Формирование изотопного состава снега на ледниках Арктики (на примере Шпицбергена и Северной Земли)

Stable isotope studies of snow cover along several itineraries through Spitsbergen were carried out (from Gronfjorden coast till ice divide of Gronfjord – Fridtjov glacier and from Barentsburg settlement till Olav mountain). Results obtained were compared with ones fixed for snow on Severnaya Zemlya archipelago. Uncertainty of condensation processes were shown for precipitation falling on Arctic polar ice domes (sometimes we fixed altitudinal isotope gradient and in other cases the gradient was absent). In periglacial zone of arctic islands isotope values are scattered randomly, covering the entire annual precipitation range due to strong snow-storms.Проведены изотопные исследования снежного покрова Шпицбергена по нескольким маршрутам: от берега до ледораздела системы Гренфьорд–Фритьоф и от пос. Баренцбург до отрогов горы Улаф. Полученные результаты сопоставляются с более ранними данными по снежному покрову архипелага Северная Земля. Показана неоднозначность процессов конденсации осадков, выпадающих на полярные ледниковые купола. Отмечаются случаи как наличия, так и отсутствия вертикального изотопного градиента. Во внеледниковой зоне арктических островов сильнейший ветровой перенос определяет случайное распределение значений изотопного состава снега. Полученный разброс значений по проведённым маршрутам практически перекрывает диапазон величин изотопного состава свежевыпавшего снега, характерных для исследуемых районов

Endolithic and hypolithic soil-like systems: structure and composition from the macroto submicro-levels

The paper presents a detailed study on structure and composition of endolithic and hypolithic systems. The following issues are discussed: morphology at macro to submicro levels, biochemical weathering, formation of carbonates and oxalates in situ, migration of Fe compounds, and spatial patterns of endolithic systems. Endolithic and hypolithic systems have major features attributed to soils: (a) rock layer exposed to external abiogenic factors, (b) lithomatrix inhabited by living organisms which are synthesizing and decomposing organic matter, (c) as a result initial parent rock (lithomatrix) is transformed in situ by biogenic and abiogenic factors, the products of transformation are retained and/or removed, the vertical heterogenity is established in a form of microhorizons composing microprofile. Examined profiles of endolithic systems in granitoids of East Antarctica with high quartz content had clear eluvial-illuvial differentiation patterns. Similar patterns have been discovered in different landscapes from the Plateau Ozark in Missouri to the Table Mountain in South Africa

Влияние снежного покрова на промерзание и протаивание грунта на Западном Шпицбергене

This paper presents the results of experimental research of snow cover influence on ground freezing/thawing in Svalbard. Observations show that even before the snow disappearance ground thaws for dozens of centimeters that increases the thaw depth later in the season. Under the snow cover of 40 cm the thaw depth can reach 35–50 cm. The thawing can be caused by melt water with slightly positive temperature, percolating under the snow cover near the ground surface. The data on ground temperature regime during a year under various snow depths are given. Under a shallow snow cover the ground cools significantly, and this process causes the slowing down subsequent thawing.Рассматриваются результаты натурных измерений и расчётов влияния снежного покрова на промерзание и протаивание грунта на Западном Шпицбергене. Установлено, что ещё до схода снежного покрова грунт протаивает на десятки сантиметров, в результате чего увеличивается толщина талого слоя. Так, под снегом, толщиной 40 см, глубина протаивания грунта составляет 35–50 см. По мнению авторов, это может быть вызвано талой водой с небольшой положительной температурой, фильтрующейся под снежным покровом в приповерхностной части грунта

RADIOCARBON DATING: PAST, PRESENT-DAY AND FUTURE - DEVELOPMENT OF I.P. GERASIMOV IDEAS

The ideas of I.P. Gerasimov on the radiocarbon soil age are outlined; the notions of absolute and relative soil age introduced by him are defined. Current trends in organic matter dating are discussed. The proposals on the “dating” soil fraction by the radiocarbon method are considered, as well as interpretations of the data obtained as related to new approaches in the studies of soil organic matter. The recent trends in search of new “dating” fractions are the following: dating of different pools of organic matter, dating of particle-size and densitometric fractions. The problems of radiocarbon dating application to soils and sediments in archaeological soil science are discussed. Basing on the results of dating performed for the organic matter of cultural layers of Early Medieval settlement it is shown that the organic matter of soils and pedosediments in archaeological objects may be a reliable source of information either for compiling chronological schemes, so for a comprehensive analysis of soil-forming processes operating in humanly modified materials. It is shown that the Radiocarbon Laboratory of the Institute of geography, RAS, is now applying progressive methodology, among which the preparation of samples - carbon graphitization to obtain data by means of accelerated mass-spectrometry is worth mentioning

Formation of the snow isotopic composition on the Arctic glaciers (case study of Spitsbergen and Severnaya Zemlya)

Stable isotope studies of snow cover along several itineraries through Spitsbergen were carried out (from Gronfjorden coast till ice divide of Gronfjord – Fridtjov glacier and from Barentsburg settlement till Olav mountain). Results obtained were compared with ones fixed for snow on Severnaya Zemlya archipelago. Uncertainty of condensation processes were shown for precipitation falling on Arctic polar ice domes (sometimes we fixed altitudinal isotope gradient and in other cases the gradient was absent). In periglacial zone of arctic islands isotope values are scattered randomly, covering the entire annual precipitation range due to strong snow-storms

The organic matter of the buried peat soils on bely island (kara sea)

The organic matter composition of buried peat horizons from the west coast of White lake (Kara Sea) was investigated using the method of dency-metric fractionation. Considerable amount of peat in studied buried horizons, the amount of which increases with depth was revealed. According to radiocarbon dating of peat was formed in the early Holocene. Great ancientry of organic matter in studied buried horizons indicates a very slow humification process. This is due to the extreme environmental conditions: lower average temperatures and short duration period of positive temperatures. The presence of a larger number poorly decomposed plant residues in the composition of the light fractions in low part of the buried horizon indicates the difference between the conditions of the decomposition of organic matter in the period of 8950-8580 years ago, namely, the less favorable conditions for microbial activity in low horizon. This could be due to the change of the local hydrological conditions that influenced the change in the rate of humification of plant residues during this relatively short period of time

Influence of snow cover on soil freezing and thawing in the West Spitsbergen

This paper presents the results of experimental research of snow cover influence on ground freezing/thawing in Svalbard. Observations show that even before the snow disappearance ground thaws for dozens of centimeters that increases the thaw depth later in the season. Under the snow cover of 40 cm the thaw depth can reach 35–50 cm. The thawing can be caused by melt water with slightly positive temperature, percolating under the snow cover near the ground surface. The data on ground temperature regime during a year under various snow depths are given. Under a shallow snow cover the ground cools significantly, and this process causes the slowing down subsequent thawing