Ice and Snow (E-Journal) / Лёд и Снег
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ПРОБЛЕМЫ ЗАЩИТЫ ОКРУЖАЮЩЕЙ СРЕДЫ И ЭКОЛОГИЧЕСКОГО МОНИТОРИНГА В ПРОЕКТАХ ИЗУЧЕНИЯ ПОДЛЕДНИКОВЫХ ОЗЁР АНТАРКТИДЫ
No full textAntarctic subglacial lakes can represent extreme natural habitats for microorganisms from the position of their evolution and adaptation, as well as they can contain the information on Antarctic ice sheet history and climatic changes in their sediments. Now only direct measurements and sampling from these habitats can answer on many fundamental questions. Special precaution should be complied at penetration into these unique relic environments without unfavorable impacts and contamination. A number of recommendations were developed on levels of cleanliness and sterility during direct exploration and research of subglacial environments. Documents considered in the article are the first and necessary steps for appropriate and long-term ecological management of subglacial Antarctic environments. Today there are three projects of subglacial aquatic environment research which are in preparation and realization – the Russian project of Lake Vostok, the similar British project of Lake Ellsworth and the American project on Whillans Ice Stream. The programs of ecological stewardship for direct exploration of these lakes are discussed. All these subglacial aquatic objects of further exploration and research are so various on their structure, age and regime, that only results of all programs as a whole can help to draw us a uniform picture of a subglacial ecological system. Ecological stewardship of these should provide the minimal ecological impact with maximal scientific results. On the basis of existing documents and recommendations the general approaches and the program of ecological stewardship for Lake Vostok research are discussed. Study of drilling fluid, drilling chips, Vostok ice core and the fresh frozen water will allow to make an assessment of biological and chemical contamination as a result of the first penetration and to modify the further stewardship program for the second penetration and direct exploration of lake water.В настоящее время на разных стадиях подготовки и реализации находятся три крупных проекта исследования подледниковых водоёмов Антарктиды – российский проект исследования озера Восток, сходный проект Великобритании по изучению озера Эллсуорт и американский проект по проникновению и взятию проб под ледниковым потоком Вильянс в Западной Антарктиде. В статье обсуждается программа экологического сопровождения прямых исследований этих уникальных природных объектов. Дан обзор документов, которые служат основой для выработки долгосрочной стратегии комплексных исследований и сохранения в первозданном виде подледниковой антарктической среды
Физико-географические закономерности формирования искусственных фирново-ледяных массивов
Get PDFПостроены карты суточной производительности намораживания искусственного фирна методом зимнего дождевания для каждого месяца с отрицательной температурой воздуха ниже −5 °С на территории России. Оценена потенциально возможная производительность намораживания ледяного материала методами зимнего дождевания и тонкослойным наливом в современных климатических условиях. Рассмотрена роль климатических изменений в снижении производительности намораживания в разных регионах России. Анализ климатических условий в 1961–2000 и 2001–2010 гг. показал, что на территории России производительность намораживания искусственного фирна снизилась с 5–10% в Сибири до 20–40% в центральных и южных районах Европейской территории России
СНЕЖНЫЙ ПОКРОВ ЦЕНТРАЛЬНОЙ АНТАРКТИДЫ (СТАНЦИЯ ВОСТОК) КАК ИДЕАЛЬНЫЙ ПРИРОДНЫЙ ПЛАНШЕТ ДЛЯ СБОРА КОСМИЧЕСКОЙ ПЫЛИ: ПРЕДВАРИТЕЛЬНЫЕ РЕЗУЛЬТАТЫ ПО ВЫЯВЛЕНИЕ МИКРОМЕТЕОРИТОВ ТИПА УГЛИСТЫХ ХОНДРИТОВ
No full textDuring the 2010/11 season nearby the Vostok station the 56th Russian Antarctic Expedition has collected surface snow in a big amount from a 3 m deep pit using 15 220 L vol. containers (about 70 kg snow each). Snow melting and processing by ultra-centrifugation was performed in a clean (class 10 000 and 100) laboratory. Total dust concentrations were not exceeded 37.4 mkg per liter with particle dispersal mode around 2.5 mkm. To analyze the elemental composition of fine dust particles aimed to reveal Antarctic micrometeorites (AMM) two electron microscopy devices equipped with different micro-beams were implemented. As a preliminary result, three particles (of 107 analyzed) featured by Mg content clearly dominated over Al along with Si and Fe as major elements (a feature of carbonaceous chondrites) were observed. By this the Vostok AMM CS11 collection was established. The occurrence of given particles was averaged 2.8% – the factual value obtained for the first time for chondritic type AMM at Vostok which should be considered as the lowest estimate for all other families of AMM. Given the reference profile of total dust content in East Antarctic snow during Holocene (18 mkg/kg) the MM deposition in Antarctica was quantified for the first time – 14 tons per day for carbonaceous chondrites for the Vostok AMM CS11 collection and up to 245 tons per day for all MM types for the Concordia AMM DC02 collection. The results obtained allowed to prove that snow cover (ice sheet in total) of Central East Antarctica is the best spot (most clean of other natural locations and always below 0 ºC) for collecting native MM deposited on the Earth during the last million years and could be useful in deciphering the origin and evolution of solid matter in our Solar System and its effects on Earth-bound biogeochemical and geophysical processes including the life origin. The farther analyses of the Vostok AMMs are in a progress
Возможные причины эмиссии метана на шельфе морей Восточной Арктики
No full textWe analyze data on methane concentration in the water and lower atmosphere over the shelf of the East Siberian Arctic Seas, which were obtained using marine, terrestrial, and satellite observations. Our study is targeted towards attribution of the enhanced concentrations of methane above the latitudinal-mean, which have been detected at selected locations of these seas. We compare two hypothesis, which attribute it to the effect of modern changes of the sub aquatic permafrost, and to geological factors (tectonics, presence of fault zones and paleo river beds in the study region). Our analysis showed that the methane concentration in sea water are directly related to the distance to the nearest fault zone or paleo river bed, where permafrost is absent and bottom sediments are perforated allowing methane to escape from the deep layers containing gas hydrates. This result indicate that the enhanced emission of methane, which was observed at selected locations of the shelf, is not related to the modern climate change. Earlier study, which was based on mathematical modeling, did not find intensive development of taliks as well as other processes that lead to increased gas permeability of the bottom sediments. Taken together, these results reject the hypothesis of methane catastrophe on the East Siberian Arctic Seas shelf over the foreseeable future
Описание миграции линии налегания в двумерной математической модели ледникового щита
No full textContemporary thinning of the marine-based areas of ice sheets is believed to be the consequence of the grounding line retreat caused mainly by ocean gradual warming beneath the ice shelves. In order to estimate potential contribution of ice sheets into the future sea-level rise grounding line migration must be accurately described in the mathematical models. We incorporated an algorithm based on application of the boundary condition on the mass flux across the grounding line into a two-dimensional ice flow model. In the numerical experiments, externally forced ice sheet returns to its initial equilibrium state after termination of the external forcing (either accumulation rate or sea-level change anomalies). In future, the model will be modified to incorporate buttressing effect.Объём ледниковых щитов, основание которых лежит ниже уровня моря, сокращается главным образом в результате смещения линии налегания в глубь континентальной области предположительно в результате потепления окружающих его вод океана. Для оценки потенциального вклада ледниковых щитов в будущее увеличение уровня моря в математических моделях необходимо как можно точнее описывать процесс миграции линии налегания. В статье рассматривается алгоритм миграции, в основе которого лежит задание граничного условия потока массы на линии налегания. В численных экспериментах ледниковый щит, будучи выведенным из равновесия внешним воздействием, возвращается к своему первоначальному состоянию при прекращении действия внешней силы. После соответствующей доработки алгоритм можно применять в комплексных моделях ледниковых щитов
ЛЕТОПИСЬ ВУЛКАНИЧЕСКИХ СОБЫТИЙ ПОСЛЕДНИХ 900 ЛЕТ В СНЕЖНО-ФИРНОВОЙ ТОЛЩЕ РАЙОНА СТАНЦИИ ВОСТОК (АНТАРКТИДА)
No full textThe results of chemical analyses of snow samples from five pits and cores drilled in the vicinities of Vostok Station, Antarctica, are presented. High resolution (every 2–3 cm, or about three samples per year) ion measurements allowed to compile a new detailed record of volcanic events for the past 900 years. About 30 low latitude volcanic eruptions were identified In core intervals with high content of nonmarine sulphates and decreased values of acidity during XIII–XX centuries. Global ones analysed in the literature were detected in the cores: Pinatubo (1991), Agung (1963), Krakatau (1883), Tambora (1815), unknown (1809), Gamkonora (1673), Huaynaputina (1600), Kuwae (1453), unknown (1259). Приводятся результаты химического анализа снежно-фирновой толщи района станции Восток по образцам из пяти снежных шурфов и кернов. Детальность отбора проб (каждые 2–3 см) позволила получить хронологию вулканических событий с высокой степенью точности. В интервалах с повышенными концентрациями неморского сульфата и пониженными значениями кислотности идентифицированы сигналы около 30 следов вулканических извержений низкоширотных вулканов на протяжении XIII–XX вв., в том числе глобальных, анализируемых в мировой литературе: Пинатубо (1991 г.), Агунг (1963 г.), Кракатау (1883 г.), Тамбора (1815 г.), неизвестный вулкан (1809 г.), Гамконора (1673 г.), Уайнапутина (1600 г.), Кувае (1453 г.), неизвестный вулкан (1259 г.)
ГЕОДЕЗИЧЕСКИЕ НАБЛЮДЕНИЯ И ИНТЕРПРЕТАЦИЯ СКОРОСТЕЙ ТЕЧЕНИЯ ЛЬДА В ЮЖНОЙ ЧАСТИ ПОДЛЕДНИКОВОГО ОЗЕРА ВОСТОК
No full textResults of geodetic in-situ observations of ice-flow velocities in the southern part of subglacialLakeVostokare combined with data sets of the ice surface topography, ice thickness, surface accumulation, basal accretion and firn/ice density for interpretations regarding the glaciological setting of theLakeVostoksystem. Based on the ice-flow velocities and the ice thickness, mean surface accumulation rates are derived applying the flux gate method. These are representative for surface segments extending from the southern part ofLakeVostokto the Ridge B ice divide. They are consistent with the present-day accumulation rate at Vostok station and its variation upstream and thus suggest that the area has been close to steady state. In addition, ice-flow dynamics are investigated along a flow line segment extending from26 kmupstream to12 kmdownstream from Vostok station. The analysis suggests deficiencies in current modelling approaches within the transition zone from floating to grounded ice
Влияние вертикальной неоднородности заполнения киля тороса на скорость его промерзания
No full textField data on ice ridges in the south-eastern and eastern parts of the Barents Sea collected by specialists of the Arctic and Antarctic Research Institute (AARI) in 2003–2007 has been used in attempt to understand the vertical inhomogeneity of the ridge keels filling. New ridges originated from one-year sea ice (with no consolidated layer or or less than 5–10 cm thick) have been analyzed. Reduction of original observations under certain additional assumptions has allowed formulating the vertical distribution of the ridge keel fill factor. This approximation has been applied in the one-dimensional thermodynamic ride model developed in AARI to simulate the ice ridges behavior in the Central Arctic and Arctic seas. The modeling of ridge freezing rates for different geographical sites has shown the more intensive freezing of ridge keels in initial stage than expected from previous modeling runs. The new results are consistent with field observations on consolidated layer thickness in ridges. Model calculations for a longer period show no big difference in results obtained with or without the approximation proposed
