XANES Iron Geochemistry in the Mineral Dust of the Talos Dome Ice Core (Antarctica) and the Southern Hemisphere Potential Source Areas

Abstract

X-ray absorption near edge structure (XANES) measurements at the Fe K-edge were performed on aeolian dust in the TALos Dome Ice CorE drilling project (TALDICE) ice core drilled in the peripheral East Antarctic plateau, as well as on Southern Hemisphere potential source area samples. While South American sources show, as expected, a progressive increase in Fe oxidation with decreasing latitude, Antarctic sources show Fe oxidation levels higher than expected in such a cold polar environment, probably because of their very high exposure ages. Results from the TALDICE dust samples are compatible with a South American influence at the site during MIS2 (marine isotopic stage 2, the last and coldest phase of the last glacial period), in particular from Patagonia and Tierra del Fuego. However, a contribution from Australia and/or local Antarctic sources cannot be ruled out. Finally, important changes also occurred during the deglaciation and in the Holocene, when the influence of Antarctic local sources seems to have become progressively more important in recent times. This research is the first successful attempt to extract temporal climatic information from X-ray absorption spectroscopic data of the insoluble mineral dust particles contained in an ice core and shows the high potential of this technique.

Contribution of combustion Fe in marine aerosols over the northwestern Pacific estimated by Fe stable isotope ratios

“…The higher peak energy of the Fe K-edge XANES spectrum corresponds to a larger amount of ferric species, as seen in the reference materials (Fig. 5a; Berry et al, 2003;Maggi et al, 2018). The peak energies of some of the samples (such as the coarse particles of sample 13-a) were approximately 7.126 keV, whereas those of other samples (such as the fine particles of 13-a) were higher in the range between 7.126 and 7.131 keV, indicating that they contained a larger fraction of ferric species.…”

Contribution of combustion Fe in marine aerosols over the northwestern Pacific estimated by Fe stable isotope ratios

“…The higher peak energy of the Fe K-edge XANES spectrum corresponds to a larger amount of ferric species, as seen in the reference materials (Fig. 5a; Berry et al, 2003;Maggi et al, 2018). The peak energies of some of the samples (such as the coarse particles of sample 13-a) were approximately 7.126 keV, whereas those of other samples (such as the fine particles of 13-a) were higher in the 320 range between 7.126 and 7.131 keV, indicating that they contained a larger fraction of ferric species.…”

Synchrotron Radiation Research and Analysis of the Particulate Matter in Deep Ice Cores: An Overview of the Technical Challenges

“…This setup allowed us to collect a full set of XRF and XAS data on the whole timespan covered by the Talos Dome perforation, located on the East Antarctic Ice Sheet [20]. This is a set of over 200 XRF and XAS individual acquisitions, which includes a significant fraction of data taken on background, blanks, and repetition measurements made necessary by the need to ensure that reproducible experimental conditions are met for all the experiments, split across several visits over a long-term project at Diamond Light Source.…”