The frozen moraine soil is geographically distributed across the Qinghai-Tibet Plateau and its surrounding areas, serving as a fundamental substrate for engineering projects such as the Sichuan-Tibet Railway and the ChinaPakistan Highway. As an economical and efficient construction technique, blasting is a commonly employed in these projects. Understanding the dynamic mechanical response, damage, and failure characteristics of moraine soil is crucial for accurately predicting the impact of blasting. Therefore, this study utilizes the Split Hopkinson Pressure Bar (SHPB) equipment to conduct impact tests on moraine soil under different temperatures and strain rates. Additionally, a model for predicting the dynamic mechanical response of frozen moraine soil has been proposed based on peridynamic theory, decohesion damage theory, and the ZWT model, in which the debonding damage and the adiabatic temperature rise are considered. This model focuses on considering the bonds between different substances within frozen moraine soil. By defining the mechanical response of these bonds, the impact deformation mechanism of frozen moraine soil is unveiled. Within this, the modeling of icecemented bonds contributes to a deeper understanding of the crack propagation characteristics in frozen moraine soil. The model prediction results demonstrate its capability to predict various aspects of the dynamic response of frozen moraine under impact loading, including the macroscopic stress-strain behavior, the mesoscopic crack initiation and propagation, and the influence of adiabatic temperature rise on the damage mechanism, as well as evaluate the damage state of frozen moraine soil under impact loading.

Rock-ice avalanches have frequently occurred in the Eastern Himalayan Syntaxis region due to climate change and active tectonic movements. These events commonly trigger catastrophic geohazard chains, including debris flows, river blockages, and floods. This study focuses on the Zelongnong Basin, analyzing the geomorphic and dynamic characteristics of high-altitude disasters. The basin exhibits typical vertical zonation, with disaster sources initiating at elevations exceeding 4000 m and runout distances reaching up to 10 km. The disaster chain movement involves complex dynamic effects, including impact disintegration, soil-rock mixture arching, dynamic erosion, and debris deposition, enhancing understanding of the flow behavior and dynamic characteristics of rock-ice avalanches. The presence of ice significantly increases mobility due to lubrication and frictional melting. In the disaster event of September 10, 2020, the maximum flow velocity and thickness reached 40 m/s and 43 m, respectively. Furthermore, continuous deformation of the Zelongnong glacier moraine was observed, with maximum cumulative deformations of 44.68 m in the distance direction and 25.96 m in the azimuth direction from March 25, 2022, to August 25, 2022. In the future, the risk of rock-ice avalanches in the Eastern Himalayan Syntaxis region will remain extremely high, necessitating a focus on early warning and risk mitigation strategies for such basin disasters.

Moraines, characterized by the accumulation of rock and soil debris transported by glacial activity, present unique challenges for tunnel construction, particularly in portal sections, due to prevailing geographical and climatic conditions that facilitate freeze-thaw action. Despite these challenges, there is a dearth of studies investigating the influence of freeze-thaw action and water content on the mechanical properties of moraines, and no research on calculating surrounding rock pressure in moraine tunnels subjected to freeze-thaw conditions. In this study, direct shear tests under freeze-thaw cycles were conducted to examine the effects of freeze-thaw cycles and water content on the mechanical properties of frozen moraine. A comprehensive parameter K, integrating the number of freeze-thaws and water content, was introduced to model cohesion c. Drawing on Terzaghi Theory, we propose an improved algorithm for calculating surrounding rock pressure at the portal of moraine tunnels. Using a tunnel as a case study, surrounding rock pressure was calculated under various conditions to validate the Improved Algorithm's efficacy. The results show that: (1) Strength loss exhibits a linear trend with the number of freeze-thaw cycles at water content levels of 4% and 8%, while at 12% water content, previous freeze-thaw cycles induce more significant damage to the soil. (2) Moraine saturation peaks between 8% and 12% water content. Following repeated freeze-thaw cycles, moraine shear strength initially increases before decreasing with varying water content. (3) The internal friction angle of moraine experiences slight reductions with prolonged freeze-thaw cycles, but both freeze-thaw cycles and water content significantly influence cohesion. (4) Vertical surrounding rock pressure increases after the initial freeze-thaw cycle, particularly with higher water content, although freeze-thaw cycles have minimal effect on it. (5) Freeze-thaw cycles lead to a substantial increase in lateral surrounding rock pressure, necessitating reinforced support structures at the arch wall, arch waist, and arch foot in engineering projects to mitigate freeze-thaw effects. This study provides a foundation for designing and selecting tunnel support structures in similar geological conditions.

Moraine soils are widely distributed in southeast Tibet of China, which poses a serious threat to local railway construction. The mechanical behavior of moraine soil containing ice in cold regions is difficult to capture under the joint action of stress conditions and temperature. To study the strength characteristics of ice-rich moraine soil, a total of 112 groups of thermal-mechanical triaxial tests under different ice forms, ice contents, and temperature conditions are carried out. The test results show that the mechanical properties of moraine soil with crushed ice and block ice are different, showing the characteristics of strain hardening and strain softening, respectively. Overall, the peak strength of moraine soil with block ice is greater than that of crushed ice. The cohesion and internal friction angle of moraine soil decreases with the temperature rise. With the increase of ice content, the peak strength of moraine soil with block ice increases, while that of crushed ice shows the opposite trend. In addition, the increase of ice content increases the cohesion of moraine soil with block ice, but there is a threshold value of ice content (25%) for moraine soil with crushed ice, which leads to the maximum cohesion at this time. Based on the test results, a unified function is proposed to describe the quantitative relationship between the strength parameters of ice-rich moraine soil, temperature, and ice content. Finally, to explore the nonlinear strength behavior of moraine soil, a binary-medium model is introduced to describe its stress-strain relationship, and the evolution of the main parameters in the model is analyzed. Comparing theoretical and experimental results demonstrates that the established model is of satisfactory applicability to simulate the mechanical behavior of moraine soil with different ice forms.

Mount Everest provides natural advantages to finding radiation-resistant extremophiles that are functionally mechanistic and possess commercial significance. (1) Background: Two bacterial strains, designated S5-59T and S8-45T, were isolated from moraine samples collected from the north slope of Mount Everest at altitudes of 5700m and 5100m above sea level. (2) Methods: The present study investigated the polyphasic features and genomic characteristics of S5-59(T) and S8-45(T). (3) Results: The major fatty acids and the predominant respiratory menaquinone of S5-59(T) and S8-45(T) were summed as feature 3 (comprising C16:1 omega 6c and/or C16:1 omega 7c) and ubiquinone-10 (Q-10). Phylogenetic analyses based on 16S rRNA sequences and average nucleotide identity values among these two strains and their reference type strains were below the species demarcation thresholds of 98.65% and 95%. Strains S5-59(T) and S8-45(T) harbored great radiation resistance. The genomic analyses showed that DNA damage repair genes, such as mutL, mutS, radA, radC, recF, recN, etc., were present in the S5-59(T) and S8-45(T) strains. Additionally, strain S5-59(T) possessed more genes related to DNA protection proteins. The pan-genome analysis and horizontal gene transfers revealed that strains of Sphingomonas had a consistently homologous genetic evolutionary radiation resistance. Moreover, enzymatic antioxidative proteins also served critical roles in converting ROS into harmless molecules that resulted in resistance to radiation. Further, pigments and carotenoids such as zeaxanthin and alkylresorcinols of the non-enzymatic antioxidative system were also predicted to protect them from radiation. (4) Conclusions: Type strains S5-59(T) (=JCM 35564T =GDMCC 1.3193T) and S8-45(T) (=JCM 34749T =GDMCC 1.2715T) represent two novel species of the genus Sphingomonas with the proposed name Sphingomonas qomolangmaensis sp. nov. and Sphingomonas glaciei sp. nov. The type strains, S5-59(T) and S8-45(T), were assessed in a deeply genomic study of their radiation-resistant mechanisms and this thus resulted in a further understanding of their greater potential application for the development of anti-radiation protective drugs.

The study analyzed synthetically spatiotemporal distribution and evolution status of moraine-dammed lakes and potential dangerous glacial lakes (PDGLs) in the Qinghai-Tibetan Plateau (QTP) and revealed integrated risk degree of county-based glacier lake outburst floods (GLOFs) disaster by combining hazard of PDGLs, regional exposure, vulnerability of exposed elements, and adaptability and using the analytic hierarchy process and weighted comprehensive method. The results show there are 654 moraine-dammed lakes (> 0.018 km(2)) with a total area of 200.25 km(2)in the QTP in the 2010s, of which 246 lakes with a total area of 78.38 km(2)are identified as PDGLs. Compared with 1990s, the number of lakes decreased only by 2.22%, whereas total lake area expanded by 25%. All PDGLs area increased by 84.40% and was higher significantly than 4.06% of non-PDGLs. The zones at very high and high integrated risk of GLOF disasters are concentrated on the middle Himalayas, middle-eastern Nyainqentanglha, and southern Tanggula Mountain. On the county scale, Nyalam, Tingri, Dinggye, Lhozhag, Zhongba, Gamba, Kangma of the Himalayas, and Nierong, Dingqing, Banbar, Baqing, Bomi, and Basu of the Nyainqentanglha are located in the very high-risk zone, whereas other areas have low and very low integrated risk. The regionalization results for GLOF disasters risk are consistent with the distribution of historical GLOF disaster sites.

A bacterial strain, designated S9-5(T), was isolated from moraine samples collected from the north slope of Mount Everest at an altitude of 5500 m above sea level. A polyphasic study confirmed the affiliation of the strain with the genus Sphingomonas. Strain S9-5(T) was an aerobic, Gram-stain-negative, non-spore-forming, non-motile and rod-shaped bacterium that could grow at 10-40 degrees C, pH 5-8 and with 0-9% (w/v) NaCl. Q-10 was its predominant respiratory menaquinone. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid, an unidentified aminophospholipid and eight unidentified lipids comprised the polar lipids of strain S9-5(T). Its major fatty acids were summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c) and C-16:0. The G+C content was 65.75mol%. Phylogenetic analysis based on 16S rRNA sequences showed that strain S9-5(T) was phylogenetically closely related to Sphingomonas panaciterrae DCY91(T) (98.17%), Sphingomonas olei K-1-16(T) (98.11%) and Sphingomonas mucosissima DSM 17494(T) (97.39%). The average nucleotide identity values among strain S9-5(T) and Sphingomonas panaciterrae DCY91(T), Sphingomonas olei K-1-16(T) and Sphingomonas mucosissima DSM 17494(T) were 78.82, 78.87 and 78.29%, respectively. Based on the morphological, physiological and chemotaxonomic data, strain S9-5(T) (=JCM 34750(T)=GDMCC 1.2714(T)) should represent a novel species of the genus Sphingomonas, for which we propose the name Sphingomonas radio-durans sp. nov.

Soils in ice-free areas of Elephant Island (South Shetland Islands) have been forming since the last deglaciation following the glacial retreat that started in the area probably later than 9.7-5.5 ka. In paraglacial landscapes, landforms and processes in transition from glacial to nonglacial conditions are experiencing rapid environmental adjustments under conditions of climate change. Soils are highly sensitive and can be good descriptors of these transitional changes. A soil sampling campaign was undertaken for characterizing soils developed on moraines and marine platforms, underlain by metamorphic rocks and with distinctive periglacial features. Eight soil profiles were sampled to investigate the processes involved in their development and the relations with main landforms and processes of ice retreat. The stony Cryosols with mosses and lichens coverage are developed in permafrost environment with an active layer depth of 15-150 cm. Soil organic C content (0.16-1.6%) and large variations of P, K and N contents are related to ornithogenic activity. Soils on moraines and platforms show differences that reflect the more recent exposure of moraines that preserve most the characteristics of the parent material. More vegetated soils on platforms show Cs-137 and Pb-210(ex) activities (11 and 25 Bq kg(-1), respectively) at the topsoil whereas absence of Cs-137 and depleted levels of Pb-210(ex) occurred in more recently exposed and less developed soils on moraines. Fallout radionuclides are good tracers for identifying characteristics of soil development and providing information on environmental changes of interest to understand the soil response to actual changes in unstable paraglacial environments.