Investigation of real time chemical compositions of PM2.5 in urban environment
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In this project, chemical components and number concentration of PM2.5 were measured by Aerosol Chemical Speciation Monitor (ACSM) and SMPS in Northern Taiwan (Judong, Sinjhung and NCTU campus). The CMB results showed that SOA was the main component of organic aerosols in Judong and NCTU campus due to photochemical reaction, which accounted for 62.2 ± 16.3 and 65 ± 19.3% of total organic aerosols, respectively. In contrast, POA was the main component of organic aerosols in Sinjhung due to traffic emission, which accounted for 61 ± 2.54% of total organic aerosols. The PPPMF results underestimated the total organic aerosols at the three sites mentioned above by 19%, 14% and 13%, while the results analyzed by CMB showed almost no difference between measured values, suggesting that CMB is more accurate comparing to PPPMF. The conversion factors of OC to OM in Judong、Sinjhung and NCTU campus were 1.63 ± 0.76, 1.93 ± 1.84 and 1.61 ± 0.79, respectively. The average number concentration measured were (1.0 ± 0.6)×104 #/cm3 in Judong, having high correlation with O3 (R2 = 0.71), (1.1 ± 0.6) ×104 #/cm3 in Sinjhung, having high correlation with NOx and CO (both R2 = 0.78), and (1.09 ± 0.59) ×104 #/cm3 in NCTU campus , having high correlation with NOx and CO (both R2 = 0.84). The results measured by NanoScan SMPS matched well with those measured by SMPS for particle diameter (dm) smaller than 400nm with R2 of 0.99. Base on the number concentrations and chemical components measured above, the effective density in Judong、Sinjhung and NCTU campus sites were 2.45, 1.49 and 2.17 g/cm3, respectively.
In this study, the applicability of the ACSM for the real time atmospheric chemical composition measurement was investigated. In the beginning at Judong
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Keyword |
aerosol chemical speciation monitor, number concentration and size distribution of nanoparticles, PM2.5 aerodynamic lens
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