Behavior of air molecules in polar ice sheets (review)

Ancient atmospheric gases are trapped in polar ice sheets. The gas molecules are stored in air bubbles at shallower depth. The air bubbles are gradually compressed with depth and begin to transform into clathrate hydrates below a level at which the hydrostatic pressure becomes greater than the forma...

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Bibliographic Details
Main Authors: Tomoko Ikeda-Fukazawa, Takeo Hondoh
Format: Report
Language:English
Published: Institute of Low Temperature Science, Hokkaido University 2003
Subjects:
Online Access:https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2473
http://id.nii.ac.jp/1291/00002473/
https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2473&item_no=1&attribute_id=18&file_no=1
Description
Summary:Ancient atmospheric gases are trapped in polar ice sheets. The gas molecules are stored in air bubbles at shallower depth. The air bubbles are gradually compressed with depth and begin to transform into clathrate hydrates below a level at which the hydrostatic pressure becomes greater than the formation pressure of the phase of air clathrate hydrate. Air bubbles and clathrate hydrates coexist in the deep ice over a long period of time. Significant gas fractionations during the transition process have been found from measurements of the depth profile of the N2/O2 composition ratios in clathrate hydrates and air bubbles in the Dome-Fuji ice and the Vostok ice. Analyzing the molecular diffusion process in ice, the gas fractionation is attributed to a larger mass flux of O2 molecules from air bubbles to clathrate hydrates through the ice matrix than that of N2. We review the process of gas fractionation caused by the formation of clathrate hydrates in polar ice sheets.