Elemental composition (Si, Fe, Ti) of atmospheric dust over the last 220 kyr from the EPICA ice core (Dome C, Antarctica)

Abstract

AbstractIn this work, we present the records of insoluble silicon (Si), iron (Fe) and titanium (Ti) from continental mineral particles (dust) archived in the first 2200m of the EPICA Dome C (EDC) ice core. More than 200 samples covering the last 220 kyr, back to marine isotopic stage 7.4, were analyzed using the particle-induced X-ray emission (PIXE) technique, applied here for the first time to the investigation of the mineral content of an Antarctic ice core. The measurements were made exclusively on the insoluble fraction, obtained from filtration of the melted ice samples. The mineral fraction of the particle mass determined from the PIXE measurements is highly correlated to the total dust mass determined by particle counting using a Coulter©Counter. The principal variations during the different climatic periods are very coherent between the PIXE analysis results and the total dust mass determined by counting. Both sets of results show increasing concentration values during glacial stages 2, 4 and 6 and very low particle content during interglacials (Holocene and stage 5e). The large increase in atmospheric dustiness during cold stages is assumed to be caused by several factors, among which are the enhanced vigour of atmospheric transport. However, the PIXE results from this work highlight some slight differences in Si, Fe and Ti concentrations with respect to the total dust mass during the different climatic periods. As a hypothesis, such variations could reflect either different atmospheric processes affecting particles during transport, or changes that occurred in the dust source regions.