EGU2020-8537
https://doi.org/10.5194/egusphere-egu2020-8537
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Towards an improved understanding of high-resolution impurity signals in deep Antarctic ice cores

Pascal Bohleber1, Marco Roman1, Carlo Barbante1, Barbara Stenni1, and Barbara Delmonte2,3
Pascal Bohleber et al.
  • 1Ca'Foscari University of Venice, Italy (pascal.bohleber@unive.it)
  • 2Università degli Studi di Milano-Bicocca, Dept. of Earth and Environmental Sciences, Milano, Italy
  • 3EUROCOLD Laboratory for Glaciology and Paleoclimate, Milano, Italy

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers minimally destructive ice core impurity analysis at micron-scale resolution. This technique is especially suited for exploring closely spaced layers of ice within samples collected at low accumulation sites or in regions of highly compressed and thinned ice. Accordingly, LA-ICP-MS promises invaluable insights in the analysis of a future “Oldest ice core” from Antarctica. However, in contrast to ice core melting techniques, taking into account the location of impurities is crucial to avoid misinterpretation of ultra-fine resolution signals obtained from newly emerging laser ablation technologies. Here we present first results from a new LA-ICP-MS setup developed at the University of Venice, based on a customized two-volume cryogenic ablation chamber optimized for fast wash-out times. We apply our method for high-resolution chemical imagining analysis of impurities in samples from intermediate and deep sections of the Talos Dome and EPICA Dome C ice cores. We discuss the localization of both soluble and insoluble impurities within the ice matrix and evaluate the spatial significance of a single profile along the main core axis. With this, we aim at establishing a firm basis for a future deployment of the LA-ICP-MS in an “Oldest Ice Core”. Moreover, our work illustrates how LA-ICP-MS may offer new means to study the impurity-microstructure interplay in deep polar ice, thereby promising to advance our understanding of these fundamental processes.

How to cite: Bohleber, P., Roman, M., Barbante, C., Stenni, B., and Delmonte, B.: Towards an improved understanding of high-resolution impurity signals in deep Antarctic ice cores, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8537, https://doi.org/10.5194/egusphere-egu2020-8537, 2020

Comments on the presentation

AC: Author Comment | CC: Community Comment | Report abuse

Presentation version 1 – uploaded on 30 Apr 2020
  • CC1: Comment on EGU2020-8537, Niccolò Maffezzoli, 01 May 2020

    Thanks for the material upload, which is something almost unexplored and very exciting ! This technique seems to have the resolution to provide new insights to really fast timescale (i.e. sub-annual) impurity signals in the very distant past, but ice dynamics could also play a major role by modifying the original concentrations. To which extent do you think this can impact the interpretation and how do you plan to address this dualism especially for the very deep part of the Beyond Epica ice core ?

    • AC1: Reply to CC1, Pascal Bohleber, 04 May 2020

      Thank you for your comment. Yes, in principle the spatial resolution of LA-ICP-MS is high enough to detect even highly thinned layers in deep ice. And also agreed: The finer the scale, the more essential it becomes to take into account signal formation and preservation. In this view we still need to deepen our understanding of the LA-ICP-MS signals at their high-resolution level. This is why we deliberately proceeded from 1D line profiles to advanced 2D chemical imaging: Now we have new means to assess the imprint of the ice grain network and the spatial variability of LA-ICP-MS signals. In fact, the noted dualism of LA-ICP-MS enables versatile future applications: With the technique presented here, LA-ICP-MS can make valuable contributions to the study of impurity localization and signal preservation. And on this ground, using LA-ICP-MS to search for a high-resolution proxy layer sequence in deep ice is at reach, in the “Beyond EPICA Oldest Ice core” and elsewhere.

      • CC3: Reply to AC1, Niccolò Maffezzoli, 06 May 2020

        Thank you Pascal !

  • CC2: Comment on EGU2020-8537, Melanie Behrens, 05 May 2020

    Hi Pascal, Do you have an idea how to combine these very high resolution measurements with e.g. CFA? Can you somehow combine "micro-scale" with "classical" concentration measurements?

    • AC2: Reply to CC2, Pascal Bohleber, 05 May 2020

      Hi Melanie, the comparison with CFA would be intriguing. So far, the comparison of LA-ICP-MS and CFA have relied on smoothing of the LA-ICP-MS line profiles. Otherwise the spatial resolution of the two methods is different by at least one order of magnitude. That said, I am optimistic that this can be addressed somehow.