Browsing by Author "Roam, Gwo-Dong"

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Characterization of carbon fractions for atmospheric fine particles and nanoparticles in a highway tunnel
(2010-07-01)
Zhu, Chong-Shu
;
Chen, Cheng-Chieh
;
Cao, Jun-Ji
;
Tsai, Chuen-Jinn
;
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
;
Tsai, Chuen-Jinn
;
Huang, Cheng-Yu
;
Chen, Hong-Dar
;
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
;
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.
Positive sampling artifacts of organic carbon fractions for fine particles and nanoparticles in a tunnel environment
(2012-07-01)
Zhu, Chong-Shu
;
Tsai, Chuen-Jinn
;
Chen, Sheng-Chieh
;
Cao, Jun-Ji
;
Roam, Gwo-Dong
"The positive artifacts in particulate organic carbon fractions for fine particles (PM2.5) and nanoparticles (PM0.1) were characterized in a tunnel environment by using the QBQ (a quartz filter behind a quartz filter) method. The OC concentrations of the backup quartz filters ranged from 3.56 to 11.38 mu g m(-3) with the average of 6.70 mu g m(-3) for PM2.5, and from 2.62 to 7.27 mu g m(-3) With the average of 4.64 mu g m(-3) for PM0.1. The most abundant species on the backup quartz filters was OC1 for both PM2.5 and PM0.1, accounting for 56.9% and 41.1% of the measured organic carbon, respectively. Most of EC fractions (EC1-EC3) on the backup filters for PM2.5 and PM0.1 were below the minimum detection limit. Therefore, only OC contributed to positive artifacts distinctly with the average percentage of 21.7% and 48.0% for PM2.5 and PM0.1, respectively. The artifacts for four organic carbon fractions ranged from 36.1% (OC1) to 4.4% (OC4) for PM2.5 and from 68.0% (OC1) to 31.9% (OC4) for PM0.1]. The uncorrected OC/EC ratios on the front quartz filters were higher by as much as 30% and 107% for PM2.5 and PM0.1 than those corrected for positive organic artifacts, respectively. That is, much higher percentage of positive artifacts was found for PM0.1 DC fractions on the front filters. The comparison of the present and previous studies shows that OC positive artifacts vary widely among various PM fractions and sampling sites attributing to many factors that are worth investigating in the future. (C) 2012 Elsevier Ltd. All rights reserved."
Source Characterization and Apportionment of PM10, PM2.5 and PM0.1 by Using Positive Matrix Factorization
(2012-08-01)
Gugamsetty, Balakrishnaiah
;
Wei, Han
;
Liu, Chun-Nan
;
Awasthi, Amit
;
Hsu, Shih-Chieh
Ambient Particulate Matters (PM10, PM2.5 and PM0.1) were investigated at Shinjung station in New Taipei City, Taiwan. Samples were collected simultaneously using a dichotomous sampler (Andersen Model SA-241) and a MOUDI (MSP Model 110) over a 24-h period from May 2011 to November 2011 at Shinjung station. Samples were analyzed for metallic trace elements using ion coupled plasma mass spectroscopy (ICP-MS) and ionic compounds by ion chromatography (IC). The average concentrations of PM10, PM2.5 and PM0.1 were found to be 39.45 +/- 11.58, 21.82 +/- 7.50 and 1.42 +/- 0.56 mu g/m(3), respectively. Based on the chemical information, positive matrix factorization (PMF) was used to identify PM sources. A total of five source types were identified, including soil dust, vehicle emissions, sea salt, industrial emissions and secondary aerosols, and their contributions were estimated using PMF. The crustal enrichment factors (EF) were calculated using Al as a reference for the trace metal species to identify the sources. Conditional probability functions (CPF) were computed using wind profiles and factor contributions. The results of CPF analysis were used to identify local point sources. The results suggest a competitive relationship between anthropogenic and natural source processes over the monitoring station.
"Source Characterization and Apportionment of PM10, PM2.5 and PM0.1 by Using Positive Matrix Factorization"
(2012-08-01)
Gugamsetty, Balakrishnaiah
;
Wei, Han
;
Liu, Chun-Nan
;
Awasthi, Amit
;
Hsu, Shih-Chieh
"Ambient Particulate Matters (PM10, PM2.5 and PM0.1) were investigated at Shinjung station in New Taipei City, Taiwan. Samples were collected simultaneously using a dichotomous sampler (Andersen Model SA-241) and a MOUDI (MSP Model 110) over a 24-h period from May 2011 to November 2011 at Shinjung station. Samples were analyzed for metallic trace elements using ion coupled plasma mass spectroscopy (ICP-MS) and ionic compounds by ion chromatography (IC). The average concentrations of PM10, PM2.5 and PM0.1 were found to be 39.45 +/- 11.58, 21.82 +/- 7.50 and 1.42 +/- 0.56 mu g/m(3), respectively. Based on the chemical information, positive matrix factorization (PMF) was used to identify PM sources. A total of five source types were identified, including soil dust, vehicle emissions, sea salt, industrial emissions and secondary aerosols, and their contributions were estimated using PMF. The crustal enrichment factors (EF) were calculated using Al as a reference for the trace metal species to identify the sources. Conditional probability functions (CPF) were computed using wind profiles and factor contributions. The results of CPF analysis were used to identify local point sources. The results suggest a competitive relationship between anthropogenic and natural source processes over the monitoring station."
The Influence of Relative Humidity on Nanoparticle Concentration and Particle Mass Distribution Measurements by the MOUDI
(2011)
Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
;
Chen, Hong-Dar
;
Huang, Cheng-Yu
;
Roam, Gwo-Dong
A humidity control system was operated upstream of two collocated-MOUDIs (micro-orifice uniform deposit impactors) for sampling ambient aerosol particles. One MOUDI used silicone-grease-coated aluminum foils (ALs) as the impaction substrates and was considered as the reference impactor, while the other used uncoated ALs or uncoated Teflon filters (TFs) as the impaction substrates for quantifying the effect of different relative humidities (RHs) and impaction substrates on the PM(0.1) concentrations and mass distributions of ambient PMs. Test results showed that decreasing RH in general increased particle bounce from uncoated substrates with the bounce from uncoated ALs being more severe than that from uncoated TFs. Particle bounce did not influence the overall mass distribution of ambient fine particles when RH ranged between 40% and 80%, whereas it led to undersampling of particles greater than 2.5 mu m in aerodynamic diameter severely. Oversampling of PM(0.1) occurred by as much as 95%-180% or 25%-55% when the MOUDI used uncoated ALs or TFs, respectively, as RH was reduced from 50% to 25%. Particle bounce was found to be negligible, and PM(0.1) and PM(2.5) could be sampled accurately with less than 5% error at the RH of 75%-80% or 65%-80% when uncoated ALs or TFs were used, respectively.
Ultrafine particles at three different sampling locations in Taiwan
(2010-02-01)
Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
;
Chou, Charles C. -K.
;
Roam, Gwo-Dong
;
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.