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| Titel |
Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment |
| VerfasserIn |
I. Salma, T. Borsós, T. Weidinger, P. Aalto, T. Hussein, M. Maso, 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 ; 11, no. 3 ; Nr. 11, no. 3 (2011-02-15), S.1339-1353 |
| Datensatznummer |
250009311
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| Publikation (Nr.) |
 copernicus.org/acp-11-1339-2011.pdf |
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| Zusammenfassung |
| Number concentrations of atmospheric aerosol particles were measured by a
flow-switching type differential mobility particle sizer in an electrical
mobility diameter range of 6–1000 nm in 30 channels near central Budapest
with a time resolution of 10 min continuously from 3 November 2008 to 2
November 2009. Daily median number concentrations of particles varied from
3.8 × 103 to 29 ×103 cm−3 with a yearly median
of 11.8 × 103 cm−3. Contribution of ultrafine particles to
the total particle number ranged from 58 to 92% with a mean ratio and
standard deviation of (79 ± 6)%. Typical diurnal variation of the
particle number concentration was related to the major emission patterns in
cities, new particle formation, sinks of particles and meteorology. Shapes
of the monthly mean number size distributions were similar to each other.
Overall mean for the number median mobility diameter of the Aitken and
accumulation modes were 26 and 93 nm, respectively, which are substantially
smaller than for rural or background environments. The Aitken and
accumulation modes contributed similarly to the total particle number
concentrations at the actual measurement location. New particle formation
and growth unambiguously occurred on 83 days, which represent 27% of all
relevant days. Hence, new particle formation and growth are not rare
phenomena in Budapest. Their frequency showed an apparent seasonal variation
with a minimum of 7.3% in winter and a maximum of 44% in spring. New
particle formation events were linked to increased gas-phase H2SO4
concentrations. In the studied area, new particle formation is mainly
affected by condensation sink and solar radiation. The formation process
seems to be not sensitive to SO2, which was present in a yearly median
concentration of 6.7 μg m−3. This suggests that the precursor gas
was always available in excess. Formation rate of particles with a diameter
of 6 nm varied between 1.65 and 12.5 cm−3 s−1 with a mean and
standard deviation of (4.2 ± 2.5) cm−3 s−1. Seasonal dependency
for the formation rate could not be identified. Growth curves of nucleated
particles were usually superimposed on the characteristic diurnal pattern of
road traffic direct emissions. The growth rate of the nucleation mode with a
median diameter of 6 nm varied from 2.0 to 13.3 nm h−1 with a mean and
standard deviation of (7.7 ± 2.4) nm h−1. There was an indicative
tendency for larger growth rates in summer and for smaller values in winter.
New particle formation events increased the total number concentration by a
mean factor and standard deviation of 2.3 ± 1.1 relative to the
concentration that occurred immediately before the event. Several indirect
evidences suggest that the new particle formation events occurred at least
over the whole city, and were of regional type. The results and conclusions
presented are the first information of this kind for the region over
one-year long time period. |
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