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| Titel |
Chemical characteristics of inorganic ammonium salts in PM2.5 in the atmosphere of Beijing (China) |
| VerfasserIn |
A. Ianniello, F. Spataro, G. Esposito, I. Allegrini, M. Hu, T. Zhu |
| 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. 21 ; Nr. 11, no. 21 (2011-11-02), S.10803-10822 |
| Datensatznummer |
250010160
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| Publikation (Nr.) |
 copernicus.org/acp-11-10803-2011.pdf |
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| Zusammenfassung |
| The atmospheric concentrations of gaseous HNO3, HCl and NH3 and
their relative salts have been measured during two field campaigns in the
winter and in the summer of 2007 at Beijing (China), as part of CAREBEIJING
(Campaigns of Air Quality Research in Beijing and Surrounding Region). In
this study, annular denuder technique used with integration times of 2 and
24h to collect inorganic and soluble PM2.5 without interferences from
gas–particle and particle–particle interactions. The results were
discussed from the standpoint of temporal and diurnal variations and
meteorological effects. Fine particulate Cl−, NH4+ and
SO42− exhibited distinct temporal variations, while fine
particulate NO3− did not show much variation with respect to
season. Daily mean concentrations of fine particulate NH4+ and
SO42− were higher during summer (12.30 μg m−3 and
18.24 μg m−3, respectively) than during winter (6.51 μg m−3 and
7.50 μg m−3, respectively). Daily mean concentrations of fine
particulate Cl− were higher during winter (2.94 μg m−3) than
during summer (0.79 μg m−3), while fine particulate
NO3− showed similar both in winter (8.38 μg m−3)
and in summer (9.62 μg m−3) periods. The presence of large amounts of fine particulate
NO3− even in summer are due to higher local and regional
concentrations of NH3 in the atmosphere available to neutralize
H2SO4 and HNO3, which is consistent with the observation that
the measured particulate species were neutralized. The composition of fine
particulate matter indicated the domination of (NH4)2SO4
during winter and summer periods. In addition, the high relative humidity
conditions in summer period seemed to dissolve a significant fraction of
HNO3 and NH3 enhancing fine particulate NO3− and
NH4+ in the atmosphere. All measured particulate species showed
diurnal similar patterns during the winter and summer periods with higher
peaks in the early morning, especially in summer, when humid and stable
atmospheric conditions occurred. These diurnal variations were affected by
wind direction suggesting regional and local source influences. The fine
particulate species were correlated with NOx and PM2.5, supporting
the hypothesis that traffic may be also an important source of secondary
particles. |
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