 |
| Titel |
Sensitivity analysis of an updated bidirectional air–surface exchange model for elemental mercury vapor |
| VerfasserIn |
X. Wang, C.-J. Lin, X. Feng |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 12 ; Nr. 14, no. 12 (2014-06-25), S.6273-6287 |
| Datensatznummer |
250118832
|
| Publikation (Nr.) |
 copernicus.org/acp-14-6273-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| A box model for estimating bidirectional air–surface exchange of gaseous
elemental mercury (Hg0) has been updated based on the latest
understanding of the resistance scheme of atmosphere–biosphere interface
transfer. Simulations were performed for two seasonal months to evaluate
diurnal and seasonal variation. The base-case results show that water and
soil surfaces are net sources, while vegetation is a net sink of Hg0.
The estimated net exchange in a domain covering the contiguous US and part of
Canada and Mexico is 38.4 and 56.0 Mg as evasion in the summer and winter
month, respectively. The smaller evasion in summer is due to the stronger
Hg0 uptake by vegetation. Modeling experiments using a two-level
factorial design were conducted to examine the sensitivity of flux response
to the changes in physical and environmental parameters in the model. It is
shown that atmospheric shear flows (surface wind over water and friction
velocity over terrestrial surfaces), dissolved gaseous mercury (DGM)
concentration, soil organic and Hg content, and air temperature are the most
influential factors. The positive effect of friction velocity and soil Hg
content on the evasion flux from soil and canopy can be effectively offset by
the negative effect of soil organic content. Significant synergistic effects
are identified between surface wind and DGM level for water surface, and
between soil Hg content and friction velocity for soil surface, leading to
~50% enhanced flux compared to the sum of their individual effects.
The air–foliage exchange is mainly controlled by surface resistance terms
influenced by solar irradiation and air temperature. Research in providing
geospatial distribution of Hg in water and soil will greatly improve the flux
estimate. Elucidation on the kinetics and mechanism of Hg(II) reduction in
soil/water and quantification of the surface resistances specific to Hg
species will also help reduce the model uncertainty. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|