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| Titel |
Fog scavenging of organic and inorganic aerosol in the Po Valley |
| VerfasserIn |
S. Gilardoni, P. Massoli, L. Giulianelli, M. Rinaldi, M. Paglione, F. Pollini, C. Lanconelli, V. Poluzzi, S. Carbone, R. Hillamo, L. M. Russell, M. C. Facchini, S. Fuzzi |
| 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 ; 14, no. 13 ; Nr. 14, no. 13 (2014-07-09), S.6967-6981 |
| Datensatznummer |
250118874
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| Publikation (Nr.) |
 copernicus.org/acp-14-6967-2014.pdf |
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| Zusammenfassung |
The interaction of aerosol with atmospheric water affects the processing and
wet removal of atmospheric particles. Understanding such interaction is
mandatory to improve model description of aerosol lifetime and ageing. We
analyzed the aerosol–water interaction at high relative humidity during fog
events in the Po Valley within the framework of the Agenzia Regionale per
la Prevenzione e l'Ambiente (ARPA) – Emilia Romagna supersite project. For the
first time in this area, the changes in particle chemical composition caused
by fog are discussed along with changes in particle microphysics.
During the experiment, 14 fog events were observed. The average mass
scavenging efficiency was 70% for nitrate, 68% for ammonium, 61% for
sulfate, 50% for organics, and 39% for black carbon. After fog
formation, the interstitial aerosol was dominated by particles smaller than
200 nm Dva (vacuum aerodynamic diameter) and enriched in
carbonaceous aerosol, mainly black carbon and water-insoluble organic aerosol.
For each fog event, the size-segregated scavenging efficiency of nitrate and
organic aerosol (OA) was calculated by comparing chemical species size
distribution before and after fog formation. For both nitrate and OA, the
size-segregated scavenging efficiency followed a sigmoidal curve, with values
close to zero below 100 nm Dva and close to 1 above 700 nm
Dva. OA was able to affect scavenging efficiency of nitrate in
particles smaller than 300 nm Dva. A linear correlation between
nitrate scavenging and particle hygroscopicity (κ) was observed,
indicating that 44–51% of the variability of nitrate scavenging in
smaller particles (below 300 nm Dva) was explained by changes in
particle chemical composition.
The size-segregated scavenging curves of OA followed those of nitrate,
suggesting that organic scavenging was controlled by mixing with
water-soluble species. In particular, functional group composition and OA
elemental analysis indicated that more oxidized OA was scavenged more
efficiently than less oxidized OA. Nevertheless, the small variability of
organic functional group composition during the experiment did not allow us
to discriminate the effect of different organic functionalities on OA
scavenging. |
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