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| Titel |
Gas and particle phase chemical characterization of photochemical smog in Beijing and Hong Kong |
| VerfasserIn |
Mattias Hallquist, Michael Le Breton, Song Guo, Jian Zhen Yu, Åsa M. Hallquist, Ravi K. Pathak, Qianyun Liu, Yuchen Wang, Jinjian Li, Chak K. Chan, Yujue Wang, Jing Zheng, Yudong Yang, Keding Lu, Zhijun Wu, Min Hu |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250149851
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| Publikation (Nr.) |
 EGU/EGU2017-14245.pdf |
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| Zusammenfassung |
| Secondary chemistry transforming primary pollutants is of high relevance for Chinese
photochemical smog. In particular, formation of ozone (O3) and particulate matter (PM),
including Secondary Organic Aerosols (SOA), are of major concern regarding impacts on
health, climate and ecosystems. The atmospheric oxidation processes leading to SOA
formation are complex and involves thousands of different compounds, both of biogenic and
anthropogenic origin. Furthermore, for a thorough understanding both the gas and the particle
phase need to be considered.
As part of an intercollaborative project to assess the photochemical smog in China, two
major field campaigns were arranged in 2016; in Changping, Bejing during springtime
and at HKUST, Hong Kong during the autumn. Alongside with other advanced
instrumentations, a Time of Flight Chemical Ionisation Mass Spectrometer (ToF CIMS)
utilising the Filiter Inlet for Gases and AEROsols (FIGAERO) was used to chemically
characterize the gas and the particle phase. This specific instrument applies soft ionization
limiting the fragmentation and one can usually identify molecular composition of
hundreds of different parent molecules. In both Beijing and Hong Kong the iodide
ionization scheme was utilised, making it possible to specifically detect oxygenated
compounds such as carboxylic acids, organic nitrates and sulphates as well as some
inorganic compounds e.g. N2O5, ClNO2, and HONO. For numerous compounds
significant levels were detected in both the gas and particle phase enabling evaluation of
partitioning and gas-to-particle transformation and its relationship to atmospheric
conditions and estimated vapour pressures. Furthermore, the detection of molecular
markers such as levoglucosan, C6H5NO3, C10H16NSO7, C5H8SO7, C5H8O4 can
support source apportionment and atmospheric process description. In order to further
investigate atmospheric ageing/processing a portable laminar flow reactor (Go:PAM)
was for selected periods utilized to oxidize the sampled air before characterisation
with the ToF-CIMS-FIGAERO. These experiments were explorative but illustrated
the potential of further formation of organic nitrates and sulfates in the observed
air-masses.
The results of the measurements with the ToF-CIMS-FIGAERO are compared and
evaluated in relation to data from other advanced instrumentations such as AMS, PTR-MS,
GC-MS to further understand the complexity of SOA formation and the differences between
the two measurement sites. The time resolution of all these measurements including the
ToF-CIMS provided more insight into the diurnal variation and how that is linked to transport
and source activities, such as traffic, biomass burning and emission from vegetation. |
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