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| Titel |
Atmospheric mercury speciation and mercury in snow over time at Alert, Canada |
| VerfasserIn |
A. Steffen, J. Bottenheim, A. Cole, R. Ebinghaus, G. Lawson, W. R. Leaitch |
| 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 ; 14, no. 5 ; Nr. 14, no. 5 (2014-03-03), S.2219-2231 |
| Datensatznummer |
250118455
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| Publikation (Nr.) |
 copernicus.org/acp-14-2219-2014.pdf |
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| Zusammenfassung |
| Ten years of atmospheric mercury speciation data and 14 years of mercury in
snow data from Alert, Nunavut, Canada, are examined. The speciation data,
collected from 2002 to 2011, includes gaseous elemental mercury (GEM),
particulate mercury (PHg) and reactive gaseous mercury (RGM). During the
winter-spring period of atmospheric mercury depletion events (AMDEs), when
GEM is close to being completely depleted from the air, the concentration of
both PHg and RGM rise significantly. During this period, the median
concentrations for PHg is 28.2 pgm−3 and RGM is 23.9 pgm−3, from
March to June, in comparison to the annual median concentrations of
11.3 and 3.2 pgm−3 for PHg and RGM, respectively. In each of the ten
years of sampling, the concentration of PHg increases steadily from January
through March and is higher than the concentration of RGM. This pattern
begins to change in April when the levels of PHg peak and RGM begin to
increase. In May, the high PHg and low RGM concentration regime observed in
the early spring undergoes a transition to a regime with higher RGM and much
lower PHg concentrations. The higher RGM concentration continues into June.
The transition is driven by the atmospheric conditions of air temperature
and particle availability. Firstly, a high ratio of the concentrations of
PHg to RGM is reported at low temperatures which suggests that oxidized
gaseous mercury partitions to available particles to form PHg. Prior to the
transition, the median air temperature is −24.8 °C and after the
transition the median air temperature is −5.8 °C. Secondly, the high PHg
concentrations occur in the spring when high particle concentrations are
present. The high particle concentrations are principally due to Arctic haze
and sea salts. In the snow, the concentrations of mercury peak in May for
all years. Springtime deposition of total mercury to the snow at Alert peaks
in May when atmospheric conditions favour higher levels of RGM. Therefore,
the conditions in the atmosphere directly impact when the highest amount of
mercury will be deposited to the snow during the Arctic spring. |
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