Search Results (192)

The planktonic pteropod Limacina helicina is increasingly studied as a bioindicator of climate-driven changes in polar marine ecosystems. Although broadly distributed across the Arctic Basin and the North Pacific, its population structure and dispersal pathways remain poorly understood, especially in the Siberian Arctic. We analyzed mitochondrial COI sequences from populations sampled in the Barents, Kara, Laptev, East Siberian, and White Seas, as well as adjacent Pacific regions. Three major haplogroups (H1, H2, H3) were identified with distinct spatial patterns. H1 is widespread, occurring across the Pacific and most Arctic seas except the White Sea. H2 is confined to the western Arctic shelves (Barents–Kara–Laptev), and H3 is unique to the White Sea. We found a pronounced genetic discontinuity corresponding to hydrographic barriers, particularly the strong freshwater inflow from the Lena River, which restricts eastward dispersal of H2 from the Laptev to the East Siberian Sea. These patterns suggest postglacial expansions from geographically separated populations that survived the Last Glacial Maximum in isolated marine regions. The White Sea population is highly isolated and genetically distinct. Our results highlight how both glacial history and modern oceanography shape Arctic plankton diversity and define biogeographic boundaries in a rapidly changing climate. Full article

Under conditions of increasing anthropogenic load, aquatic ecosystems all over the world are undergoing a transformation, expressed in the growth of eutrophication, the overgrowing of water bodies with higher vegetation of macrophytes, cyanobacterial bloom, and the increased concentrations of different pollutants in these objects. In the region of Eastern Siberia that we studied, located in the middle reaches of the Lena River basin, there is the city of Yakutsk—the largest city in the world built in a permafrost region. Within the city and its surroundings, there are many small lakes (less than 1 km² in area) which over the past decades have been subject to varying degrees of pressure associated with human activity (nutrients and organic matter loads, urban landscape transformation). This study is the first to combine the metabolomic profiling of Potamogeton perfoliatus with microalgal bioindication to assess anthropogenic impacts in permafrost urban lakes, providing a novel framework for monitoring ecological resilience in extreme environments. We studied four lakes with varying degrees of anthropogenic pressure. Using a comprehensive assessment of the bioindicator properties of planktonic microalgae and the chemical parameters of water using statistical methods and principal component analysis (PCA), the lakes most susceptible to anthropogenic pressure were identified. Concentrations of pollutant elements in the tissues of the submerged macrophyte aquatic plant Potamogeton perfoliatus L., which inhabits all the lakes we studied, were estimated. Data on the content of pollutant elements in aquatic vegetation and the results of metabolomic analysis made it possible to identify the main sources of anthropogenic impact in the urbanized permafrost area. The pollution of water bodies with some key pollutants leads to Potamogeton perfoliatus’s metabolites decreasing, such as sucrose, monosaccharides (arabinose, mannose, fructose, glucose, galactose), organic acids (glyceric acid, malic acid, erythronic acid, fumaric acid, succinic acid, citric acid), fatty acids (linoleic and linolenic acids), myo-inositol, 4-coumaric acid, caffeic acid, rosmarinic acid, shikimic acid, and catechollactate, caused by pollution which may decrease the photosynthetic activity and worsen the sustainability of water ecosystems. Linkage was established between the accumulation of pollutants in plant tissues, the trophic status of the lake, and the percentage of eutrophic microalgae, which can be used in monitoring the anthropogenic load in the permafrost zone. Knowledge of the composition and concentration of secondary metabolites produced by macrophytes in permafrost lakes can be useful in organizing water resource management in terms of reducing the level of cyanobacterial blooms due to allelochemical compounds secreted by macrophytes. This new work makes possible the evaluation of the permafrost-zone small-lake anthropogenic load in the frame of a changing climate and the growing attention of the industry to Arctic resources. Full article

Fires significantly influence the ecosystems of Western Siberia’s forest–tundra zone. Namely, they alter soil processes, including the transformation of different forms of iron and the redistribution of carbon flows. Recent climate change, associated with increased fire frequency, has had a long-term effect on the Arctic and sub-Arctic soil systems. Iron plays a key role in stabilizing organic carbon through the sorption and coagulation processes, yet the long-term changes in iron’s fractional composition under post-fire conditions remain insufficiently studied. This research investigates the impact of natural fires on the transformation of iron forms (amorphous, crystalline, and mobile), as well as on the dynamics of organic carbon in soils within the northern boundary of the forest–tundra natural zone in Western Siberia, between the Pur and Taz rivers. In our study, we have relied on granulometric and chemical analyses, magnetic susceptibility measurements, and iron fraction extractions. Our findings reveal that in post-fire areas, the depth of the seasonally thawed layer increases, accompanied by changes in the thermal and water regimes. This leads to reduced organic carbon content, particularly in intermediate horizons (5–30 cm), and the transformation of amorphous iron into a crystalline form. Crystallization growth is confirmed by increased magnetic susceptibility. Our results highlight the dual role of iron compounds: they contribute to the long-term stabilization of organic carbon, as well as causing its accelerated mineralization by affecting redox conditions. This study is crucial for understanding the biogeochemical processes associated with climate change and increasing fire frequency. Full article

We conducted a helicopter survey in 2010 for cliff-nesting raptors along the Dalton Highway in northern Alaska. The study area extended from the Yukon River northward ~395 km through the Brooks Range to the Arctic Plain. We documented 55 occupied raptor nesting territories, including 25 Golden Eagle (Aquila chrysaetos), 11 Gyrfalcon (Falco rusticolus), and 10 Peregrine Falcon (Falco peregrinus) territories. We also recorded vacant stick nests and raptor perch sites on cliffs. We identified more occupied eagle territories and hundreds more vacant eagle stick nests than were previously known in the study area. The average number of Golden Eagle nestlings/nesting pairs at the time of the survey was 1.5 ± 0.6. The most productive Golden Eagle pairs were located in the northern part of the study area. The number of occupied eagle territories in 2010 is far fewer than the number of eagle stick nests we recorded. Our data indicate that the distribution of nesting eagles in the 2010 study area is different than in the past. Whether this reflects changes in eagle density; a response to availability of prey, climate change, human activities, or a combination of these; or some other factor warrants further investigation. Intensive surveys along the Dalton Highway in the 1970s found no occupied nests for Peregrine Falcons or Gyrfalcons but we found 10 and 11, respectively. Therefore, the Peregrine Falcon and Gyrfalcon nests we recorded in 2010 reflect an increase in the number of known nesting pairs there. Full article

Berthierine was found in a natrolite vein intersecting volcanogenic-sedimentary rocks on the slope of Mt. Quamdespakh in the upper reaches of the Suolwai River, Lovozero alkaline massif, Kola peninsula, Russian Arctic. The mineral occurs as well-formed translucent pyramidal crystals up to 250 μm in size. The chemical composition determined by electron microprobe analysis corresponds to the empirical formula ^VI(Fe²⁺_1.99Al_0.94Mg_0.03Mn_0.04)_Σ3.00[^IV(Si_1.15Al_0.85)_Σ2.00O₅] [(OH)_3.92O_0.08]_Σ4.00; the idealized formula is ^VI(Fe²⁺₂Al)[^IV(SiAl)O₅](OH)₄. The crystal-structure determination (the first detailed crystal-structure characterization of berthierine) shows that the Lovozero mineral is hexagonal, P6₃cm (a = 5.3903(4), c = 14.0146(10) Å, V = 352.64(6) ų, R₁ = 0.053 for 338 unique observed reflections), and corresponds to the 2H₁ polytype of serpentine-group minerals with 1:1 tetrahedral-octahedral layers. The unit cell contains two M₃[T₂O₅](OH)₄ layers (M = Fe²⁺,Al; T = Si,Al) stacked along the c axis. The calculations of information-based structural and topological complexity parameters indicate that berthierine is structurally and topologically simpler than its chlorite-group polymorph chamosite. Since berthierine usually crystallizes metastably in the stability field of chamosite, the complexity analysis is agreement with the Goldsmith rule that states that, in Ostwald sequences of crystallization, metastable phases are simpler and more disordered than their stable counterparts. This observation can be applied to a general case of the metastable formation of serpentine-group minerals prior to the crystallization of chlorites. Full article

This article presents the findings of a comprehensive statistical analysis based on one of the largest and most up-to-date datasets on average monthly water temperatures at 286 hydrological stations from 1961 to 2021. Through this analysis, a detailed examination of the factors influencing temperature formation in different landscape-diverse regions in the Russian Arctic has been conducted. It has been determined that air temperature plays a crucial role in determining water temperature, although its influence is constrained by geographical factors, primarily geographical latitude. An analysis of discontinuities in uniformity and the presence of trends was carried out, along with a regression analysis of the relationships between air and water temperatures. The results of estimating changes in river water temperature were simultaneously compared both with respect to generally accepted climatic periods (1961–1990 and 1991–2020) and with respect to revealed change point years. The results of the statistical analysis indicate a relatively slow increase in water temperature in the Arctic rivers of Russia over the past 60 years, by 0.11–0.74 K/decade. These changes are mainly due to changes in air temperature (about 70% of cases), which in turn are influenced by the altitude of the location of the objects and other local factors. Full article

The multiphase components of natural ice contain gas, ice, unfrozen water, sediment and brine. X-ray computed tomography (CT) analysis of ice multiphase components has the advantage of high precision, non-destructiveness and visualization; however, it is limited by the segmentation thresholds. Due to the proximity of the CT value ranges of gas, ice, unfrozen water, sediment and brine within the samples, there is uncertainty in the artificial determination of the CT image segmentation thresholds, as well as unsuitability of the global threshold segmentation methods. In order to improve the accuracy of multi-threshold segmentation in CT images, a CT system was used to scan the Yellow River ice, the Wuliangsuhai lake ice and the Arctic sea ice. The threshold ranges of multiphase components within the ice were determined by watershed algorithm to construct a high-precision three-dimensional ice model. The results indicated that CT combined with watershed algorithm was an efficient and non-destructive method for obtaining microscopic information within ice, which accurately segmented the ice into multiphase components such as gas, ice, unfrozen water, sediment, and brine. The gas CT values of the Yellow River ice, the Wuliangsuhai lake ice and the Arctic sea ice ranged from −1024 Hu~−107 Hu, −1024 Hu~−103 Hu, and −1024 Hu~−160 Hu, respectively. The ice CT values of the Yellow River ice, the Wuliangsuhai lake ice and the Arctic sea ice ranged from −103 Hu~−50 Hu, −100 Hu~−38 Hu, −153 Hu~−51 Hu. The unfrozen water CT values of the Yellow River ice and the Wuliangsuhai lake ice ranged from −8 Hu~18 Hu, −8 Hu~13 Hu. The sediment CT values of the Yellow River ice and the Wuliangsuhai lake ice ranged from 20 Hu~3071 Hu, 20 Hu~3071 Hu, and the brine CT values of the Arctic sea ice ranged from −6 Hu~3071 Hu. The errors between the three-dimensional ice model divided by threshold ranges and measured sediment content were less than 0.003 g/cm³, which verified the high accuracy of the established microscopic model. It provided a scientific basis for ice engineering, ice remote sensing, and ice disaster prevention. Full article

Planktonic unicellular cyanobacteria are the dominant biomass producers and carbon fixers in the global ocean ecosystem, but they are not abundant in polar seawater. The interseasonal dynamics of picocyanobacterial (PC) abundance, picophytoplankton primary production, and phylogenetic diversity of PC Synechococcus were studied in the sub-Arctic White Sea. The PC abundance varied from 0.2–0.3 × 10⁶ cells/L in February to 5.2–16.7 × 10⁶ cells/L in July. Picophytoplankton primary production ranged from 0.22 mg C/m³ per day in winter to 11.32 mg C/m³ per day in summer. Synechococcus abundance positively correlated with water temperature and river discharge that increased in recent years in the White Sea. Phylogenetic analysis of the 16S rRNA gene and ITS region clone libraries from the White Sea and Barents Sea eDNA revealed picocyanobacterial sequences related to marine Synechococcus subclusters 5.1-I, 5.I-IV, 5.2, and 5.3. All Synechococcus S5.1-I were common in the White and Barents seas and were consistently present in the picophytoplankton composition throughout the year. Synechococcus S5.2 and S5.3 appear in the PC community in summer, suggesting their river origin, and Synechococcus S5.1-IV inhabits only the Barents Sea and was not detected in the White Sea. A unique Synechococcus phylotype was revealed. It is expected that the increase in the abundance of PC and their increasing role in ecosystem functioning, as well as the enrichment of the species composition with new phylotypes in the semi-enclosed sub-Arctic White Sea, which is vulnerable to the effects of climate change, will be characteristic of all Arctic seas in general. Full article

The Arctic river basins, among the most sensitive regions to climate warming, are experiencing rapid temperature rise and permafrost thawing that profoundly affect their hydrological and hydrochemical systems. However, our understanding of chemical export from Arctic basins to oceans remains limited due to scarce data, particularly in permafrost-dominated regions. This study examines the spatiotemporal variations and seasonal dynamics of major ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, SO₄²⁻) and dissolved organic carbon (DOC) concentrations across three river basins with varying permafrost extents: the Severnaya Dvina (2006–2008, 2012–2014), the Pechora (2016–2019) and the Taz Rivers (2016–2020). All the data were sourced from published Chemical Geological researches and were taken from Mendeley and PANGAEA datasets. Our results showed that DOC concentrations ranged from 1.75 to 26.40 mg/L, with the Severnaya Dvina River exhibiting the highest levels of DOC concentrations, alongside significantly elevated ion concentrations compared to the other two basins. A positive correlation was observed between DOC concentrations and river discharge, with peaks during the spring flood and summer baseflow due to leaching processes. The Severnaya Dvina and Pechora Rivers exhibited the highest DOC values during the spring flood, reaching 26.40 mg/L and 8.07 mg/L, respectively. In contrast, the Taz River had the highest runoff during the spring flood season, but the DOC concentration reached its highest value of 11.69 mg/L in the summer. Specifically, a 1% increase in river discharge corresponded to a 1.25% rise in DOC concentrations in the Severnaya Dvina River and a 1.04% increase in the Pechora River, while there was no significant correlation between runoff and DOC concentrations in the Taz River. Major ion concentrations demonstrated a negative correlation with river discharge, remaining relatively high during winter low-flow period. A robust power-law relationship between river discharge and concentration of DOC and major ions was observed, with distinct variations across the three river basins depending on permafrost extent. The Pechora and Taz Rivers, characterized by extensive permafrost, exhibited increasing trends in river discharge and DOC concentrations, accompanied by decreasing major ion concentrations, whereas the non-permafrost-dominated Severnaya Dvina River basin showed the opposite pattern. The Taz River, with the most extensive permafrost, also displayed a delayed DOC peak and more complex seasonal ion concentration patterns. These findings highlight the importance of varying permafrost extents and their implications for water quality and environmental protection in these vulnerable regions. Full article

Pasvik State Nature Reserve is situated in the Arctic zone and its chrysophyte flora is poorly studied. The diversity of the golden-brown algae (chrysophytes) from the Paz river, as well as the peat-bog on its bank, has been investigated using light and scanning electron microscopy. Overall, 34 chrysophyte taxa have been recorded. They represent fifteen genera from five orders. A new species of Synura, S. skaloudiorum, has been described. Morphologically, it resembles S. hibernica, a species restricted in its distribution to Ireland and Newfoundland, but differs mainly in size and structure of the apical scales. Nomenclatural issues on the selected chrysophyte taxa are discussed. The name Kephyrion starmachii was invalidly published, and it was validated. The new nomenclatural combination Chrysothecopsis tubulosus has been proposed. Also, Dinobryon sertularia var. annulatum Shi and Wei has been synonymized with D. annulatum Hilliard and Asmund. Full article

The results of studies on the content of aluminum and heavy metals in benthic sediments and algae in the estuaries of the Arctic island Vaygach are presented. This island is located on the Barents and Kara Sea border, and it is part of the Pay-Khoi ridge which can be called a “continuation” of the Ural Mountains to the north. The observations were conducted in Krasnaya and Varkulyakha Rivers located in the island’s southern part and flow into the Yugorsky Shar Strait. Krasnaya River is located near a polymetallic ore deposit, which was developed in 1931–1934. Reconnaissance fieldwork was carried out in the river estuaries through measurements of salinity and water level. Measurements of the mass concentration of elements in the studied samples of sediments and algae were carried out by atomic emission spectrometry. The preparation of plant samples was by microwave decomposition, and that for samples of bottom sediments was carried out by acid decomposition in an open manner. The obtained concentration samples were compared using “Tukey exploratory data analysis (EDA)”. The presence of anomalies in the high content of copper, manganese, and zinc in filamentous algae at the control site in the Krasnaya River estuary was revealed. For some elements, the enrichment index was calculated relative to the upper part of the earth’s crust content. It is assumed that the occurrence of this situation is due to the long-term consequences of mining polymetallic ores. The accumulation of metals in river estuaries may be related to the observed warming of the climate in the western sector of the Arctic region. Full article

In recent years, extreme climate events have shown to be occurring more frequently. As a highly populated area in central China, the Jialing River Basin (JRB) should be more deeply explored for its patterns and associations with climatic factors. In this study, based on the daily precipitation and atmospheric temperature datasets from 29 meteorological stations in JRB and its vicinity from 1960 to 2020, 10 extreme indices (6 extreme precipitation indices and 4 extreme temperature indices) were calculated. The spatial and temporal variations of extreme precipitation and atmospheric temperature were analyzed using Mann–Kendall analysis, to explore the correlation between the atmospheric circulation patterns and extreme indices from linear and nonlinear perspectives via Pearson correlation analysis and wavelet coherence analysis (WTC), respectively. Results revealed that among the six selected extreme precipitation indices, the Continuous Dry Days (CDD) and Continuous Wetness Days (CWD) showed a decreasing trend, and the extreme precipitation tended to be shorter in calendar time, while the other four extreme precipitation indices showed an increasing trend, and the intensity of precipitation and rainfall in the JRB were frequent. As for the four extreme temperature indices, except for TN10p, which showed a significant decreasing trend, the other three indices showed a significant increasing trend, and the number of low-temperature days in JRB decreased significantly, the duration of high temperature increased, and the basin was warming continuously. Spatially, the spatial variation of extreme precipitation indices is more obvious, with decreasing stations mostly located in the western and northern regions, and increasing stations mostly located in the southern and northeastern regions, which makes the precipitation more regionalized. Linearly, most of the stations in the extreme atmospheric temperature index, except TN10p, show an increasing trend and the significance is more obvious. Except for the Southern Oscillation Index (SOI), other atmospheric circulation patterns have linear correlations with the extreme indices, and the Arctic Oscillation (AO) has the strongest significance with the CDD. Nonlinearly, NINO3.4, Pacific Decadal Oscillation (PDO), and SOI are not the main circulation patterns dominating the changes of TN90p, and average daily precipitation intensity (SDII), maximum daily precipitation amount (RX1day), and maximum precipitation in 5 days (Rx5day) were most clearly associated with atmospheric circulation patterns. This also confirms that atmospheric circulation patterns and climate tend not to have a single linear relationship, but are governed by more complex response mechanisms. This study aims to help the relevant decision-making authorities to cope with the more frequent extreme climate events in JRB, and also provides a reference for predicting flood, drought and waterlogging risks. Full article

Microplastic pollution is a pervasive issue, with remarkably high concentrations observed even in the most remote locations such as Arctic sea ice and snow. The reason for such large microplastic abundances in sea ice is still speculative and applies mainly to saline or freshwater conditions. In this study, we investigated seasonal ice core samples collected in March 2021 from the northern Baltic Sea (Gulf of Bothnia) for their microplastic distributions. The Baltic Sea is characterized by low salinity and can be ice-covered for up to six months annually. Microplastics were analyzed in the melted ice samples using an adsorption technique and Raman microscopy to identify their abundances, colors, shapes, and sizes to calculate their masses. Due to the strong dynamic of the ice layer and the repeated melting and freezing processes during the ice formation, no discernible trends in microplastic abundances, masses, or polymer types were observed throughout the ice core length. The average microplastic abundance (±SD) in the Baltic Sea ice was determined to be 22.3 ± 8.6 N L⁻¹, with 64.9% of the particles exhibiting a particulate shape and 35.1% having a fibrous shape. The most prevalent polymer type was polyethylene terephthalate (PET), accounting for 44.4% of all polymers. This is likely due to the high proportion of PET fibers (93.8%). The majority of particle-shaped microplastics were identified as polyethylene (PE; 37.2%), followed by PET (17.2%), polyvinyl chloride (PVC; 15.9%), and polypropylene (PP; 15.9%). No correlations were found between microplastic concentrations and proximity to land, cities, industries, or rivers, except for PP mass concentrations and particle sizes, which correlated with distances to industries in Luleå, Sweden. Full article

Over the past few decades, climate warming has driven alterations in both the discharge volume and biogeochemical composition of Arctic riverine fluxes. This study investigated the content of macro- and microelements in the lower reaches of the Ob River (western Siberia). Seasonal sampling was performed over a four-year period (2020–2023) during the main hydrological seasons (winter low water, spring-summer floods, and early fall low water) at three river stations. The results revealed significant seasonal variations in the elemental content of the Ob River water associated with changes in catchment inputs, physical and chemical conditions of the aquatic environment, and the amount and composition of incoming suspended sediment. During high water flow events in the Ob River, the concentration of suspended solids increased substantially. During the winter period when the Ob River was ice-covered, a two- to three-fold rise was observed in the concentration of Na, Mg, Ca, K, Si, and Mn. Having accounted for these seasonal variations in water chemistry, we were able to refine our estimates of elemental export to the Arctic Ocean. Compared to estimates from previous studies, we observed 2.3-fold higher dissolved loads of Mn, and the dissolved loads were higher by 2.1-fold for Zn, 1.6-fold for Fe, and 1.4-fold for Pb. The observed rise in elemental export is likely attributable to a confluence of factors, including permafrost thaw, enhanced water inflow from wetland catchments, and intensifying snowfall leading to increased flood runoff. Full article

Melt pond is one of the most significant and important features of Arctic sea ice in the summer and can dramatically reduce the albedo of ice, promoting more energy into the upper ocean. The observation of the seasonal evolution of melt pond can improve our fundamental understanding of the role and sensitivity of sea ice in the context of global climate change. In this study, an ice-tethered observation system is developed for melt pond evolution with vision and temperature profile measurements. The system composition, structure of the ice-tethered buoy, freeze-resistant camera, and thermistor chain are analyzed. A sealed shell and electric heating wires are used to increase the temperature to around the camera in low-temperature environments. The ice thickness and depth of melt pond can be inverted using a specific interface recognition algorithm. A low-light image enhancement strategy is proposed to improve the quality of images under the low lighting conditions in polar regions. The proposed system was tested in the second reservoir of Fen River, Yellow River, from 15 January to 27 January 2021. An artificial freshwater pond was used as the location for thermistor chain deployment and observation. The differences in mean square error (MSE), peak signal-to-noise ratio (PSNR), and feature similarity index (FSIM) between the original and enhanced images indicate that the proposed algorithm is suitable for low-light image enhancement. The research on the ice-tethered observation system will provide a new framework and technical support for the seasonal observation for melt pond. Full article