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| Titel |
Size distributions of non-volatile particle residuals (Dp<800 nm) at a rural site in Germany and relation to air mass origin |
| VerfasserIn |
C. Engler, D. Rose, B. Wehner, A. Wiedensohler, E. Brüggemann, T. Gnauk, G. Spindler, T. Tuch, W. Birmili |
| 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 ; 7, no. 22 ; Nr. 7, no. 22 (2007-11-22), S.5785-5802 |
| Datensatznummer |
250005259
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| Publikation (Nr.) |
 copernicus.org/acp-7-5785-2007.pdf |
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| Zusammenfassung |
| Atmospheric aerosol particle size distributions at a continental background site in Eastern Germany
were examined for a one-year period. Particles were classified using a twin differential mobility
particle sizer in a size range between 3 and 800 nm. As a novelty, every second measurement of
this experiment involved the removal of volatile chemical compounds in a thermodenuder at
300°C. This concept allowed to quantify the number size distribution of non-volatile
particle cores – primarily associated with elemental carbon, and to compare this to the original
non-conditioned size distribution. As a byproduct of the volatility analysis, new particles
originating from nucleation inside the thermodenuder can be observed, however, overwhelmingly at
diameters below 6 nm. Within the measurement uncertainty, every particle down to particle sizes of
15 nm is concluded to contain a non-volatile core. The volume fraction of non-volatile particulate
matter (non-conditioned diameter < 800 nm) varied between 10 and 30% and was largely
consistent with the experimentally determined mass fraction of elemental carbon. The average size
of the non-volatile particle cores was estimated as a function of original non-conditioned size
using a summation method, which showed that larger particles (>200 nm) contained more
non-volatile compounds than smaller particles (<50 nm), thus indicating a significantly
different chemical composition. Two alternative air mass classification schemes based on either,
synoptic chart analysis (Berliner Wetterkarte) or back trajectories showed that the volume and
number fraction of non-volatile cores depended less on air mass than the total particle number
concentration. In all air masses, the non-volatile size distributions showed a more and a less
volatile ("soot") mode, the latter being located at about 50 nm. During unstable
conditions and in maritime air masses, smaller values were observed compared to stable or continental conditions. This reflects the significant emission of non-volatile material over the
continent and, depending on atmospheric stratification, increased concentrations at ground level. |
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