Link for citation: Butakov V.I., Slagoda E.A., Zavatsky M.D., Ivanov V.I. Gas composition and microorganisms of ground ice in Russian Arctic. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 9, рр. 63-75. In Rus. Relevance. The increase in the concentration of greenhouse gases in the atmosphere is a fundamental problem on a planetary scale. The source of greenhouse gases in the subsurface horizon of soil can be both deep deposits of hydrocarbons and organic matter processed by microorganisms during the thawing of the ice-rich soil. To determine the source of the gas it is necessary to examine both its quantity and composition and the microorganism content in the subsurface ice. Taking into account the dynamic development of the energy complex in the north of Western Siberia it is necessary to take into account the geotechnical risks associated with the release of greenhouse gases from frozen deposits. Purpose: to study the composition and identify the sources of greenhouse gases in the ice and the ice-rich soil on account of the ice formation conditions and the microorganism content. Objects: ice wedge, hydrogenic and segregational genesis of ice, ice-rich soil of northern Western Siberia and Central Yakutia, collected by expeditions Earth Cryosphere Institute, Tyumen scientific center SB RAS in 2011–2021. Methods of research and interpretation of chemical composition. The structure of frozen deposits has been investigated by cryolitological methods. The monoliths of the ice and the frozen deposits were stored at –18 °C. Gas was extracted from the monoliths with the determination of volume fraction by thermovacuum degassing method. The composition of gases is determined by gas chromatography. Normalization of the gas composition with solubility values in water was carried out. Volume fractions of gas in free and dissolved forms was calculated. The data processing were implemented by means of «Geochem Anomaly» program. Cultivated psychrophilic microorganisms were studied by seeding on nutrient media; the total number of microorganisms was determined by epifluorescent microscopy. Results. The contents of N2 (74,9–87,8 %), O2 (11,7–20,3 %), CO2 (0,01–3,28 %), CH4 (0,003–7, 35 %), H2 (0,001–0,035 %) and hydrocarbons with an atom content from 2 to 6 (2,0×10–5–2,8×10–3 %) are determined in ice and ice-rich soil. The value of N2 and O2 in the gas composition of ice is close to atmospheric air. The ice has wide variations in gas saturation (1,1–21,1 %), CH4 and CO2 content. The freezing of gas-saturated solution occurred for the ice formation, part of the air was in a free form (from 30 to 75 %). Calculated indexes CH4/(C2H6+C3H8) and C2H6/C2H4 indicate biogenic hydrocarbon genesis. The composition of gas bubbles is recalculated for the volume of the entire sample: CH4 content is insignificant in ice wedge, closed-cavity ice and icing (averages 51, 81 and 1 ppmV, respectively). The low amounts of CH4 could be produced by forming these types of ice from the sediments of the active layer, as the dependence of the gas composition on the peat element amount is established. CH4, CO2 and H2 contents increased in samples with peat elements. In interbedding ice the CH4 content is high (216 ppmV). CO2 (up to 3007 ppmV) was accumulated in the texturing ice, and hydrogenic wedge-shaped ice showed high levels of CH4 (up to 4032 ppmV) as the ice was frozen in an enclosed volume. The ice of peat mound has a maximum content of CH4 (15545 ppmV) and high CO2 (2466 ppmV); inclosing sediments flooded with marginal-marine waters are the source of high values of CH4 and CO2. The cultivated psychrophilic microorganisms were identified in the surface ice, and their maximum quantities were identified in segregated formations – up to 1680 KOU/ml, in textural ice – up to 1032 KOU/ml. High concentrations of greenhouse gases are found in frozen peat – CO2 (1075 ppmV), H2 (9 ppmV), CH4 (262 ppmV) and other hydrocarbons due to activity of microorganisms, which results in accumulation of these gases. High gas saturation and CH4 and CO2 levels indicate the formation of gaseous composition by both aerobic and anaerobic microorganisms.

Heterogeneous ice wedges were studied within the peatland of the drained lake on the Pur‐Taz interfluve (67°20′14.8″, 078°55′47.1″, Northwest Siberia). The elements of the ice‐wedge structure were identified: young ice wedge, shoulders, selvages, closed‐cavity ices, and ice lenses in a peatland. Different genetic types of ice (ice vein, congelation ice, and segregated ice) were revealed by analyzing the elements of the ice‐wedge structure under polarized light and analyzing their chemical compositions. Genetic types of the ice indicate the different mechanisms of ice‐wedge formation. The ice vein forms due to fast bilateral freezing of primarily meltwater in a thermal contraction crack. The congelation ice forms due to the slow freezing of free water that has accumulated into a thermokarst cavity. The segregated ice forms due to pore water migration to the freezing zone. The elements of the ice‐wedge structure have variable stable isotope values (δ18O from −13.5‰ to −21.9‰ and δD from −87.7‰ to −154.6‰). The high range of deuterium excess values (13.8‰ to 32‰) indicates fractionation at condensation. The mean winter paleotemperature calculated using Vasil’chuk’s equations for the ice‐wedge pats formed by the ice veins varied in the range of −18 to −22°C, which is not very different from current values and is consistent with the isotopic data of ice wedges from nearby regions of Northwest Siberia. The paleotemperature average error can equal 4.5°C if we ignore the data on the ice petrographic analysis. The error depends on where and how the ice wedges are sampled, because of varying genetic types within the ground ice. This could lead to different palaeoclimatological interpretations.

The analysis of about 200 samples taken from 42 permafrost-affected soil profiles was carried out on four key sites in different regions of cryolithozone (West Siberia, Central, North, and North-East Yakutia) characterized by different active layer depths and soil lithology. The aim of the study was to determine the influence of different processes of cryogenic mass-exchange on the redistribution and accumulation of major pollutants such as petroleum products, acid-soluble forms of trace elements, polycyclic hydrocarbons, and technogenic radionuclides transferred via atmospheric transport or after the local anthropogenic impact in different soil horizons of Cryosols and in the upper layers of permafrost. Samples were analyzed using modern precise techniques (direct γ-spectrometric measurements with Ge(Li) and NaI(Tl) detectors; fluorometric method; reversed-phase high-performance liquid chromatography; spectrofluorimetric detection; atomic absorption spectrometry with flame atomization). The study has shown that processes (cryoturbations, frost heaving, gelifluction along with fluvial processes) that strongly affect Cryosols’ profile structure can also lead to the active migration and accumulation of local and global pollutants in the middle and lowermost suprapermafrost soil horizons. The accumulation of some pollutants in suprapermafrost horizons of cryogenic soils and in the upper layers of permafrost (in particular, petroleum products and mobile forms of trace elements) can be associated with a combination of factors, such as the relatively light particle size distribution, relatively weak manifestation of cryoturbation processes, and low thickness of the active layer (about 40–60 cm). The integral calculation of the geoaccumulation index values has shown that all of the groups of human-affected soil horizons are moderately to extremely polluted by petroleum hydrocarbons (and at a relatively lower level by trace elements) and the maximum pollution stands for the suprapermafrost horizons as well as in cryoturbated or buried fragments of organogenic matter in some cases. The maxima of the heavy PAH content in permafrost-affected soils can be confined to horizons enriched with anthropogenic inclusions and artifacts (for example, construction slag, coal) and to individual horizons of soils buried as a result of both cryogenic and alluvial processes. The specific activity of the technogenic radionuclide cesium in cryogenic soils revealed its association mainly with the surface organogenic and organomineral horizons of the studied profiles and rarely observed in the cryoturbated fragments of these horizons in the middle and suprapermafrost layers of soil profiles. The necessity of the complex analytical assessment of the permafrost-affected soils has been revealed especially in case of studying of the ecological state of the anthropogenically affected Cryosols.

The texture, structure, ionic and trace element composition of samples of fast (coastal-sea) and lake ice collected in 2014 in the area of Cape Marre-Sale (the North-Western Siberia) were analyzed. The following main types of the ice structure were identified in ice sections: firn ice with randomly oriented small crystals; lake large- and small-crystalline bubble ice; layered fast sea ice with small isometric and vertically elongated crystals. The upper part of the lake ice is formed by recrystallized snow containing marine aerosols and lake water. The coefficient of involvement of the main ions from the solution during the ice formation varies for lake ice from 0.02 to 1.51, for sea ice - from 0.10 to 0.23, and for coastal-marine - from 0.03 to 0.04. The difference in the degree of ion involvement into the lake ice is related to the sources of components entering the process of formation of firn and large ice crystals from lake water. Coastal sea ice has high concentrations of trace elements relative to the darks of sea waters. The income of trace elements into the coastal sea ice is probably determined by continental runoff. It is established that the mineralization of seasonal ice increases with a decrease in the size of crystals. The dependence of the values of the Europium anomaly on the rate of ice formation was revealed. The Europium anomaly in coastal sea ice is inherited from seawater, and the upper part of lake ice is inherited from precipitation.

Ссылка для цитирования: Бутаков В.И., Слагода Е.А., Тихонравова Я.В. Содержание и состав атмосферных и парниковых газов в подземных льдах разного генезиса // Известия Томского политехнического университета. Инжиниринг георесурсов. – 2021. – Т. 332. – № 11. – С. 22-36 Актуальность. Парниковый эффект связывают с поступлением метана и углекислого газа из оттаивающих газонасыщенных льдистых пород, а их содержание в подземных льдах недостаточно изучено. Для оценки содержания газов в отложениях и льдах, объемов поступления газов в атмосферу используют разные и несопоставимые методы отбора проб газа. При обобщении данных об углеродной эмиссии в Арктической зоне необходимо учитывать методы определения содержания и состава газов и химический состав, наличие органических и минеральных включений в генетических типах подземных льдов. Цель: определить содержание и состав газов в распространенных генетических типах подземных льдов и мерзлых отложений; определить сопоставимость результатов разных методов отбора газа для оценки масштабов эмиссии парниковых газов в атмосферу на фоне протаивания мерзлоты. Объекты: подземные льды сегрегационного, термокарстово-полостного и повторно-жильного генезиса, льдистые мерзлые отложения севера Западной Сибири на о. Белый, Западном Ямале, севере Гыдана и Пур-Тазовском междуречье, собранные экспедициями ИКЗ ТюмНЦ СО РАН в 2014–2019 гг. Методы исследования и интерпретации химического состава. Использованы два метода извлечения газа из монолитов мерзлых пород и льда: метод термовакуумной дегазации и метод «headspace». Метод термовакуумной дегазации в лабораторных условиях с определением объёма газа в образце льда был использован как референтный. Состав атмосферных и парниковых газов определен методом газовой хроматографии. Проведено сравнение содержания газа во льдах и мерзлом торфе с содержанием газа в атмосфере, значениями растворимости газа в воде. Выполнен корреляционный анализ содержания газов в распространенных типах подземных льдов и мерзлом торфе. Результаты. Установлено, что газ, заключенный в подземных льдах и мерзлом торфе, по относительному содержанию азота и кислорода близок к атмосферному. В пробах выявлены большие вариации содержания метана от 4 до 1,7×104 ppmV и углекислого газа от 7 до 2,7×103 ppmV, которые связаны с различными условиями для продуцирования и накопления парниковых газов в мерзлой толще. Установлено преобладание содержаний углекислого газа над метаном в сегрегационных и повторно-жильных льдах. Максимальные концентрации метана (от 1,1×103 до 1,7×104 ppmV) обнаружены в сегрегационно-миграционных льдах бугра пучения и клиновидных льдах. Избыток метана в приповерхностных сегрегационно-миграционных льдах связан с его накоплением в оттаивавших отложениях таликов и последующим льдовыделением при промерзании в замкнутой системе. Установлены высокие содержания углекислого газа (до 1,1×103 ppmV) и метана (до 222 ppmV) в сегрегационном льду в торфе, их источником является органическое вещество, разлагающееся в переменных аэробных и анаэробных условиях под действием бактерий, поэтому торфяники являются значительным источником поступления углекислого газа в атмосферу. Проведена оценка воспроизводимости и сопоставимости методов термовакуумной дегазации и «headspace» при исследовании льдов и мерзлых отложений в разрезе торфяника в районе с. Газ-Сале. Установлено, что концентрации метана при опробовании методом «headspace» завышены в 3–70 раз по сравнению с величинами, определенными методом термовакуумной дегазации. Это обусловлено низкой растворимостью метана и преобладанием его в пузырьках, а углекислый газ и часть кислорода остаются растворены в воде и не переходят в пробу газа. Следовательно, данных о содержании газа, определенного методом «headspace», недостаточно для оценки объемов эмиссии парниковых газов, поскольку эти величины характеризуют состав нерастворенного газа. Метод термовакуумной дегазации позволяет рассчитать и оценить объемы поступления газов из оттаивающих мерзлых толщ.

Изучение более чем 40 профилей криогенных почв на четырёх ключевых участках в различных районах криолитозоны показало, что процессы криогенного массообмена, проявляющиеся в профилях (криотурбации, пучение, пятнообразование, мерзлотная солифлюкция в т.ч., в сочетании с флювиальными процессами), способны приводить к миграции и аккумуляции различных локальных и глобальных загрязнителей (нефтепродуктов, подвижных форм тяжелых металлов, ПАУ, техногенных радионуклидов и пр.) в срединных и надмерзлотных горизонтах. Установлена необходимость всестороннего и полнопрофильного аналитического исследования мерзлотных почв с морфологически выраженными процессами криогенного массообмена, особенно при характеристике экологического состояния почв, подверженных в настоящее время (или подвергавшихся в прошлом) антропогенному воздействию.

The relevance. The greenhouse effect is often associated with methane and carbon dioxide emission from the thawing gas-saturated icy deposits. The relationship between the increase in concentrations of greenhouse gases in the atmosphere and their content in underground ice and frozen deposits has not been sufficiently studied. Different and incomparable methods of gas sampling from frozen deposits and ice are used to assess the content of gases in sediments and ice, the volume of gases entering the atmosphere. When generalizing the data on carbon emissions in the Arctic zone, it is necessary to take into account both the methods of determining the content and composition of gases and the different chemical composition, the presence of organic and mineral inclusions in genetic types of underground ice. The aim of the research is to determine the results of different methods of gas sampling from ice and to establish the relationship between the content and composition of gases in common genetic types of ground ice. Objects: genesis types of ice (segregated, closed-cavity, and ice wedge), icy frozen deposits of the north of Western Siberia: on the Bely island, on Western Yamal, on the north of Gydan and the Pur-Taz interfiuve, collected in expeditions of the Earth Cryosphere Institute, Tyumen scientific center SB RAS in 2014-2019. Research methods and interpretation of chemical composition. The thermal vacuum degassing method and the "headspace" method were used for gas extraction from frozen monoliths and ice. The thermal vacuum degassing method in laboratory conditions with the determination of the gas volume in the ice sample was used as a reference. The method of gas chromatography was applied to determine the composition of atmospheric and greenhouse gases. Gas content in ice and gas content in frozen peat that contains gas in the atmosphere, and the values of the gas solubility in water were compared. The correlation analysis of the gas content in common types of underground ice, as well as frozen peat, was carried out. Results. It was established that gas entrapped in ground ice and frozen peat was similar to atmospheric gas in terms of the relative content of nitrogen and oxygen. It was found out the large variations in methane content from 4 to 1,7 - 10(4) ppmV and carbon dioxide from 7 to 2,7 - 10(3) ppmV in samples are associated with different conditions for production and accumulation of greenhouse gases in the permafrost. The prevalence of carbon dioxide content over methane in segregated ice and ice wedge was established, and maximum methane concentrations (from 1,1 - 10(3) to 1,7 - 10(4) ppmV) in segregated-migration ice of heaving mound and wedge-shaped ice. An excess of methane in the near-surface segregated-migration ice is associated with its accumulation in thawed talik deposits and subsequent ice formation during freezing in a closed system. High concentrations of carbon dioxide (up to 1,1 -10(3) ppmV) and methane (up to 222 ppmV) in segregated ice in peat were found; their source is organic matter degradation under variable aerobic and anaerobic conditions under the action of bacteria. As a result, the peatlands are a significant source of carbon dioxide emissions into the atmosphere. Assessing reproducibility and comparability of the methods of thermal vacuum degassing and "headspace" was carried out in the study of ice and frozen sediments in the cross section of peat bog in the area of the village Gaz-Sale. It was found that methane concentrations during testing by the "headspace" method are overestimated by 3-70 times in comparison with the values determined by the method of thermal vacuum degassing. This is due to the low solubility of methane and its predominance in bubbles, while carbon dioxide and some oxygen remain dissolved in water and do not pass into the gas sample. Consequently, the data on the gas content determined by the "headspace" method is insufficient to estimate the volumes of greenhouse gas emissions, since these values characterize the qualitative composition of the gas in the bubbles. Thermal vacuum degassing method allows calculating and estimating the volumes of gas receipts from thawing permafrost.

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.

The concentration of main organic and inorganic pollutants (heavy metals, polyaromatic hydrocarbons, radionuclides) in surface waters and in water-soil solutions was analysed on three keysites within the permafrost zone: Tazovsky Peninsula (North-West Siberia), Kolyma Lowland (North Yakutia) and adjacent to Yakutsk (Central Yakutia). In the majority of sampling points that are not directly impacted by human activity, the pollutants accumulate in the uppermost organogenic and organo-mineral horizons of natural soils. At the human-affected keysites the major pollutants may accumulate not only in the superficial horizons of the disturbed soils due to the surface runoff but also in the central parts of the profile, in the material buried by cryogenic, solifluction or fluvial processes and in some cases – in the suprapermafrost horizons and in the upper layer of permafrost transported via suprapermafrost water runoff.

Structure of arctic peatlands with massive ice and structure-forming ice were studied in drained lake ("khasyrey") of the Pur-Taz interfluves (the north of West Siberia). The period of accumulation of two-meter thickness of the peat was established to be changed from 8413 +/- 90 to 897 +/- 90 years BR Composition of the peat deposits is represented by Betula nana, Sphagnum sp., Vaccinium oxycoccos, Eriophorum sp., Equiseturn sp. The massive ice is represented by ice wedges with large shoulders and young ice wedges. The central part of the ice wedge is composed by recrystallized crystals of ice veins. Melting zones (elongated crystals of segregated ice and closed-cavity ice) were found in the shoulders of the ice wedge and in the upper part of the young ice wedge. Young ice wedges in the central and lateral parts the main wedge have a similar structure in the cross-section, but they are built by different genetic types of ice: the ice veins or closed-cavity ice with segregated ice. Ice-rich peat contains different types of ice inclusions and subhorizontal ice belts and ice lenses. Ice lenses in the peat can be formed by the segregated ice and/or infiltrated-segregated ice. The hydrochemical composition of the ice wedges, ice lenses, surface water samples and the aqueous extract from peat was analyzed. Hydrochemical analysis did show that polygonal-core ice has basically similar composition with the present-day atmospheric precipitation and surface waters of the polygonal bath; in the area of the shoulder - the composition is intermediate between the ground waters of peat and the central part of the vein. The hydrochemical composition of the ice lenses is similar to the composition of the lake water and peat underlying the active layer. The methane concentrations and its distribution within the ice wedges, peat and lens ice were determined. The closed-cavity ice doesn't contain methane; the ice wedges with ice veins have minimal methane concentrations; large ice lenses have differentiation of methane concentrations. High concentrations of methane are typical for the frozen peat with inclusions of closed-cavity ice in the uppermost part of permafrost layer; the maximum methane concentration was determined inside the peat with ice lenses. The heterogeneous ices inside the ice wedges, distribution of hydrochemical compounds and methane distribution were conditioned by dynamics of the melting depth during the peatland formation under changing climate of the Holocene in the Arctic.

Structure of arctic peatlands with massive ice and structure-forming ice were studied in drained lake («khasyrey») of the Pur-Taz interfluves (the north of West Siberia). The period of accumulation of two-meter thickness of the peat was established to be changed from 8413±90 to 897±90 years BP. Composition of the peat deposits is represented by Betula nana, Sphagnum sp., Vaccinium oxycoccos, Eriophorum sp., Equisetum sp. The massive ice is represented by ice wedges with large shoulders and young ice wedges. The central part of the ice wedge is composed by recrystallized crystals of ice veins. Melting zones (elongated crystals of segregated ice and closed-cavity ice) were found in the shoulders of the ice wedge and in the upper part of the young ice wedge. Young ice wedges in the central and lateral parts the main wedge have a similar structure in the cross-section, but they are built by different genetic types of ice: the ice veins or closed-cavity ice with segregated ice. Ice-rich peat contains different types of ice inclusions and subhorizontal ice belts and ice lenses. Ice lenses in the peat can be formed by the segregated ice and/or infiltrated-segregated ice. The hydrochemical composition of the ice wedges, ice lenses, surface water samples and the aqueous extract from peat was analyzed. Hydrochemical analysis did show that polygonal-core ice has basically similar composition with the present-day atmospheric precipitation and surface waters of the polygonal bath; in the area of the shoulder – the composition is intermediate between the ground waters of peat and the central part of the vein. The hydrochemical composition of the ice lenses is similar to the composition of the lake water and peat underlying the active layer. The methane concentrations and its distribution within the ice wedges, peat and lens ice were determined. The closed-cavity ice doesn’t contain methane; the ice wedges with ice veins have minimal methane concentrations; large ice lenses have differentiation of methane concentrations. High concentrations of methane are typical for the frozen peat with inclusions of closed-cavity ice in the uppermost part of permafrost layer; the maximum methane concentration was determined inside the peat with ice lenses. The heterogeneous ices inside the ice wedges, distribution of hydrochemical compounds and methane distribution were conditioned by dynamics of the melting depth during the peatland formation under changing climate of the Holocene in the Arctic.

Relevance of the research. Information on composition, ice content and geochemical characteristics of frozen rocks is necessary for exploration of oil and gas condensate fields of Yamal, Gydan and Taimyr. Among the factors determining the tundra landscapes ecology of the cryolithozone, underground ice and their melting have great importance. The hydrochemical composition and rare-earth elements content in syngenetic ice wedge retain the information on the moisture sources and conditions of their formation. The main ions correlation and rare-earth elements distribution in the ice composition can be used to estimate the influence of such natural factors as precipitation, sea and volcanic aerosols and anthropogenic pollution. The main aim of the research is to identify chemical elements sources and to assess the impact of the ice type on hydrochemical composition and rare-earth elements distribution in different genetic types of ice - wedge, seasonal and firn ice. Objects: ice wedge, sediments rocks, seasonal ice, surface water, taken in expeditions Earth Cryosphere Institute, Tyumen scientific centre SB RAS in 2009-2014. Methods of chemical research: inductively coupled plasma mass spectrometry, atomic absorption spectrometry, emission photometry, chromatography. Results. It is established that marine and continental aerosols influenced the chemical composition of ice wedge studied in the coastal zone of the key areas of Belyj island, Sibiryakova island, Western Yamal and Western Taimyr. Fresh and ultrafresh syngenetic ice wedge is formed by freezing melt water, which contains snow-sorbed sea aerosols - suspended in the atmosphere solid and liquid particles. Ice wedge in the lake Sokhonto area long-distanced from the sea has no signs of marine influence according to the main ions content. Ice wedge with mineral inclusions was formed not only due to snow melt water with aerosols of continental origin, but also due to the suprapermafrost water. It was found out that lanthanide content in water-soluble form has increased in comparison with both clark values and the content in the modern surface ice. In the most of examined syngenetic ice wedge the participation of marine aerosols is confirmed taking into account the cerium anomaly. Moreover according to the distribution of rare-earth elements the correlation between light and heavy rare-earth elements typical for ice wedge, equal to 0,9, and correlation between lanthanum and the other lanthanides, equal to 0,2, are observed. Sea ice inherits the mineralization and composition of sea water. Lake ice varies in depth and reflects seasonal changes in hydrochemical composition of ice and increases in concentration of marine aerosols in the snow covering the lake ice. Firn ice of the polar Urals has a very low mineralization, there are no impurities of sea aerosol. The natural mechanism of rare earth elements accumulation in water-soluble form in combination with iron, thorium and yttrium is implemented in ice wedge of the Holocene and Neopleistocene. Melting out ice wedge may lead to the flow of rare-earth elements in the surface water.

In 2016-2017, we have detected numerous organic frost boils on the surface of khasyrey peat plateau in the southern tundra part of Pur-Taz interfluve (the north of West Siberia). They are related to the microrelief depressions in polygons and to the swales between tussocks. Cross-sections, cryogenic structure, properties of peat in active layer (moisture, density, heaving, chemical composition) and peat distribution within the khasyreys were studied. In the active layer, we distinguished soil and vegetation cover, upper and middle solid layers of weakly decomposed peat, lower layer of a well decomposed peat. Under the microrelief depressions, the top of permafrost is lowered, thickness and moisture of decomposed peat is increased due to the recent thawing in comparison to the elevated parts of polygons. In the cross-sections of seasonally thawing peat, we determined injections of organic matter from the lower layer of peat to the surface. We propose the mechanism of organic frost boils formation in peat plateau due to the injections during the summer seasons of 2016-2018 against the increase of a thaw depth without freezing. During the observation period, the amount of frost boils on polygonal peat plateau was found to increase.

The syngenetic ice and ice-ground composite veins in khasyrey (alas) and interalas plateaus were studied on the second lake-alluvial terrace located in the North of the Gydan Peninsula near the village of Gyda. On the basis of the radiocarbon dating, the time of formation of deposits containing veins from was established – from 16 640 to 854 BP. The peat deposits are mainly represented by the following species: Carex sp., Eriophorum sp., Betula nana, Equisetum sp., Calamagrostis sp., Vaccinium vitis-idaea, Drepanocladus sp., Empetrum sp., Vaccinium uliginosum, Rubus arcticus, Petasites sp. It is established that the polygonal-veined ice of khasyrey and interalas plateaus, except for vertical-striped «clean» ice, contain areas with vertical wavy streaks of ice-ground. Ice of elementary veins and segregation ice were revealed in the composition of veins according to structural and textural features in polarized light. Elementary ice veins compose «clean» ice sections of veins and segregation ice which are their ice-ground sections. Elementary veins are indicative of the predominance of the process of frost cracking during the formation of polygonal-vein ices. The presence of inclusions of ice-ground in the structure of veins points is evidence of a manifestation of local thermokarst processes under the growth of polygonal-vein ice. Ice-ground veins were formed by repeated thawing of the initial ice veins. The formation of ice-ground veins during syngenetic freezing of sediments of the second lake-alluvial terrace is related to uneven manifestation of thermokarst in different facies situations and and climate changes at the Early Pleistocene and Holocene.

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.

В 2016-2018 гг. обнаружены многочисленные органические пятна-медальоны на поверхности торфяников хасыреев южнотундровой части Пур-Тазовского междуречья (север Западной Сибири). Они приурочены к понижениям микрорельефа на полигонах и западинам между кочками. Изучены разрезы, криогенное строение и свойства торфа в сезонно-талом слое (влажность, плотность, пучинистость, химический состав и распространение в пределах хасыреев). В сезонно-талом слое выделены почвенно-растительный, верхний и средний плотные слои сильноразложенного торфа, нижний слой рыхлого слаборазложенного торфа. Под понижениями микрорельефа кровля многолетнемерзлых пород опущена, мощность и влажность рыхлого торфа увеличена за счет современного оттаивания по сравнению с повышенными участками поверхности полигонов. В разрезах сезонно-талого торфа выделены инъекции органического материала из нижнего слоя торфа на поверхность. Предложен механизм образования органогенных пятен-медальонов в торфяниках за счет инъекций в летние сезоны 2016-2018 гг. на фоне увеличения глубины оттаивания без участия промерзания. За период наблюдений отмечено увеличение количества пятен-медальонов на полигональных торфяниках.