Browsing by Author "Chou, Charles C. -K."

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Characterization of carbon fractions for atmospheric fine particles and nanoparticles in a highway tunnel
(2010-07-01)
Zhu, Chong-Shu
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Chen, Cheng-Chieh
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
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Chou, Charles C. -K.
Fine particles (PM(2.5)) and nanoparticles (PM(0),1)were sampled using Dichotomous sampler and MOUDI, respectively, in Xueshan Tunnel, Taiwan. Eight carbon fractions were analyzed using IMPROVE thermal-optical reflectance (TOR) method. The concentrations of different temperature carbon fractions (OC1-OC4, EC1-EC3) in both PM(2.5) and PM(0.1) were measured and the correlations between OC and EC were discussed. Results showed that the ratios of OC/EC were 1.26 and 0.67 for PM(2.5) and PM(0.1), respectively. The concentration of EC1 was found to be more abundant than other elemental carbon fractions in PM(2.5), while the most abundant EC fraction in PM(0.1) was found to be EC2. The variation of contributions for elemental carbon fractions was different among PM(2.5) and PM(0.1) samples, which was partly owing to the metal catalysts for soot oxidation. The correlations between char-EC and soot-EC showed that char-EC dominated EC in PM(2.5) while soot-EC dominated EC in PM(0.1). Using eight individual carbon fractions, the gasoline and diesel source profiles of PM(0.1) and PM(2.5) were extracted and analyzed with the positive matrix factorization (PMF) method. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
Chemical Mass Closure and Chemical Characteristics of Ambient Ultrafine Particles and other PM Fractions
(2010)
Chen, Sheng-Chieh
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Tsai, Chuen-Jinn
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Huang, Cheng-Yu
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Chen, Hong-Dar
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Chen, Shui-Jen
Ambient ultrafine particles (UPs or PM(0.1)), PM(2.5) and PM(10) were investigated at the roadside of Syuefu road in Hsinchu city and in the Syueshan highway tunnel in Taipei, Taiwan. A SMPS (TSI Model 3936), three Dichotomous samplers (Andersen Model SA-241), and three MOUDIs (MSP Model 110) were collocated to determine the PM number and mass concentrations simultaneously. The filter samples were further analyzed for organic carbon (OC), element carbon (EC), water-soluble ions, and trace elements. The OC artifact was studied and quantified using the quartz behind quartz (QBQ) method for all PM fractions. Taking into account the OC artifact, chemical mass closure (ratio of the reconstructed chemical mass to the gravimetrical mass) of PM(0.1), PM(2.5), and PM(10) was then calculated and found to be good. The chemical analysis results of UPs at both sites showed that UPs in the present tunnel was mostly contributed from the vehicle emissions while UPs at the roadside was mainly influenced by urban sources.
Dynamic variations of ultrafine, fine and coarse particles at the Lu-Lin background site in East Asia
(2013-10-01)
Chen, Sheng-Chieh
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Hsu, Shih-Chieh
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Tsai, Chuen-Jinn
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Chou, Charles C. -K.
;
Lin, Neng-Huei
The characteristics of atmospheric ultrafine particles (i.e. <100 nm, nanoparticles or PM0.1), PM2.5 and PM10 were studied at the Lulin Atmospheric Background Station (LABS, 2862 m a.s.l., Taiwan) as part of the 7SEAS/Dongsha campaign. Sampling was conducted in July and August of 2009 and September to November of 2010, during which two 96-h and four 72-h PM samples were taken. Real-time particle size distributions were measured continuously from July to August of 2009 and July to November of 2010. PM0.1, PM2.5 and PM10 were collected by using two MOUDIs (micro-orifice uniform deposit impactor, MSP 110) and a Dichotomous PM10 sampler (Andersen SA-241) while real-time size distributions of particles of 5.5-350 nm in diameter were measured by an SMPS (scanning mobility particle sizer, TSI 3936). Filter samples were analyzed for gravimetric mass and chemical compositions, including organic carbon (OC), element carbon (EC), water-soluble ions and trace elements. Meteorology parameters and gaseous O-3 and CO concentrations were also monitored along with the SMPS data for studying particle nucleation, condensation, SOA (secondary organic aerosol) formation and long-range air pollutant transport at the LABS. SMPS data showed that nanoparticle concentrations at the LABS remained relatively stable at low level (similar to 300-500 #/cm(3)) during the nighttime (22:00-04:00), increased during daytime, and reached a maximum (similar to 2000-4000 #/cm(3)) in the afternoon (12:00-16:00). The NMD (number median diameter) showed an opposite trend with the peak number concentrations observed in the afternoon corresponding to the smallest NMD (20-40 nm). These results indicate the dominance of local sources rather than the transport from other atmospheric air because that the lifetime of nanoparticles was only few minutes. Chemical analysis of filter samples showed that the concentrations of trace elements K and Mn, which serve as biomass burning markers, were elevated in the fine particle fractions during November 9-12th when the air mass passed through South and Southeast Asia prior to reaching the LABS. The concentrations of K and Mn would have been low if the aerosols had local origins The biomass burning derived K was found in all fine particle samples at the LABS suggesting that the free troposphere around Taiwan is frequently impacted by the long-range transport of biomass burning plumes via the westerly winds. (c) 2012 Elsevier Ltd. All rights reserved.
Ultrafine particles at three different sampling locations in Taiwan
(2010-02-01)
Chen, Sheng-Chieh
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Tsai, Chuen-Jinn
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Chou, Charles C. -K.
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Roam, Gwo-Dong
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Cheng, Sen-Sung
Atmospheric ultrafine particles (UPs or PM(0.1)) were investigated at the roadside of Syuefu road in Hsinchu city, in the Syueshan highway tunnel in Taipei and in the NTU Experimental Forest in Nantou, Taiwan. A SMPS (TSI 3936) and three MOUDIs (MSP 110) were collocated to determine the number and mass concentrations of the PM(0.1) simultaneously. The filter samples were further analyzed for organic carbon (CC), element carbon (EC), water-soluble ions and trace elements. Taking into account the OC artifact of PM(0.1), good chemical mass closure (ratio of the reconstructed chemical mass to the gravimetrical mass of PMs) was obtained with an unknown percentage of 10.6, 26.2 and 37.2% at the roadside, tunnel and forest, respectively. The unexplained mass was attributed to aerosol water in this study. The artifact at the roadside, tunnel and the forest PM(0.1) mass was found to be as high as 51.6 +/- 10.7%, 20.0 +/- 5.4% and 85.6 +/- 18.4%, respectively. Finally, the effective density of the roadside, tunnel and forest PM(0.1) was calculated based on the results of chemical speciation and found to be 1.45, 1.29 and 1.22 g cm(-3), respectively, which was in good agreement with that obtained by using the method of Spencer et al. (2007). Based on these results, it is foreseeable that the number concentration of the SMPS can be converted using the effective density determined by Spencer et al. (2007) for the real time measurement of the PM(0.1) concentration. (C) 2009 Elsevier Ltd. All rights reserved.