High-time-resolution profiles of soluble ions in the last glacial period of a Dome Fuji (Antarctica) deep ice core

Abstract

We measured the depth profiles of soluble ions in the Dome Fuji (Antarctica) ice core to search for possible paleoclimate indications of seasonal climate variations in the last glacial period. A 523 mm long core section between 587.65 and 588.18 m depth was selected for this pilot study, and the high-resolution chemical analysis was done on 2 mm thick samples. Our results indicate that anion-cation trapping in ice affects the profiles of the soluble ions and [Na+] in the core may preserve its seasonal signal. Correlation coefficients and the equivalent balances of the soluble ions suggest the following selective coexistences: (1) [Cl-] = [Na+], (2) [NO3-] = 1/2[Ca2+] + [K+], and (3) [SO42-] = 1/2[Ca2+] + [H+] + [Mg2+]. These coexistences are probably due to (1) a sea-salt source of Na+ and Cl-, (2) reaction of NO3- with dust for Ca2+ and NO3-, and (3) anion-cation trapping in ice for SO42- and Ca2+ (Mg2+), respectively.