High-Time Resolution Analysis of Dust in the Dome Fuji Deep Ice Core, Antarctica: Relationship Between Dust and Calcium Ion

Microparticles (dust) in deep ice cores in polar area are well-known as an indicator of terrestrial materials. Dust concentration variations in deep ice cores depend on variations of dust origin areas and atmospheric transport intensity. Iizuka et al. (2004, 2006) reported that the short cycle signals such seasonal to a few years on sodium and calcium ions preserved in Dome Fuji deep ice core. We conducted the high-depth resolution analysis of dust in an deep ice core at Dome Fuji, Antarctica to study for possible paleoclimate indications of seasonal and/or annual climate variations in the Holocene (depth:294.960 m-295.460 m), last glacial maximum (LGM: 540.725 m- 541.250 m) and glacial periods (2203.990 m-2204.500 m: MIS7c-7d). High-resolution analysis of dust was conducted from 2 to 5 mm in thickness in these core samples. Dust concentrations in the ice cores are the lowest in the Holocene samples (mean: 11.9 ppb), secondly in the glacial samples (mean: 41.0 ppb) and the highest in the LGM samples (mean: 387 ppb), respectively. Correlation between dust concentration and non- seasalt (nss)- calcium ion concentration in the cores are the highest in the LGM samples (r=0.91) and secondly in the glacial samples (r=0.82), respectively. But, both correlation was not unclear (r=0.26) in the Holocene core samples. Nss-calcium ion/dust mass ratios, which were ratios of soluble calcium in terrestrial dust, were 0.133±0.098 (mean S.D.) in the Holocene samples, 0.067±0.010 in the LGM samples and 0.129±0.032 in the glacial samples, respectively, suggesting that mineral composition of calcium in dust varied in different climate stages. Especially, standard deviation of the ratio was greater in the Holocene samples than other samples, suggesting that mineral composition of calcium in dust changed in seasonal to a few years scale. On the other hand, it is indicated that mineral composition of calcium in dust was relative stabilized in LGM samples, because the fluctuation range of these ratios was smaller in this period than other periods.