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L. Felgitsch, M. Bichler, T. Häusler, V. Weiss, M. Marchetti-Deschmann, G. Allmaier, H. Grothe:
"Macromolecular ice nucleation activity of birch pollen";
Talk: 16. Österreichische Chemietage 2015, Innsbruck; 09-21-2015 - 09-24-2015.

Macromolecular ice nucleation activity of birch pollen

Laura Felgitsch a, Magdalena Bichler a, Thomas Häusler a, Victor U. Weiss b, Martina Marchetti-Deschmann b, Günter Allmaier b, Hinrich Grothe a

a TU Wien, Institute of Materials Chemistry, Getreidemarkt 9/165, 1060 Vienna, Austria
b TU Wien, Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164, 1060 Vienna, Austria

Ice clouds inherently influence the radiation balance of the Earth. The main question is, which aerosol particles may act as efficient ice nuclei (IN) and therefore might trigger ice nucleation in the atmosphere. Biological aerosols show the highest freezing temperatures when acting as IN and are therefore in the center of interest. One of the known biological IN are birch pollen, which increase freezing temperatures by approx. 20°C. For a long time it was believed that this is due to macroscopic features at the pollen surface but recent findings from us [1] show that the IN are not bound to the pollen surface and can be easily washed off. Due to their fast sinking velocity, pollen were previously not considered to be important in ice cloud formation, but as the IN can be washed off the pollen surface, they could form a bioaerosol or could be attached to other particles reaching higher altitudes. Hence their contribution to ice nucleation in the atmosphere could have been underestimated to date.
We work with a broad range of analytic methods elucidating the structure of the macromolecules responsible for the ice nucleation activity of birch pollen, as well as the mechanism by which they trigger the formation of ice; 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 cascades are applied.
At current we assume an aggregation of macromolecules, showing a specific surface structure, to be responsible for pollen induced ice nucleation.
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[1] Pummer, et al.: Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen; Atmos. Chem. Phys., 12, 2541 - 2550, 2012.

heterogeneous ice nucleation, atmosphere, pollen