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| Titel |
Atmospheric mercury over sea ice during the OASIS-2009 campaign |
| VerfasserIn |
A. Steffen, J. Bottenheim, A. Cole, T. A. Douglas, R. Ebinghaus, U. Frieß, S. Netcheva, S. Nghiem, H. Sihler, R. Staebler |
| 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 ; 13, no. 14 ; Nr. 13, no. 14 (2013-07-24), S.7007-7021 |
| Datensatznummer |
250018777
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| Publikation (Nr.) |
 copernicus.org/acp-13-7007-2013.pdf |
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| Zusammenfassung |
| Measurements of gaseous elemental mercury (GEM), reactive gaseous mercury
(RGM) and particulate mercury (PHg) were collected on the Beaufort Sea ice
near Barrow, Alaska, in March 2009 as part of the Ocean-Atmosphere-Sea
Ice-Snowpack (OASIS) and OASIS-Canada International Polar Year programmes.
These results represent the first atmospheric mercury speciation
measurements collected on the sea ice. Concentrations of PHg averaged 393.5 pg m−3 (range 47.1–900.1 pg m−3) and RGM concentrations averaged
30.1 pg m−3 (range 3.5–105.4 pg m−3) during the two-week-long
study. The mean concentration of GEM during the study was 0.59 ng m−3
(range 0.01–1.51 ng m−3) and was depleted compared to annual Arctic
ambient boundary layer concentrations. It is shown that when ozone (O3)
and bromine oxide (BrO) chemistry were active there is a positive linear
relationship between GEM and O3, a negative one between PHg and
O3, a positive correlation between RGM and BrO, and none between RGM and
O3. For the first time, GEM was measured simultaneously over the tundra
and the sea ice. The results show a significant difference in the magnitude
of the emission of GEM from the two locations, with significantly higher
emission over the tundra. Elevated chloride levels in snow over sea ice are
proposed to be the cause of lower GEM emissions over the sea ice because
chloride has been shown to suppress photoreduction processes of RGM to GEM
in snow. Since the snowpack on sea ice retains more mercury than inland
snow, current models of the Arctic mercury cycle may greatly underestimate
atmospheric deposition fluxes because they are based predominantly on
land-based measurements. Land-based measurements of atmospheric mercury
deposition may also underestimate the impacts of sea ice changes on the
mercury cycle in the Arctic. The predicted changes in sea ice conditions and
a more saline future snowpack in the Arctic could enhance retention of
atmospherically deposited mercury and increase the amount of mercury
entering the Arctic Ocean and coastal ecosystems. |
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