Role of atmospheric aerosol in the sudden climate change indicated in the Antarctic ice core.

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Climate changes over the past 320 kyr are preserved in a 1st ice core (2503m length) from Dome Fuji (77°19'S, 39°42'E), Antarctica. In this research, we measured total (dissolved+particulate) concentration of metals in this core and clarified the variation of the concentration and flux of aerosol accompanying the climate change. Focusing on the depth applicable to the Terminations, an ice block with about 7cm thickness and 70g mass was cut from the core at 0.5-lkr intervals. The sample was melted and evaporated to dryness in a 7-ml Teflon container in order to avoid loss of particulates. The residue was decomposed by microwave acid digestion method and the concentrations of Al, Fe, Mn, Ca etc. in the sample solution were measured by ICPMS and ICPAES. The total concentration of Al (t-Al) in the core was high in the period of glacial maximum compared with the interglacial. This variation was coincide with the result of particulate Al (p-Al, >0.45μm diameter) from the Dome C core. The t-Al concentrations in the Dome Fuji core were ranged from 3.94 to 276ppb, and the maximum value was more than 2 times larger than that of p-Al in the Dome C core. The result, if it is not due to local variation, indicates that the significant part of Al in Antarctic ice sheet would be fine particles less than 0.45μm diameter and/or would be water soluble. Estimated mineral dust fluxes to Dome Fuji were 21.7±11.9 mg m^<-2> yr^<-1> in LGM and 2.56±1.91 mg m^<-2> yr^<-1> in Holocene. These values were comparable to predicted values by a climate model and were approximately three orders of magnitude smaller than the presumed fluxes in the mid-latitude region.