University of Oulu

Prisle, N. L., Lin, J. J., Purdue, S., Lin, H., Meredith, J. C., and Nenes, A.: Cloud condensation nuclei activity of six pollenkitts and the influence of their surface activity, Atmos. Chem. Phys., 19, 4741–4761,, 2019.

Cloud condensation nuclei activity of six pollenkitts and the influence of their surface activity

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Author: Prisle, Nønne L.1,2,3,4; Lin, Jack J.1,3; Purdue, Sara3;
Organizations: 1University of Oulu, Nano and Molecular Systems Research Unit, P.O. Box 3000, 90014, University of Oulu, Oulu, Finland
2University of Helsinki, Department of Physics, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland
3Georgia Institute of Technology, School of Earth & Atmospheric Sciences, 311 Ferst Drive, Atlanta, GA 30332, USA
4Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA 30332, USA
5Institute of Chemical Engineering Sciences (ICE-HT), Foundation for Research, Patras, 26504, Greece
6Institute for Environmental Research and Sustainable Development, National Observatory of Athens, 15236, Athens, Greece
7Laboratory of Atmospheric Processes and their Impacts, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.6 MB)
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Language: English
Published: Copernicus Publications, 2019
Publish Date: 2019-09-26


The role of surfactants in governing water interactions of atmospheric aerosols has been a recurring topic in cloud microphysics for more than two decades. Studies of detailed surface thermodynamics are limited by the availability of aerosol samples for experimental analysis and incomplete validation of various proposed Köhler model frameworks for complex mixtures representative of atmospheric aerosol. Pollenkitt is a viscous material that coats grains of pollen and plays important roles in pollen dispersion and plant reproduction. Previous work suggests that it may also be an important contributor to pollen water uptake and cloud condensation nuclei (CCN) activity. The chemical composition of pollenkitt varies between species but has been found to comprise complex organic mixtures including oxygenated, lipid, and aliphatic functionalities. This mix of functionalities suggests that pollenkitt may display aqueous surface activity, which could significantly impact pollen interactions with atmospheric water. Here, we study the surface activity of pollenkitt from six different species and its influence on pollenkitt hygroscopicity. We measure cloud droplet activation and concentration-dependent surface tension of pollenkitt and its mixtures with ammonium sulfate salt. Experiments are compared to predictions from several thermodynamic models, taking aqueous surface tension reduction and surfactant surface partitioning into account in various ways. We find a clear reduction of surface tension by pollenkitt in aqueous solution and evidence for impact of both surface tension and surface partitioning mechanisms on cloud droplet activation potential and hygroscopicity of pollenkitt particles. In addition, we find indications of complex nonideal solution effects in a systematic and consistent dependency of pollenkitt hygroscopicity on particle size. The impact of pollenkitt surface activity on cloud microphysics is different from what is observed in previous work for simple atmospheric surfactants and more resembles recent observations for complex primary and secondary organic aerosol, adding new insight to our understanding of the multifaceted role of surfactants in governing aerosol–water interactions. We illustrate how the explicit characterization of pollenkitt contributions provides the basis for modeling water uptake and cloud formation of pollen and their fragments over a wide range of atmospheric conditions.

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Series: Atmospheric chemistry and physics
ISSN: 1680-7316
ISSN-E: 1680-7324
ISSN-L: 1680-7316
Volume: 19
Issue: 7
Pages: 4741 - 4761
DOI: 10.5194/acp-19-4741-2019
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
1172 Environmental sciences
1171 Geosciences
Funding: This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement no. 717022 (project SURFACE) and grant agreement no. 726165 (project PyroTRACH). Nønne L. Prisle and Jack J. Lin are also grateful for the financial contribution from the Academy of Finland (grant nos. 308238, 314175, 290145, and 257411). Athanasios Nenes acknowledges support from a Georgia Power Faculty chair and a Cullen-Peck Fellowship from the Georgia Institute of Technology.
EU Grant Number: (717022) SURFACE - The unexplored world of aerosol surfaces and their impacts.
Academy of Finland Grant Number: 308238
Detailed Information: 308238 (Academy of Finland Funding decision)
314175 (Academy of Finland Funding decision)
290145 (Academy of Finland Funding decision)
Copyright information: © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.