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| Titel |
The Influence of NOx and Iron on Halogen Activation |
| VerfasserIn |
Sergej Bleicher, Franz D. Oeste, Julian Wittmer, Joelle Buxmann, Rolf Sander, Ulrich Platt, Cornelius Zetzsch |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078237
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| Zusammenfassung |
| Reactive Halogen Species (RHS) have a high impact on tropospheric trace gases, such as ozone and methane. Their activation from halides in sea spray aerosol and salt pans is a topic of intensive research. Here we present smog chamber measurements on both: aerosol and salt pans, using NOx and iron(III) as activation species. The experiments were performed in a Teflon (FEP) chamber, equipped with Differential Optical Absorption Spectroscopy (DOAS) in a White setup. Using DOAS we were able to observe BrO, OClO and ClO directly. Moreover, we could observe the concentration of chlorine atoms with the radical clock technique. In addition, we calculated the ionic composition and pH of the aerosol using an adapted CAABA/MECCA model.
In contrast to salt pans the activation of both: bromide and chloride is strongly dependent on the initial NOx concentration in the aerosol. Experiments with salt pans show almost no influence of NOx on activation of chloride. Moreover, although the total surface of salt pans compared to aerosol was a factor of 10^2 to 10^3 larger, no rapid consumption of NOx was observed over wet salt pans (RH>50%). While in the aerosol case NOx had a lifetime of approx. 15 min, its observed consumption over salt pans was a factor of 10 slower.
Additionally, experiments on the salt pan with added iron(III) will be shown. The related photo-Fenton cycle is supposed to release chlorine to the gas phase, which could be considered to remove tropospheric methane in future, potential climate-engineering applications. |
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