 |
| Titel |
Simulation of atmospheric mercury depletion events (AMDEs) during polar springtime using the MECCA box model |
| VerfasserIn |
Z.-Q. Xie, R. Sander, U. Pöschl, F. Slemr |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 23 ; Nr. 8, no. 23 (2008-12-09), S.7165-7180 |
| Datensatznummer |
250006488
|
| Publikation (Nr.) |
 copernicus.org/acp-8-7165-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
Atmospheric mercury depletion events (AMDEs) during polar springtime
are closely correlated with bromine-catalyzed tropospheric ozone
depletion events (ODEs). To study gas- and aqueous-phase reaction
kinetics and speciation of mercury during AMDEs, we have included
mercury chemistry into the box model MECCA (Module Efficiently
Calculating the Chemistry of the Atmosphere), which enables dynamic
simulation of bromine activation and ODEs.
We found that the reaction of Hg with Br atoms dominates the loss of
gaseous elemental mercury (GEM). To explain the experimentally
observed synchronous depletion of GEM and O3, the reaction
rate of Hg+BrO has to be much lower than that of Hg+Br. The
synchronicity is best reproduced with rate coefficients at the lower
limit of the literature values for both reactions, i.e.
kHg+Br≈3×10−13 and kHg+BrO≤1×10−15 cm3 molecule−1 s−1, respectively.
Throughout the simulated AMDEs, \chem{BrHgOBr} was the most abundant
reactive mercury species, both in the gas phase and in the aqueous
phase. The aqueous-phase concentrations of BrHgOBr,
HgBr2, and HgCl2 were several orders of magnitude
larger than that of Hg(SO3)22−.
Considering chlorine chemistry outside depletion events (i.e. without
bromine activation), the concentration of total divalent mercury in
sea-salt aerosol particles (mostly HgCl42−) was much higher than
in dilute aqueous droplets (mostly Hg(SO3)22−), and did
not exhibit a diurnal cycle (no correlation with HO2
radicals). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|