Sensitivity of chemical species to climate changes in the last 45 ka as revealed by high resolution Dome C (Antarctica) ice core analysis

To assess the cause/effect relationship between climatic and environmental changes, we report high-resolution chemical profiles of the Dome C ice core (788 m, 45 kyr), drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA). Snow-concentration and depositional-flux changes during the last deglaciation were compared with climatic changes, derived by δD profile. Concentration and temperature profiles showed an anticorrelation, driven by changes in source intensity and transport efficiency of the atmospheric aerosol and by snow accumulation-rate variations. The flux calculation allowed correction for accumulation rate. While sulphate and ammonium fluxes are quite constant, Na +, Mg 2+ and Ca 2+ underwent the greatest changes, showing fluxes respectively about two, three and six times lower in the Holocene than in the Last Glacial Maximum. Chloride, nitrate and methanesulphonic acid (MSA) also exhibited large changes, but their persistence depends on depositional and post-depositional effects. The comparison between concentrations and δD profiles revealed leads and lags between chemical and temperature trends: Ca 2+ and nitrate preceded by about 300 years the δD increase at the deglaciation onset, while MSA showed a 400 year delay. Generally, all components reached low Holocene values in the first deglaciation step (18.0-14.0 kyr bp), but Na +, Mg 2+ and nitrate show changes during the Antarctic Cold Reversal (14.0-12.5 kyr bp).