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

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 m -3 ), OC (16.7 μg m -3 ) and EC (17.1 μg m -3 ) 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 OC2were 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.

Water-soluble organic carbon (WSOC) and its temperature-resolved carbon fractions in atmospheric aerosols in Beijing

“…Therefore, this OC fraction may be associated with vehicle emissions based on the above assumption. This is in agreement with the study of Cao et al (2006) and Liu et al (2006), who found enhanced OC3 in vehicle emissions.…”

Chemical Characterization and Mass Closure of Fine Aerosol for Different Land Use Patterns in Mumbai City

“…The high percentage of VOCs is due to vehicles and industries like refineries. The percentage of OC2 fraction in TC was 24%, 26%, 32% and 27% at C, K, R and I sites, while OC3 in TC was 20-22% and OC4 in TC was between 10-14% (Cao et al, 2006) indicated that high OC2 and OC3 are associated with presence of gasoline and liquefied petroleum gas emissions and secondary organic carbon. The OC4 components may consist of a mixture of high boiling point hydrocarbons e.g PAHs.…”

Spatial Variation and Relationship of Indoor/Outdoor PM2.5 at Residential Homes in Guangzhou City, China

“…In a study conducted by Cao et al (2005) found that the average indoor and outdoor concentrations of 24 h PM 2.5 were 56.7 and 43.8 µg/m 3 , respectively, at residential homes in Hong Kong. It was found that the concentrations of air particulates of indoors sometimes were much higher than that of outdoors (Lee et al, 2000;Ramachandran et al, 2000;Adgate et al, 2002;Ramachandran et al, 2003;Cao et al, 2006). Therefore, studies on indoor particles characteristics are as important as the outdoors'.…”