2024-03-29T06:43:01Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/351672022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Air-hydrate crystals in deep ice-core samples from Vostok Station, AntarcticaUchida, T.Hondoh, T.Mae, S.Lipenkov, V. Ya.Duval, P.open access© 1994 International Glaciological Society450Microscopic observation of air-hydrate crystals was carried out using 34 deep ice-core samples retrieved at Vostok Station, Antarctica. Samples were obtained from depths between 1050 and 2542m, which correspond to Wisconsin/Sangamon/Illinoian ice. It was found that the volume and number of air-hydrate varied with the climatic changes. The volume concentration of air-hydrate in the interglacial ice was about 30% larger than that in the glacial ice. In the interglacial ice, the number concentration of air-hydrate was about a half and the mean volume of air-hydrate was nearly three times larger than that in the glacial-age ice. The air-hydrate crystals were found to grow in the ice sheet, about 6.7×10^-12cm^3 year^-1, in compensation for the disappearance of smaller ones. The volume concentration of air-hydrate was related to the total gas content by a geometrical equation with a proportional parameter α. The mean value of α below 1250m, where no air bubbles were found, was about 0.79. This coincided with an experimentally determined value of the crystalline site occupancy of the air-hydrate in a 1500m core obtained at Dye 3, Greenland (Hondoh and others, 1990). In the depth profile of calculated α for many samples, α in the interglacial ice was about 30% smaller than that in the glacial-age ice.International Glaciological Society1994engjournal articleVoRhttp://hdl.handle.net/2115/351670022-1430AA0025244XJournal of Glaciology401347986https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/35167/1/uchida.pdfapplication/pdf5.08 MB1994