Dispersive soils, due to their high erodibility and cation exchange sensitivity, pose significant challenges in geotechnical applications. This study investigates the engineering behavior of such soils under a wide range of thermal regimes (25-900 degrees C), focusing on their mechanical, hydraulic, and physicochemical properties. Unlike previous studies that emphasized microstructure alone, this research integrates a broad range of analytical methodsmineralogical (XRD, SEM), chemical (CEC, SSA, carbonate content), and geotechnical (Atterberg limits, unconfined compressive strength, permeability, TGA) to capture a comprehensive understanding of thermal stabilization effects. Results reveal that thermal treatment significantly enhances soil performance: at 300 degrees C, dispersion decreased by 65% due to complete free water removal; at 500 degrees C, dehydroxylation induced structural rearrangement and mineral breakdown, improving both strength and permeability. At 700 degrees C and beyond, the formation of cementitious phases such as gehlenite and anorthite transforms the soil into a dense, non-dispersive medium, increasing UCS by 36.5 times and permeability by 12,000 times. These findings emphasize the effectiveness of high-temperature treatment as a sustainable and technically sound approach for stabilizing dispersive soils in geotechnical and environmental applications, including landfill liners, geothermal barriers, and contaminant containment zones.

The fine-scale controls of active layer dynamics remain poorly understood, particularly at the southern boundary of continuous permafrost. We examined how environmental conditions associated with upland tundra heath, open graminoid fen, and palsa/peat plateau landforms affected active layer thermal regime (timing, magnitude, and rate of thaw) in a subarctic peatland in the Hudson Bay Lowlands, Canada. A significant increase in active layer thaw depth was evident between 2012 and 2024. Within-season thaw patterns differed among landforms, with tundra heath exhibiting the highest thaw rates and soil temperatures, succeeded by fen and palsa. Air temperature mediated by soil properties, topography, and vegetation affected thaw patterns. The increased thermal conductivity of gravel/sandy tundra heath soils exerted a more pronounced influence on thaw patterns relative to fens and palsas, both of which had a thicker organic layer. Near-surface soil moisture was the lowest in tundra, followed by palsas, and fens. Increased soil moisture impeded active layer thaw, likely due to a combination of soil surface evaporation and meltwater percolation. These findings elucidate the relationship between the biophysical properties of landform features and climate, revealing their role in influencing active layer thaw patterns in a subarctic ecosystem.

Understanding the thermal regime of road embankments in cold climates during winter is essential for efficient road design and accurate estimation of maintenance frequencies to reduce freeze-induced damage. In response to the challenging climate conditions in northern Sweden, an experimental field setup was designed to assess the thermal impact of culverts and accumulated snow in ditches on the thermal regime of road embankments during a winter season. This study provides detailed information on the experimental setup, highlights potential challenges from installation phase to data acquisition, and addresses measurement errors. Methods to ensure accuracy and obtain reliable data are also presented. Additionally, some of the obtained measurement results are included in this paper. The results show that snow impacts the thermal regime of the embankment from the onset of accumulation in the ditch, when the snow cover is still thin, until it reaches a depth of 65 cm. Beyond this depth, the soil beneath the snow remains almost unfrozen throughout the winter season. Additionally, the temperature distribution measurements within the embankment indicate that freezing progresses faster near the culvert compared to the rest of the embankment. However, once the culvert ends are insulated by snow cover, the frost depth in the soil near the culvert does not increase significantly, while the rest of the road continues to freeze gradually to greater depths throughout the winter season. The measurement results presented in this study provide researchers with a reliable dataset for validating numerical models in related research areas simulating cold-climate conditions. Additionally, these results enhance the understanding of the thermal regime of road embankments in typical cold climates and offer valuable insights for planning road maintenance and construction in such regions. Furthermore, this study provides essential information for researchers aiming to design and optimize experimental measurement setups in similar investigations.

Understanding the dynamics of soil respiration (Rs) in response to freeze-thaw cycles is crucial due to permafrost degradation on the Qinghai-Tibet Plateau (QTP). We conducted continuous in situ observations of Rs using an Li-8150 automated soil CO2 flux system, categorizing the freeze-thaw cycle into four stages: completely thawed (CT), autumn freeze-thaw (AFT), completely frozen (CF), and spring freeze-thaw (SFT). Our results revealed distinct differences in Rs magnitudes, diurnal patterns, and controlling factors across these stages, attributed to varying thermal regimes. The mean Rs values were as follows: 2.51 (1.10) mu mol center dot m(-2)center dot s(-1) (CT), 0.37 (0.04) mu mol center dot m(-2)center dot s(-1) (AFT), 0.19 (0.06) mu mol center dot m(-2)center dot s(-1) (CF), and 0.68 (0.19) mu mol center dot m(-2)center dot s(-1) (SFT). Cumulatively, the Rs contributions to annual totals were 89.32% (CT), 0.79% (AFT), 5.01% (CF), and 4.88% (SFT). Notably, the temperature sensitivity (Q10) value during SFT was 2.79 times greater than that in CT (4.63), underscoring the significance of CO2 emissions during spring warming. Soil temperature was the primary driver of Rs in the CT stage, while soil moisture at 5 cm depth and solar radiation significantly influenced Rs during SFT. Our findings suggest that global warming will alter seasonal Rs patterns as freeze-thaw phases evolve, emphasizing the need to monitor CO2 emissions from alpine meadow ecosystems during spring.

A new type of thermally controlled subgrade is proposed to mitigate persistent frost heave issues of railway subgrades in seasonally frozen regions. A dedicated ground-source heat pump system collects low-grade geothermal energy from the stable soil layer near the subgrade, converts it into high-grade thermal energy, and transfers it to the frigid subgrade for active heating and temperature control, thereby eliminating the adverse effects of frost heave. A 20-metre-long test of thermally controlled subgrade was constructed in a frost heave of the Junggar-Shenchi Railway in Shanxi Province, China. During the winter spanning 2021 and 2022, the heating temperature of the heat pump, the thermal regime of the test subgrade and the natural subgrade, the frost depth, and the track heave were measured. The results indicate that the heat pump temperature could reach a peak of 59.4 degrees C, with the average daily heating temperature during intermittent operation reaching 25.2 degrees C or higher, indicating an efficient heat source that plays a favourable role. The freezing period of the natural subgrade lasted for 141 days, while the subgrade in the test was 20 days shorter. The maximum frost depths at the track centre, shoulder, and embankment slope toe in the test were 88 cm, 75 cm, and 58 cm, respectively. These depths were 60 cm, 122 cm, and 78 cm less than those of the natural subgrade, effectively controlling the frost depth within the threshold that may cause potential structural damage. Under natural conditions, the track heave reached a peak of 9.4 mm, leading to a harmful frost heave scenario. In contrast, the track deformation in the test was less than 3 mm, which did not exceed the regular maintenance threshold. The thermally controlled subgrade proves to be an effective method for preventing and controlling persistent frost heave damage in critical locations such as low embankments, cut subgrades, turnout areas, and culvert roofs.

Together with warming air temperatures, Arctic ecosystems are expected to experience increases in heavy rainfall events. Recent studies report accelerated degradation of permafrost under heavy rainfall, which could put significant amounts of soil carbon and infrastructure at risk. However, controlled experimental evidence of rainfall effects on permafrost thaw is scarce. We experimentally tested the impact and legacy effect of heavy rainfall events in early and late summer for five sites varying in topography and soil type on the High Arctic archipelago of Svalbard. We found that effects of heavy rainfall on soil thermal regimes are small and limited to one season. Thaw rates increased under heavy rainfall in a loess terrace site, but not in polygonal tundra soils with higher organic matter content and water tables. End-of-season active layer thickness was not affected. Rainfall application did not affect soil temperature trends, which appeared driven by timing of snowmelt and organic layer thickness, particularly during early summer. Late summer rainfall was associated with slower freeze-up and colder soil temperatures the following winter. This implies that rainfall impacts on Svalbard permafrost are limited, locally variable and of short duration. Our findings diverge from earlier reports of sustained increases in permafrost thaw following extreme rainfall, but are consistent with observations that maritime permafrost regions such as Svalbard show lower rainfall sensitivity than continental regions. Based on our experiment, no substantial in-situ effects of heavy rainfall are anticipated for thawing of permafrost on Svalbard under future warming. However, further work is needed to quantify permafrost response to local redistribution of active layer flow under natural rainfall extremes. In addition, replication of experiments across variable Arctic regions as well as long-term monitoring of active layers, soil moisture and local climate will be essential to develop a panarctic perspective on rainfall sensitivity of permafrost. permafrost are limited, locally variable and of short duration. Our findings diverge from earlier reports tained increases in permafrost thaw following extreme rainfall, but are consistent with observations time permafrost regions such as Svalbard show lower rainfall sensitivity than continental regions. Based experiment, no substantial in-situ effects of heavy rainfall are anticipated for thawing of permafrost on under future warming. However, further work is needed to quantify permafrost response to local redistribution active layer flow under natural rainfall extremes. In addition, replication of experiments across variable regions as well as long-term monitoring of active layers, soil moisture and local climate will be essential develop a panarctic perspective on rainfall sensitivity of permafrost.

The absence of vegetation in most ice-free areas of Antarctica makes the soil surface very sensitive to atmosphere dynamics, especially in the western sector of the Antarctic Peninsula, an area within the limits of the permafrost zone. To evaluate the possible effects of regional warming on frozen soils, we conducted an analysis of ground surface temperatures (GSTs) from 2007 to 2021 from different monitoring sites in Livingston and Deception islands (South Shetlands archipelago, Antarctica). The analysis of the interannual evolution of the GST and their daily regimes and the freezing and thawing indexes reveals that climate change is showing impacts on seasonal and perennially frozen soils. Freezing Degree Days (FDD) have decreased while Thawing Degree Day (TDD) have increased during the study period, resulting in a balance that is already positive at the sites at lower elevations. Daily freeze-thaw cycles have been rare and absent since 2014. Meanwhile, the most common thermal regimes are purely frozen - F1 (daily temperatures = +0.5 degrees C). A decrease in F1 days has been observed, while the IS and T1 days increased by about 60 days between 2007 and 2021. The annual number of days with snow cover increased between 2009 and 2014 and decreased since then. The GST and the daily thermal regimes evolution point to general heating, which may be indicative of the degradation of the frozen soils in the study area.

The knowledge of soil thermal properties is important for determining how a soil will behave under changing climate conditions, especially in the sensitive environment of permafrost affected soils. This paper represents the first complex study of the interplay between the different parameters affecting soil thermal conductivity of soils in Antarctica. Antarctic Peninsula is currently the most rapidly warming region of the whole Antarctica, with predictions of this warming to continue in the upcoming decades. This study focuses on James Ross Island, where the Abernethy Flats automatic weather station is located in a lowland area with semi-arid climate. Air and ground temperature, soil heat flux and soil moisture during the thawing season were monitored on this site from 2015 to 2023. Moreover, two approaches to determining soil thermal conductivity were compared - laboratory measurements and calculation from field data. During this period, mean annual temperatures have increased dramatically for both air (from-6.9 degrees C in 2015/2016 to-3.8 degrees C in 2022/2023) and ground (from-6.5 degrees C to-3.2 degrees C), same as active layer thickness (from 68 cm to 95 cm). Average soil thermal conductivity for the thawing period reached values between 0.49 and 0.74 W/m.K-1 based on field data. Statistically significant relationships were found between the seasonal means of volumetric water content and several other parameters - soil thermal conductivity (r = 0.91), thawing degree days (r = -0.87) and active layer thickness (r = - 0.88). Although wetter soils generally have a higher conductivity, the increase in temperature exhibits a much stronger control over the active layer thickening, also contributing to the overall drying of the upper part of the soil profile.

Soil freezing is observed throughout almost the entire forested area of the Russian Federarion in winter. The effect of negative temperatures on dusty-clay soils causes a number of adverse processes that change the properties of the soils themselves. One of the most unfavorable of these processes is the accumulation of moisture in soils under the influence of the movement of the freezing front. When freezing, water-saturated clay soils increase dramatically in volume. This leads to the appearance of frost heaving in the active zone of the forest roadbed, which has an extremely adverse effect on the structure of the entire pavement and can lead to damage to the pavement with a sharp deterioration in the transport and operational qualities of forest roads. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The depth of freezing of the pavement and the roadbed is of the greatest importance for predicting frost heaving and developing measures to combat this phenomenon. The article describes the developed system for monitoring the temperature of the road structure to a depth of 3 m and the measurement results which allow us to evaluate the temperature change at different depths from the road surface and determine the freezing depth. A total of 32 sensors have been installed with a step of 10 cm. A numerical simulation of the freezing process of the pavement and the upper part of the roadbed of a forest road has been performed, with the results compared with the indicators of field observations. Good data convergence has been revealed. According to the results of experimental studies, the freezing value has been 173 cm, and according to the results of numerical simulation - 190 cm. The average error in the results of numerical simulation of the freezing process of the pavement and the upper zone of the forest roadbed has been 8-10 % compared to the experimental data.

Ice-free areas occupy 5 m in bedrock sites in the Antarctic Peninsula. The deepest and most variable ALTs (ca. 40 to >500 cm) were found in the Antarctic Peninsula, whereas the maximum ALT generally did not exceed 90 cm in Victoria Land and East Antarctica. Notably, found that the mean annual near-surface temperature follows the latitudinal gradient of-0.9 degrees C/deg. (R2 = 0.9) and the active layer thickness 3.7 cm/deg. (R2 = 0.64). The continuous permafrost occurs in the vast majority of the ice-free areas in Antarctica. The modelling of temperature on the top of the permafrost indicates also the permafrost presence in South Orkneys and South Georgia. The only areas where deep boreholes and geophysical surveys indicates discontinuous or sporadic permafrost are South Shet-lands and Western Antarctic Peninsula.