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| Titel |
Molecular Ice Nucleation Activity of Birch Pollen |
| VerfasserIn |
Laura Felgitsch, Magdalena Bichler, Thomas Häusler, Victor U. Weiss, Martina Marchetti-Deschmann, Günter Allmaier, 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 |
250102251
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| Publikation (Nr.) |
 EGU/EGU2015-1560.pdf |
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| Zusammenfassung |
| Heterogeneous ice nucleation plays a major part in ecosystem and climate. Due to the
triggering of ice cloud formation it influences the radiation balance of the earth, but also on
the ground it can be found to be important in many processes of nature. So far the process of
heterogeneous ice nucleation is not fully understood and many questions remain to be
answered. Biological ice nucleation is hereby from great interest, because it shows the
highest freezing temperatures. Several bacteria and fungi act as ice nuclei. A famous example
is Pseudomonas syringae, a bacterium in commercial use (Snomax®), which increases the
freezing from homogeneous freezing temperatures of approx. -40Ë C (for small volumes as in
cloud droplets) to temperatures up to -2Ë C. In 2001 it was found that birch pollen
can trigger ice nucleation (Diehl et al. 2001; Diehl et al. 2002). For a long time it
was believed that this is due to macroscopic features of the pollen surface. Recent
findings of Bernhard Pummer (2012) show a different picture. The ice nuclei are not
attached on the pollen surface directly, but on surface material which can be easily
washed off. This shows that not only the surface morphology, but also specific
molecules or molecular structures are responsible for the ice nucleation activity of birch
pollen.
With various analytic methods we work on elucidating the structure of these molecules as
well as the mechanism with which they trigger ice nucleation. To solve this we use various
instrumental analytic techniques like Nuclear Magnetic Resonance spectroscopy (NMR),
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS), and
Gas-phase Electrophoretic Mobility Molecular Analysis (GEMMA). Also standard
techniques like various chromatographic separation techniques and solvent extraction are in
use.
We state here that this feature might be due to the aggregation of small molecules, with
agglomerates showing a specific surface structure. Our results indicate that the substance is
amphiphilic in character leading finally to micelle formation.
Diehl, K., Quick, C., Matthias-Maser, S., Mitra, S. K., and Jaenicke, R.: The ice
nucleation ability of pollen, part I, Atmos. Res., 58, 75–87, 2001.
Diehl, K., Matthias-Maser, S., Jaenicke, R., and Mitra, S. K.: The ice nucleation ability of
pollen, part II, Atmos. Res., 61, 125–133, 2002.
Pummer, B., Bauer, H., Bernardi, J., Bleicher, S., Grothe, H.; Suspendable macromolecules
are responsible for ice nucleation activity of birch and conifer pollen; Atmos. Chem. Phys.,
12, 2541 – 2550, 2012. |
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