Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions
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Authors
Herich, Hanna
Tritscher, Torsten
Wiacek, Aldona
Lohmann, Ulrike
Baltensperger, Urs
Cziczo, Daniel J.
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Publication date
01.04.2009
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01A - Journal article
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Physical Chemistry Chemical Physics
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Volume
11
Issue / Number
36
Pages / Duration
7804-7809
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Publisher / Publishing institution
Royal Society of Chemistry
Place of publication / Event location
London
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Abstract
Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter k. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived k values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and B3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had k B 0.003. The kaolinite samples were less hygroscopic and had k = 0.001. SD (k = 0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (k = 0.007) and ATD (k = 0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which leads to the addition of more than B3% soluble material will significantly enhance its hygroscopicity and CCN activity.
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550 - Geowissenschaften
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1463-9076
1463-9084
1463-9084
Language
English
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No
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Published
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Citation
HERICH, Hanna, Torsten TRITSCHER, Aldona WIACEK, Martin GYSEL, Ernest WEINGARTNER, Ulrike LOHMANN, Urs BALTENSPERGER und Daniel J. CZICZO, 2009. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions. Physical Chemistry Chemical Physics. 1 April 2009. Bd. 11, Nr. 36, S. 7804–7809. DOI 10.1039/b901585j. Verfügbar unter: https://irf.fhnw.ch/handle/11654/46669