Sensitivity of chemical species to climatic changes in the last 45 kyr as revealed by high-resolution Dome C (East Antarctica) ice-core analysis 

Annals of Glaciology, Vol 39, p. 457-466, 2004 

Roberto Udisti, Silvia Becagli, Silvia Benassai and Rita Traversi
Department of Chemistry, University of Florence, Via della Lastruccia 3, I-50019 Sesto F.no (Florence), Italy
Martine DeAngelis
Laboratoire de Glaciologie et Géophysique de l'Environnement du CNRS, 54 rue Moliére, BP 96, 38402 Saint-Martin-d'Hères Cedex, France
Margareta E. Hansson
Department of Physical Geography and Quaternary Geology, Stockholm University, S-106 91 Stockholm, Sweden
Jean Jouzel
Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA-CNRS, 91191 Gif-sur-Yvette, France
Jacob Schwander
Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
Jørgen P. Steffensen
Ice and Climate, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
Eric Wolff
British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, UK

ABSTRACT.
To assess the cause/effect relationship between climatic and environmental changes, we report high-resolution chemical profiles of the Dome C ice core (788m, 45kyr), 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⁺, Mg²⁺ and Ca²⁺ 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 egffects. The comparison between concentrations and δD profiles revealed leads and lags between chemical and temperature trends: Ca²⁺ 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⁺, Mg²⁺ and nitrate show changes during the Antarctic Cold Reversal (14.012.5 kyr BP).