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| Titel |
Aerosol chemistry in Beijing, China: Different pollution regimes and diurnal profiles |
| VerfasserIn |
D. van Pinxteren, E. Brüggemann, T. Gnauk, Y. Iinuma, K. Müller, A. Nowak, P. Achtert, A. Wiedensohler, H. Herrmann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023327
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| Zusammenfassung |
| The rapid economic development during the last three decades in China has led to a severe
decrease in air quality, especially in densely populated regions such as Beijing, Shanghai, and
the Pearl River Delta. Although during last years a number of measures for air pollution
control have been implemented especially in the capital Beijing, air pollution is still regarded
to be one of the top environmental concerns in China during the next decade. To better
characterize the processes leading to the frequently observed high concentrations of air
pollutants on a regional scale, the international field campaign “Campaigns of Air Quality
Research in Beijing 2006” (CAREBEIJING2006) was conducted in summer 2006. Organized
by the Peking University, project partners from Japan, Korea, Hong Kong, Germany,
and China studied the various aspects of gaseous and particulate air pollution in a
megacity environment. In this contribution, we present chemical data of size-resolved
particles, obtained by a 5-stage Berner impactor (0.05–10 μm) during 3 weeks at
both an urban and a suburban site in the area of Beijing, China. The sampling time
of the impactors was about 4-5 hours. This allowed for taking four size-resolved
samples per day and obtaining rough diurnal profiles of particle components. The
samples were analyzed for inorganic ions (Cl-, SO42-, NO3-, NH4+, K+, Ca2+,
Na+, Mg2+), carbon sum parameters (OC, EC, WSOC), and a variety of organic
compounds such as dicarboxylic acids, alkanes, PAHs and, for the first time in China,
nitrooxy-organosulfates.
On average, the observed PM10 mass concentrations were 133 μg m-3 and 112 μg m-3
at the urban and suburban site, respectively. In general, the observed concentrations of
particulate pollutants were similarly high as reported from previous studies in the Beijing
summer atmosphere. A back trajectory analysis allowed the classification of the
samples into different meteorological categories with different air mass origins.
A high influence of meteorology on the PM pollution was observed: The highest
concentrations of both PM mass and particle constituents were measured when
sampled air masses originated south of Beijing and moved over the area with low wind
speeds. During such periods, a strong increase of daytime concentrations of the
secondary ions sulfate, nitrate, ammonium, and also some dicarboxylic acids could be
observed.
The comparison of a suburban sampling site to an urban one revealed a clear influence of
urban emissions on top of the regional pollution level for a period with relatively stagnant
meteorological conditions and high photochemical processing. In contrast, during
measurement periods with higher wind speeds and different air mass origins, the
concentration levels of particulate pollutants were basically the same at the two
sites.
During an intensive period, a strong diurnal variation of particle sulfate concentration
with increasing values from morning to afternoon was observed, which could be attributed to
regional production. Similar observations where made for oxalic acid. Generally,
water soluble organic carbon concentrations were enhanced by a factor of 2 in fine
particles during the studied period of intense photochemistry. Elemental carbon,
alkanes, and PAHs showed clear nighttime concentration maxima obviously due to
enhanced emissions and a relatively low mixing volume during night. For the newly
studied compound group of nitrooxy-organosulfates qualitative data can be presented
indicating an influence of night-time chemistry and/or anthropogenic activities on their
concentrations.
The investigation of an intense nucleation and particle growth event revealed that the
youngest particles largely consist of ammonium sulfate and primary carbonaceous material,
with a possible contribution of secondary organic compounds. |
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