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Химический состав гидрокриогенной системы озёр Мунозеро и Урозеро (Республика Карелия, Россия)
Get PDFThe article presents the results of researches on the content of ions, biogenic and organic substances in the system «snow on ice – ice – under the ice water» in two lakes – Munozero and Urozero (Russia, Republic of Karelia), conducted in February 2019. Since the beginning of the 1990s, the southern and south-western parts of the catchment and the water area of Lake Munozero have been undergone the anthropogenic impact by discharges of domestic waste waters and feed from the trout farm. Influence of human activities upon the Lake Urozero is negligible. Composition of its under-ice water is bicarbonate-calcium. Among the inorganic forms of nitrogen-containing compounds in snow, ice and the under-ice water, the nitrate ion prevails (85%). High concentrations of total phosphorus (up to 10 μg/l) and organic nitrogen (up to 0.19 mg/l) in the lower layers of ice in the system “ice-water” for the Lake Munozero are comparable with the content of them in the under-ice water. The ice cover of both lakes Munozero and Urozero is characterized by a low content of organic carbon (on average, 1.0 and 0.8 mg/l), while in the under-ice water its concentration is 4 and 2 times higher, respectively. To determine the intensity of the involvement of dissolved substances into the ice in combination with ice-forming water, the coefficient of involvement Kv was used. Studies have shown that among the cations in the ice of both lakes, potassium is more involved, while among the anions this is the sulfate ion. In Lake Munozero, undergone the anthropogenic effects, the concentration of chlorine ions in the ice changes from 0.2 to 0.5 mg/l (17 and 36%‑eq).На основе исследований содержания минеральных, органических и биогенных веществ в гидрокриогенной системе двух озёр Южной Карелии в феврале 2019 г. установлено, что в кристаллогидратах льда этих озёр среди катионов превалирует ион калия, а среди анионов – сульфат-ион. Сильное антропогенное воздействие на оз. Мунозеро вызвало увеличение концентрации ионов хлора в нижних слоях льда, содержания органического азота и общего фосфора, что стало сравнимо с их концентрациями в подлёдной воде
Изменения ледника Чалаати (Грузинский Кавказ) с малого ледникового периода по данным космогенных изотопов (10Be) и дендрохронологии
Get PDFGlacier variations over the past centuries are still poorly documented on the southern slope of the Greater Caucasus. In this paper, the change of Chalaati Glacier in the Georgian Caucasus from its maximum extent during the Little Ice Age has been studied. For the first time in the history of glaciological studies of the Georgian Caucasus, 10Be in situ Cosmic Ray Exposure (CRE) dating was applied. The age of moraines was determined by tree-ring analysis. Lichenometry was also used as a supplementary tool to determine the relative ages of glacial landforms. In addition, the large-scale topographical maps (1887, 1960) were used along with the satellite imagery – Corona, Landsat 5 TM, and Sentinel 2B. Repeated photographs were used to identify the glacier extent in the late XIX and early XX centuries. 10Be CRE ages from the oldest lateral moraine of the Chalaati Glacier suggest that the onset of the Little Ice Age occurred ~0.73±0.04 kyr ago (CE ~1250–1330), while the dendrochronology and lichenometry measurements show that the Chalaati Glacier reached its secondary maximum extent again about CE ~1810. From that time through 2018 the glacier area decreased from 14.9±1.5 km2 to 9.9±0.5 km2 (33.8±7.4% or ~0.16% yr−1), while its length retreated by ~2280 m. The retreat rate was uneven: it peaked between 1940 and 1971 (~22.9 m yr−1), while the rate was slowest in 1910– 1930 (~4.0 m yr−1). The terminus elevation rose from ~1620 m to ~1980 m above sea level in ~1810–2018.Для реконструкции колебаний ледника Чалаати в Грузии использовались космические снимки, старые карты, повторные фотографии, дендрохронология, лихенометрия и анализ космогенных изотопов. Максимальное наступание ледника в начале малого ледникового периода произошло в ~1250–1330 гг., второй максимум, когда ледник достиг почти такой же длины, датируется примерно 1810 г. С этого времени до 2018 г. площадь ледника уменьшилась с 14,9±1,5 до 9,9±0,5 км2 (33,8±7,4%, или ~0,16% год−1), а его длина сократилась на ~2280 м
Активизация обвалов на Центральном Кавказе и их влияние на динамику ледников и селевые процессы
Get PDFWe analyzed multi-time satellite images of the Central Caucasus glacial zone and interpreted more than thirty rock avalanche events in the 21st century with a total damage area of more than 25 km2 (including the collapse zone of the Kolka Glacier disaster). The highest rock and rock-ice avalanche activity is detected in the section of The Greater Caucasus range (northern and southern slopes) with a length of about 20 km between the Bashkara and Kulaktau peaks (16 rock avalanches) and in the section of the Kazbek-Dzhimaray Massif (series of rock avalanches to the surface of Kolka, Suatisi and Devdoraki glaciers). The feature of the rock and ice-rock avalanches is the large runout distance. For 12 events (about 40%) the distance was more than 2000 m. One ice-rock avalanche from the Mount Kazbek (excluding the Kolka Glacier disaster in 2002) reached the runout distance more than 10 km. In some areas, the rock avalanches occurred several times. In particular, a large number of avalanches were in the cirque of the Kolka Glacier; the last of them at the end of 2019. Thrice шт each case, rock avalanches originated from Mount Bashkara, in the cirques of the Murkvam Glacier, the East Shtulu Glacier, and the Devdoraki Glacier. Ice and rock avalanches were the initial stage of the complex process of the Kolka Glacier disaster and following catastrophic glacial debris flow in the Genaldon/Gizeldon River valley in 2002. Also, they were causes of glacier surges, formation of dammed lakes, and debris flows. As a result of the collapse of the hanging glacier and bedrock, the former right tributary of the Kolka Glacier surged to 200 m in 2006. Ice-rock avalanche from Mount Kazbek in 2014 load up the former right tributary of the Devdoraki Glacier and caused its advancing in 2015–2019, at a distance of more than 400 m. The avalanches caused catastrophic debris flows in the Amilishka/Kabakhi River valley in 2014, the Mestiachala River valley in 2019. Rock avalanches can cause outbursts of lakes and debris flows. Two dammed lakes formed as a result of the rock avalanche from the cirque above the Seri Glacier in the Tviberi River valley of the in May 2016. The lakes (total area was more than 0.05 km2) have outburst at the end of August 2017 after heavy rains. Rock avalanches of the 20th century led to an abrupt deceleration in the retreat of the Yusengi, Bartuytsete, East Shtulu and Mosota glaciers. The formation of rock avalanches in the 21st century took place at high altitudes (an average of about 3900 m). Possibly, the reason was associated with an increase of the «0» isotherm and of the high border of the zone of intense frost weathering due to climate warming. Some rock avalanches in the section of the Kazbek-Dzhimarai Massif have been caused by endogenous factors (seismicity and volcanism).На основе анализа разновременных космических снимков приведены данные о 32 обвалах в ледниковой зоне Центрального Кавказа в ХХI в. Половина из них сосредоточена на участке северного и южного склонов Главного Кавказского хребта восточнее горы Башкара. Отмечена высокая активность обвалов в 2019 г., показано влияние обвалов на динамику ледников и селевые процессы
Поверхностные скорости и айсберговый сток ледникового купола Академии Наук на Северной Земле
Get PDFWe have determined the ice-surface velocities of the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian Arctic, during the period November 2016 – November 2017, using intensity offset-tracking of Sentinel-1 synthetic-aperture radar images. We used the average of 54 pairs of weekly velocities (with both images in each pair separated by a12-day period) to estimate the mean annual ice discharge from the ice cap. We got an average ice discharge for 2016–2017 of 1,93±0,12 Gt a−1, which is equivalent to −0,35±0,02 m w.e. a−1 over the whole area of the ice cap. The difference from an estimate of ~1,4 Gt a−1 for 2003–2009 can be attributed to the initiation of ice-stream flow in Basin BC sometime between 2002 and 2016. Since the front position changes between both periods have been negligible, ice discharge is equivalent to calving flux. We compare our results for calving flux with those of previous studies and analyse the possible drivers of the changes observed along the last three decades. Since these changes do not appear to have responded to environmental changes, we conclude that the observed changes are likely driven by the intrinsic characteristics of the ice cap governing tidewater glacier dynamics.По 54 парам космических снимков Sentinel‐1, сделанных с ноября 2016 г. по ноябрь 2017 г., определены скорости движения ледникового купола Академии Наук на Северной Земле. На этой основе оценён среднегодовой расход льда в море этого купола (1,93±0,12 Гт/год), установлены основные пути стока льда, проведено сравнение с прежними оценками
Гляциальные сели в Заилийском Алатау за последние 120 лет
Get PDFZailiyskiy Alatau is the most mudflow hazardous mountain region of the Republic of Kazakhstan. At the same time, this area is one of the most densely populated and economically developed one, so mudflows here cause the great damage. The paper presents results of our analysis of the glacial mudflow activity for the period from 1900 to 2019. Amount and total volume of glacial mudflows per year were used as indicators of the mudflow activity. 481 mudflows were recorded over 120 years of observations in the Zailiyskiy Alatau, and 24% of them were glacial mudflows. Glacial mudflows are the largest and most destructive. Of the nine mudflows with a volume of more than 1 million m3, seven were glacial mudflows. The chronicle of mudflow disasters is shown. From 1950 to 2019, 87 glacial mudflows were observed in the Zailiyskiy Alatau. Of these, 16 mudflows had volumes exceeding 100 thousand m3. The largest ones occurred in 1977 (6.0 million m3), 1963 (5.8 million m3), 1958 (4.0 million m3), and 1973 (3.8 million m3 ). The causes for formation of glacial mudflows are outbursts of moraine lakes or water from underground reservoirs, as well as collapses of moraines’ slopes. The largest of them occur when a lake is bursting through an open channel. Since 1951, occurrence of glacial mudflows has been increasing and reached its maximum in the 1970s. Since 1978, the number of glacial mudflows has been decreasing, although their volumes remained large until the late 1990s. From 1997 to 2013, mudflow activity was low. During 11 of the 15 years, no mudflow was observed. Every year only one mudflow happened with a volume below 10 thousand m3. Since 2014, there has been a tendency for an increase in mudflow activity. Large glacial mudflows were recorded in 2014 and 2019. To protect against mudflows in the valleys of the Zailiysky Alatau, 14 dams have been built and two more are planned. To prevent outbursts of moraine lakes, they are emptied using pumps and siphons. In 2019, the network of automated monitoring of early warning about mudflows is being organized, which will cover all the valleys of the Northern slope of the Zailiysky Alatau.Проанализированы данные о гляциальных, в том числе катастрофических, селях с 1900 по 2019 г., рассмотрены внутри- и межгодовые колебания селевой активности. С 1951 г. активность гляциальных селей стала расти и достигла максимума в 1970-х годах, с 1978 по 1996 г. активность таких селей снижалась, а с 1997 по 2013 г. была низкой. С 2014 г. наметилась тенденция усиления активности гляциальных селей
Влияние диффузии солей на состояние и распространение многолетнемёрзлых пород и зоны стабильности метан-гидратов шельфа моря Лаптевых
Get PDFSalt transport in shelf sediments can affect the state of the submarine permafrost and the thermodynamic stability of hydrates. To estimate the effect of salt transport, we used a model analysis of salinization of underwater sediments. It is assumed that the salininization follows the flooding of the shelf, which accompanies transgression of the ocean during the end of the glaciations of the Quaternary period. We used the model of thermal processes in the bottomset bed, developed in collaboration with the Institute of Numerical Mathematics and Mathematical Geophysics, Siberian Branch of the Russian Academy of Sciences and the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Science. The model was augmented by the equation of salt diffusion in the bottom sediments. In calculations with the model, changes in the temperature of the upper surface of bottom sediments and sea level over the past 400 kyr were prescribed (set). It is shown that the combined effect of heat and salinization of bottom sediments during oceanic transgressions (shelf flooding) leads to the sinking of the current upper boundary of the marine permafrost by about 10–25 m below the sea floor, depending on the current depth of the shelf. Accounting for the salt diffusion is necessary to determine the position of the upper boundary of the permafrost, as well as to calculate the rate of its degradation. In particular, salt transport is able to change both the current position and the rate of displacement of the upper permafrost boundary in several times relative to the case of a time-independent freezing temperature. Note, that this effect is insignificant for estimation of the position of the lower permafrost boundary in the bottom sediments of the inner shelf. Lowering the freezing point leads to the fact that frozen rocks on the outer shelf completely thaw at negative temperatures of bottom sediments under the influence of heat and salts in the present period (experiments TF‑2, TFSAL2). The influence of salinity on the characteristics of the stability zone of methane hydrates in the submarine permafrost is insignificant due to deep level of their occurrence in the shelf sediments.Проанализировано влияние засоления на состояние затопленных морем многолетнемёрзлых толщ шельфа моря Лаптевых. Результаты моделирования показали, что в результате засоления донных осад- ков современная верхняя граница многолетнемёрзлых пород находится на глубине 10–15 м ниже морского дна на внутренней части шельфа и на глубине 20–25 м ниже морского дна на внешнем шельфе. Учёт диффузии соли при исследовании динамики субаквальной мерзлоты необходим для определения положения её верхней границы, а также расчёта скорости её деградации. Согласно расчётам, перенос солей может в несколько раз изменить положение и скорость смещения верхней границы многолетнемёрзлых пород по сравнению со случаем неизменной во времени солёности и, следовательно, постоянной во времени температурой замерзания. Вместе с тем перенос солей заметно не влияет на положение нижней границы многолетнемёрзлых пород и характеристики зоны стабильности метан-гидратов
Пространственные различия плотности разрывов в ледяном покрове приатлантической части Арктического бассейна
Get PDFWe analyzed data on the spatial distribution (density) of large breaks (gaps) in the drifting sea ice cover in the Western Arctic for the period from October 2005 to September 2017, obtained through decoding of lowresolution images from the NOAA satellites. The specific length of gaps, which is the total length of them over an area of 1 km2, is used as a characteristic of the spatial density. It was found that along the continental slope, approximately from the meridian 70° E to the Lincoln Sea, there is a well-defined area of high density, which remains throughout most part of the ice cycle. In this area, the values of the specific gap length averaged over two-month periods exceeded 24 m/km2. In the near-polar region, the density of breaks was smaller throughout the whole ice cycle. The least values of the specific length take place in May–June that is caused by changes in the general state of the ice cover. It was determined that the density of gaps in this area of the Arctic basin well correlated with the speed of wind drift of ice: the more intensive the drift, the larger the density. On the continental slope, two local zones with maximum values of the specific length of breaks reaching 32 m/km2 are considered. It is suggested that the stability of their location in space and time is connected with the increased influence of tidal processes on the deformation of the ice cover over local bottom elevations on the continental slope. A correlation between the bottom profile and the values of the specific length of the gaps along two conditional lines passing through the maximum value zones did show that the largest values of the density are noticed in areas with significant gradients of the depth.На основе расчёта плотности разрывов в ледяном покрове приатлантической части Арктического бассейна по спутниковым данным за 2006–2017 гг. установлено, что на протяжении большей части ледового цикла в полях распределения удельной длины разрывов хорошо выражена обширная область её повышенных значений. Обосновано предположение, что причина возникновения локальных зон с повышенной плотностью разрывов – приливные явления. В открытой части Арктического бассейна значения удельной длины разрывов согласуются в основном со скоростью ветрового дрейфа льда
Геофизические изыскания в районе станции Прогресс, Восточная Антарктида, в сезон 63-й РАЭ (2017/18 г.)
Get PDFIn recent years, when organizing works of the Russian Antarctic Expedition (RAE), considerable attention is given to the safety of logistics operations carried out at Russian stations and field bases. The main factors that threaten polar explorers are extensive systems of cracks and water breakthroughs, confined to the marginal, the most dynamic part of the outlet glaciers, in the area of which the most part of stations are located. One example of the impact of these processes on transport communications in Antarctica is the breakthrough of an intraglacial reservoir in the Dolk glacier near the station Progress (Larsemann Hills, Eastern Antarctica) in the season of the 62nd RAE (2016/17). The outburst resulted in the formation of a huge hole in the glacier body and an extensive system of cracks directed towards its flanks. This took place on the part of the route connecting the Progress Station with the point of organization the sledge-tractor train marches to inner regions of the Antarctic continent. Thus, this destroyed the transport links between these points. That is why during the seasonal works of the 63rd RAE (2017/18) geophysical surveys were carried out around the hole by means of the GPR profiling for the purpose to find the best way and organize a new all-season route. The GPR soundings performed at frequencies of 900 and 150 MHz, made possible to fix numerous cracks and large volumes of melt water accumulations in the near-surface part of the ice layer. The analysis of the obtained time sections and the assessment of the depths of cracks and watered areas did show that the detected objects in the glacier body were not dangerous for advancing of the sledge-caterpillar equipment passing by the hole. These surveys allowed planning the optimal new route, after which it was rolled up and put into operation. The logistical connection between the station and the airfield has been restored. Until the end of the field season, the new all-season route was actively used for transportation.Представлены результаты исследований в районе Холмов Ларсеманн на участке ледника Долк в поисках безопасного места для организации новой всесезонной трассы с целью возобновления транспортного сообщения между станцией Прогресс, аэродромом и пунктом формирования санно‑гусеничных походов, прерванного в результате образования провала в леднике Долк
Гетерогенное строение полигонально-жильных льдов в торфяниках Пур-Тазовского междуречья
Get PDFStructure 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.Изучены состав и строение голоценового торфяника возрастом от 8413±90 до 897±90 радиоуглеродных лет. В строении жилы установлены генетически разные типы льда: элементарные жилки, термокарстово-полостной, сегрегационный. Определёны химический состав водно-растворимых соединений, а также концентрация метана во льду и торфе, которая связана с динамикой глубины протаивания в условиях меняющегося климата в голоцене