The article presents the results of digitizing the maps of submarine permafrost on the shelf of the Arctic seas of Russia. Submarine permafrost mapping relies heavily on expert knowledge because there is a lack of data regarding the structure and thickness of permafrost. Maps compiled by different authors vary significantly due to the use of different approaches, paleogeographic scenarios, ideas about the geological structure, evolution of shelf permafrost, sea level and climatic changes. The first maps were based on the analysis of shelf morphology and seawater temperature; they represent only the assumed boundaries of the submarine permafrost distribution. Later, the distribution of submarine permafrost was associated with neotectonic movements on the modern shelf. As the first drilling and seismoacoustic data were received, more detailed maps were compiled, and the discontinuous distribution of submarine permafrost was substantiated, especially in the Western Arctic. By now, a large amount of seismoacoustic and drilling data has been accumulated, which has made it possible to create new maps based on these data. In recent decades, methods of mathematical modeling the formation and evolution of submarine permafrost have been rapidly developed. Calculated maps of the distribution and depth of submarine permafrost top in the Russian Arctic have been compiled. For the first time, it has become possible to predict the rate of degradation of submarine permafrost under climate warming.

Приводятся результаты изучения проявлений и размеров газовых воронок в озерах трех биоклиматических зон Ямала - северной (арктической), типичной и южной тундры. Установлено, что диаметр газовых воронок в озерах закономерно увеличивается от 1.9 м в северной тундре до 7.7 м в южной кустарниковой тундре. Газовые воронки занимают от 0.5 до 4.3 % мелководий озер. Содержание метана в озерных отложениях в два и более раз выше, чем в породах сезонноталого и переходного слоев доминантных ландшафтов. В зоне типичной тундры содержание метана в озерных отложениях обычно составляет около 7 мл/кг, но в отдельных случаях может достигать 18 мл/кг и более. Вероятно, именно в таких озерах с повышенным содержанием метана в донных отложениях происходят газовые выбросы и формируются газовые воронки. После дренирования (осушения) озер начинается промерзание озерных котловин (хасыреев) и формирование криогенного строения отложений. Через 8-10 лет после осушения озерных котловин продолжаются сукцессионные изменения, формирование переходного слоя еще не завершено. The paper presents the results of studying the appearance and sizes of pockmarks in lakes of three bioclimatic zones of Yamal: northern (arctic), typical, and southern tundra. The diameter of pockmarks in the lakes increases from 1.9 m in the northern tundra to 7.7 m in the southern shrub tundra. Pockmarks occupy from 0.5 to 4.3 % of the shallow-water lake area. The content of methane in lake sediments is two or more times higher than in the sediments of the active and transition layers of dominant landscapes. In the typical tundra zone, the methane content in lake sediments is usually about 7 mL/kg, but in some cases it can reach 18 mL/kg and more. Probably, these are the lakes with the high methane content in bottom sediments, where gas emissions can occur and pockmarks can form. After drainage (drying) of the lakes, lake basins (khasyreys) are subjected to freezing, and the cryogenic structure of lake sediments is formed. Eight-ten years after drying, succession changes in the former lake bottoms continue, and the formation of the transition layer is not yet completed.

Rapid Arctic warming is expected to result in widespread permafrost degradation. However, observations show that site-specific conditions (vegetation and soils) may offset the reaction of permafrost to climate change. This paper summarizes 43 years of interannual seasonal thaw observations from tundra landscapes surrounding the Marre-Sale on the west coast of the Yamal Peninsula, northwest Siberia. This robust dataset includes landscape-specific climate, active layer thickness, soil moisture, and vegetation observations at multiple scales. Long-term trends from these hierarchically scaled observations indicate that drained landscapes exhibit the most pronounced responses to changing climatic conditions, while moist and wet tundra landscapes exhibit decreasing active layer thickness, and river floodplain landscapes do not show changes in the active layer. The slow increase in seasonal thaw depth despite significant warming observed over the last four decades on the Yamal Peninsula can be explained by thickening moss covers and ground surface subsidence as the transient layer (ice-rich upper permafrost soil horizon) thaws and compacts. The uneven proliferation of specific vegetation communities, primarily mosses, is significantly contributing to spatial variability observed in active layer dynamics. Based on these findings, we recommend that regional permafrost assessments employ a mean landscape-scale active layer thickness that weights the proportions of different landscape types.

The results of studying the emission, content, and isotopic composition of methane in soils of the active layer in the zones of typical and southern shrubby tundra of the western Russian Arctic are presented. Methane in the soils of the active layer is of biogenic origin. The maximum methane contents have been recorded in the bogs and the catchment depressions amounting to 1.11 ± 0.95 mg CH4/kg with a maximum value of 4.6 mg CH4/kg. In the well-drained landscapes, the methane content is significantly lower. For the bog landscapes, a strong correlation between methane contents in the soils and sums of positive air temperatures has been determined. Climate warming causes an increase in the methane content in the soils of the active layer and higher methane emission. The gradient distribution of the methane content and its isotopic composition in water-saturated and drained soils indicates a significant contribution of the diffusion mechanism to the methane transport to the surface.

Потепление климата является одной из самых обсуждаемых тем в научном сообществе. Прогнозные оценки эмиссии парниковых газов часто могут быть заниженными из-за сложности учета изменения ландшафтных условий, связанных с деградацией многолетнемерзлых пород в северных регионах. В связи с этим, проводимый авторами геокриологический мониторинг и полученные новые данные о содержании парниковых газов в талых и мерзлых породах могут дать наиболее полное представление об эмиссии метана в различных ландшафтных зонах Арктики. Это поможет дополнить будущие модели изменения климата. Авторами собрана база данных и проведен анализ содержания и распределения метана в различных геолого-генетических типах четвертичных многолетнемерзлых и талых пород, а также в подземных льдах.

The Kara Sea coast and part of the shelf are characterized by wide presence of the ice-rich permafrost sequences containing massive tabular ground ice (MTGI) and ice wedges (IW). The investigations of distribution, morphology and isotopic composition of MTGI and IW allows paleoenvironmental reconstructions for Late Pleistocene and Holocene period in the Kara Sea Region. This work summarizes result of long-term research of ice-rich permafrost at eight key sites located in the Yamal, Gydan, Taimyr Peninsulas, and Sibiryakov Island. We identified several types of ground ice in the coastal sediments and summarized data on their isotopic and geochemical composition, and methane content. We summarized the available data on particle size distribution, ice chemical composition, including organic carbon content, and age of the enclosing ice sediments. The results show that Quaternary sediments of the region accumulated during MIS 5 – MIS 1 and generally consisted of two main stratigraphic parts. Ice-rich polygenetic continental sediments with syngenetic and epigenetic IW represent the upper part of geological sections (10–15 m). The IW formed in two stages: in the Late Pleistocene (MIS 3 – MIS 2) and in the Holocene cold periods. Oxygen isotope composition of IW formed during MIS 3 – MIS 2 is on average 6‰ lower than that of the Holocene IW. The saline clay with rare sand layers of the lower part of geological sections, formed in marine and shallow shelf anaerobic conditions. MTGI present in the lower part of the sections. The MTGI formed under epigenetic freezing of marine sediments immediately after sea regression and syngenetic freezing of marine sediments in the tidal zone and in the conditions of shallow sea.

Many researchers study the Earth's climate change and the impact of the greenhouse effect on this process. The large amount of methane (CH4) is preserved in permafrost. In this regard, scientists recently pay a great attention to the problem of methane emission during the permafrost degradation in the Arctic zone. Until now, the methane content in underground ice, frozen Quaternary sediments has been studied insufficiently. The methane content in the active layer is especially poorly studied. The authors researched methane content in frozen grounds of the upper permafrost horizon (transition zone) and in thawed sediments of the active layer for different tundra landscapes near the Marre-Sale polar station on the western coast of the Yamal peninsula and for landscapes of the Pechora river estuary area (Russia). More than 420 samples of gas from sediments in active and transient layer were collected in Marre-Sale and 36 samples in Pechora area. To determine the methane content, the samples were placed in syringes and degassed using the “head space” technique. CH4 measurements were carried out on a chromatograph with flame ionization detector (FID) Shimadzu GC-2014 (Japan) in the laboratory of Federal State Institution “VNIIOkeangeologiya” (Saint-Petersburg, Russia). Methane content in the frozen and thawed sediments of different dominant landscapes of typical tundra on Yamal peninsula and landscapes of southern tundra on Pechora area is extremely variable. The greatest amount of methane is typical for the most wet landscapes with primarily of silt loam soils. In dry primarily sandy well-drained landscapes, the methane content is low. The highest methane content is measured within the low floodplain of river, water tracks, swampy depressions of polygonal relief, and lake basins landscapes (mean varied from 0.8 to 2.5 ml [CH4] / kg, with a maximum of 9.0 ml [CH4] / kg). For landscapes of the moist surface of typical tundra, the average values of methane content were approximately 0.4 ml [CH4] / kg (with a maximum of 3.4 ml [CH4] / kg). The lowest methane contents in soils were characteristic of the landscapes of well-drained tundra, and sand fields where the average values do not exceed 0.2 ml [CH4] / kg. Mean methane content in soils of Pechora river mouth landscapes varied from 0.05 to 4.5 ml [CH4] / kg, with a maximum of 15.8 ml [CH4] / kg. Determined that methane contents in the frozen soils of the transition zone is 2 to 5 times higher than in the soils of the active layer. High content of methane in upper layers of permafrost should be considered as a significant source of methane, which can be involved in emission of greenhouse gases into the atmosphere during permafrost degradation.

We present the results of studies of the methane content in soils of the active layer and underlying permafrost, as well as data on the emission of methane into the atmosphere in the dominant landscapes of typical tundra of the western coast of the Yamal Peninsula. A detailed landscape map of the study area was compiled, the dominant types of landscapes were determined, and vegetation cover was described. We determined that a high methane content is characteristic of the wet landscapes: peat bogs within the floodplains, water tracks, and lake basins. Average values of the methane content in the active layer for such landscapes varied from 2.4 to 3.5 mL (CH4)/kg, with a maximum of 9.0 mL (CH4)/kg. The distribution of methane in studied sections is characterized by an increase in its concentration with depth. This confirms the diffuse mechanism of methane transport in the active layer and emission of methane into the atmosphere. The transition zone of the upper permafrost contains 2.5–5-times more methane than the active layer and may become a significant source of methane during the anticipated permafrost degradation. Significant fluxes of methane into the atmosphere of 2.6 mg (CH4) * m−2 * h−1 are characteristic of the flooded landscapes of peat bogs, water tracks, and lake basins, which occupy approximately 45% of the typical tundra area.

Определено содержание метана в доминантных ландшафтах типичной тундры Западного Ямала. Наиболее высокая концентрация метана в сезонно-талом слое присуща тундровым болотам, обводнённым днищам логов, оврагов и полигональным тундрам. В них концентрация метана до 5000 ppm, в остальных ландшафтах концентрация метана не превышает 300 ppm. Таким образом, только болота, полигональные тундры и днища логов, занимающие -30–40% территории, – существенные источники метана в зоне типичной тундры. Выполнены измерения эмиссии метана в атмосферу. На пике летней эмиссии суточный поток метана в болотах до 14,4 мг/м (20,3 мл/м 2 ).

Methane concentration in dominant landscapes of typical tundra of Western Yamal has been measured. The highest methane content in the active layer was measured in tundra bogs, wet gully bottoms, and polygonal tundra. Within these landscapes, methane concentration reaches 5000 ppm, while in other landscapes it does not exceed 300 ppm. Thus, only bogs, polygonal tundra, and gully bottoms, which occupy approximately 30–40% of the area, are the main sources of methane emission in the typical tundra zone. Measurements of methane emission to the atmosphere have been performed. During the summer maximum of emission, daily methane flux in bogs reaches 14.4 mg/m2 (20.3 ml/m2).

Permafrost degradation of coastal and marine sediments of the Arctic Seas can result in large amounts of methane emitted to the atmosphere. The quantitative assessment of such emissions requires data on variability of methane content in various types of permafrost strata. To evaluate the methane concentrations in sediments and ground ice of the Kara Sea coast, samples were collected at a series of coastal exposures. Methane concentrations were determined for more than 400 samples taken from frozen sediments, ground ice and active layer. In frozen sediments, methane concentrations were lowest in sands and highest in marine clays. In ground ice, the highest concentrations above 500 ppmV and higher were found in massive tabular ground ice, with much lower methane concentrations in ground ice wedges. The mean isotopic composition of methane is −68.6‰ in permafrost and −63.6‰ in the active layer indicative of microbial genesis. The isotopic compositions of the active layer is enriched relative to permafrost due to microbial oxidation and become more depleted with depth. Ice-rich sediments of Kara Sea coasts, especially those with massive tabular ground ice, hold large amounts of methane making them potential sources of methane emissions under projected warming temperatures and increasing rates of coastal erosion.

The classification of the shores of the Kara Sea has been carried out, and data were obtained on the morphology, composition, ice content and destruction rate of thermal abrasion shores.It has been established that as a result of the sea coasts destruction, about 15-20 million m 2 of terrigenous material containing methane enters the Kara Sea each year.The mean content of methane in the receding shores was determined.The value of methane emissions due to the destruction of the Kara Sea shores is estimated at 10-30 million m 3 or 0.8-2.0tons per year.

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.

Modern glaciers of the Polar Urals are small and usually located 1000 m below the climatic snow line, rarely descending below 400 500 m above sea level. Glaciers are formed by blowing the snow from surrounding slopes and their internal accumulated cold, which contributes to the formation of superimposed ice. The isotope composition of snowfields and glaciers of the Polar Urals was studied (a small glacier on the Paipudynsky ridge and the Romantics glacier); changes in the initial isotopic characteristics during ice formation are discussed.