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| Titel |
On the formation of sulphuric acid – amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation |
| VerfasserIn |
P. Paasonen, T. Olenius, O. Kupiainen, T. Kurtén, T. Petäjä, W. Birmili, A. Hamed, M. Hu, L. G. Huey, C. Plass-Duelmer, J. N. Smith, A. Wiedensohler, V. Loukonen, M. J. McGrath, I. K. Ortega, A. Laaksonen, H. Vehkamäki, V.-M. Kerminen, M. Kulmala  |
| 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 ; 12, no. 19 ; Nr. 12, no. 19 (2012-10-05), S.9113-9133 |
| Datensatznummer |
250011497
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| Publikation (Nr.) |
 copernicus.org/acp-12-9113-2012.pdf |
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| Zusammenfassung |
| Sulphuric acid is a key component in atmospheric new particle formation.
However, sulphuric acid alone does not form stable enough clusters to
initiate particle formation in atmospheric conditions. Strong bases, such as
amines, have been suggested to stabilize sulphuric acid clusters and thus
participate in particle formation. We modelled the formation rate of
clusters with two sulphuric acid and two amine molecules (JA2B2) at
varying atmospherically relevant conditions with respect to concentrations
of sulphuric acid ([H2SO4]), dimethylamine ([DMA]) and
trimethylamine ([TMA]), temperature and relative humidity (RH). We also
tested how the model results change if we assume that the clusters with two
sulphuric acid and two amine molecules would act as seeds for heterogeneous
nucleation of organic vapours (other than amines) with higher atmospheric
concentrations than sulphuric acid. The modelled
formation rates JA2B2 were functions of sulphuric acid concentration
with close to quadratic dependence, which is in good agreement with
atmospheric observations of the connection between the particle formation
rate and sulphuric acid concentration. The coefficients KA2B2 connecting
the cluster formation rate and sulphuric acid concentrations as
JA2B2=KA2B2[H2SO4]2 turned out to depend also on
amine concentrations, temperature and relative humidity. We compared the
modelled coefficients KA2B2 with the corresponding coefficients
calculated from the atmospheric observations (Kobs) from environments
with varying temperatures and levels of anthropogenic influence. By taking into account the modelled
behaviour of JA2B2 as a function of [H2SO4], temperature and
RH, the atmospheric particle formation rate was reproduced more closely than
with the traditional semi-empirical formulae based on sulphuric acid
concentration only. The formation rates of clusters with two sulphuric acid
and two amine molecules with different amine compositions (DMA or TMA or one
of both) had different responses to varying meteorological conditions and
concentrations of vapours participating in particle formation. The observed
inverse proportionality of the coefficient Kobs with RH and temperature
agreed best with the modelled coefficient KA2B2 related to formation of
a cluster with two H2SO4 and one or two TMA molecules, assuming
that these clusters can grow in collisions with abundant organic vapour
molecules. In case this assumption is valid, our results suggest that the
formation rate of clusters with at least two of both sulphuric acid and
amine molecules might be the rate-limiting step for atmospheric particle
formation. More generally, our analysis elucidates the sensitivity of the
atmospheric particle formation rate to meteorological variables and
concentrations of vapours participating in particle formation (also other
than H2SO4). |
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