 |
| Titel |
Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes |
| VerfasserIn |
T. D. Fairlie, D. J. Jacob, J. E. Dibb, B. Alexander, M. A. Avery, A. Donkelaar, L. Zhang |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 8 ; Nr. 10, no. 8 (2010-04-29), S.3999-4012 |
| Datensatznummer |
250008386
|
| Publikation (Nr.) |
 copernicus.org/acp-10-3999-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| We use a 3-D global chemical transport model (GEOS-Chem) to interpret
aircraft observations of nitrate and sulfate partitioning in transpacific
dust plumes during the INTEX-B campaign of April–May 2006. The model
includes explicit transport of size-resolved mineral dust and its
alkalinity, nitrate, and sulfate content. The observations show that
particulate nitrate is primarily associated with dust, sulfate is primarily
associated with ammonium, and Asian dust remains alkaline across the
Pacific. This can be reproduced in the model by using a reactive uptake
coefficient for HNO3 on dust (γ(HNO3) ~10−3)
much lower than commonly assumed in models and possibly reflecting
limitation of uptake by dust dissolution. The model overestimates gas-phase
HNO3 by a factor of 2–3, typical of previous model studies; we show
that this cannot be corrected by uptake on dust. We find that the fraction
of aerosol nitrate on dust in the model increases from ~30% in
fresh Asian outflow to 80–90% over the Northeast Pacific, reflecting in
part the volatilization of ammonium nitrate and the resulting transfer of
nitrate to the dust. Consumption of dust alkalinity by uptake of acid gases
in the model is slow relative to the lifetime of dust against deposition, so
that dust does not acidify (at least not in the bulk). This limits the
potential for dust iron released by acidification to become bio-available
upon dust deposition. Observations in INTEX-B show no detectable ozone
depletion in Asian dust plumes, consistent with the model. Uptake of
HNO3 by dust, suppressing its recycling to NOx, reduces Asian
pollution influence on US surface ozone in the model by 10–15% or up to
1 ppb. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|