Changes in cadmium concentrations in Antarctic ice and snow during the past 155,000 years

Changes in Cd concentrations in Antarctic ice and snow during the last full climatic cycle (the past 155,000 yrs) have been investigated by analysing various sections of the Dome C and Vostok deep Antarctic ice cores and several blocks of recent Antarctic snow. Each sample was mechanically decontaminated using ultraclean procedures and then analysed for Cd by the new ultrasensitive laser excited atomic fluorescence technique. Cd concentrations are found to have been highly variable in ancient Antarctic ice and therefore in the past pristine south polar atmosphere during the last climatic cycle, the highest values being observed during the cold terminal stages of the last and next to last ice ages. Concentrations measured in recent Antarctic snows are comparable with those in Antarctic Holocene ice several thousand years old, which suggests that the anthropogenic influence is probably still negligible for this heavy metal in the south polar atmosphere. For some of the samples, measured Cd concentrations can be simply accounted for by rock and soil dust and volcanic emissions, while for others there is a significant excess over the contributions from these two sources