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| Titel |
Identification of Ice Nucleation Active Sites on Silicate Dust Particles |
| VerfasserIn |
Tobias Zolles, Julia Burkart, Thomas Häusler, Bernhard Pummer, Regina Hitzenberger, Hinrich Grothe |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250113851
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| Publikation (Nr.) |
 EGU/EGU2015-14085.pdf |
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| Zusammenfassung |
| Mineral dusts originating from Earth’s crust are known to be important atmospheric ice
nuclei. In agreement with earlier studies, feldspar was found as the most active of the tested
natural mineral dusts [1-3]. Nevertheless, among those structures K-feldspar showed by far
the highest ice nucleation activity. In this study, the reasons for its activity and the difference
in the activity of the different feldspars were investigated in closer details. Conclusions are
drawn from scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy,
and oil-immersion freezing experiments.
We give a potential explanation of the increased ice nucleation activity of K-feldspar. The
ice nucleating sites are very much dependent on the alkali ion present by altering the water
structure and the feldspar surface. The higher activity of K-feldspar can be attributed to the
presence of potassium ions on the surface and surface bilayer. The alkali-ions have different
hydration shells and thus an influence on the ice nucleation activity of feldspar. Chaotropic
behavior of Calcium and Sodium ions are lowering the ice nucleation potential of
the other feldspars, while kosmotropic Potassium has a neutral or even positive
effect.
Furthermore we investigated the influence of milling onto the ice nucleation of quartz
particles. The ice nucleation activity can be increased by mechanical milling, by introducing
more molecular, nucleation active defects to the particle surface. This effect is larger than
expected by plane surface increase.
[1] Atkinson et al. The Importance of Feldspar for Ice Nucleation by Mineral Dust in
Mixed-Phase Clouds. Nature 2013, 498, 355–358.
[2] Yakobi-Hancock et al.. Feldspar Minerals as Efficient Deposition Ice Nuclei. Atmos.
Chem. Phys. 2013, 13, 11175–11185.
[3] Zolles et al. Identification of Ice Nucleation Active Sites on Feldspar Dust Particles. J.
Phys. Chem. A 2015 accepted. |
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