title: Sulfate spikes in the deep layers of EPICA-Dome C ice core: evidence of glaciological artifacts.
abstract: A detailed ionic component record was performed on EPICA Dome C ice core (East Antarctica) to a depth of 3190 m using Ion Chromatography and Fast Ion Chromatography (FIC). At depths greater than 2800 m, the sulfate profile shows intense, sharp spikes which are not expected due to the smoothing of sulfate peaks by diffusion processes. Moreover, these spikes show an "anomalous" chemical composition (e.g., unusually low acidity, high Mg(2+) concentration and high Mg(2+)/Ca(2+) ratio). These peaks and the surrounding layers also exhibit good Mg(2+) vs SO(4)(2-) and Cl(-) vs Na(+) correlations through both glacial and interglacial periods. Furthermore, the high-resolution analysis of two horizontally contiguous ice sections showed that some fraction of the impurities are characterized by a heterogeneous distribution. Altogether, these results suggest the occurrence of long-term postdepositional processes involving a rearrangement of impurities via migration in the vein network, characterized by sulfuric acidity and leading to the formation of soluble particles of magnesium sulfate salts, along with ionic association of ions in the liquid films along boundaries. This evidence should be taken into consideration when inferring information on for rapid climatic and environmental changes from ice core chemical records at great depths. At Dome C, the depth threshold was found to be 2800 m.
authors: Chemistry Department, University of Florence, I-50019 Sesto F.no, Florence, Italy. rita.traversi@unifi.it
authors: Rita
authors: R
authors: Traversi
authors: Silvia
authors: S
authors: Becagli
authors: Emiliano
authors: E
authors: Castellano
authors: Federica
authors: F
authors: Marino
authors: Francesco
authors: F
authors: Rugi
authors: Mirko
authors: M
authors: Severi
authors: Martine
authors: M
authors: de Angelis
authors: Hubertus
authors: H
authors: Fischer
authors: Margareta
authors: M
authors: Hansson
authors: Bernhard
authors: B
authors: Stauffer
authors: Jørgen P
authors: JP
authors: Steffensen
authors: Matthias
authors: M
authors: Bigler
authors: Roberto
authors: R
authors: Udisti
mesh_terms: D000864:Antarctic Regions; D002845:Chromatography; D004602:Elements; D005060:Europe; D046448:Ice Cover / Q000737:chemistry*; D013431:Sulfates / Q000032:analysis*
chemical_list: D004602:Elements; D013431:Sulfates