Contribution of sulfuric acid and oxidized organic compounds to particle formation and growth

Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in glob
Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in global models. We performed chamber experiments designed to study the contributions of sulfuric acid and organic vapors to formation and to the early growth of nucleated particles, respectively. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and α-pinene) showed the ability of these compounds to reproduce the formation rates observed in the low troposphere. These results were obtained measuring the sulfuric acid concentrations with two Chemical Ionization Mass Spectrometers confirming the results of a previous study which modeled the sulfuric acid concentrations in presence of 1,3,5-trimethylbenzene.

New analysis methods were applied to the data collected with a Condensation Particle Counter battery and a Scanning Mobility Particle Sizer, allowing the assessment of the size resolved growth rates of freshly nucleated particles. The effect of organic vapors on particle growth was investigated by means of the growth rate enhancement factor (Γ), defined as the ratio between the measured growth rate in the presence of α-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed Γ values indicate that the growth is dominated by organic compounds already at particle diameters of 2 nm. Both the absolute growth rates and Γ showed a strong dependence on particle size supporting the nano-Köhler theory. Moreover, the separation of the contributions from sulfuric acid and organic compounds to particles growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. The size resolved growth analysis finally indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.
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Metadaten
Author:Francesco Riccobono, Linda Rondo, Mikko Sipilä, Peter Barmet, Joachim Curtius, Josef Dommen, Mikael Ehn, Sebastian Ehrhart, Markku Kulmala, Andreas Kürten, Jyri Mikkilä, Tuukka Petäjä, Ernest Weingartner, Urs Baltensperger
URN:urn:nbn:de:hebis:30:3-252622
DOI:http://dx.doi.org/doi:10.5194/acpd-12-11351-2012
ISSN:1680-7375
ISSN:1680-7367
Parent Title (English):Atmospheric chemistry and physics / Discussions
Publisher:European Geosciences Union
Place of publication:Katlenburg-Lindau
Document Type:Article
Language:English
Date of Publication (online):2012/05/03
Date of first Publication:2012/05/03
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2012/06/19
Volume:12
Pagenumber:49
First Page:11351
Last Page:11389
Institutes:Geowissenschaften
Dewey Decimal Classification:550 Geowissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 3.0

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