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| Titel |
Seasonal and diurnal variations of atmospheric mercury across the US determined from AMNet monitoring data |
| VerfasserIn |
X. Lan, R. Talbot, M. Castro, K. Perry, W. Luke |
| 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 ; 12, no. 21 ; Nr. 12, no. 21 (2012-11-13), S.10569-10582 |
| Datensatznummer |
250011583
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| Publikation (Nr.) |
 copernicus.org/acp-12-10569-2012.pdf |
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| Zusammenfassung |
| Speciated atmospheric mercury observations collected over the period from
2008 to 2010 at the Environmental Protection Agency and National Atmospheric
Deposition Program Atmospheric Mercury Network sites (AMNet) were analyzed
for its spatial, seasonal, and diurnal characteristics across the US. Median
values of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and
particulate bound mercury (PBM) at 11 different AMNet sites ranged from
148–226 ppqv (1.32–2.02 ng m−3), 0.05–1.4 ppqv
(0.47–12.4 pg m−3) and 0.18–1.5 ppqv (1.61–13.7 pg m−3),
respectively. Common characteristics of these sites were the similar median
levels of GEM as well as its seasonality, with the highest mixing ratios
occurring in winter and spring and the lowest in fall. However, discernible
differences in monthly average GEM were as large as 30 ppqv, which may be
caused by sporadic influence from local emission sources. The largest diurnal
variation amplitude of GEM occurred in the summer. Seven rural sites
displayed similar GEM summer diurnal patterns, in that the lowest levels
appeared in the early morning, and then the GEM mixing ratio increased after
sunrise and reached its maxima at noon or in the early afternoon. Unlike GEM,
GOM exhibited higher mixing ratios in spring and summer. The largest diurnal
variation amplitude of GOM occurred in spring for most AMNet sites. The GOM
diurnal minima appeared before sunrise and maxima appeared in the afternoon.
The increased GOM mixing ratio in the afternoon indicated a photochemically
driven oxidation of GEM resulting in GOM formation. PBM exhibited diurnal
fluctuations in summertime. The summertime PBM diurnal pattern displayed
daily maxima in the early afternoon and lower mixing ratios at night,
implying photochemical production of PBM in summer. |
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