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| Titel |
Speciated mercury at marine, coastal, and inland sites in New England – Part 2: Relationships with atmospheric physical parameters |
| VerfasserIn |
H. Mao, R. Talbot, J. Hegarty, J. Koermer |
| 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. 9 ; Nr. 12, no. 9 (2012-05-11), S.4181-4206 |
| Datensatznummer |
250011128
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| Publikation (Nr.) |
 copernicus.org/acp-12-4181-2012.pdf |
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| Zusammenfassung |
| Long-term continuous measurements of gaseous elemental mercury (Hg0),
reactive gaseous mercury (RGM), and particulate phase mercury (HgP)
were conducted at coastal (Thompson Farm, denoted as TF), marine (Appledore
Island, denoted as AI), and elevated inland rural (Pac Monadnock, denoted as
PM) monitoring sites of the AIRMAP Observing Network. Diurnal, seasonal,
annual, and interannual variability in Hg0, RGM, and HgP from the
three distinctly different environments were characterized and compared in
Part 1. Here in Part 2 relationships between speciated mercury (i.e.,
Hg0, RGM, and HgP) and climate variables (e.g., temperature, wind
speed, humidity, solar radiation, and precipitation) were examined. The best
point-to-point correlations were found between Hg0 and temperature in
summer at TF and spring at PM, but there was no similar correlation at AI.
Subsets of data demonstrated regional impacts of episodic dynamic processes
such as strong cyclonic systems on ambient levels of Hg0 at all three
sites, possibly through enhanced oceanic evasion of Hg0. A tendency of
higher levels of RGM and HgP was identified in spring and summer under
sunny conditions in all environments. Specifically, the 10th,
25th, median, 75th, and 90th percentile mixing ratios of RGM
and HgP increased with stronger solar radiation at both the coastal and
marine sites. These metrics decreased with increasing wind speed at AI
indicating enhanced loss of RGM and HgP through deposition. RGM and
HgP levels correlated with temperature positively in spring, summer and
fall at the coastal and marine locations. At the coastal site relationships
between RGM and relative humidity suggested a clear decreasing tendency in
all metrics from <40% to 100% relative humidity in all seasons
especially in spring, compared to less variability in the marine
environment. The effect of precipitation on RGM at coastal and marine
locations was similar. At the coastal site, RGM levels were a factor of 3–4
to two orders of magnitude higher under dry conditions than rainy conditions
in all seasons. In winter RGM mixing ratios appeared to be mostly above the
limit of detection (LOD) during snowfalls suggesting less scavenging
efficiency of snow. Mixing ratios of HgP at the coastal and marine
sites remained above the LOD under rainy conditions. Precipitation had
negligible impact on the magnitude and pattern of diurnal variation of
HgP in all seasons in the marine environment. |
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