The reduction of chloride ion concentration in basal ice near Hamna Icefall, East Antarctica

• Main Authors: イイズカ ヨシノリ, サタケ ヒロシ, ワタナベ オキツグ, Yoshinori Iizuka, Hiroshi Satake, Okitsugu Watanabe
• Format: Report
• Language: English
• Published: Scientific Note 2001
• Subjects: East Antarctica; Queen Maud Land; Hamna Icefall; Hamna; Antarc*; Antarctica; Polar meteorology and glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2934; http://id.nii.ac.jp/1291/00002934/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2934&item_no=1&attribute_id=18&file_no=1

The present paper mainly discusses chloride ions (Cl^-) in debris-laden basal ice near Hamna Icefall, Queen Maud Land, East Antarctica. The basal ice consists of alternating layers of bubble-free and bubbly ice of the order of mm to cm in thickness. Detailed analyses of Cl^- and stable isotopes (δ^<18>O and δD) on the alternating layers were performed. The Cl^- concentrations in the bubble-free ice layers and in the bubbly ice layers whose isotopic fluctuations decrease from neighboring bubble-free ice layers are reduced compared to those in the bubbly ice layers having quasi-neutral values on the isotopic profile. The reduction of Cl concentration in frozen ice compared to that in pre-freezing water was also observed from an experiment on ion fractionation by freezing. These results suggest that the bubble-free ice layers and the bubbly ice layers whose isotopic fluctuation is decreased from that in neighboring bubble-free ice layers were formed by melt-refreezing processes. The reduction of Cl concentration in the basal ice is considered to be an indicator to distinguish whether the basal ice has experienced melt-refreezing or not.