Thermokarst Lakes Research Articles

Role of Suprapermafrost Groundwater Recharge in Dissolved Organic Carbon Dynamics of Thermokarst Lakes

Role of Suprapermafrost Groundwater Recharge in Dissolved Organic Carbon Dynamics of Thermokarst Lakes

HABITATION CONDITIONS OF THE CAVE LION IN THE MIDDLE INDIGIRKA RIVER BASIN, NORTH-EAST SIBERIA, DURING THE MIDDLE AND LATE PLENIGLACIAL: RECONSTRUCTION BASED ON PALYNOLOGICAL DATA

Pollen analyses of the sediment from skulls cavities of two cave lions Panthera spelaea from the middle Indigirka River basin, North-East Siberia, were performed to reconstruct the habitat conditions of the animals and to estimate changes in vegetation and climatic conditions in the region. Composition of the pollen and non-pollen palynomorphs indicates that the predators most likely died on the river floodplain or near the shore of the thermokarst lake, where grass/sedge meadows and shrub thickets, providing rich grazing grounds for large herbivores, existed. Palynological data indicate that both in the early Middle Pleniglacial and in the LGM the regional vegetation included forest, shrub tundra, meadow, mire and steppe communities similar to modern cold steppes in central Yakutia. During early Marine Isotope Stage (MIS) 3, the participation of arboreal vegetation was greater than in the Last Glacial Maximum (LGM) due to higher summer temperatures. In MIS 2, the role of open herbaceous cryoxerotic communities was greater, which is associated with a higher continentality of climate and a decrease in winter temperatures. This reconstruction is consistent with the general sequence of landscape and climatic changes in the Arctic and Subarctic regions of Siberia in the Middle and Late Pleniglacial, based on paleobotanical studies of the locations of mammoth fauna and multidisciplinary studies of the Late Pleniglacial sediments from a broader area.

Distribution and changes of thermokarst lakes along the Qinghai-Tibet Railway from 1991 to 2022

Permafrost degradation on the Qinghai–Tibet Plateau has led to the rapid development of thermokarst lakes, but their distribution along the Qinghai-Tibet Railway (QTR) has not been fully studied. In this study, we established the Landsat, Sentinel-2A and GF-1 image datasets and a 50 ​km wide transect along the QTR, and used ENVI software to extract lake data. The distribution characteristics of thermokarst lakes at different distances from the QTR in 2022 were analyzed. The spatiotemporal evolution of thermokarst lakes and their relationship with climatic factors from 1991 to 2022 were examined. The results showed that, from 1991 to 2022, the number and area of thermokarst lakes in the study area increased by about 3,892 and 70.08 ​km2, respectively. It was found that climate warming and intensified precipitation are the main reasons for the increase in the number and area of thermokarst lakes in the study area. This study provides basic support for an in-depth understanding of the long-term interannual changes of the thermokarst lakes along the QTR and the maintenance of the QTR.

Investigating soil properties and their effects on freeze-thaw processes in a thermokarst lake region of Qinghai-Tibet Plateau, China

Soil parameters form the foundation of hydrogeological research and are crucial for studying engineering construction and maintenance, climate change, and ecological environment effects in cold regions. However, the soil properties in the permafrost region of the Qinghai–Tibet Plateau (QTP) remain unclear. Hence, in this study, soil temperature (Ts), volumetric specific heat capacity (C), thermal conductivity (K), thermal diffusivity (D), soil water content (SWC), electric conductivity (EC), vertical (Kv) and horizontal (Kh) saturated hydraulic conductivity, bulk density (ρb), and soil texture near the Qinghai-Tibet Railway were measured, and their effects on the freeze-thaw process were evaluated. The results revealed a predominantly sandy loam soil texture, with Kh and Kv showing strong spatial variability, while the other parameters presented moderate spatial variability. Thermokarst lake had a limited influence on D, C, K, and ρb but significantly reduced Kh and Kv. Groundwater affected SWC, Ts, and EC. The model results showed that all parameters indicated small sensitivities to the maximum thawing depth (MTD), with MTD positively responding to all parameters except for Kv and porosity (ρp). Except for Kh and Kv, all parameters showed high sensitivities to the time from starting to complete freezing (TSCF). TSCF responded positively to C, ρp, and density (ρd) and negatively to K and Kh. This study expanded the quantification of soil properties in the QTP, which can help improve the accuracy of cryohydrogeologic models, thus guiding the construction and maintenance of infrastructure engineering.

Landsat Analysis of Terraced Thermokarst Lake Variability on Alaska's Coastal Plain

ABSTRACTThermokarst lakes are abundant across the Arctic landscape. Although they are largely understood to form due to thawing permafrost and subsidence, these lakes exist in a variety of forms, shapes, and sizes. Some lakes across the Arctic exhibit shallow subaqueous terraces. The terraces have previously been shown to maintain permafrost beneath them due to the presence of bedfast ice during most of the year, whereas a talik develops beneath the deeper central pool. However, the formation of these terraces and their prevalence across the Arctic are currently unknown. In this study, we mapped the locations of thermokarst lakes and their terraces in the Alaska coastal plain using Landsat imagery. We found that terraces are larger and more abundant in sandy deposits, occupying an average of 40% of the lake area, compared to 20% of the lake area in non‐sandy lithologies. Terraces are most often found on the eastern and western lake shorelines, likely associated with regional wind directions, forming on the long sides of northwest–southeast oriented lakes. We propose a conceptual model for terrace formation in sandy deposits that describes the growth of shallow littoral shelves that protect the eastern and western shorelines from erosion while allowing lake extension in the northwest and southeast directions. Finally, given the close association between bedfast ice, talik extent, and the shallow subaqueous terraces, we suggest that mapping of these relatively stable terraces may provide insights about talik extent across the Arctic coastal region. Continued warming and changes to lake ice regimes are likely to increase talik extent, which may be easily observable by temporal analysis of terrace abundance and extent in widely available remotely sensed imagery.

A novel framework for multiple thermokarst hazards risk assessment and controlling environmental factors analysis on the Qinghai-Tibet Plateau

Due to the influence of climate warming, the degradation of permafrost on the Qinghai-Tibet Plateau (QTP) has become evident. The formation of thermokarst hazards induced by the degradation of ice-rich permafrost has a significant impact on infrastructure construction and local ecology; therefore, it is necessary to assess its risk. Currently, high-precision and harmonized assessment tools for multiple thermokarst hazards risk assessment are lacking, and the mechanisms governing the environmental interactions of thermokarst hazards have not been fully clarified. In this study, a novel multiple thermokarst hazards risk assessment framework was proposed by combining stacking machine learning and potential environmental factors to assess the risk of thermokarst hazards in the Yangtze River source region (YRSR). In addition, model performance was improved by model optimization. Finally, structural equation modeling (SEM) was used to assess the controlling environmental factors for the thermokarst hazards in the YRSR. The results show that slope and precipitation contribute the most to the modeling accuracy of thermokarst lakes and thaw slumps, respectively. Model optimization improved the base model modeling accuracy by approximately 2 % ∼ 7 %, with XGBoost having the highest sensitivity to model optimization and the highest modeling accuracy. In terms of the ensemble strategy, the stacking model and ensemble model significantly improved the risk mapping accuracy, and the stacking model was better than the ensemble model, with accuracies of 92.39 % and 93.36 % for thermokarst lakes and thaw slumps, respectively. Compared with previous results, the results of this study are more representative of the YRSR. Finally, via SEM, terrain factors and soil factors were identified as controlling environmental factors for the risk of thaw slumps and thermokarst lakes, respectively. This study proposes a high-precision risk assessment method for thermokarst hazards in permafrost regions, and contributes to a deeper understanding of the interaction mechanisms between thermokarst hazards and environmental factors.

Passive Seismology: Lightweight and Rapid Detection of Arctic Subsea and Sub‐Aquatic Permafrost

AbstractLow sea levels during the last Ice Age exposed millions of square kilometers of Arctic shelves which have been subsequently submerged, creating subsea permafrost. In onshore settings, permafrost can also exist beneath water bodies such as coastal lagoons, rivers, and thermokarst lakes. We explored passive seismology as a method for mapping unfrozen sediment thickness above subsea and sub‐aquatic permafrost. We present passive seismic data collected with the Mobile Ocean Bottom Seismic Instrument (MOBSI) from the Beaufort Sea near Tuktoyaktuk in Canada, Ivashkina Lagoon on the Bykovsky Peninsula, as well as a lake and river in the Lena Delta, Siberia, Russia. We use borehole data and frost probe measurements to identify permafrost‐related H/V measurement peaks and calibrate shear wave velocities for frequency‐to‐depth conversion. We employ the shortest path and maximum signal amplitude to connect peaks and generate geological profiles. The MOBSI detected the ice‐bonded permafrost table beneath the Beaufort Sea, as well as beneath a Siberian lake and lagoon. At Tuktoyaktuk, an ocean bottom seismometer revealed a 5% scatter about the peak frequency for three‐minute time windows and over 8 hr of recording time. With peak frequencies ranging from 4.9 ± 0.2 Hz to 27.6 ± 1.4 Hz, the depth to subsea permafrost ranged from 1.4 ± 0.1 m bsl at the shoreline to 14.0 ± 0.4 m bsl 240 m offshore. Given an accurate shear wave velocity, our findings highlight that MOBSI deployment times as short as 3 min are adequate for detecting Arctic subsea and sub‐aquatic permafrost.

Planktonic Microbial Communities of Thermokarst Lakes of Central Yakutia Demonstrate a High Diversity of Uncultivated Prokaryotes with Uncharacterized Functions

Although thermokarst alas lakes of Central Yakutia are of great climatic and economic importance, there is currently virtually no information on microbial communities and microbial processes in these lakes. This paper characterizes the hydrochemical features and presents a primary analysis of the diversity of planktonic microbial communities in three alas lakes of Central Yakutia — Tyungulyu, Taby, and Kharyyalakh. It was shown that in terms of the water physicochemical composition, the studied lakes were quite typical for this region; they had increased alkalinity and trophicity, but differed from each other in microbiological indicators. Chemoheterotrophic prokaryotes predominated in the studied planktonic communities, but a significant proportion of the 16S rRNA gene sequences were most similar to uncultured microorganisms whose functional potential is still unknown.

North American Circum-Arctic Permafrost Degradation Observation Using Sentinel-1 InSAR Data

In the context of global warming, the accelerated degradation of circum-Arctic permafrost is releasing a significant amount of carbon. InSAR can indirectly reflect the degradation of permafrost by monitoring its deformation. This study selected three typical permafrost regions in North America: Alaskan North Slope, Northern Great Bear Lake, and Southern Angikuni Lake. These regions encompass a range of permafrost landscapes, from tundra to needleleaf forests and lichen-moss, and we used Sentinel-1 SAR data from 2018 to 2021 to determine their deformation. In the InSAR process, due to the prolonged snow cover in the circum-Arctic permafrost, we used only SAR data collected during the summer and applied a two-stage interferogram selection strategy to mitigate the resulting temporal decorrelation. The Alaskan North Slope showed pronounced subsidence along the coastal alluvial plains and uplift in areas with drained thermokarst lake basins. Northern Great Bear Lake, which was impacted by wildfires, exhibited accelerated subsidence rates, revealing the profound and lasting impact of wildfires on permafrost degradation. Southern Angikuni Lake’s lichen and moss terrains displayed mild subsidence. Our InSAR results indicate that more than one-third of the permafrost in the North American study area is degrading and that permafrost in diverse landscapes has different deformation patterns. When monitoring the degradation of large-scale permafrost, it is crucial to consider the unique characteristics of each landscape.

A new inventory and future projections of thermokarst lakes in the permafrost regions of the Qilian Mountains, northeastern Qinghai-Tibet Plateau, China

Thermokarst lakes—lacustrine basins formed by thermokarst processes—are key components of permafrost ecosystems that significantly influence the geomorphology, hydrology, ecology, and the stability of infrastructure, while also contributing to greenhouse gas emissions. High-resolution mapping of thermokarst lakes' current and future distribution presents a considerable challenge. In this study, we leverage a deep learning approach to delineate the boundaries of thermokarst lakes in the permafrost regions of the Qilian Mountains at the northeastern margin of the Qinghai-Tibet Plateau (QTP) using Sentinel-2 imagery, followed by an estimation of future susceptibility to thermokarst lake formation by employing a machine learning method. We identified a total of 2795 thermokarst lakes covering an area of approximately 51.6 km2. Based on future climate scenarios, there will be a significant reduction in the proportion of high-susceptibility areas. Specifically, under the most extreme SSP5–8.5 scenario, the proportion of areas highly susceptible to thermokarst lake formation decreases from the current 6.7 % to 0.01 % in the period 2081–2100. Our comprehensive inventory provides essential data for research on permafrost hydrology and the evaluation and management of water resources, and enhances our understanding of thermokarst lake formation in relation to environmental factors.

Different trends in the dynamics of Arctic lakes in North Siberia under climate change in 1985–2021

The methods and results of a comparative analysis of the effects of climate changes on the dynamics of the areas of thermokarst lakes over the past 36 years in the Arctic regions on the Yamal, Gydan, and Taimyr peninsulas are considered, the areas of which are 114, 175 and 426 thousand km2, respectively. All three regions are located within the permafrost zone of the Siberian Arctic. Using images of the Landsat 4, 5, 7, and 8 satellites, time series of data on average values of lake areas for the indicated regions were obtained on the basis on averaging areas of lakes over 23 test (key) areas. The total area of the test sites is about 800 km2. Using the ERA5 reanalysis system, time series of data on the mean annual air temperature in these territories have been generated, which show a rise of the temperature over the studied period 1985–2021. A comparison of trends in changes in regional mean areas of lakes and mean annual air temperature shows that with approximately the same rate of the temperature rise on these peninsulas, different trends in the dynamics of the lake areas are observed, which are manifested, on the one hand, in a noticeable reduction in the areas of lakes in the territories of Yamal and Gydan and, on the other hand, in their growth in Taimyr. Air temperature averaged over the period 1985–2021 and coefficients of the linear trend of changes in the lake areas in each of the above regions were compared. The results show that on the territories of Yamal and Gydan, where the lake areas decrease, the mean air temperature for the same period is equal to –8.1±0.9 and –8.9±0.9 °С, respectively. On the Taimyr territory, where the lake areas increase, the mean air temperature is significantly lower: –12.8±0.94 °С. Thus, this makes possible to make a conclusion that these considered regions differ significantly from each other by values of mean air temperature, and respectively, they are characterized by different trends in changes in areas of the thermokarst lakes.

Susceptibility Modeling and Potential Risk Analysis of Thermokarst Hazard in Qinghai–Tibet Plateau Permafrost Landscapes Using a New Interpretable Ensemble Learning Method

Climate change is causing permafrost in the Qinghai–Tibet Plateau to degrade, triggering thermokarst hazards and impacting the environment. Despite their ecological importance, the distribution and risks of thermokarst lakes are not well understood due to complex influencing factors. In this study, we introduced a new interpretable ensemble learning method designed to improve the global and local interpretation of susceptibility assessments for thermokarst lakes. Our primary aim was to offer scientific support for precisely evaluating areas prone to thermokarst lake formation. In the thermokarst lake susceptibility assessment, we identified ten conditioning factors related to the formation and distribution of thermokarst lakes. In this highly accurate stacking model, the primary learning units were the random forest (RF), extremely randomized trees (EXTs), extreme gradient boosting (XGBoost), and categorical boosting (CatBoost) algorithms. Meanwhile, gradient boosted decision trees (GBDTs) were employed as the secondary learning unit. Based on the stacking model, we assessed thermokarst lake susceptibility and validated accuracy through six evaluation indices. We examined the interpretability of the stacking model using three interpretation methods: accumulated local effects (ALE), local interpretable model-agnostic explanations (LIME), and Shapley additive explanations (SHAP). The results showed that the ensemble learning stacking model demonstrated superior performance and the highest prediction accuracy. Approximately 91.20% of the total thermokarst hazard points fell within the high and very high susceptible areas, encompassing 20.08% of the permafrost expanse in the QTP. The conclusive findings revealed that slope, elevation, the topographic wetness index (TWI), and precipitation were the primary factors influencing the assessment of thermokarst lake susceptibility. This comprehensive analysis extends to the broader impacts of thermokarst hazards, with the identified high and very high susceptibility zones affecting significant stretches of railway and highway infrastructure, substantial soil organic carbon reserves, and vast alpine grasslands. This interpretable ensemble learning model, which exhibits high accuracy, offers substantial practical significance for project route selection, construction, and operation in the QTP.

Evaluation of the energy budget of thermokarst lake in permafrost regions of the Qinghai–Tibet Plateau

Thermokarst lake formation accelerates permafrost degradation due to climate warming, thereby releasing significant amounts of carbon into the atmosphere, complicating hydrological cycles, and causing environmental damage. However, the energy transfer mechanism from the surface to the sediment of thermokarst lakes remains largely unexplored, thereby limiting our understanding of the magnitude and duration of biogeochemical processes and hydrological cycles. Therefore, herein, a typical thermokarst lake situated in the center of the Qinghai–Tibet Plateau (QTP) was selected for observation and energy budget modeling. Our results showed that the net radiation of the thermokarst lake surface was 95.1, 156.9, and 32.3 W m−2 for the annual, ice-free, and ice-covered periods, respectively, and was approximately 76% of the net radiation consumed by latent heat flux. Alternations in heat storage in the thermokarst lake initially increased from January to April, then decreased from April to December, with a maximum change of 48.1 W m−2 in April. The annual average heat fluxes from lake water to sediments were 1.4 W m−2; higher heat fluxes occurred during the ice-free season at a range of 4.9–12.0 W m−2. The imbalance between heat absorption and release in the millennium scale caused the underlying permafrost of the thermokarst lake to completely thaw. At present, the ground temperature beneath the lake bottom at a depth of 15 m has reached 2.0 °C. The temperatures and vapor-pressure conditions of air and lake surfaces control the energy budget of the thermokarst lake. Our findings indicate that changes in the hydrologic regime shifts and biogeochemical processes are more frequent under climate warming and permafrost degradation.

Взрывная дегазация Земли на полуострове Ямал и прилегающей акватории Карского моря

Remote sensing data from space and using UAVs make it possible to solve a wide range of tasks related to the study of Earth degassing processes in the Arctic. For the first time, via comprehensive aerospace research on the Yamal Peninsula, we have discovered 4992 zones of gas blowouts (explosions) in the form of craters (pockmarks) at the bottom of 3551 thermokarst lakes and 16 rivers. In addition, we have identified another 669 zones of explosive degassing in the coastal zones of the Kara Sea, mainly in gulfs, estuaries and bays. Taking into account the Yugorsky Peninsula and Bely Island, we have detected 6022 explosive degassing zones in the studying region, including 905 ones offshore. We have proved previously made conclusions that the Neytinsko-Seyakhinsky and Sabetta districts are the most gas-explosive. It is substantiated that possible intense natural degassing of the Earth, especially occurring in the process of degradation of subaquatic permafrost and dissociation of gas hydrates, can radically change the elastic-strength properties of bottom soil, while its saturation with gas can disrupt conditions for the construction of various objects, including underwater gas pipelines. Widespread gas blowouts in the north of Western Siberia with the formation of craters on land and offshore can lead to emergencies and even disasters at oil and gas industrial facilities and to fires in the tundra.

Dissolved organic matter quality in thermokarst lake water and sediments across a permafrost gradient, Western Siberia

Thermokarst (thaw) lakes of permafrost peatlands are among the most important sentinels of climate change and sizable contributors of greenhouse gas emissions (GHG) in high latitudes. These lakes are humic, often acidic and exhibit fast growing/drainage depending on the local environmental and permafrost thaw. In contrast to good knowledge of the thermokarst lake water hydrochemistry and GHG fluxes, the sediments pore waters remain virtually unknown, despite the fact that these are hot spots of biogeochemical processes including GHG generation. Towards better understating of dissolved organic matter (DOM) quality at the lake water – sediment interface and in the sediments pore waters, here we studied concentration and optical (UV, visual) properties of DOM of 11 thermokarst lakes located in four permafrost zones of Western Siberia Lowland. We found systematic evaluation of DOM concentration, SUVA and various optical parameters along the vertical profile of lake sediments. The lake size and hence, the stage of lake development, had generally weak control on DOM quality.The permafrost zone exhibited clear impact on DOM porewater concentration, optical characteristics, aromaticity and weight average molecular weight (WAMW). The lowest quality of DOM, reflected in highest SUVA and WAMW, corresponding to the dominance of terrestrial sources, was observed at the southern boundary of the permafrost, in the sporadic/discontinuous zone. This suggests active mobilization of organic matter leachates from the interstitial peat and soil porewaters to the lake, presumably via subsurface or suprapermafrost influx. Applying a substitute space for time scenario for future evolution of OM characteristics in thermokarst lake sediments of Western Siberia, we foresee a decrease of DOM quality, molecular weight and potential bioavailability in lakes of continuous permafrost zone, and an increase in these parameters in the sporadic/discontinuous permafrost zone.

Contemporary formation of ice-wedge pseudomorphs during the expansion of a thermokarst lake in Old Crow Flats, Yukon, Canada

Ice-wedge pseudomorphs (IWPs) are thermokarst structures that form by the secondary infilling of cavities left by the slow melting of ice wedges. Contemporary IWP formation in periglacial environments informs our understanding of past processes and dynamics implied by their presence in the stratigraphic record. However, contemporary IWPs are seldom studied as they are difficult to locate and observe due to the general lack of surface expression and because they can deform with time or be confused with sediment wedges. This study presents detailed information about the morphology and soil composition of IWPs that formed beneath a thermokarst lake in Old Crow Flats, northern Yukon (Canada), and provides the first conceptual model of lacustrine IWP development. Seven IWPs were unearthed along a transect perpendicular to a former eroding lakeshore in a recently (2019), partially drained lake basin. The IWPs were between 76 cm and 122 cm high and had varying morphologies, generally forming triangles pointing down or T shapes. They had a much higher organic matter content and were composed of slightly coarser sediment than their host sediment, characteristics that were shared by basin floor surface sediment found in the near-shore zone (<15 m) of the former lake. Within five meters of the former shoreline, some troughs showed pronounced subsidence due to the melting of remnant wedge ice following lake drainage. Based on ice-wedge dimensions, bank height, shore erosion rates, and field measurements of sublake active-layer thickness prior to lake drainage, it is likely that ice wedges were entirely melted by the development of the sublake active layer, prior to talik development. Together, the results indicate that the IWPs formed within 5 to 10 m of the eroding shore bank, 9 to 18 years after lake submergence, and were filled with the organic-rich lacustrine sediment that accumulated in the near-shore zone due to sediment sorting by wave action following the erosion of peaty polygonal tundra. This study highlights that IWPs can form during the natural evolution of thermokarst lakes in regions with stable permafrost and are not necessarily indicators of conditions leading to generalized permafrost degradation.

Drivers of rare earth elements (REEs) and radionuclides in changing subarctic (Nunavik, Canada) surface waters near a mining project

The emergence of mining projects for rare earth elements (REEs) in response to rising global demand and geopolitical factors introduces environmental concerns, such as the suspected release of anthropogenic REEs to aquatic systems and the coexistence of radionuclides (U, Th). Northern regions confront heightened challenges from limited research and accelerated climate change. Drivers of REEs in surface waters (including George and Koroc rivers, their tributaries, and thermokarst lakes) were studied (2017–2023) in subarctic Canada within a climate transition zone, near a prospective REE mine. Dissolved REEs (<0.45 μm) correlated positively with Al, Fe, Th, U, Cl– and DOC. A novel relationship with water temperature demonstrated an approximate 10-fold decrease in REE concentrations over the environmental gradient (2–20 ℃), suggesting complex implications for REE speciation under climate pressures. Optical analyses further predicted REEs were mobilized by humic-rich, terrestrial DOC, with correlations presenting a possible co-transport with Al, Fe and Th. Relationships for redox-sensitive Ce anomalies (Ce/Ce* = 0.18–1.2) with multi-valent trace metals (Al, Fe, Ti) and DOC were suggestive of a preferential adsorption of Ce by inorganic colloids in low-DOC systems. Findings emphasized the potential for changes in REE geochemistry with ongoing northern surface warming and vegetation shifts.

Hydrological responses to permafrost degradation on Tibetan Plateau under changing climate

The Tibetan Plateau (TP) has undergone significant warming and humidification in recent years, resulting in rapid permafrost degradation and spatiotemporal variations in hydrological processes, such as subsurface water transport, hydrothermal conversion, and runoff generation. Understanding the mechanisms of hydrological processes in permafrost areas under changing climate is crucial for accurately evaluating hydrological responses on the TP. This study comprehensively discusses the permafrost hydrological processes of the TP under changing climate. Topics include climate conditions and permafrost states, subsurface water transport under freeze–thaw conditions, development of thermokarst lakes and hydrothermal processes, and runoff response during permafrost degradation. This study offers a comprehensive understanding of permafrost changes and their hydrological responses, contributing significantly to water security and sustainable development on the TP.

The Role of Digital Elevation Models in Increasing the Accuracy of Geophysical Studies of Anthropogenic Metallic Pollution

The study focuses on improving the accuracy of geophysical investigations of anthropogenic metallic pollution using digital elevation models (DEMs). The methodology was tested at the Norilsk site, located in close proximity to the slag heaps of the nickel plant, based on DEM data obtained through unmanned aerial vehicles (UAVs) to conduct a detailed geomorphological analysis of the area. Geophysical methods such as the natural field (NF) method and frequency sounding were also used to identify zones of potential metallic pollution, as well as the characteristics and spatial positions of predicted permafrost layers. The main emphasis is on the advantages of integrating geophysical methods with DEMs and derived cartographic materials to improve the accuracy and reliability of surface metallic pollution detection and mapping, considering the geocryological situation within the study area. Geophysical methods of natural field (NF) and frequency sounding were employed to determine the geoelectrical properties of the study area. Reconnaissance surveys and flight missions were conducted to create the digital elevation model and orthoimage, and a surface water runoff map was developed based on the generated rasters and their interpretation. Based on the obtained geophysical data, zones of possible metallic pollution spread from the slag heaps were identified, which were confirmed through DEM analysis by the geomorphology of the study site. The distribution of specific electrical resistance fields was also interpreted in consideration of the collected data and validated through borehole drilling. It is worth noting that the integrated approach helped reveal the need to revise the interpretation plan, as only through the analysis of the nature and intensity of metallic pollution could the abnormally low resistance values in areas far from thermokarst lakes, with relatively shallow permafrost depths, be explained. Additionally, it became possible to qualitatively assess the zones of dust material accumulation.

Planktonic Microbial Communities of Thermokarst Lakes of Central Yakutia Demonstrate a High Diversity of Uncultivated Prokaryotes with Uncharacterized Functions

Planktonic Microbial Communities of Thermokarst Lakes of Central Yakutia Demonstrate a High Diversity of Uncultivated Prokaryotes with Uncharacterized Functions