Browsing by Author "Lin, Sih-Fan"

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Sampling and conditioning artifacts of PM2.5 in filter-based samplers
(2014-03-01)
Liu, Chun-Nan
;
Lin, Sih-Fan
;
Awasthi, Amit
;
Tsai, Chuen-Jinn
;
Wu, Yueh-Chuen
Field studies were conducted at Taiwan National Chiao-Tung University (NCTU) campus to evaluate the evaporation loss of fine particles (PM2.5) collected by the multi-filter PM10-PM2.5 sampler (MFPPS), which was collocated with a dichotomous sampler (Dichot, Andersen, Model SA-241), a WINS PM2.5 sampler (Thermo, Model 2000-FRM), and a tapered element oscillating microbalance with the filter dynamic measurement system (TEOM-FDMS, Thermo, Model 1405-DF). Porous-metal denuder samplers (PDSs) were installed in sampling channels of the MFPPS to measure the concentration of evaporated ion species. Results showed that the evaporation loss in PM2.5 was severe during sampling, accounting for 5.8-36.0% of the corrected PM2.5 concentration and the percentage increased with decreasing loaded particle mass and increasing filtration velocity. During 24-h sampling, the evaporated NH4+, NO3- and Cl- concentrations accounted for 9.5 +/- 6.2, 5.4 +/- 3.7, and 2.0 +/- 1.3% in corrected PM(2.)5 concentration, respectively, or 46.4 +/- 19.2, 66.9 +/- 18.5, and 74.4 +/- 14.0% in the concentration of each species, respectively. Due to the evaporation loss, PM2.5 concentrations measured by the WINS, Dichot, and MFPPS were lower than those the TEOM-FDMS by 16.6 +/- 9.0, 15.2 +/- 10.6 and 12.5 +/- 8.8%, respectively. When the MFPPS PM(2.)5 concentrations were corrected for the evaporated loss determined by the PDS, good agreement with those by the TEOM-FDMS was achieved. (C) 2013 Elsevier Ltd. All rights reserved.
Theoretical model for the evaporation loss of PM2.5 during filter sampling
(2015-05-01)
Liu, Chun-Nan
;
Lin, Sih-Fan
;
Tsai, Chuen-Jinn
;
Wu, Yueh-Chuen
;
Chen, Chung-Fang
The evaporation losses of PM2.5 particles in eight different size ranges corresponding to the 4th-10th stages and after filter of the MOUDI were calculated theoretically and then integrated to obtain the total PM2.5 evaporation loss. Results show that when PM2.5 particles are nearly neutral with pH in the range of 7-8, the evaporated concentrations predicted by the present model agree well with the experimental data with an average absolute difference of 20.2 +/- 11.1%. When PM2.5 aerosols are acidic with pH less than 3.5, additional loss of nitrate and chloride can occur due to chemical interactions between collected particles and strong acids which are not considered in the present model. Under pH neutral conditions, the theoretical model was then used to examine the effect of PM2.5 concentration, gas-to-particle ratio, ambient temperature and relative humidity on the extent of evaporation loss. Results show that evaporated PM2.5 concentration increases with increasing temperature and decreasing relative humidity, PM2.5 concentration and gas-to-particle ratio. (C) 2015 Elsevier Ltd. All rights reserved.
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.