Browsing by Author "Wu, Guo-Jei"

Now showing 1 - 2 of 2

Development of an Automated System (PPWD/PILS) for Studying PM2.5 Water-Soluble Ions and Precursor Gases: Field Measurements in Two Cities, Taiwan
(2017-02-01)
Li, Ziyi
;
Liu, Yingshu
;
Lin, Yujie
;
Gautam, Sneha
;
Kuo, Hui-Chuan
An automated system consisting of a particle-into-liquid sampler (PILS) and a parallel plate wet denuder (PPWD) coupled with an ion chromatography was used for simultaneous measurement of ambient water-soluble ions in PM2.5 and precursor gases. The performance of the PPWD/PILS was validated by comparing it with the PDS (porous metal denuder sampler) for precursor gases (NH3, HONO, HNO3 and SO2) and PM2.5 ionic species (NH4+, NO3-, SO42-, Na+, Cl- and K+) measured in Taipei and Hsinchu Cities of Taiwan. Good correlations were demonstrated with linear regression slopes ranging from 0.92 to 1.04 and 0.84 to 0.97 as well as R-2 ranging from 0.76 to 0.83 and 0.89 to 0.94, for precursor gases and PM2.5 ions, respectively. The accuracy of the current system for precursor gases outperforms the other commercial systems. Field continuous data showed that NH3 was the most abundant precursor gas with the diurnal pattern peaking at low nocturnal boundary heights and during rush hours with local traffic emissions in Taipei, and with the pattern peaking only at mid-day associated with regional sources in Hsinchu. A reverse diurnal pattern for HONO in Taipei reflected the daytime photolysis and its nocturnal heterogeneous reaction, while its concentration was relatively constant at very low level in Hsinchu. SO42-, NH4+ and NO3- exhibited very similar diurnal patterns with the mean concentrations of 4.56 +/- 3.14, 1.55 +/- 1.16 and 0.52 +/- 0.5 mu g m(-3) in Taipei, and 7.95 +/- 5.52, 2.41 +/- 1.95 and 0.96 +/- 1.10 mu g m(-3) in Hsinchu, respectively. Correspondingly high concentrations of major ions to precursor gases were associated with the photochemical secondary aerosol formations and heavy traffic in Taipei. Based on an ammonia-rich atmosphere and high SOR values, (NH4)(2)SO4 and NH4NO3 were inferred to be the dominant inorganic salts in PM2.5 at both sites, which were also verified by the ion balance analysis.
Ultrafine Particles and PM2.5 at Three Urban Air Monitoring Stations in Northern Taiwan from 2011 to 2013
(2015-11-01)
Lin, Guan-Yu
;
Lee, Guo-Rui
;
Lin, Sih-Fan
;
Hung, Yi-Hung
;
Li, Shih-Wei
In this study, long term measurements of PM2.5 and ultrafine particles (UFPs) for daily average mass concentration at Zhongshan (ZS), Sinjhuang (SJ), and Jhudong (JD) urban air monitoring stations were conducted from 2011 spring to 2013 autumn. The results showed that daily average UFPs mass concentrations in spring (average at 3 stations: 1.58 +/- 0.74 mu g m(-3)) and summer (average at 3 stations: 1.59 +/- 0.53 mu g m(-3)) were higher than those in autumn (average at 3 stations: 1.02 +/- 0.28 mu g m(-3)) and winter (average at 3 stations: 1.04 +/- 0.48 mu g m(-3)) due to the impacts by heavy traffic emission and new particle formation event. The effective density (rho(eff)) and dynamic shape factor (chi) for ultrafine particles (UFPs) were found to be 0.68 +/- 0.16 g cm(-3) and 2.06 +/- 0.19, respectively, suggesting that the particle morphology was irregular shape. Based on the calculated rho(eff) and chi, the average number and surface area concentration ratio of UFPs to those of PM2.5 at these monitoring stations was determined to be 89.0 +/- 5.5% and 42.1 +/- 12.8%, respectively, suggesting that UFPs contribute significantly to the health-relevant PM2.5 aerosol fraction in these stations.