AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
The Hygroscopic Properties of Pollenkitt and Its Importance for Regulating Water Uptake by Pollen Particles
SARA PURDUE, Nonne Prisle, Haisheng Lin, Carson Meredith, Athanasios Nenes, Georgia Institute of Technology
Abstract Number: 600 Working Group: Bioaerosols
Abstract Pollen is an important class of bioaerosol that exhibits a remarkable breadth of complex solid surface features. In addition, many pollen grains are coated with a viscous liquid, “pollenkitt”, thought to play important roles in pollen dispersion and adhesion. The formation of adhesive forces associated with pollenkitt mainly depends on the volume and wetting properties of the fluid. However, the influence of relative humidity and water absorption by pollenkitt on these capillary forces and the biological function of pollen is virtually unknown, but may be critically important for its activation and allergenicity, and may regulate its atmospheric lifetime and ability to nucleate cloud droplets and ice crystals. In the present work, we present a comprehensive characterization of the hygroscopicity of pollenkitt for a wide range of water vapor saturations. For this purpose, pollenkitt extracted from a variety of pollen species is aerosolized, dried and size selected by a Differential Mobility Analyzer to obtain a monodisperse aerosol composed of the material. The cloud condensation nuclei (CCN) activity and hygrosocopicity of the pollenkitt is then quantified using a DMT Continuous-Flow Streamwise Thermal Gradient CCN Counter. The subsaturated water uptake and hygroscopicity is also measured with Atomic Force Microscopy (AFM), by observing the shifts in the fundamental resonance frequency of an AFM cantilever bearing pollen. We then present the derived pollenkitt hygroscopicity and determine its contribution to water uptake of pollen as a function of humidity. The implications of this water uptake for the adhesive properties of pollen, nucleation of droplets and ability to freeze ice is then presented.