TERRAPUB Geochemical Journal

Geochemical Journal, Vol. 51 (No. 3), pp. 293-298, 2017


Overview of the chemical composition and characteristics of Na+ and Cl distributions in shallow samples from Antarctic ice core DF01 (Dome Fuji) drilled in 2001

Yuko Motizuki,1 Hideaki Motoyama,2 Yoichi Nakai,1 Keisuke Suzuki,3 Yoshinori Iizuka4 and Kazuya Takahashi1*

1RIKEN Nishina Center, Hirosawa 2-1, Wako 351-0198, Japan
2National Institute of Polar Research, Research Organization of Information and Systems, Midoricho 10-3, Tachikawa, Tokyo 190-8518, Japan
3Department of Environmental Sciences, Shinshu University, Asahi 3-1-1, Matsumoto 690-8621, Japan
4Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0808, Japan

(Received November 13, 2015; Accepted November 12, 2016)

Abstract: Ice core samples record information about the geological history of the Earth, including past climate changes. Dome Fuji, situated at the highest point of Queen Maud Land, is considered one of the best drilling locations for procuring samples to reconstruct past climates and environments. We present here fundamental data on the concentrations of dissolved ions in shallow samples, between 7.7 m and 65.0 m depth, from the Dome Fuji ice core drilled in 2001. The measured anions were HCOO, CH3COO, CH3SO3, F, Cl, NO2, NO3, SO42−, C2O42−, and PO43−, and the cations were Na+, K+, Mg2+, Ca2+, and NH4+. The temporal resolution of the depth profiles of the ion concentrations was less than one year. No significant correlations were observed among the ions except between Na+ and Cl. The ion balance in the core, based on the averaged ion concentrations of the samples, was different to that of sea salt, a result consistent with the findings of previous studies. In several samples, however, synchronous concentration peaks of Na+ and Cl were identified, and the Cl/Na+ ratios of the corresponding samples were close to the sea salt ratio. This observation indicates the possibility that climate conditions were such that precipitation containing sea salt occurred in the Dome Fuji area. The Cl/Na+ ratio of samples that did not exhibit Na+ and Cl peaks in the depth profile differed from that previously reported for the covering snow. This result implies that Cl, but not Na+, was redistributed after deposition. High concentrations of SO42− in some samples may account for this alteration of Cl/Na+ ratios. To interpret these observations and elucidate the climatic conditions, further studies, such as isotopic analyses of δ18O and δD, are required.
Key words: ice core, Dome Fuji, chemical composition, ion balance

*Corresponding author E-mail: kazuyat@riken.jp

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