Ice and Snow (E-Journal) / Лёд и Снег
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МЕТАН В ПОДЗЕМНЫХ ЛЬДАХ И МЁРЗЛЫХ ОТЛОЖЕНИЯХ НА ПОБЕРЕЖЬЕ И ШЕЛЬФЕ КАРСКОГО МОРЯ
Get PDFSummary 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.В трёх береговых разрезах и в одной точке на шельфе Карского моря исследованы состав и свойства подземных льдов и мёрзлых отложений, включая газовый состав и концентрацию метана. Наиболее высокие концентрации метана (до 23 352 ppm) установлены в пластовых льдах, а в жильных льдах она достигает лишь 1112 ppm. Большие концентрации метана в воздушных пузырьках пластовых льдов и их изотопный состав указывают на не ледниковый генезис этих льдов
Изменчивость ледовитости Онежского озера в период 2000-2018 гг. по спутниковым данным
Get PDFStudying of characteristics of the Lake Onega ice regime and investigating of the climate influence on the formation and destruction of the ice cover requires a continuous chronological series of data on the Lake ice coverage. Ice cover is the percentage of the ice area to the total area of the lake. In 1955–1990, calculations of the ice coverage of the Lake were based on the use of the results of airborne ice reconnaissance. On average for this period, from 5 to 15 values were annually obtained, which was not enough for a comprehensive analysis of the ice coverage variability. In this paper, for the frst time, a daily series of values of the ice coverage of the Lake Onega for the period 2000–2018 had been formed basing on the results of a combined analysis of the following satellite data sets: NSIDC, NOAA NESDIS, corrected by data of the satellite MODIS sensor. Values from November to May were grouped from the above data sets without regards for years of observations, and then the regression analysis of these values made possible to create a model (a polynomial of the 8th degree) of the chronological course of the ice coverage during the period of the ice phenomena existence on the Lake Onega. Te coefcient of determination of the model is 0.74, and the error in determining the ice coverage is 21%. Te average dates of the beginning, end, and duration of periods of the formation (from November 25th to January 19th), the destruction (from April 13th to May 17th) of the ice cover, as well as the total freeze-up time (from January 20th to April 12th) on the Lake Onega for the period 2000–2018 was determined. Te period of ice phenomena on the Lake Onega on average lasts for almost half a year (175 days), of which a signifcant part of the time is a complete freeze-up (84 days). It was found that the rate of formation of the ice cover (1.76% per day) on the Lake Onega is 1.65 times smaller than the rate of its destruction (2.90% per day), which approximately corresponds to similar results obtained for the Lake Ladoga (1.5 times).Впервые получен непрерывный суточный ряд значений ледовитости Онежского озера за 2000–2018 гг. на основе результатов комбинированного анализа наборов спутниковых данных NSIDC, NOAA NESDIS, скорректированных спутниковыми данными MODIS. Представлена регрессионная модель хронологического хода ледовитости в период ледовых явлений на Онежском озере
ОЦЕНКА СОВРЕМЕННОЙ ДИНАМИКИ И ПРОГНОЗ ГЛЯЦИОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК ЛЕДНИКА МАЛЫЙ АКТРУ (ЦЕНТРАЛЬНЫЙ АЛТАЙ)
Get PDFIn the context of global and regional climatic changes in the Altai mountain region, observations performed in 1949–2014 demonstrated evident rises of air temperatures, both annual and seasonal means. Relative to the climatic norm (1949–1985), mean annual temperature (averaged for the period 1986–2014) had risen by 0.8– 1.9 °С. The most significant warming took place in winter and spring. In winter, the positive difference with the mean value is approximately equal to 0.9–3.8 °C, while in spring 0.9 and 1.7 °C. Air temperatures in summer and autumn periods were rising as well. Changes in annual and seasonal precipitations were more variable. The autumn and winter periods are characterized by a decrease in precipitation. On average, it is respectively 17% and 6%. In the spring and summer seasons, the tendency is opposite since these periods are characterized by a weak increase in precipitation. On average for the whole territory, the increase in the mean climatic amount of seasonal precipitation was equal to 2% and 4% relative the climatic norm for 1966–1985, for spring and summer respectively. The amount of annual precipitation on theterritoryofGorny Altairemained unchanged. Under current climate conditions which are characterized by decreasing in winter precipitation, the air temperature rise during all seasons, and longer warm period the mass balance of the Malyi Aktru Glacier becomes drastically negative. Total accumulation decreases, the ablation increases, and as a result, the negative mass balance grows. Using the methods of exponential smoothing, given the type of the trend component in series of meteorological quantities, a forecast of a 10‑year mean air temperature and the amount of atmospheric precipitation was made for the period 2021–2030. Using the appropriate regression equations, this allowed calculating predictive mean values of accumulation, ablation, and mass balance of the Malyi Aktru Glacier for the third decade of the XXI centuryВыполнен анализ современных изменений температуры воздуха и осадков на территории Горного Алтая и масс-балансовых характеристик ледника Малый Актру. Проведена верификация ранее разработанной модели прогноза суммарной аккумуляции и абляции на леднике. Дана прогнозная оценка средних величин суммарной аккумуляции, абляции и годового баланса массы на период 2021–2030 гг
Изменение стока снегового половодья на южном макросклоне Русской равнины в период 1930–2014 гг
Get PDFIn recent decades, in the southern macro-slope (catchment) of Te Russian Plain, mainly within the basins of the Volga and the Don rivers, the spring flood flow decreased due to both anthropogenic and climatic factors. Of anthropogenic factors, the creation of reservoirs played a signifcant role in changing the water regime of the Volga and the Don. Another important factor, affecting the river runoff, is agricultural activities on flat interfluves and slopes. Compared with the conventional-natural period (for the Volga from 1879, and for the Don from 1876 to 1929) to the date (for the period 1930–2014), the flood flow of the Volga has been decreased by more than 4300 km3, and the Don – by almost 900 km3. Te contribution of anthropogenic factors to this decrease in the Volga basin exceeded 70%, and for the Don it was equal to 45%, while the climatic ones contributed 30 and 55%, respectively. During the period of instrumental observations on the rivers of the region, long-lasting phases of high/low water content with duration from 15–20 to 90 years or longer, caused by the climatic changes, were determined. Tese are a characteristic feature of long-term changes in flood flow (and in a runoff of other seasons) on both medium and large rivers of the southern macro-slope of the Russian Plain. Te period since early 2000s was a start of the decreased flood flow everywhere, i.e. on medium and large rivers. It is most clearly (by tens of percent) manifested in the decrease of the spring surface flow due to the following factors: more frequent thaws, reduction of the depth of soil freezing, increase of infltration, especially in the forest-steppe and steppe zones. Increase in flow of the infltration origin does only partially compensate the decrease of the flow in rivers.Рассматриваются сток снегового половодья в пределах бассейнов Волги и Дона и его изменения под влиянием антропогенных и климатических факторов. Изложены методы исследования изменений речного стока, оценены его изменения за последние десятилетия. Общая тенденция – уменьшение стока половодья, что связано с гидротехническим воздействием и климатическими факторами
МИКРОЭЛЕМЕНТНЫЙ И ИЗОТОПНЫЙ СОСТАВ СНЕЖНОГО ПОКРОВА КАТУНСКОГО ПРИРОДНОГО БИОСФЕРНОГО ЗАПОВЕДНИКА (РЕСПУБЛИКА АЛТАЙ)
Get PDFThe present-day regional level of various trace elements contents together with characteristics of isotopic composition was for the first time estimated in seasonal snow cover of Altai. As a background territory, the State Nature Biosphere reserve «Katunsky» had been chosen. This reserve is included into the World network of biosphere reserves under the UNESCO Program «Man and biosphere». The route snow survey had been carried out at the end of February 2014 since this is a period of maximum snow accumulation. The snow survey involved evaluation of snow storages, stratigraphic analysis of the snow cover, and layer-by-layer snow sampling for analysis of its trace element and isotopic compositions. Isotopic and stratigraphic analysis of visually selected layers of the snow cover revealed substantial variation in the values of δ18O and δD (the maximum difference between layers was 120.1 and 15.3 ‰, respectively), whiledexc changed within the range from 5.6 to 16.6 ‰. The weighted-mean values of the snowpack isotopic composition are the following: δ18O = −24.9 and δD = −188.9 ‰, and the isotopic ratio of oxygen and deuterium is described by the equation δD = 8,3δ18О + 18.9. The analysis of microelement composition of the snow samples made with the use of the crustal enrichment factor (EFc) and correlation matrix allowed determination of elements (Ba, Be, V, Co, Li, Mn, Ni, Sr, Tl, Th, U и Cs) released into the atmosphere above the territory under investigation mainly with particles of fly ash, in which the ratio of elements corresponds to the regional natural sources – soils and underlying rocks. It was shown that the main part of elements Ag, As, Bi, Cu, Mo, Sb, Zn come preferably from anthropogenic sources which are non-ferrous metallurgy enterprises of East Kazakhstan and pits of operating and abandoned mines of Rudny Altai.По наблюдениям зимой 2013/14 г. оценён современный фоновый уровень содержания широкого спектра микроэлементов в сезонном снежном покрове Алтая и изучены особенности изменения его изотопного состава. С помощью расчётных коэффициентов «обогащения» определены элементы (Ba, Be, V, Co, Li, Mn, Ni, Sr, Tl, Th, U и Cs), поступающие в основном в составе золы уноса при сжигании углей и имеющие схожие с природными источниками соотношения данных металлов, тогда как основные источники поступления Ag, As, Bi, Cu, Mo, Sb и Zn – это предприятия цветной металлургии и шламоотвалы горнодобывающих карьеров Рудного Алтая
ФАКТОРЫ, ВЛИЯЮЩИЕ НА ПРОЦЕССЫ СУЛЬФАТРЕДУКЦИИ И МЕТИЛИРОВАНИЯ РТУТИ ВО ЛЬДАХ РЕКИ АМУР
Get PDFResults of the layer-by-layer studies of distribution of organic matter (OM) and mercury in ice cores sampled from the Amur River near the Khabarovsk city: its mainstream and the Pemzenskaya and Amurskaya branches, are presented. Comprehensive investigation of ice performed at the end of the freeze-up period allows making a retrospective analysis of the river ecosystem pollution during winter. Analysis of the total content of dissolved organic substances and aromatic compounds, determining a level of humification of the aquatic environment, was carried out with a spectrophotometer Shimadzu UV-3600 at 254 and 275 nm. The mercury content was determined by inductively coupled plasmamass spectrometry (ICP-MS). The number of cultured heterotrophic bacteria, sulfate-reducing bacteria (SRB) and their resistance to mercury (0.0005 and 0.001 mg/L) were used as indicators of biogeochemical processes going on in vitro. The maximum resistance to mercury at concentration of 0.001 mg/l was revealed from the sulfate-reducing bacteria in cores taken from the upper ice layer (0-10 cm) near the right bank of the Amurskaya branch. Periodical high mercury contamination of ice (up to 0.71 mkg/L) is estimated as a risk factor. In Pemzenskoy branch, the main factors for the mercury methylation in the ice were fine detritus, coming at the reservoir discharges, and the SRB resistant to mercury. These microorganisms were found in upper layers of the ice (10-35 cm) near the left bank and in the middle of the water stream (60–80 cm). A layer of ice (70–117 cm) with conditions also favourable for the sulfate reduction and the mercury methylation had been revealed in the mainstream of the Amur River near its right bank that is the cross-boundary area in the zone of influence of the Songhua river runoff. Among these conditions are high levels of OM, the presence of heterotrophic bacteria, which are destructors of high-molecular compounds, the potential producers of metabolites with methyl radicals, and the activity of the SRB resistant to mercury.Представлены результаты послойного исследования кернов речного льда с использованием спектральных и микробиологических методов. Активность биогеохимических процессов во льдах определяется высокими концентрациями органических веществ (растворённых и в виде детрита), загрязнением водной среды ртутью при формировании ледяного покрова, численностью культивируемых гетеротрофных бактерий и сульфатредуцирующих бактерий. К основным предпосылкам метилирования ртути во льдах р. Амур относятся: поступление из водохранилищ гумифированных вод и детрита; трансграничное загрязнение летучими ароматическими соединениями; образование бактериальных метаболитов с метильными радикалами; устойчивость сульфатредуцирующих бактерий к ртути
ВЛИЯНИЕ РИФТОВЫХ ЗОН И ТЕРМОКАРСТОВЫХ ОЗЁР НА ФОРМИРОВАНИЕ СУБАКВАЛЬНОЙ МЕРЗЛОТЫ И ЗОНЫ СТАБИЛЬНОСТИ МЕТАНОГИДРАТОВ ШЕЛЬФА МОРЯ ЛАПТЕВЫХ В ПЛЕЙСТОЦЕНЕ
Get PDFThis paper presents results of the analysis of the influence of talik zones associated with thermokarst lakes and processes in rift zones on the dynamics of subaqueous permafrost and zones of stability of methane hydrates for conditions of theLaptev Seashelf. The model of thermophysical processes in the bottom sediments together with the scenario of climate change on the Arctic shelf for the last 400 thousand years (kyr) were used. Typical value of geothermal heat flux for the most part of the shelf and for the shallow shelf (with the present-day depth of ≤50 m) is estimated as 60 mW/m2. It is shown that with this value the duration of the interglacials and the corresponding ocean transgression periods is not sufficient for the complete degradation of permafrost and destruction of the gas hydrates. For a deeper shelf, however, the complete disappearance of the stability zone of the methane hydrates is possible during the interglacial periods. In the areas of oceanic faults (rifts), higher values of the deep heat flux increase rates of degradation of the underwater permafrost rocks in the interglacial periods as compared with the condition when the heat flux is 60 mW/m2. Intensification of degradation of the subsea permafrost is manifested in areas where thermokarst lakes arise, but here it is associated with the temperature rise at the upper boundary of the bottom sediments. The presence of the rift zones and/or the thermokarst lakes promotes decreasing of the presentday thickness of the permafrost, and simultaneous impact of these two factors can lead to a through thawing of the shelf in the interglacials (including Holocene).Проведён модельный анализ характеристик многолетнемёрзлых пород и зоны стабильности газовых гидратов на арктическом шельфе для последних 400 тыс. лет. При интенсивности геотермического потока 60 мВт/м2 для мелководного шельфа (с современной глубиной моря ≤ 50 м) продолжительность межледниковий и соответствующих периодов трансгрессии океана недостаточна для полной деградации многолетнемёрзлых пород и разрушения газогидратов. При более глубоководном шельфе возможно полное исчезновение зоны стабильности газовых гидратов во время межледниковий
Изотопная индикация условий образования ледяных ядер булгунняхов (пинго)
Get PDFTe isotopic characteristics of the pingo ice cores are considered. Te distribution of δ18O and δ2H values, dexc, δ18O–δ2H and δ2H–d exc relationships, and the simulation of the distribution of δ18O and δ2H values during the ice formation in a closed system, allowed drawing conclusion about the hydrological conditions and stages of the ice core growth. All pingos (Pestsovoye, Weather, Pingo-20) were formed in draining lake basins in the course of freezing of closed taliks. It is established that the water, which served as a source for the formation of the ice core, was subjected to evaporation still before the ice formation. According to our estimates, the water from which the ice of the Pestsovoye pingo was formed was heavier in values of δ18O and δ2H by 3.9 and 29.7‰, respectively, than the current average annual precipitation in the region. Similarly, for the ice of the core of the Pingo Weather it is 2.9 and 14.5‰, and 5.1 and 27.7‰ for the Pingo-20, respectively. In the ice cores of all considered pingos there is an ice formed in a closed system: in Pingo-20 it is a pure injection ice, while in the Pestsovoye and the Weser ones – the injected-segregated ice. Te frost mounds Pestsovoe and Weser grew under changing hydrological conditions: one part of the ice was formed when there was a free flow of water to the freezing front (open system); the other one – when the water-saturated lenses of the closed talik were frozen (closed system). Te isotopic composition of ice being formed under conditions of a closed system reflects isotopic depletion during freezing and ice formation according to the Rayleigh model. It is expressed in a successive decrease in the values of δ18O and δ2H from the frst portions of ice to the last ones as the freezing continued. Te contrast values of δ18O and δ2H in different parts of the ice being formed in the closed system may be used as an additional tool to identify direction of freezing. In a closed system, the last portions of ice have the greater contrast of the isotope values as compared to the frst portions.Рассмотрено распределение значений δ18О, δ2Н и dexc в ледяных ядрах инъекционных бугров пучения (булгуннях, пинго). Установлено, что булгуннях Песцовое (Тазовский п-ов), пинго Уэзер (залив Прудо, Аляска) и пинго-20 на Аляске сформировались при образовании льда из воды осушающихся озёр, которая до начала пучения подверглась испарению. Контрастность значений δ18О в разных частях ледяного ядра может быть использована как дополнительный инструмент для установления направления промерзания
ВАРИАЦИИ ИЗОТОПОВ КИСЛОРОДА И ВОДОРОДА В СОВРЕМЕННОЙ ПЛАСТОВОЙ ЛЕДЯНОЙ ЗАЛЕЖИ В УСТЬЕ Р. АККАНИ, ВОСТОЧНАЯ ЧУКОТКА
Get PDFThe object of this study is a recently (or in the Holocene) formed thick (up 2.7 m in height) buried massive ice body, exposed in 2 km South-East from the mouth of the river Akkani in the North-East of Chukotka in the vicinity of the settlement Lavrentiya. The structural-textural characteristics of ice and enclosing deposits are considered. It is shown that the overlying layers of sediments are loams with a slab structure and vertical-layer medium and thin-chill cryogenic structure and ice sockets. The ice of the body is very pure and transparent, visible to a depth of 0.5 m. There are some inclusions found in massive ice: sand and loams presented in forms of thin interlayers of particles or granules. The ice is full of bubbles. The main method of the research was the analysis of isotopes of oxygen and hydrogen within the stratified ice body, and also relationships between them as well as ratios between the deuterium excess and δ2Н. The thick and relatively contemporary massive ice layer buried under a layer of proluvial sediments had been found for the first time, and together with this, the isotope variations of the buried ice (δ2Н and δ18O) were determined. The mean values of δ18О and δ2H in the ice are rather stable and equal to −17.1 and −128.3‰, respectively. These isotope characteristics may be used for cryogenic reconstructions of massive ice formations widely distributed in the late Quaternary deposits in Eastern Chukotka.Изучен изотопный состав кислорода и водорода мощного современного (голоценового) ледяного пласта, погребённого под слоем пролювиальных отложений на побережье Чукотки вблизи посёлка Лаврентия. Значения δ18О и δ2H во льду довольно однородны и составляют −17,1 и −128,3 ‰ соответственно. Изученный пластовый лёд в устье р. Аккани представляет собой захороненный перелетовывающий снежник, сформировавшийся с участием поверхностных вод и атмосферной влаги весенне-летнего периода
ТРОПИЧЕСКИЕ ЛЕДНИКИ СЕГОДНЯ
Get PDFThe continuing global warming causes a significant reduction and vanishing of glaciers in the tropics. The glaciers in Africa, New Guinea, and Venezuela can completely melt during next decade under current trend in climate change.Продолжающееся глобальное потепление приводит к значительному сокращению и исчезновению ледников в тропиках. Ледники в Африке, Новой Гвинее и Венесуэле могут полностью растаять в течение следующего десятилетия при текущей тенденции изменения климата