| 英文摘要 |
With more and more understanding about environmental influence and
health effects induced by suspended particles, Taiwan EPA began to plan and build
“Taiwan Supersite” in August 2000. The objective of supersite was to continuously
monitor aerosol physical and chemical compositions to explore its properties in
depth.
In March 2002, Taiwan supersite was operated with full capacity at
Hsindrum sports park. The instruments installed in Taiwan supersite include PM2.5
TEOM mass monitor, PM2.5 carbon analyzer, PM2.5 nitrate and sulfate analyzers,
aerosol integrating nephelometer, aerosol aethalometer, optical aerosol spectrometer
(PMS), and scanning mobility particle sizer (SMPS) as well as manual collectors like
R＆P 2300, Andersen RAAS, and R＆P ACCU.
From March to September in 2002, the effective data-acquisition rates are
98% for PM10, 97% for PM2.5, 73% for PM2.5 carbon, 94% for PM2.5 nitrate, 90% for
PM2.5 sulfate, 83% for PM2.5 black carbon, 74% for aerosol light-scattering
coefficient, 61% for aerosol size distribution from PMS, and 69% for aerosol size
distribution from SMPS, respectively.
Based on the continuous monitoring data from supersite, the average
concentration of PM10 in yellow sand (YS) events was 90μg/m3, which is greater
than that of non-yellow-sand (NYS) periods. In contrast, the average concentration of
PM2.5 in YS events was lower than that of NYS periods. Moreover, the organic
carbon (OC), elemental carbon (EC), and sulfate concentrations in PM2.5 in YS
events were also greater than that during NYS periods. However, for all time periods
and events, the EC concentration is always lower than OC. Aerosol light-scattering
coefficients during NYS periods were also shown to be greater than that in YS
events.
Interestingly, from the record of wind speed (WS) and wind direction
(WD), we found an increase of WS and a change of WD from the northeast to the
north- northeast. The situation was turn around when the YS was passed. This during
of stay of YS was evidenced by the rise of coarse particles (PM10-PM2.5).
From collocated comparison at supersite, the trend of data variation is
agreed between manual collectors and automatic mass monitor. The deviations
between R＆P2300 manual collector and TEOM monitor were 1% for PM2.5
and –7% for PM10, respectively. For aerosol carbon monitoring, the manual and
automatic data were agreed qualitatively but was lower for automatic carbon analyzer.
The possible explanation for the deviation in OC can be attributed to the difference in
detection method, while the cause for the deviation in elemental carbon might be due
to the cut-size of collection impactor at 0.14μm in automatic analyzer. For the
collocated comparison finished in October, both aerosol sulfate and nitrate were in
consistent between manual collector and automatic analyzers qualitatively. However,
the results from manual collectors were greater in concentrations of sulfate and
nitrate. The deviation got even greater when the concentration getting higher. The
vaporized nitrate was found to increase with the deposited nitrate on filter; however,
this vaporized nitrate should include the gaseous nitric acid.
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