Lead-210 profile in firn layer over Antarctic ice sheet and its relation to the snow accumulation environment

Abstract

Vertical distributions of ²¹⁰Pb in surface firn were obtained at five locations in east Dronning Maud Land, Antarctica. The distributions obtained in the inland high-plateau region are well described by the theoretical radioactive decay curve. On the other hand, the distributions obtained in the katabatic wind region have significant fluctuations including intervals where higher activity is found below layers with lower activity. We examined the relationship between the fluctuation of the ²¹⁰Pb profile and the temporal variation of the snow accumulation rate obtained by the snow stake method, and found a clear negative correlation between them. This result suggests that the fluctuation of the ²¹⁰Pb profile in the firn layer is closely related to the environment in the ice sheet surface, i.e. the extent of erosion—redistribution of snow. The measurement of the ²¹⁰Pb distribution in the ice sheet will be useful as an indicator of the surface stability in the Antarctic ice sheet.