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T. Häusler, L. Felgitsch, E. Khaybulkina, H. Grothe:
"Cellulose and Their Characteristic Ice Nucleation Activity";
Vortrag: ICCPA International Conference on Carbonaceous Particles in the Atmosphere, Lawrence Berkeley National Laboratory, Berkeley, California; 10.08.2015 - 13.08.2015.

The important role of the aerosol-cloud interaction in earth´s radiation and thereby in earth´s climate is well investigated.[1] Cloud microphysics determine for example cloud lifetime and precipitation properties. Furthermore are clouds cooling the climate system by reflecting incoming solar radiation and warm its surface by trapping outgoing infrared radiation.[2] In the atmosphere ice crystals form through heterogeneous and homogeneous ice nucleation. For homogeneous nucleation, a temperature below -38°C is needed. Freezing processes at higher temperatures occur heterogeneously.[3] In this case, an aerosol particle acts like an initiator to trigger the process. These particles provide a specific surface, which reduces the energy barrier for nucleation.

Previous research in our group has been related to biological ice nucleation.[4] Here, we present a proxy for biological macromolecular substances, microcrystalline cellulose. Cellulose is the main component of herbal cell walls (about 50 wt%). It is a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units.

Immersion experiments with a self-made unique reaction gadget were carried out. In this device a water-cellulose suspension was cooled till the freezing point and observed via a light microscope.
The evaluation of the microscope records shows different INA due to the particle size and concentration of cellulose in the suspension. Further analysis methods as scanning electron microscope (SEM), small angle X-Ray scattering (SAX) and infrared spectroscopy (ATR-IR) were carried out to completely describe the cellulose and their ice nucleation activity.


[1] IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1-30, doi:10.1017/CBO9781107415324.004.
[2] Baker, M. B.; Peter, T., Small-scale cloud processes and climate. Nature 2008, 451 (7176), 299-300.
[3] Pruppacher, H.; Klett, G., Microphysics of Clouds and Precipitation. Kluwer Academic Publisher: Amsterdam: 1997.
[4] B. Pummer, L. Atanasova, H. Bauer, H. Bernardi, I. S. Druzhinina, J. Froehlich-Nowoisky, H. Grothe. Spores of many common airborne fungi reveal no ice nucleation activity in oil immersion freezing experiments. Biogeosciences, 2013, 10, 8083- 8091

ice, nucleation, cellulose

http://publik.tuwien.ac.at/files/PubDat_243141.pdf