Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets
The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and −10 °C, on...
Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-02-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/16/1693/2016/acp-16-1693-2016.pdf |
Summary: | The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by
ozone was measured in laboratory-generated clouds created in the
Cosmics Leaving OUtdoor Droplets (CLOUD)
chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and −10 °C, on
acidic (sulfuric acid) and on partially to fully neutralised (ammonium
sulfate) seed aerosol. Clouds were generated by performing an adiabatic
expansion – pressurising the chamber to 220 hPa above atmospheric
pressure, and then rapidly releasing the excess pressure, resulting in a
cooling, condensation of water on the aerosol and a cloud lifetime of
approximately 6 min. A model was developed to compare the observed aerosol
growth with that predicted using oxidation rate constants previously measured in bulk
solutions. The model captured the measured aerosol growth very well for
experiments performed at 10 and −10 °C, indicating that, in
contrast to some previous studies, the oxidation rates of SO<sub>2</sub> in a
dispersed aqueous system can be well represented by using accepted rate constants, based on
bulk measurements. To the best of our knowledge, these are the first
laboratory-based measurements of aqueous phase oxidation in a dispersed,
super-cooled population of droplets. The measurements are therefore important
in confirming that the extrapolation of currently accepted reaction rate constants to
temperatures below 0 °C is correct. |
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ISSN: | 1680-7316 1680-7324 |