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| Titel |
Oxidation of elemental Hg in anthropogenic and marine airmasses |
| VerfasserIn |
H. Timonen, J. L. Ambrose, D. A. Jaffe |
| 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. 5 ; Nr. 13, no. 5 (2013-03-08), S.2827-2836 |
| Datensatznummer |
250018485
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| Publikation (Nr.) |
 copernicus.org/acp-13-2827-2013.pdf |
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| Zusammenfassung |
| Mercury (Hg) is a neurotoxin that bioaccumulates in the food chain. Mercury
is emitted to the atmosphere primarily in its elemental form, which has a
long lifetime allowing global transport. It is known that atmospheric
oxidation of gaseous elemental mercury (GEM) generates reactive gaseous
mercury (RGM) which plays an important role in the atmospheric mercury cycle
by enhancing the rate of mercury deposition to ecosystems. However, the
primary GEM oxidants, and the chemical composition of RGM are poorly known.
Using speciated mercury measurements conducted at the Mt. Bachelor
Observatory since 2005 we present two previously unidentified sources of RGM
to the free troposphere (FT). Firstly, we observed elevated RGM
concentrations, large RGM/GEM-ratios, and anti-correlation between RGM and
GEM during Asian long-rang transport events, demonstrating that RGM is
formed from GEM by in-situ oxidation in some anthropogenic pollution plumes
in the FT. During the Asian pollution events the measured RGM/GEM-enhancement
ratios reached peak values, up to ~0.20, which
are significantly larger than ratios typically measured (RGM/GEM < 0.03) in the Asian source region. Secondly, we observed very high RGM levels
– the highest reported in the FT – in clean air masses that were processed
upwind of Mt. Bachelor Observatory over the Pacific Ocean. The high RGM
concentrations (up to 700 pg m−3), high RGM/GEM-ratios (up to 1), and
very low ozone levels during these events provide observational evidence
indicating significant GEM oxidation in the lower FT in some conditions. |
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