based platforms, such as Google Earth Engine, for processing medium-resolution images. However, longer time series and higher resolution data are required to detect subtle trends. The use of spectral indices and topographic metrics in conjunction provides a reproducible framework for monitoring thermokarst activity in Arctic regions.

Aerosol pollution of the atmosphere at southeastern coast of Lake Baikal during of wildfires in Siberia

2025-07-30T19:54:42+08:00

Comprehensive studies of aerosol pollution in the atmosphere were conducted at “Boyarsky” scientific station from spring to autumn 2024. The results of expeditionary work revealed the impact of smoke aerosol on the air quality at “Boyarsky” station, transported from both western and eastern directions. The highest concentrations of aerosols PM_2.5 up to 42 µg/m³ and PM₁₀ up to 104.4 µg/m³ were recorded from July 31 to August 1, as well as on August 16 and 20, 2024, due to the transport of smoke aerosols from wildfire areas in the Irkutsk region, the Republic of Buryatia, and Yakutia. During the same study, measurements of the number concentration of submicron aerosol (SMA) were conducted. The measurement results showed that from August 16 to 24, 2024, the temporal variation in the number concentration of SMA mirrored the variation in the mass concentration of PM_2.5 and PM₁₀ aerosols at “Boyarsky” station. A sharp increase in the number concentration of submicron aerosol up to 150 cm⁻³ and the mass concentration of PM₁₀ up to 95 µg/m³ during daytime hours indicates the transport of smoke aerosol.

Assessment of Dissolved Heavy Metal Pollution and Ecological Risk in the Waters of Lake Kotokel (Eastern Cisbaikalia, Russia)

2025-08-01T20:20:39+08:00

Safeguarding the ecological integrity of aquatic ecosystems is a national priority. Lake Kotokel, one of the largest lakes in the Baikal region, is hydrologically connected to Lake Baikal through a system of channels and holds considerable socio-economic significance. This study presents the first detailed seasonal analysis of dissolved heavy metal (HM) concentrations in the lake. Their relative abundance followed the order: Fe > Mn > Zn > Ni > Cr > Cu > Pb > Cd. Clear patterns of seasonal dynamics and spatial distribution were identified. The highest concentrations of manganese, zinc, and copper occurred during the under-ice period, driven by mobilization from silty bottom sediments and groundwater. In contrast, during the open-water period, elevated concentrations of iron, chromium, and nickel were associated with meltwater and rainfall inputs, which transport weathering products of rocks and soil organic matter from the watershed into the lake. To investigate the relationships between HM concentrations and water parameters—including physicochemical characteristics, nutrient levels, chlorophyll-a (chl-a), and total organic carbon (TOC)—Spearman correlation and principal component analyses (PCA) were applied. The results demonstrated that seasonal variations in physicochemical conditions and the intensity of biological processes exert a decisive influence on HM dynamics. For the first time, HM pollution and the associated ecological risk were assessed for Lake Kotokel. The pollution indices—Heavy Metal Evaluation Index (HEI), Nemerov Pollution Index (NPI), as well as Ecological Risk Index (ERI) indicated that HM pollution originates primarily from natural sources, with iron and manganese as the dominant contributors. However, the detection of cadmium in isolated samples near settlements elevated the potential ecological risk for aquatic organisms, underscoring the need for continuous monitoring of local pollution sources.