Underground Ice Research Articles

Water on Mars—A Literature Review

To assess Mars’ potential for both harboring life and providing useable resources for future human exploration, it is of paramount importance to comprehend the water situation on the planet. Therefore, studies have been conducted to determine any evidence of past or present water existence on Mars. While the presence of abundant water on Mars very early in its history is widely accepted, on its modern form, only a fraction of this water can be found, as either ice or locked into the structure of Mars’ plentiful water-rich materials. Water on the planet is evaluated through various evidence such as rocks and minerals, Martian achondrites, low volume transient briny outflows (e.g., dune flows, reactivated gullies, slope streaks, etc.), diurnal shallow soil moisture (e.g., measurements by Curiosity and Phoenix Lander), geomorphic representation (possibly from lakes and river valleys), and groundwater, along with further evidence obtained by probe and rover discoveries. One of the most significant lines of evidence is for an ancient streambed in Gale Crater, implying ancient amounts of “vigorous” water on Mars. Long ago, hospitable conditions for microbial life existed on the surface of Mars, as it was likely periodically wet. However, its current dry surface makes it almost impossible as an appropriate environment for living organisms; therefore, scientists have recognized the planet’s subsurface environments as the best potential locations for exploring life on Mars. As a result, modern research has aimed towards discovering underground water, leading to the discovery of a large amount of underground ice in 2016 by NASA, and a subglacial lake in 2018 by Italian scientists. Nevertheless, the presence of life in Mars’ history is still an open question. In this unifying context, the current review summarizes results from a wide variety of studies and reports related to the history of water on Mars, as well as any related discussions on the possibility of living organism existence on the planet.

Structural and textural features of genetic types of the massive and ice wedges, and the conditions of their formation in the lower reaches of the Gyda River

In the structure of the frozen thickness of the 2nd lake-alluvial terrace of the Gyda River were detected polygonal-wedge, lens massive and lensoid ice were. A detailed analysis of structural and textural peculiarities in the layers was carried out for the first time for these morphological types of underground ice. Based on the cryolithological structure of host rocks and structural-textural features of ice, the main mechanisms of deposit formation – polygonal-wedge, infiltration-segregational, and congelation were determined. The development of polygonal-wedge ice occurred in an alluvial floodplain setting of sedimentation accompanied by the climate fluctuations in the end of the Late Pleistocene and Holocene. The growth of ice wedge in the second half of the Sartan Period was interrupted under the reservoirs with shallow talik waters, after freezing of which there formed infiltration-segregational lensoid formation ices. The structure of frozen thickness was complicated by the lenses of congelation ice formed in thermoerosive niches in the Holocene optimum of about 6.5 thousand years ago. At the present time is possible the formation of similar types of ice on various sections of the relief. The established peculiarities of cryogenic structure are important for the creation of paleogeographic reconstructions and forecasting the dynamics of permafrost-facies environments accompanied by the modern changes in the depth of the seasonal thaw layer and the development of thermokarst.

Hydrology and Ion Sink of the Arctic River Alazeya

The features of hydrology and flow of dissolved substances of the Alazeya River located above the Arctic Circle in the area of continuous distribution of permafrost are considered. As starting materials the results of field studies and laboratory analyses of water samples made by the complex research expedition were used. The Alazeya River in hydrological and hydro chemical relation is a little-studied river of the Arctic zone. The river basin is characterized by minimal human pressure. The territory of the Alazeya basin is one of the hard-to-reach Arctic regions of the North-East Yakutia with natural complexes. Precipitation, groundwater and underground ice of active layer and permafrost are the primary power supply of surface waters. Annually 0.5 million tons of dissolved substances are removed by the processes of fluvial denudation from the Alazeya basin to the East Siberian Sea. Module of the ion sink is very low - 6.8 tons/km2. It is typical for the sluggish rivers of the Arctic regions. Minimum value is a result of the Arctic climatic and landscape parameters affecting the intensity of chemical weathering of rocks. The ion sink of the Alazeya River is almost independent from human influence and determined by the geochemical properties of elements, lithological features of rocks and soil composition of the river basin, climatic conditions, and vegetation

ГИДРОХИМИЧЕСКИЙ СОСТАВ И РЕДКОЗЕМЕЛЬНЫЕ ЭЛЕМЕНТЫ В ПОЛИГОНАЛЬНО-ЖИЛЬНЫХ ЛЬДАХ КЛЮЧЕВЫХ РАЙОНОВ КРИОЛИТОЗОНЫ КАРСКОГО РЕГИОНА

Актуальность исследования. Информация о составе, льдистости и геохимических особенностях мерзлых пород необходима при освоении нефтегазоконденсатных месторождений Ямала, Гыдана и Таймыра. Среди факторов, определяющих экологию тундровых ландшафтов криолитозоны, большое значение имеют подземные льды, в том числе полигонально-жильные, и последствия их вытаивания. Гидрохимический состав и содержание редкоземельных элементов в сингенетических жилах фиксируют информацию об источниках влаги и условиях, при которых происходило их формирование. Соотношение основных ионов и распределение редкоземельных элементов в растворе может быть использовано для оценки влияния на состав льда атмосферных осадков, морских и вулканических аэрозолей, антропогенного загрязнения. Цель: выявить источники поступления химических элементов и оценить влияние типа льдовыделения на гидрохимический состав и распределение редкоземельных элементов в различных генетических типах льда – полигонально-жильном, морском, озерном и фирновом льдах. Объекты: полигонально-жильный лед, вмещающие его отложения, сезонные льды, поверхностные воды, отобранные в экспедициях ИКЗ ТюмНЦ СО РАН в 2009–2014 гг. Методы исследования химического состава: масс-спектрометрия с индуктивно связанной плазмой, атомно-абсорбционная спектрометрия, эмиссионная фотометрия, хроматография. Результаты. Установлено, что на химический состав полигонально-жильных льдов, изученных в прибрежной зоне ключевых участков о. Белый, о. Сибирякова, Западного Ямала и Западного Таймыра, имели влияние морские и континентальные аэрозоли. Сингенетические полигонально-жильные льды, пресные и ультрапресные по минерализации, сформированы при промерзании талых вод, которые содержат сорбированные снегом морские аэрозоли – взвешенные в атмосфере твердые и жидкие частицы. Полигонально-жильные льды в удаленном от моря районе оз. Сохонто не имеют признаков морского влияния по соотношению основных ионов. Полигонально-жильные льды с минеральными включениями формировались не только за счет талых снеговых вод с аэрозолями континентального происхождения, но и за счет надмерзлотных вод. В полигонально-жильных льдах выявлено увеличение содержаний лантаноидов в водорастворимой форме по сравнению с кларковыми значениями и современными поверхностными льдами. По цериевой аномалии в большинстве изученных сингенетических ледяных жил подтверждается участие морских аэрозолей. По распределениям редкоземельных элементов выявлено характерное для полигонально-жильных льдов соотношение легких и тяжелых редкоземельных элементов равное 0,9, и соотношение лантана к остальным лантаноидам, равное 0,2. Морской лед наследует минерализацию и состав морской воды. Озерный лед различается по глубине и отражает сезонное изменение гидрохимического состава при ледоставе и повышение концентрации морских аэрозолей в снеге, перекрывающем озерный лед. Фирновый лед полярного Урала имеет очень низкую минерализацию, в нем отсутствуют примеси морского аэрозоля. В полигонально-жильных льдах голоценового и неоплейстоценового возраста реализован природный механизм накопления редкоземельных элементов в водорастворимой форме в комплексе с железом, торием и иттрием. Вытаивание ледяных жил может приводить к поступлению редкоземельных элементов в поверхностные воды.

Landscape-permafrost conditions and factors of summer runoff formation of small coastal lowland rivers

River feed and flow regime in the Anadyr lowland remain stable with significant interannual fluctuations in the amount of summer precipitation (70-180 mm). The lack of summer precipitation is compensated by the suprapermafrost groundwater of the active layer, which is formed by meltwater from seasonal underground ice. In July 2019, complex permafrost-hydrological studies were conducted in the Ugolnaya-Dionisia river basin (Chukotka, Russia) to determine the patterns of formation and dynamics of underground and surface runoff. Seasonal active layer groundwater storage that formed as a result of the melting of seasonal ice was estimated. The territory was classified according to the unite discharge, potential and established water sources. Patterns and factors of seasonal and daily dynamics of the river regime are revealed.

Temperature Dependence of Stress-Strain Properties of Freshwater Ice

We present the results of experimental investigation of the temperature dependences of the stress-strain properties of freshwater ice and pykrete. It is shown that, as the temperature of freshwater ice decreases from −1.0 down to −6.0 °C, the ultimate conditionally instant and long-term strengths of freshwater ice increase according to a linear law, whereas the temperature dependence of the viscosity coefficient is nonlinear. For a fixed temperature, the viscosity coefficient of the natural underground ice increases with its density and strongly decreases as the load increases.

Satellite images in the new Atlas «Russian Arctic»

The increasing interest in the Arctic promotes appearance of new cartographic products to provide information for the primary tasks of this region development. So, several atlases of the Arctic have been already published. At the initiative and with the financial support from the oil and gas industry, a new Atlas «Russian Arctic» is being prepared for publication, in which considerable attention is given to the environmental aspects of the development of the North with account for conditions of changing climate. Unlike previous atlases, this Atlas contains thematic sets of satellite images reflecting changes in the natural environment, in particular, different types of natural ice under conditions of warming. The space part of the Atlas developed by the authors of this article covers a number of subjects. Thus, the decrease in the area of sea ice is illustrated by the materials of shooting from the space of the Northern polar cap for the period of the largest reduction in the area. Images made in different time fix retreating of the shores, composed of underground ice, being the result of the processes of thermal abrasion, thermal erosion and thermal denudation. Complicated ice conditions of navigation in the Ob Bay and characteristics of the Arctic rivers mouths are presented by pictures of tidal estuaries of the rivers Mezen and Kuloi. Images of ice jams at the mouth of the Northern Dvina River and materials of space monitoring of measures for liquidation of them are also given in the Atlas. Special attention is given to forms of permafrost relief, which are well displayed in high-resolution images. They show a polygonal micro-relief of different types and stages of development of them, as well as frost mounds, dales, and thermo-erosion forms. Formation of aufeises (naleds), thermokarst lakes, and craters of gas outbursts is also shown. The wildlife of the Arctic is represented in the Atlas as well. The pictures present a visual image of different types of tundra. The influence of warming on vegetation development is well reflected in the photo map of the dynamics of the vegetation index for 2000-2009, showing the growth of phytomass in the European North. The Atlas contains unique materials of satellite monitoring of Arctic mammals - walruses and seals. The impact of using mineral resources on the vulnerable nature of the Arctic is shown in the Khibiny region. Prominent examples of the vegetation degradation in the areas of Norilsk and Monchegorsk cities are given, where technogenic wastelands have been formed under the sulfuric acid fumes of the copper-nickel plants.

About the nature of short-period fluctuations of seasonal thawing depth in tundra soils

The series of 20-year-long observations of seasonal thawing have been studied on CALM plots in Eurasia and North America. The short-term (2-5 years) fluctuations of the active layer are considered. Similarities and differences in seasonal thawing of tundra soils in circumpolar countries are noted. The dynamics of seasonal thawing is analyzed by the example of two CALM plots in the Chukotka Autonomous District. Time series of changes in the depth of seasonal thawing are described using the mathematical methods. The amplitude, frequency and periods of oscillations are determined for them. The comparative graphical and statistical analysis of climate and seasonally thawed layer variations allowed us to judge on the nature and degree of influence of meteorological factors on the depth of soil thawing. The problems of interpretation of intra-century fluctuations of climatic parameters and seasonal thawing are considered. It is concluded that the duration of the warm season affects significantly the depth of seasonal thawing. It is noted that ignoring the intra-century variations in the parameters of climatic and permafrost landscapes is the cause of inconsistency of judgments about climate change trends and forecasts of permafrost degradation.
 A new concept of “climatic year” was proposed as the conjugation of weather conditions for 2-3 years equally affecting the depth of thawing. The established statistical regularities in changing permafrost-climatic conditions can be used for the preparation of 3-5 and 10-15 summer weather forecasts. The use of the ratio of the average values of the amplitude to the period of short oscillations as an indicator of the stability of the roof of permafrost is justified.
 The hypothesis of the influence of solar and technogenic electromagnetic radiation in the radio-wave range on the degradation of underground ice of the active layer and Arctic ice is proposed.

Total and Potentially Active Bacterial Communities Entrapped in a Late Glacial Through Holocene Ice Core From Scarisoara Ice Cave, Romania.

Our understanding of the icy-habitat microbiome is likely limited by a lack of reliable data on microorganisms inhabiting underground ice that has accumulated inside caves. To characterize how environmental variation impacts cave ice microbial community structure, we determined the composition of total and potentially active bacterial communities along a 13,000-year-old ice core from Scarisoara cave (Romania) through 16S rRNA gene Illumina sequencing. An average of 2,546 prokaryotic gDNA operational taxonomic units (OTUs) and 585 cDNA OTUs were identified across the perennial cave ice block and analyzed in relation to the geochemical composition of ice layers. The total microbial community and the putative active fraction displayed dissimilar taxa profiles. The ice-contained microbiome was dominated by Actinobacteria with a variable representation of Proteobacteria, while the putative active microbial community was equally shared between Proteobacteria and Firmicutes. Accordingly, a major presence of Cryobacterium, Lysinomonas, Pedobacter, and Aeromicrobium phylotypes homologous to psychrotrophic and psychrophilic bacteria from various cold environments were noted in the total community, while the prevalent putative active bacteria belonged to Clostridium, Pseudomonas, Janthinobacterium, Stenotrophomonas, and Massilia genera. Variation in the microbial cell density of ice strata with the dissolved organic carbon (DOC) content and the strong correlation of DOC and silicon concentrations revealed a major impact of depositional processes on microbial abundance throughout the ice block. Post-depositional processes appeared to occur mostly during the 4,000–7,000 years BP interval. A major bacterial composition shift was observed in 4,500–5,000-year-old ice, leading to a high representation of Beta- and Deltaproteobacteria in the potentially active community in response to the increased concentrations of DOC and major chemical elements. Estimated metabolic rates suggested the presence of a viable microbial community within the cave ice block, characterized by a maintenance metabolism in most strata and growth capacity in those ice deposits with high microbial abundance and DOC content. This first survey of microbial distribution in perennial cave ice formed since the Last Glacial period revealed a complex potentially active community, highlighting major shifts in community composition associated with geochemical changes that took place during climatic events that occurred about 5,000 years ago, with putative formation of photosynthetic biofilms.

Analysis of roadbed destabilization causes on sections with thaw underground ice and reinforcement reconstruction measures

The roadbed on over-wet permafrost and underground ice sections requires a thorough examination after a long-term exploitation period. Its strengthening design requires an individual technological approach. The paper considers two examples. The first one is located on the 28th km section of the Chulman passing siding entrance, and the second one is on the 59th km of the Amur-Yakutsk Mainline. The causes of the roadbed deformation are determined by the analysis of different surveys, special engineering and geological methods as well as the geometry car ongoing data. Some new technological design solutions that are patented and introduced on working sites are covered in the paper.

Geochemistry of ice in frost mounds in the valley of the River Sentsa (Oka plateau, East Sayan)

Te authors examined the chemical composition of underground ice sampled from the frost mounds located in the loose (unconsolidated) sediments of the Sentsa River valley (Oka plateau, Eastern Sayan) with the purpose of reconstruction the formation history of these cryogenic creations. Numerous frost mounds of various sizes are mainly composed of alternating icy loams, sandy loams, and lenses of pure ice. Samples of underground ice taken in the outcrops of the river ledges and cores from wells together with samples of river and lake waters were analyzed by traditional hydrochemical techniques (methods) in the center "Geodynamics and geochronology" (Institute of the Earth's Crust of the Siberian branch of RAS, Irkutsk). It was found that the chemical composition of pure ice melts from lenses and layers of the frost mounds is hydrocarbonate calcium (HCO3 Ca, SO4-HCO3 Ca and NH4-HCO3 Ca) with mineralization of 6.5 – 15.6 mg/L, pH = 5.6÷6.1. Mineralization of melts of texture-forming ice, taken from icy ground (i.e. with fractions of enclosing loams) was much higher – from 50 to 792.5 mg/L. River and lake water is ultra-fresh with 99–132 mg/L salinity, and according to geochemical type it is hydrocarbonate calcium (HCO3 Ca). Te specifc features of chemical composition of the underground ice (high content of ammonium salts and sulfates) depend on a water-rock interaction, the presence of organic matter in the loose (unconsolidated) sediments and a repeated volcanic activity in the late Pleistocene–Holocene. Te frost mounds are confned to a lacustrine sediments area in the backwater zone that was formed by the Late Pleistocene terminal moraine. Teir formation in the Holocene took place as a result of segregational ice formation during freezing of water-saturated lake sediments, and, presumably, repeated injections of underground waters of the under-channel and floodplain aquifers hydraulically connected with river waters. Tus, the genesis of the studied frost mounds is probably a mixed segregation-injection process.

REGULARITIES OF GEOCHEMICAL COMPOSITION FORMATION OFUNDERGROUND ICE AND DEPOSITS ON THE NORTH OF THE GYDAN PENINSULA

The study of underground ice and frozen soils on the north of the Gydan Peninsula was made in 2016. The article is devoted to the results of the study. The granulometric and geochemical composition of the frozen deposits, the hydrochemical composition of the underground ice were determined. The interrelation between the composition and genesis of ice, with accumulation and freezing conditions of deposits was identified.

Bacterial and archaeal community structures in perennial cave ice

Ice entrenched microcosm represents a vast reservoir of novel species and a proxy for past climate reconstitution. Among glacial ecosystems, ice caves represent one of the scarcely investigated frozen habitats. To characterize the microbial diversity of perennial ice from karst ecosystems, Roche 454 sequencing of 16S rRNA gene amplicons from the underground ice block of Scarisoara Ice Cave (Romania) was applied. The temporal distribution of bacterial and archaeal community structures from newly formed, 400, and 900 years old ice layers was surveyed and analyzed in relation with the age and geochemical composition of the ice substrate. The microbial content of cave ice layers varied from 3.3 104 up to 7.5 105 cells mL−1, with 59–78% viability. Pyrosequencing generated 273,102 reads for the five triplicate ice samples, which corresponded to 3,464 operational taxonomic units (OTUs). The distribution of the bacterial phyla in the perennial cave ice varied with age, organic content, and light exposure. Proteobacteria dominated the 1 and 900 years old organic rich ice deposits, while Actinobacteria was mostly found in 900 years old ice strata, and Firmicutes was best represented in 400 years old ice. Cyanobacteria and Chlorobi representatives were identified mainly from the ice block surface samples exposed to sunlight. Archaea was observed only in older ice strata, with a high incidence of Crenarchaeota and Thaumarchaeaota in the 400 years old ice, while Euryarchaeota dominated the 900 years old ice layers, with Methanomicrobia representing the predominant taxa. A large percentage (55.7%) of 16S rRNA gene amplicons corresponded to unidentified OTUs at genus or higher taxa levels, suggesting a greater undiscovered bacterial diversity in this glacial underground habitat. The prokaryotes distribution across the cave ice block revealed the presence of 99 phylotypes specific for different ice layers, in addition to the shared microbial community. Ice geochemistry represented an important factor that explained the microbial taxa distribution in the cave ice block, while the total organic carbon content had a direct impact on the cell density of the ice microcosm. Both bacterial and archaeal community structures appeared to be affected by climate variations during the ice formation, highlighting the cave ice microbiome as a source of putative paleoclimatic biomarkers. This report constitutes the first high-throughput sequencing study of the cave ice microbiome and its distribution across the perennial underground glacier of an alpine ice cave.

METHANE IN GROUND ICE AND FROZEN SEDIMENTS IN THE COASTAL ZONE AND ON THE SHELF OF KARA SEA

Summary Degradation of permafrost on the continental shelf and shores of the Arctic seas may be a main cause of the methane emission to the atmosphere from marine sediments. To quantify this effect it is necessary to have reliable data on the methane content in the underground ice and frozen Quaternary deposits. Samples of frozen (permafrost) sediments and ground ice, taken in three reference coastal sections made in the Mid- and Late Pleistocene coastal exposures and on the Kara sea shelf, were collected and studied. The samples were analyzed to determine composition, salinity, organic carbon content, and other characteristics of the underground ices. About 270 samples allowed determination of the gas composition and the methane concentration. The gas is present in the pores of the rocks and air bubbles in the ice. Gas was present in pores of sediments and in bubbles within the ice. It has been established that the composition of non-hydrocarbon gases in the underground ice does not correspond to the composition of the atmosphere in the time of formation of them. The methane content in the underground ice and frozen sediments is characterized by very high variability. The highest concentrations of methane are inherent in layers of the massive ground ice and reach up to 23000 ppm; the maximum concentration of methane in the massive vein ices does not exceed 900 ppm. High concentrations of methane in layers of the massive ice confirm their non-glacier formation. The highest, up to 6400 ppm, methane concentrations in permafrost sediments are characteristic for the Late Pleistocene marine clays, while in the Mid Pleistocene marine clays it does not exceed 1700 ppm. The isotopic composition of methane in frozen sediments and ground ice in both, the Cara Sea coast and shelf, is indicative of similar bacterial genesis of the gas. The total organic carbon content plays the limiting role in the methane production and its accumulation in the frozen sediments and ground ice.

Geologic - geotechnical characteristics and preservation proposals for the Historic Site and Monument n° 38, Nordenskjöld’s Hut, Antarctica

The historic site and monument nº 38, Nordenskjöld Hut, is located on Snow Hill Island, James Ross archipelago, Antarctica. This is a place of great historic and heritage value because there are very few centennial buildings in Antarctica. This building was built in February 1902 as a refuge by the Swedish expedition directed by Otto Nordenskjöld, between 1901 and 1904. The building is located over an embankment with ice-rich permafrost, which produces unstable conditions for the foundation. In the past, anthropic factors accelerated this process, for example, the use of the hut as a refuge and garage for other field campaigns. Intensive and potentially destructive signs are observed as a consequence of the thermokarst and erosion active processes in the last decades, in relation to climate warming. Around the embankment, the erosion processes are connected with underground ice thaw occurring in the top of the permafrost. The embankment area contains 17–20% of underground ice, and the mean active layer depth is 1.2 m. A potential maximum settlement of the embankment top surface between 0.15-0.25 m has been estimated. The above-mentioned processes are a consequence of ice thaw in the permafrost table. This would modify the natural surface and could produce significant damages. This study analyzes contingency and mitigation strategies to prevent or reduce the rate of settlement and avoid altering the top of the embankment. The goal is to protect the slopes and foundation from surface erosion and thermo-erosion. We propose increasing the thickness of the embankment, making a frame on the shoulder of the embankment, and carrying out a retaining wall or socket in the foundation.

Geomorphological and geochemistry changes in permafrost after the 2002 tundra wildfire in Kougarok, Seward Peninsula, Alaska

AbstractGeomorphological and thermohydrological changes to tundra, caused by a wildfire in 2002 on the central Seward Peninsula of Alaska, were investigated as a case study for understanding the response from ice‐rich permafrost terrain to surface disturbance. Frozen and unfrozen soil samples were collected at burned and unburned areas, and then water isotope geochemistry and cryostratigraphy of the active layer and near‐surface permafrost were analyzed to investigate past hydrological and freeze/thaw conditions and how this information could be recorded within the permafrost. The development of thermokarst subsidence due to ice wedge melting after the fire was clear from analyses of historical submeter‐resolution remote sensing imagery, long‐term monitoring of thermohydrological conditions within the active layer, in situ surveys of microrelief, and geochemical signals recorded in the near‐surface permafrost. The resulting polygonal relief coincided with depression lines along an underground ice wedge network, and cumulative subsidence to 2013 was estimated as at least 10.1 to 12.1 cm (0.9–1.1 cm/year 11 year average). Profiles of water geochemistry in the ground indicated mixing or replenishment of older permafrost water with newer meteoric water, as a consequence of the increase in active layer thickness due to wildfire or past thaw event. Our geocryological analysis of cores suggests that permafrost could be used to reconstruct the permafrost degradation history for the study site. Distinct hydrogen and oxygen isotopic compositions above the Global Meteoric Water Line were found for water from these sites where permafrost degradation with geomorphological change and prolonged surface inundation were suggested.

Underground ice wall at Fukushima nears completion

Underground ice wall at Fukushima nears completion

Methane in ground ice and frozen Quaternary deposits of Western Yamal

The content and the genesis of methane in underground ice and frozen Quaternary sediments of Western Yamal is studied. The minimum concentration of methane in frozen Quaternary deposits was found for sand: 15–100 ppm V. The maximum concentration of methane reaches 3000 ppm V in marine clays. The concentration of methane in the ice wedges is 100–700 ppm V, and in the massive ground ice can be more than 10 000 ppm V. The high content of methane in the massive ground ice we explain by migration of methane from freezing deposits into ice body during its formation. The close connection between methane concentration and organic carbon content is found.

Influence of carbon dioxide on melting of underground ice

Influence of carbon dioxide on melting of underground ice

Main Problems and Solutions on Design and Construction of Qinghai-Tibet DC Transmission Project in Permafrost Region

The Qinghai-Tibet direct-current transmission project crosses the high-altitude permafrost region of the Qinghai-Tibet plateau. The permafrost foundation is characterized by being poor in thermal stability, rich in underground ice, very sensitive to climate warming, and strong in water-thermal activity. The foundation of the transmit electricity engineering therefore faces great challenges including tower foundation type selection and design, permafrost protection in the process of foundation construction and long-term stability. Based on an analysis of the geological engineering conditions and principal geological engineering problems of the project, a study is carried out on the design and construction problems of the transmission tower foundations in the permafrost region, the systematic analysis is also made regarding the main solutions to these problems with consideration of tower foundations long-term stability. This study will provide a theoretical basis and technical guide for design and construction of transmission lines in the permafrost region, and a reference for construction of transmission line projects in similar regions in China or even in the world.