Vorträge und Posterpräsentationen (mit Tagungsband-Eintrag):
H. Grothe, B. G. Pummer, H. Bauer, J. Bernardi, P. Schmitt-Kopplin, C. Müller, S. Augustin, S. Hartmann, D. Niedermeier, T. Clauss, J. Voigtländer, L. Tomsche, H. Wex, F. Stratmann:
"Immersion Freezing of Birch Pollen Washing Water";
Vortrag: 32nd Annual Conference AAAR (American Association for Aerosol Research),
Portland, Oregon, USA (eingeladen);
- 04.10.2013; in: "32nd Annual Conference AAAR - Book of abstracts",
The ice nucleation of bioaerosols (bacteria, pollen, spores, etc.) is a topic of growing interest, since their impact on ice cloud formation and thus on radiative forcing, an important parameter in global climate, is not yet fully understood. Here we show that pollen of different species strongly differ in their ice nucleation behavior. The average freezing temperatures in laboratory experiments range from 240 K to 255 K. As the most efficient nuclei (silver birch, Scots pine and common juniper pollen) have a distribution area up to the Northern timberline, their ice nucleation activity may be a cryo-protective mechanism. Far more intriguingly, it has turned out that water, which has been in contact with pollen and then been separated from the bodies, nucleates as good as the pollen grains themselves. So the ice nuclei have to be easily-suspendable macromolecules located on the pollen surface. Once extracted, they can be distributed further through the atmosphere than the heavy pollen grains and so augment the impact of pollen on ice cloud formation even in the upper Troposphere. These ice nucleating active (INA) macromolecules were investigated at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). For that, washing water of two different birch pollen samples with different regional origin - Northern (N) birch and Southern (S) birch - was used. Main differences between these were between 255 K and 249 K, where the ice fraction increased with decreasing temperature. There, the N-birch pollen washing water featured two different slopes, with one being steeper and one being similar to the slope of the S-birch pollen washing water. As we assume single INA macromolecules being the reason for the ice nucleation. We have tried to separate these macromolecules by chromatography and to analyze by ESI-FTICR mass spectrometry.
Erstellt aus der Publikationsdatenbank der Technischen Universitšt Wien.