Chemical Properties of Glacial and Ground Ice

Vasil’chuk, Y.K.

Автор: Vasil’chuk Yu K.
Сборник: Encyclopedia of Life Support Systems (EOLSS). Ed.: M.G. Khublaryan
Том: 2
Год издания: 2009
Первая страница: 265
Последняя страница: 295
Аннотация: Marine aerosols are the main source of Cl, Mg, Na, K, Mg, SO4, in ice sheets of Greenland and Antarctic. Marine salts accumulate along the coastline, their concentration decreases sharply away from the coastline. Concentration of elements of continental origin is independent on the distance from coastline. In Greenland dust concentrations in ice–age ice are 3 to 70 times those in Holocene ice. The ice–age dust contains a strong component of calcium carbonate. This neutralized acid aerosols in atmosphere so that in contrast to Holocene ice, nearly all ice–age ice is alkaline. Air clathrate hydrates are observed in deeper ice sheets. Mineralization of ground ice is an important indicator of ice origin; ground ices are classified according to their salinity. Ice with mineralization 0.02– 0.1 g/l is predominant in Holocene ice wedges of Northern Yakutia. The mineralization of Pleistocene ice wedges is 60 – 478 mg/l. Salt concentration ranges in dependence of distance from the sea. Most ice–wedge ice is fresh. Maximum concentration of heavy metals in Greenland ice cores Pb –151 pg/g, Cu – 238 pg/g, Zn – 644 pg/g, Cd – 3.0 pg/g and in Vostok ice core: Pb –38 pg/g, Cu – 33 pg/g, Zn – 101 pg/g, Cd – 3.0 pg/g. Because the delta18О composition of water infiltrating through the snow layer reflects the isotopic composition of the snow, the isotopic composition of modern ice wedges also corresponds with that of winter snow. For example, the mean values of delta18О composition of snow from three localities in the permafrost zone of Northern Eurasia are similar to or isotopically lighter than delta18О values in modern adjacent ice wedges. The isotope record of ice wedges is averaged oxygen isotope composition of snow precipitation for many years. The oxygen isotope composition of ice–wedge ice varies spatially along the northern coastline of Siberia and temporally during the last 40 ka. This indicates a dependence of the delta18О composition of ice wedges upon climatic conditions. 18O trends in Late Pleistocene syngenetic ice wedges in Siberia suggest that the air mass transport throughout Subarctic Asia was similar to that today. Westerly transport was prevalent over a considerable part of Northern Eurasia. Atlantic influences prevailed from the Yamal Peninsula to North–East Yakutia, but these influences were possibly weaker then, due to more frequent cold and dry Arctic air–mass advection. It is also likely that the influence of Pacific air masses was negligible then in the eastern part of Northern Asia. A continental anticyclone regime apparently dominated here, particularly in winter. The delta18O trend in Holocene ice wedges is similar to that in modern ice wedge (both the character of trend and values): delta18O fluctuated from –14 to –20‰ in Western Siberia and from –23 to –29‰ in Northern Yakutia ice wedge systems, then it became as high as –16 to –22‰ in Chukotka. The delta18О data show a positive shift of delta18О values of syngenetic ice wedges at the Pleistocene–Holocene boundary (10 ka BP). For example, Pleistocene, early to middle Holocene and modern trends we can compare the data from one site, for example, from Duvanny Yar in Northern Yakutia. Above-mentioned data are shown that: Late Pleistocene ice wedges are delta18О values from –32.7 to –28.7‰, Holocene from –27.0 to –24.8‰ and modern: from –26 to –24‰, i.e. the range of isotope differences increases for the regions with more changeable environments (facial and landscape).
Добавил в систему: Васильчук Юрий Кириллович

	ИСТИНА	Войти в систему Регистрация
	Интеллектуальная Система Тематического Исследования НАукометрических данных
	Главная Поиск Статистика О проекте Помощь

ИСТИНА

Интеллектуальная Система Тематического Исследования НАукометрических данных

Chemical Properties of Glacial and Ground Iceстатья

Прикрепленные файлы