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| Titel |
Model for acid-base chemistry in nanoparticle growth (MABNAG) |
| VerfasserIn |
T. Yli-Juuti, K. Barsanti, L. Hildebrandt Ruiz, A.-J. Kieloaho, U. Makkonen, T. Petäjä, T. Ruuskanen, M. Kulmala  , I. Riipinen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 24 ; Nr. 13, no. 24 (2013-12-20), S.12507-12524 |
| Datensatznummer |
250085899
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| Publikation (Nr.) |
 copernicus.org/acp-13-12507-2013.pdf |
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| Zusammenfassung |
| Climatic effects of newly-formed atmospheric secondary aerosol particles are
to a large extent determined by their condensational growth rates. However,
all the vapours condensing on atmospheric nanoparticles and growing them to
climatically relevant sizes are not identified yet and the effects of
particle phase processes on particle growth rates are poorly known. Besides
sulfuric acid, organic compounds are known to contribute significantly to
atmospheric nanoparticle growth. In this study a particle growth model
MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) was developed
to study the effect of salt formation on nanoparticle growth, which has been
proposed as a potential mechanism lowering the equilibrium vapour pressures
of organic compounds through dissociation in the particle phase and thus
preventing their evaporation. MABNAG is a model for monodisperse aqueous
particles and it couples dynamics of condensation to particle phase
chemistry. Non-zero equilibrium vapour pressures, with both size and
composition dependence, are considered for condensation. The model was
applied for atmospherically relevant systems with sulfuric acid, one organic
acid, ammonia, one amine and water in the gas phase allowed to condense on
3–20 nm particles. The effect of dissociation of the organic acid was found
to be small under ambient conditions typical for a boreal forest site, but
considerable for base-rich environments (gas phase concentrations of about
1010 cm−3 for the sum of the bases). The contribution of the bases
to particle mass decreased as particle size increased, except at very high
gas phase concentrations of the bases. The relative importance of amine
versus ammonia did not change significantly as a function of particle size.
While our results give a reasonable first estimate on the maximum
contribution of salt formation to nanoparticle growth, further studies on,
e.g. the thermodynamic properties of the atmospheric organics,
concentrations of low-volatility organics and amines, along with studies
investigating the applicability of thermodynamics for the smallest
nanoparticles are needed to truly understand the acid-base chemistry of
atmospheric nanoparticles. |
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