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| Titel |
N2O5 measurement in Hong Kong by a chemical ionization mass spectrometry: Presence of high N2O5 and implications |
| VerfasserIn |
Tham Yee Jun, Wang Tao, Wang Zhe, Wang Xinfeng, Yan Chao, Zha Qiaozhi, Xu Zheng, Likun Xue |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092184
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| Publikation (Nr.) |
 EGU/EGU2014-6512.pdf |
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| Zusammenfassung |
| Dinitrogen pentoxide (N2O5) plays key roles in a number of nocturnal chemical processes
within the troposphere, including the sink of nitrogen oxides (NOx). However, accurate
measurement of this atmospheric trace compound remains as a challenging task, especially in
polluted environment like China. We initially deploy a thermal dissociation chemical
ionization mass spectrometry (TD-CIMS) for N2O5 field measurement in Hong Kong from
2010-2012. Unusual high N2O5 signal measured as NO3- (62 amu) were frequently
observed. Various interference tests and correction were conducted to verify the data, but we
caution the use of 62 amu for measuring ambient N2O5 in a high NOx environment like Hong
Kong. Therefore, we optimized the CIMS to measure N2O5 as ion cluster of I(N2O5)- at 235
amu with some minor improvements and demonstrated to has the ability for simultaneous
in situ measurements of N2O5 at an urban site. Then, the CIMS was deployed to
another field study at a mountain-top site (Tai Mo Shan). A comparison of N2O5
measurement with a cavity ring-down spectrometry was performed and found to be
in good correlation with the CIMS. High concentration of N2O5 was observed
between the boundary layer and there are some occasions where N2O5 exceeds several
ppb, which is among the highest values ever reported. These results provide deeper
understanding on the chemistry of NOx in a polluted environment. Furthermore, our
first observation of nitryl chloride (ClNO2) and its co-existence with N2O5 also
implies an active heterogeneous reactivity between N2O5 and chloride particles in
an Asian environment. Thus, N2O5 is an important nocturnal intermediate and
has the potential in jump-starting the atmospheric photochemistry in this region |
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