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| Titel |
Trends in long-term gaseous mercury observations in the Arctic and effects of temperature and other atmospheric conditions |
| VerfasserIn |
A. S. Cole, A. Steffen |
| 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 ; 10, no. 10 ; Nr. 10, no. 10 (2010-05-21), S.4661-4672 |
| Datensatznummer |
250008468
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| Publikation (Nr.) |
 copernicus.org/acp-10-4661-2010.pdf |
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| Zusammenfassung |
| Gaseous elemental mercury (GEM) measurements at Alert, Canada, from 1995 to
2007 were analyzed for statistical time trends and for correlations with
meteorological and climate data. A significant decreasing trend in annual
GEM concentration is reported at Alert, with an estimated slope of
−0.0086 ng m−3 yr−1 (−0.6% yr−1) over this 13-year period. It is
shown that there has been a shift in the month of minimum mean GEM
concentration from May to April due to a change in the timing of springtime
atmospheric mercury depletion events (AMDEs). These AMDEs are found to
decrease with increasing local temperature within each month, both at Alert
and at Amderma, Russia. These results support the temperature dependence
suggested by previous experimental results and theoretical kinetic
calculations on both bromine generation and mercury oxidation and highlight
the potential for changes in Arctic mercury chemistry with climate. A
correlation between total monthly AMDEs at Alert and the Polar/Eurasian
Teleconnection Index was observed only in March, perhaps due to higher GEM
inputs in early spring in those years with a weak polar vortex. A
correlation of AMDEs at Alert with wind direction supports the origin of
mercury depletion events over the Arctic Ocean, in agreement with a previous
trajectory study of ozone depletion events. Interannual variability in total
monthly depletion event frequency at Alert does not appear to correlate
significantly with total or first-year northern hemispheric sea ice area or
with other major teleconnection patterns. Nor do AMDEs at either Alert or
Amderma correlate with local wind speed, as might be expected if depletion
events are sustained by stable, low-turbulence atmospheric conditions. The
data presented here – both the change in timing of depletion events and
their relationship with temperature – can be used as additional constraints
to improve the ability of models to predict the cycling and deposition of
mercury in the Arctic. |
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