PM_1.0and PM_2.5Characteristics in the Roadside Environment of Hong Kong

Abstract

Daily mass concentrations of PM 1.0 (particles less than 1.0 µm in diameter), PM 2.5 (particles less than 2.5 µm in diameter), organic carbon (OC), and elemental carbon (EC) were measured from January through May 2004 at a heavily trafficked sampling site in Hong Kong (PU). The average concentrations for PM 1.0 and PM 2.5 were 35.9 ± 12.4 µg cm −3 and 52.3 ± 18.3 µg cm −3 . Carbonaceous aerosols were the dominant species in fine particles, accounting for ∼45.7% of PM 1.0 and ∼44.4% of PM 2.5 . During the study period, seven fine-particle episodes occurred, due to the influence of longrange transport of air masses from mainland China. PM 1.0 and PM 2.5 responded in similar ways; i.e., with elevated mass and OC concentrations in those episode days. During the sampling period, PM 1.0 OC and EC generally behaved similarly to the carbonaceous aerosols in PM 2.5 , regardless of seasonal variations and influence by regional pollutions. The low and relatively constant OC/EC ratios in PM 1.0 and PM 2.5 indicated that vehicular emissions were major sources of carbonaceous aerosols. PM 1.0 and PM 2.5 had the same dominant sources of vehicular emissions in winter, while in spring PM 2.5 was more influenced by PM 1−2.5 (particles 1-2.5 µm in diameter) that did not form from vehicle exhausts. Therefore, PM 1.0 was a better indicator for vehicular emissions at the Roadside Station.

Characteristics of Traffic-related Emissions: A Case Study in Roadside Ambient Air over Xi’an, China

“…As a whole, the OC/EC ratio during the three rush periods, to some extent, may reflect the source profile of vehicle exhaust over Xi'an. The OC/EC ratio in this study was higher than the value of 1.0 observed at a roadside site in Hong Kong Lee et al, 2006). OC includes PAHs and other organic matter which can be directly emitted from primary sources or produced from secondary atmospheric reactions involving gaseous organic precursors.…”

Chemical Characteristics of Fine Particles (PM1) from Xi'an, China

“…The fourth factor, characterized by K + and Cl -, is consistent with biomass burning emissions (Andreae 1993;Shen et al 2009). The fifth factor, enriched with OC3, OC4, and EC1, is best explained by emissions from coal combustion (Watson et al 1994;Cao et al 2006). The sixth factor was loaded with ammonium, sulfate, and nitrate, indicative of a secondary aerosol source.…”

“…The average composition of the six factors generated by the PMF analysis was compared with known source profiles, and the results are shown in Figure 6. The first factor was characterized by EC2 and EC3, which are characteristic of diesel exhaust (Watson et al 1994;Cao et al 2006). The second factor was loaded with OC1 and OC2, representing exhaust from gasoline-powered engines (Watson et al 1994;Cao et al 2006).…”

“…The first factor was characterized by EC2 and EC3, which are characteristic of diesel exhaust (Watson et al 1994;Cao et al 2006). The second factor was loaded with OC1 and OC2, representing exhaust from gasoline-powered engines (Watson et al 1994;Cao et al 2006). Soil dust was identified as the third factor, based on the high abundances of Ca 2+ and Mg 2+ .…”

Characterization of Atmospheric Organic and Elemental Carbon of PM2.5 in a Typical Semi-Arid Area of Northeastern China

“…Carbonaceous aerosols contributed 20-50% to the total aerosol mass from urban to regional scales in China (He et al, 2001;Cao et al, 2003;Lee et al, 2006;Cao et al, 2007). The mass fraction of organic aerosols ranged from 10-70% in fine modes (Andrews et al, 2000).…”