Characterization of Roadside Fine Particulate Carbon and its Eight Fractions in Hong Kong

J.J. Cao; S.C. Lee; K.F. Ho; Kochy Fung; Judith C. Chow; John G. Watson

doi:10.4209/aaqr.2006.06.0001

Characterization of Roadside Fine Particulate Carbon and its Eight Fractions in Hong Kong

J.J. Cao¹^,2^,5, S.C. Lee ¹, K.F. Ho¹, Kochy Fung³, Judith C. Chow⁴, John G. Watson⁴

¹Research Center for Environmental Technology and Management, Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China
²State Key Laboratory of Loess & Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China
³AtmAA Inc., Calabasas, California, USA
⁴Desert Research Institute, Reno, Nevada, USA
⁵Department of Environmental Science & Technology, Xi'an Jiaotong University, Xi'an, China

Received: May 31, 2006
Revised: May 31, 2006
Accepted: May 31, 2006
Download Citation: ||https://doi.org/10.4209/aaqr.2006.06.0001

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Cite this article:
Cao, J., Lee, S., Ho, K., Fung, K., Chow, J.C. and Watson, J.G. (2006). Characterization of Roadside Fine Particulate Carbon and its Eight Fractions in Hong Kong. Aerosol Air Qual. Res. 6: 106-122. https://doi.org/10.4209/aaqr.2006.06.0001

ABSTRACT

Simultaneous measurements of PM_2.5 mass, OC and EC and eight carbon fractions were conducted in a roadside microenvironment around Hong Kong for a week in May-June 2002 to obtain the characterization of freshly emitted traffic aerosols. Traffic volume (diesel-powered, liquefied-petroleum gas and gasoline-powered vehicles), meteorological data, and sourcedominated samples were also measured. PM_2.5 samples were collected on pre-fired quartz filters with a mini-volume sampler and a portable fine-particle sampler, then analyzed for OC and EC using thermal optical reflectance (TOR) method, following the IMPROVE protocol. High levels of PM_2.5 mass (64.4 μg/m³), OC (16.7 μg/m³) and EC (17.1 μg/m³) observed in the roadside microenvironment were found to be well-correlated with each other. The average OC/EC ratio was 1.0, indicating that OC and EC were both primary pollutants. Marked diurnal PM_2.5 mass OC and EC concentration profiles were observed in accordance with the traffic pattern (especially for diesel vehicles). Average daytime concentrations were 1.3-1.5 times greater than nighttime values. Carbon profiles from source-dominated samples (diesel, LPG and gasoline vehicles) and diurnal variations of eight carbon fractions (OC1, OC2, OC3, OC4, EC1, EC2, EC3 and OP) demonstrated EC2 and OC2 were the major contributors to the diesel exhaust, and OC3 and OC2 were the larger contributors to the LPG and gasoline exhaust. Thus, carbon fractions derived from the IMPROVE protocol could be used to identify different carbon sources.

Keywords: Organic carbon; Elemental carbon; Roadside; Source profiles