Ice cores drilled from the frozen Antarctic landscape are made up of layer upon layer of frozen snow, dating back hundreds of thousands of years. Trapped within the ice are minute dust particles which can yield valuable information on temperature, precipitation, atmospheric composition and volcanic activity, frozen at the time of the snowfall. A group of Italian scientists have been using one of Diamond’s spectroscopy beamlines, B18, and the Stanford Synchrotron Radiation Lightsource to determine the mineral composition of dust particles dating back over 800,000 years. Their work has been published in the Journal of Analytical Atomic Spectrometry.
Snowflakes falling onto Antarctic ice sheets trap mineral particles from the atmosphere, carried to the Antarctic by the wind. As the snow is compressed to form ice, the trapped particles build up into a historical record of climate conditions. Analysing samples from deep ice cores and recognising where the minerals originated provides valuable insights into historical environmental and atmospheric circulation and regional to global climate change. Shifts in the patterns of atmospheric circulation could explain significant variations in rapid, large scale changes in regional and global climate that have taken place in recent millennia.
The key challenge is in the low concentration of dust particles in the ice that are available in crystalline form. The group used synchrotron X-ray Fluorescence (XRF) to determine elemental composition and X-ray Absorption Spectroscopy (XAS) to provide mineralogical information. The data gathered by these techniques were used to complement data gathered by conventional methods to provide a more complete picture of these challenging samples.
The study showed that XRF and XAS studies were able to gather unique information about the mineral particles. Although the study evaluated a limited number of samples it demonstrates a valuable proof of principle, that combining these techniques can provide information on the sources of mineral particles and aerosol transport mechanisms from the source to the Antarctic glaciers. Giannantonio Cibin took part in the research.
“We were able to identify the main mineralogical families of dust particles from the Antarctic deep ice cores using synchrotron X-ray spectroscopy. This opens the way to being able to identify the dust source areas, with the potential to understand past climate change processes on both a regional and global scale.”
Giannantonio Cibin, Diamond Light Source
XRF-XANES characterization of deep ice core insoluble dust, Augusto Marcelli,Dariush Hampai,Francesca Giannone,Marco Sala,Valter Maggi,Federica Marino,Stefano Pignotti,Giannantonio Cibin, Journal of Analytical Atomic Spectrometry DOI: 10.1039/c1ja10169b
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