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| Titel |
The uptake of SO2 on Saharan dust: a flow tube study |
| VerfasserIn |
J. W. Adams, D. Rodriguez, R. A. Cox |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 5, no. 10 ; Nr. 5, no. 10 (2005-12-12), S.2679-2689 |
| Datensatznummer |
250003100
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| Publikation (Nr.) |
 copernicus.org/acp-5-2679-2005.pdf |
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| Zusammenfassung |
| The uptake of SO2 onto Saharan mineral dust from the Cape Verde Islands
was investigated using a coated wall flow tube coupled to a mass
spectrometer. The rate of loss of SO2 to the dust coating was measured
and uptake coefficients were determined using the measured BET surface area
of the sample. The uptake of SO2, with an initial concentration between
(2-40)x1010molecule cm-3 (0.62-12 µTorr), was found
to be strongly time dependent over the first few hundred seconds of an
experiment, with an initial uptake γ0,BET of (6.6±0.8)x10-5 (298 K), declining at longer times. The amount of
SO2 adsorbed on the dust samples was measured over a range of SO2 concentrations and mineral dust loadings. The uptake of SO2
was found to be up to 98% irreversible over the timescale of these
investigations. Experiments were also performed at 258 K, at a relative
humidity of 27% and at 298 K in the presence of ozone. The initial uptake
and the amount of SO2 taken up per unit area of BET dust surface was
the same within error, irrespective of the conditions used; however the
presence of ozone reduced the amount of SO2 released back into the
gas-phase per unit area once exposure of the surface ended. Multiple uptakes
to the same surface revealed a loss of surface reactivity, which did not
return if the samples were exposed to gas-phase water, or left under vacuum
overnight. A mechanism which accounts for the observed uptake behaviour is
proposed and numerically modelled, allowing quantitative estimates of the
rate and amount of SO2 removal in the atmosphere to be estimated.
Removal of SO2 by mineral dust is predicted to be significant at high
dust loadings. |
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