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

Abstract

ABSTRACT. In this work, we present the records of insoluble silicon (Si), iron (Fe) and titanium (Ti) from continental mineral particles (dust) archived in the first 2200 m 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.

Ice‐core record of methyl chloride over the last glacial–Holocene climate change

“…A potential chemical production of CH 3 Cl is reaction among chloride, an electron acceptor such as Fe (III), and organic matter such as humic substances. This reaction is responsible for CH 3 Cl production in soil [ Keppler et al , 2000] and could potentially take place in the ice sheet because microbial mediation is not required; moreover, the reactants have been transported from their source regions to the ice sheets as well as Ca 2+ [ Watanabe et al , 2003a; Marino et al , 2004; Grannas et al , 2006]. If we assume that the impurity‐related production was the sole cause of the excess CH 3 Cl, the CH 3 Cl concentration during the last glacial is estimated to be around 700 pptv based on the CH 3 Cl data (n = 7) for the samples with Ca 2+ concentrations as low as those in interglacial ice (Figure 3).…”

Defining the geochemical composition of the EPICA Dome C ice core dust during the last glacial‐interglacial cycle

“…The average contribution measured in several blanks was subtracted from each sample. Further details about sampling, target preparation and blanks evaluation have been previously presented [ Marino et al , 2004].…”

PIXE and PIGE techniques for the analysis of Antarctic ice dust and continental sediments

“…The samples here analysed were sampled in sections corresponding to the main cold events of the last 220 kyr. A protocol of ice core samples preparation was followed in order to minimize contaminations [10]: it consists in melting ice samples and filtering the liquid through Nuclepore membranes (pore size: 0.45 lm), taking particular care in rinsing the filtration apparatus after filtering to guarantee the highest recovery of dust particles. 2.…”