Browsing by Author "Cao, Jun-Ji"

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Biomass burning tracers in rural and urban ultrafine particles in Xi'an, China
(2017-07-01)
Zhu, Chong-Shu
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
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Zhang, Zhi-Sheng
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Tao, Jun
To investigate the impact of biomass burning emissions on ultrafine particles (PM0.133: particulate matter with an aerodynamic diameter less than 0.133 mu m), biomass burning tracers (including levoglucosan, mannonsan and K+) were measured at a rural and an urban sites in Xi'an during winter heating period. The average levoglucosan concentrations of rural and urban PM0.133 were 0.93 +/- 0.32 mu g m(-3) and 0.29 +/- 0.14 mg m(-3), respectively. Comparable PM0.133 mannosan concentrations were observed in rural samples (0.16 +/- 0.26 mu g m(-3)) and urban samples (0.17 +/- 0.10 mu g m(-3)). Higher correlation between levoglucosan and K+ was obtained for urban samples (R = 0.86) than that for rural samples (R = 0.72). The levoglucosan to K+ ratio was found to be higher for rural samples (0.77 +/- 0.39) compared to that for urban samples (0.32 +/- 0.14). Levoglucosan to mannosan ratios averaged 7.86 and 2.83 for rural and urban samples, respectively. It can be concluded that the major source of rural biomass burning was the combustion of crop residuals and softwood. The contributions of biomass burning to OC ranged from 19% to 32%, with an average of 24% for rural samples. The results provide a better understanding on the rural and urban magnitude of levoglucosan and contributions of biomass burning in Xi'an. (C) 2017 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.
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.
Comparison and implications of PM2.5 carbon fractions in different environments
(2014-01-01)
Zhu, Chong-Shu
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
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Shen, Zhen-Xing
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Han, Yong-Ming
The concentrations of PM2.5 carbon fractions in rural, urban, tunnel and remote environments were measured using the IMPROVE thermal optical reflectance (TOR) method. The highest OC1 and EC1 concentrations were found for tunnel samples, while the highest OC2, OC3, and OC4 concentrations were observed for urban winter samples, respectively. The lowest levels of most carbon fractions were found for remote samples. The percentage contributions of carbon fractions to total carbon (TC) were characterized by one peak (at rural and remote sites) and two peaks (at urban and tunnel sites) with different carbon fractions, respectively. The abundance of char in tunnel and urban environments was observed, which might partly be due to traffic-related tire-wear. Various percentages of optically scattering OC and absorbing EC fractions to TC were found in the four different environments. In addition, the contribution of heating carbon fractions (char and soot) indicated various warming effects per unit mass of TC. The ratios of OC/EC and char/soot at the sites were shown to be source indicators. The investigation of carbon fractions at different sites may provide some information for improving model parameters in estimating their radiative effects. (C) 2013 Elsevier B.V. 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
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Tsai, Chuen-Jinn
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Chen, Sheng-Chieh
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Cao, Jun-Ji
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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."
The Indoor and Outdoor Carbonaceous Pollution during Winter and Summer in Rural Areas of Shaanxi, China
(2010-12-01)
Zhu, Chong-Shu
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
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Shen, Zhen-Xing
;
Ho, Kin-Fai
Indoor and outdoor concentrations of PM(2.5), OC, EC and BC were investigated at three rural sites during the winter of 2007 and the summer of 2008 in Shaanxi, China. The average indoor concentrations of PM(2.5), OC, EC and BC were found to be higher in winter (237.2 mu g/m(3), 61.1 mu g/m(3), 6.2 mu g/m(3), and 14.3 mu g/m(3), respectively) than in summer (99.0 mu g/m(3), 18.0 mu g/m(3), 2.8 mu g/m(3), and 7.4 mu g/m(3), respectively). The average indoor/outdoor (I/O) ratios for PM(2.5) and EC were close to or less than 1.0 and those for OC and BC were above 1.0. The correlation coefficients of PM(2.5) and carbon species also indicated that the indoor concentrations of PM(2.5) and carbonaceous aerosol were correlated with the corresponding outdoor concentrations. Average OC/EC ratios ranged from 4.6 to 23.6 with an average of 9.1 during winter and from 4.2 to 12.0 with an average of 6.3 during summer. The results of this study showed that the OC and EC concentrations and OC/EC ratios in rural areas were higher than those of an urban area in Xi'an. These findings showed that improving energy efficiency and structure will be very important in reducing emissions in rural areas of Shaanxi.
The rural carbonaceous aerosols in coarse, fine, and ultrafine particles during haze pollution in northwestern China
(2016-03)
Zhu, Chong-Shu
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
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Shen, Zhen-Xing
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Liu, Sui-Xin
The carbonaceous aerosol concentrations in coarse particle (PM10: Dp <= 10 mu m, particulate matter with an aerodynamic diameter less than 10 mu m), fine particle (PM2.5: Dp <= 2.5 mu m), and ultrafine particle (PM0.133: Dp <= 0.113 mu m) carbon fractions in a rural area were investigated during haze events in northwestern China. The results indicated that PM2.5 contributed a large fraction in PM10. OC (organic carbon) accounted for 33, 41, and 62 % of PM10, PM2.5, and PM0.133, and those were 2, 2.4, and 0.4 % for EC (elemental carbon) in a rural area, respectively. OC3 was more abundant than other organic carbon fractions in three PMs, and char dominated EC in PM10 and PM2.5 while soot dominated EC in PM0.133. The present study inferred that K+, OP, and OC3 are good biomass burning tracers for rural PM10 and PM2.5, but not for PM0.133 during haze pollution. Our results suggest that biomass burning is likely to be an important contributor to rural PMs in northwestern China. It is necessary to establish biomass burning control policies for the mitigation of severe haze pollution in a rural area.