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| Titel |
Ice nucleation by water-soluble macromolecules |
| VerfasserIn |
B. G. Pummer, C. Budke, S. Augustin-Bauditz, D. Niedermeier, L. Felgitsch, C. J. Kampf, R. G. Huber, K. R. Liedl, T. Loerting, T. Moschen, M. Schauperl, M. Tollinger, C. E. Morris, H. Wex, H. Grothe, U. Pöschl, T. Koop, J. Fröhlich-Nowoisky |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 8 ; Nr. 15, no. 8 (2015-04-21), S.4077-4091 |
| Datensatznummer |
250119653
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| Publikation (Nr.) |
 copernicus.org/acp-15-4077-2015.pdf |
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| Zusammenfassung |
| Cloud glaciation is critically important for the global radiation budget
(albedo) and for initiation of precipitation. But the freezing of pure water
droplets requires cooling to temperatures as low as 235 K. Freezing at
higher temperatures requires the presence of an ice nucleator, which serves
as a template for arranging water molecules in an ice-like manner. It is
often assumed that these ice nucleators have to be insoluble particles. We
point out that also free macromolecules which are dissolved in water can
efficiently induce ice nucleation: the size of such ice nucleating
macromolecules (INMs) is in the range of nanometers, corresponding to
the size of the critical ice embryo. As the latter is temperature-dependent,
we see a correlation between the size of INMs and the ice nucleation
temperature as predicted by classical nucleation theory. Different types of INMs have been found in a
wide range of biological species and comprise a variety of chemical
structures including proteins, saccharides, and lipids. Our investigation of
the fungal species Acremonium implicatum, Isaria farinosa, and Mortierella alpina shows that their ice nucleation activity is
caused by proteinaceous water-soluble INMs. We combine these new results and
literature data on INMs from fungi, bacteria, and pollen with theoretical
calculations to develop a chemical interpretation of ice nucleation and
water-soluble INMs. This has atmospheric implications since many of these
INMs can be released by fragmentation of the carrier cell and subsequently
may be distributed independently. Up to now, this process has not been
accounted for in atmospheric models. |
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