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The process of frost heaving during seasonal freezing and other affecting factors on the projected Moscow-Kazan railway are considered. Despite the fact that the region has been extensively developed, the heave properties, especially under modern climate conditions, have not been examined sufficiently. The results of fields studies of the frost heave properties of soils on the monitoring sites located in the typical natural complexes along the projected Moscow–Kazan railway line are presented; they include the physical properties of soils, the depth of seasonal freezing, the thermal regime of soils, the groundwater regime, and the thickness of the snow cover, as well as the basic characteristics of frost heaves.

This work summarizes the archived data of geocryological and hydrogeological conditions in the west of Nordenskiold Land on the Spitsbergen Archipelago. The historical data obtained in the Soviet period during coal exploration are reviewed together with the results of our own studies performed as part of the Russian Scientific Arctic Expedition on Spitsbergen (RAE-S) in 2016–2020. With respect to geocryology, the region is assigned to the zone of continuous permafrost. The thickness of rocks and sediments with temperatures below zero is about 100 m near the coast and increases to 540 m on watersheds. The mean annual ground temperature near the zero-amplitude depth varies from –3.6 to –2.2°C. Below this layer, the temperature curve in the top part of the section tends to deviate toward positive temperatures, reflecting the modern cycle of climate warming. From the hydrogeological point of view, the area belongs to the marginal zone of the West Spitsbergen cryoadartesian basin. Seawater intrusions near the coast form saline subpermafrost aquifers, including those with temperatures below zero, reflecting the seawater (sodium chloride) composition and hydraulic heads close to sea level. Fresh and slightly saline (sodium bicarbonate on the east coast of Grønfjorden and magnesium–calcium sulfate in gypsum-bearing deposits on the west coast) subpermafrost water with hydraulic heads reaching 100 m above sea level is fed by water-saturated ice in the deep layers of large glaciers.

This work reports on the laboratory study of gas filtration in ice samples with various salinities and frozen soils. For this purpose, the frozen soils were affected by pressurized gas in a specially designed apparatus. Then, the structure of the samples was studied with the use of the texture and structure observations in transmitted, reflected, and polarized light. During the experiments, it was possible to identify the processes that accompany gas filtration in ice with various salinities and frozen soils, and to establish the temperatures at which gas filtration begins.

The active development of the Russian Arctic in the last 10 years requires relevant data on the bearing capacity of rocks on the Arctic shelf of the Russian Federation. To assess the bearing capacity of soils, knowledge of the distribution and state of permafrost on the Arctic shelf is needed. This article discusses the rationale and possibilities of the proposed integrated geocryological and geophysical analysis. The technique of the research includes sea electroprospecting works, drilling on the shelf, thermometric observations in the drilled wells, bench tests of soils, and modeling of electromagnetic and thermal fields on the shelf. It is shown that the most informative geophysical method for studying of permafrost on the shelf is electromagnetic sounding by the TEM method. The most informative geophysical method for studying of permafrost in the “land–shelf” transit zone is frequency electromagnetic (FS) sounding. In this article there are examples of the standard interpretation of geophysical data and inversion of geophysical data in the mode of the fixed model of specific electrical resistivity. Using the example of the Yamal shelf it is shown that the standard interpretation does not allow an unambiguous solution of geocryologic tasks on the shelf. Specific electric results of determination of electric properties of soils in laboratory are necessary in the case of the inversion of geophysical data in the mode of thickly stratified models and the fixed model. An important component of the proposed complex is boring and thermometric research, which provide validation of the results of geophysical inversion. Measurement of the temperatures of soils in the wells is especially important under the conditions of the Arctic shelf. Calculations for thermal models complete the complex of research. The collateral analysis of geoelectric and thermal models allows one to estimate the depth to the bottom of permafrost, as well as the thickness of gas hydrate strata. Use of the developed complex of studies on the shelf of the Pechora, Karsky, Laptev, and Chukchi Seas made it possible to obtain new ideas about the distribution permafrost rocks and the development of gas hydrates on the shelf of the seas of the Russian Arctic.

The active development of the Russian Arctic in the last 10 years requires relevant data on the bearing capacity of rocks on the Arctic shelf of the Russian Federation. To assess the bearing capacity of soils, knowledge of the distribution and state of permafrost on the Arctic shelf is needed. The article discusses the rationale and possibilities of the proposed integrated geocryological and geophysical analysis. The technique of researches includes realization of sea electroprospecting works, drilling on the shelf, thermometric observations in the drilled wells, bench tests of soils, modeling of electromagnetic and thermal fields on the shelf. It is shown that the most informative geophysical method for studying of permafrost on the shelf is electromagnetic sounding by the TEM method. The most informative geophysical method for studying of permafrost in the transit zone “land-shelf” represents the frequency electromagnetic (FS) sounding. In the article there are examples of standard interpretation of geophysical data and inversion of geophysical data in the mode of the fixed model specific electrical resistivity. With the example of the yamal shelf it is shown that standard interpretation doesn’t allow to receive the unambiguous solution of geocryologic tasks on the shelf. Specific electric results of determination of electric properties of soils in laboratory are necessary in case of inversion of geophysical data in the mode of thickly stratified models and the fixed model. An important component of the offered complex is boring and thermometric research which provide validation of results of geophysical inversion. Measurement of temperatures of soils in the stood wells is especially important in the conditions of the Arctic shelf. Calculations for thermal models complete a complex of researches. The collateral analysis of geoelectric and thermal models allows to estimate depths to a sole of permafrost and also capacities of gaseous-hydrate thicknesses. The use of the developed research complex on the Pechora, Karsky, Laptev and Chukchi seas shelves provided new insights into the distribution, continuity and condition of permafrost and the development of gas hydrates on the shelf of the Russian Arctic seas.

Acoustic and electrical properties determined for frozen saline soils (sand and silt) of massive cryogenic structure with different water contents (three values for each type of soil), salinities (seven values for silt and five for sand) and temperatures (–2, –4, and –6°C) are presented in the paper. A good correlation between the specific electrical resistivity and the concentration of the pore solution and between the ratio of the concentration of the pore solution to the temperature and the velocity of longitudinal waves was obtained. The electrical resistivity of the low saline soil was 2–22 times higher than that of the highly saline soils, while the longitudinal wave velocities only differ by factor of two. Therefore, the electrical properties are the most suitable parameter for ranking soils by their salinity.

The results of determining acoustic and electrical properties of frozen saline soils (sand and silt) of massive cryogenic texture at different water content (3 values for each type of soil), salinity (7 values for silt and 5 for sand) and temperatures (–2, –4, –6 ᵒC) are given in the article. As a result, data on the high correlation between specific electrical resistivity and concentration of the pore solution and between ratio of a concentration of the pore solution to temperature and the velocity of longitudinal waves were obtained. Electrical resistivity can decrease by 2–22 times during the transition from a low-saline to a highly saline state and for longitudinal wave velocities only two times. Therefore, it is the electrical properties that are most suitable for the ranking of soils by the degree of salinity.

Testing of modern innovation field methods of engineering-geocryological research, master class workout by leading specialists of engineering-geocryological surveys, checking out of measurement equipment for thermal field ground massif researches which were done at “The day of science and innovation” field conference in Zvenigorod biological station of Lomonosov Moscow state university. Necessity of innovation methods usage has approved.

Drilling of a 21.8-m-deep borehole on top of the 10.5-m-high Nori pingo that stands at 32 m asl in Grondalen Valley (Spitsbergen) revealed a 16.1-m-thick massive ice enclosed by frozen sediments. The hydrochemical compositions of both the massive ice and the sediment extract show a prevalence of Na+ and Cl� ions throughout the core. The upper part of the massive ice (stage A) has low mineralization and shows an isotopically closed-system trend in δ18O and δD isotopes decreasing down-core. Stage B exhibits high mineralization and an isotopically semi-open system. The crystallographic structure of Nori pingo’s massive ice provides evidence of several large groundwater intrusions that support the defined formation stages. Analysis of local aquifers leads to suggest that the pingo was hydraulically sourced through a local fault zone by low mineralized sodium–bicarbonate groundwater of a Paleogene strata aquifer. This groundwater was enriched by sodium and chloride ions while filtering through marine valley sediments with residual salinity. The comparison between the sodium–chloride-dominated massive ice of the Nori pingo and the sodium–bicarbonate-dominated ice of the adjacent Fili pingo that stands higher up the valley may serve as an indicator for groundwater source patterns of other Nordenskiold Land pingos.

Rock instability in high-altitude areas is an important risk factor for humans and infrastructure, especially in the context of climate change. The presence of water in the rock leads to a clear increase in the strength of the rock, the effect is enhanced at lower temperatures and a higher degree of saturation. Since the decrease in rock strength due to the phase transition from frozen to thawed state has a great impact on the strength and stability of the rock soil, the paper proposes a model and a numerical method for estimating the depth of rock soil freezing based on data on air temperature and the thickness of the snow cover. The paper also evaluates the effect of air temperature and snow cover on the rock soil stability and depth of freezing according to the proposed calculation algorithm which is applied for the winter periods 2010/2011-2019/2020 at the Anzob pass in Tajikistan. The calculating scheme is constructed according to the three-layer medium thermal conductivity problem (snow, frozen and thawed rock) with a phase transition on the boundary frozen and thawed rock soil. The equation of heat balance contains the heat of the phase transition, the energy of inflow from the thawed rock and the outflow into the frozen rock and, in the presence of snow cover, the outflow into the atmosphere air through it.

Continental slopes north of the East Siberian Sea potentially hold large amounts of methane (CH4) in sediments as gas hydrate and free gas. Although release of this CH4 to the ocean and atmosphere has become a topic of discussion, the region remains sparingly explored. Here we present pore water chemistry results from 32 sediment cores taken during Leg 2 of the 2014 joint Swedish–Russian–US Arctic Ocean Investigation of Climate–Cryosphere–Carbon Interactions (SWERUS-C3) expedition. The cores come from depth transects across the slope and rise extending between the Mendeleev and the Lomonosov ridges, north of Wrangel Island and the New Siberian Islands, respectively. Upward CH4 flux towards the seafloor, as inferred from profiles of dissolved sulfate (SO42−), alkalinity, and the δ13C of dissolved inorganic carbon (DIC), is negligible at all stations east of 143° E longitude. In the upper 8 m of these cores, downward SO42− flux never exceeds 6.2 mol m−2 kyr−1, the upward alkalinity flux never exceeds 6.8 mol m−2 kyr−1, and δ13C composition of DIC (δ13C-DIC) only moderately decreases with depth (−3.6 ‰ m−1 on average). Moreover, upon addition of Zn acetate to pore water samples, ZnS did not precipitate, indicating a lack of dissolved H2S. Phosphate, ammonium, and metal profiles reveal that metal oxide reduction by organic carbon dominates the geochemical environment and supports very low organic carbon turnover rates. A single core on the Lomonosov Ridge differs, as diffusive fluxes for SO42− and alkalinity were 13.9 and 11.3 mol m−2 kyr−1, respectively, the δ13C-DIC gradient was 5.6 ‰ m−1, and Mn2+ reduction terminated within 1.3 m of the seafloor. These are among the first pore water results generated from this vast climatically sensitive region, and they imply that abundant CH4, including gas hydrates, do not characterize the East Siberian Sea slope or rise along the investigated depth transects. This contradicts previous modeling and discussions, which due to the lack of data are almost entirely based on assumption.

There are only a few Earth System processes that can cause a net transfer of carbon from land/ocean to the atmosphere (as CO2 and CH4) on the century timescale– top candidates are thawing permafrost and collapsing CH4 hydrates in the Arctic. Nevertheless, there are huge uncertainties regarding the composition, inventories and functioning of these different Cryosphere-Carbon pools.Most investigations of Arctic CH4/CO2 releases have studied inland permafrost (PF), yet there is increasing attention towards coastal and subsea permafrost and hydrates. The East Siberian Arctic Ocean (ESAO) is the target area as it is experiencing among the highest climate warming and because of its vast, yet poorly constrained stores of vulnerable carbon. The ESAO is the largest yet shallowest shelf of the World Ocean, being a seaward extension of the Siberian tundra that was flooded during the Holocene transgression 7-15 kyr ago. Recent drilling campaigns of the Laptev Sea subsea permafrost have provided the opportunity for progress in understanding its current state, composition and functioning. The temperature profiles of the PF underneath the coastal waters were in general much higher and close to zero, compared to nearby still on-land permafrost. Several sites that were drilled 30 years ago were recently re-drilled, which revealed that the thaw horizon has been moving down by several meters in just a few decades. There is thus both a potential for degradation of the organic matter (including to methane) in this subsea PF as well as an increasing permeability for pre-formed methane to penetrate toward the surface.Methane in the ESAS water column is over extensive scales present at concentrations much above what would be predicted from equilibrium with overlying atmospheric mixing ratios. The spatial patterns can now start to be compared with geophysical data on the composition of the sediments. The water column to atmosphere transfer of methane is affected both by the relative importance of diffusive exchange of dissolved methane and through ebullition. Storm-induced ventilation of the water column is shown to be an important process.The relative contributions of different subsea compartments to the methane fluxes is also approached through isotopes. We are exploring triple isotope fingerprinting of bottom water methane to apportion its sources (i.e. d13C/dD/D14C-CH4.). Preliminary results from two active seep regions, one in Laptev Sea and one in the East Siberian Sea will be presented.

The inconsistency between the position of the submarine permafrost table in the East Arctic seas revealed by simulation and anomalies in the distribution of dissolved methane associated with ascending torchlike ejections of bubbling methane made it necessary to develop a representative geophysical express method, which allows the position of the submarine permafrost table to be determined. The method is based on sounding of the generated primary electromagnetic field in the near zone of the medium and measurement of the induced secondary EM field. The reliability of the method is confirmed by core drilling in the Laptev Sea.

Surface heat flow data in the Arctic Ocean are needed to assess hydrocarbon and methane hydrate distributions, and provide constraints into the tectonic origins and nature of underlying crust. Howe ...

Seeps found offshore in the East Siberian Arctic Shelf may mark zones of degrading subsea permafrost and related destabilization of gas hydrates. Sonar surveys provide an effective tool for mapping seabed methane fluxes and monitoring subsea Arctic permafrost seepage. The paper presents an overview of existing approaches to sonar estimation of methane bubble flux from the sea floor to the water column and a new method for quantifying CH4 ebullition. In the suggested method, the flux of methane bubbles is estimated from its response to insonification using the backscattering cross section. The method has demonstrated its efficiency in the case study of single- and multi-beam acoustic surveys of a large seep field on the Laptev Sea shelf.

The rates of subsea permafrost degradation and occurrence of gas-migration pathways are key factors controlling the East Siberian Arctic Shelf (ESAS) methane (CH4) emissions, yet these factors still require assessment. It is thought that after inundation, permafrost-degradation rates would decrease over time and submerged thaw-lake taliks would freeze; therefore, no CH4 release would occur for millennia. Here we present results of the first comprehensive scientific re-drilling to show that subsea permafrost in the near-shore zone of the ESAS has a downward movement of the ice-bonded permafrost table of ∼14 cm year−1 over the past 31–32 years. Our data reveal polygonal thermokarst patterns on the seafloor and gas-migration associated with submerged taliks, ice scouring and pockmarks. Knowing the rate and mechanisms of subsea permafrost degradation is a prerequisite to meaningful predictions of near-future CH4 release in the Arctic., The rate of subsea permafrost degradation is a key factor controlling marine methane emissions in the Arctic. Here, using re-drilled boreholes, the authors show that the ice-bonded permafrost table in the near-shore East Siberian Arctic Shelf has deepened by ∼14 cm per year over the past 31–32 years.

It has been suggested that increasing freshwater discharge to the Arctic Ocean may also occur as submarine groundwater discharge (SGD), yet there are no direct observations of this phenomenon in the Arctic shelf seas. This study tests the hypothesis that SGD does exist in the Siberian-Arctic shelf seas but its dynamics may be largely controlled by complicated geocryological conditions such as permafrost. The field-observational approach in the southeast Laptev Sea used a combination of hydrological (temperature, salinity), geological (bottom sediment drilling, geoelectric surveys) and geochemical (224Ra, 223Ra and 222Rn) techniques. Active SGD was documented in the vicinity of the Lena River delta with two different operational modes. In the first system, groundwater discharges through tectonogenic permafrost talik zones was registered in both wintertime and summertime seasons. The second SGD mechanism was cryogenic squeezing out of brine and water-soluble salts detected on the periphery of ice hummocks in the wintertime season. The proposed mechanisms of groundwater transport and discharge in the arctic land-shelf system is elaborated. Through salinity versus 224Ra and 224Ra/223Ra diagrams, the three main SGD-influenced water masses were identified and their end-member composition was constrained. Further studies should apply these techniques to a broader scale with the objective to reach an estimate of the relative importance of the SGD transport vector relative to surface freshwater discharge for both the water balance and aquatic components such as dissolved organic carbon, carbon dioxide, methane, and nutrients.

The Eastern Siberian Margin (ESM), a vast region of the Arctic, potentially holds large amounts of methane in sediments as gas hydrate and free gas. Although this CH4 has become a topic of discussion, primarily because of rapid regional climate change, the ESM remains sparingly explored. Here we present pore water chemistry results from 32 cores taken during Leg 2 of the 2014 SWERUS-C3 expedition. The cores come from depth transects across the continental slope of the ESM between Wrangel Island and the New Siberian Islands. Upward CH4 flux towards the seafloor, as inferred from profiles of dissolved sulfate (SO42−), alkalinity, and the δ13C-dissolved inorganic Carbon (DIC), is negligible at all stations east of where the Lomonosov Ridge abuts the ESM at about 143° E. In the upper eight meters of these cores, downward sulfate flux never exceeds 9.2 mol/m2-kyr, the upward alkalinity flux never exceeds 6.8 mol/m2-kyr, and δ13C-DIC only slowly decreases with depth (−3.6 ‰/m on average). Additionally, dissolved H2S was not detected in these cores, and nutrient and metal profiles reveal that metal oxide reduction by organic carbon dominates the geochemical environment. A single core on Lomonosov Ridge differs, as diffusive fluxes for SO42− and alkalinity were 13.9 and 11.3 mol/m2-kyr, respectively, the δ13C-DIC gradient was 5.6 ‰/m, and Mn2+ reduction terminated within 1.3 m of the seafloor. These are among the first pore water results generated from this vast climatically sensitive region, and they imply that significant quantities of CH4, including gas hydrates, do not exist in any of our investigated depth transects spread out along much of the ESM continental slope. This contradicts previous assumptions and hypothetical models and discussion, which generally have assumed the presence of substantial CH4.

The SayanTuva Highland is the only region in South Siberia for which the evolution of lakes and lacustrine sedimentation is absolutely unknown. This constrains studies of the regional evolution of the Late Pleistocene-Holocene period. The results of the present study are aimed to fill this gap. Sedimentary cores in TereKhol Lake have been studied by a set of methods. The columns cover the whole history of the modern lake basin here, so the time and causes of lake appearance have been determined, variations in the water regime of the lake have been traced, and the first data on humidity of the paleoclimate, paleohydrology, and paleocryogenesis in the southeastern SayanTuva Highland during the Holocene have been obtained. The TereKhol Basin ( 50°40' N, 97°30' E) is a small

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (∼140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening., The development of pan-Arctic Ocean ice shelves during peak glacials was proposed in the 1970s, an idea that has been disputed due to lack of evidence. Here, the authors present geophysical mapping data supporting the presence of such an ice shelf during the peak of the penultimate glaciation ∼140–160 ka.