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Description |
Chemistry
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Meteorology |
Emissions |
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Breton Wilderness Area |
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| Chemical components
responsible for haze |
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In Breton wilderness area
during the sampling period of 9/2000 – 12/2002, the average PM2.5 mass
concentration is 7.9 µg/m3. The average total light extinction coefficient (Bext)
is 76.2 Mm-1 (Visual Range ~ 51.2 Km; Deciview ~ 20.3).. The average
contributions of the major aerosol components to Breton haze (including
Rayleigh scattering) are particulate sulfate 59.9%, nitrate 7.6%, organic
matter (OMC) 8.0%, elemental carbon (light absorbing carbon, LAC) 4.2%, fine
soil 0.8% and coarse mass (CM) 6.3%.
Sulfate is the dominant aerosol
chemical component that contributes to regional haze in the Breton
wilderness area. In the 20% worst days, it contributes in average ~ 67% to
regional haze (more than 70% to the aerosol light extinction (excluding
Rayleigh scattering)). |
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| Figure 2. Average
contributions of major aerosol chemical components to light extinction
(Based on data available in 1997-2002) |
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Figure 3 suggests that the highest occurrence of the 20%
worst days happened in May and September, in which more than 40% of the
sampling days are the 20% haziest days at Breton. |
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| Figure 3. Percentage of
sampling days that are 20% worst days in each month (Based on data available
in 1997-2002) |
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As shown in Figure 4, sulfate
is the largest aerosol contributor to haze throughout the year, especially
from May to October during which the contribution of sulfate to haze is more
than ~70% in the worst days. OMC and nitrate contribute ~15 - 20% in
February and December during the 20% worst days. |
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| Figure 4. Average
contributions of major aerosol chemical components to light extinction
during 20% worst days in each month (Based on data available in 1997-2002) |
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| For a detailed examination of
the aerosol characteristics at Breton consult the
aerosol description web page. |
