Article

Chemically-speciated on-road PM2.5 motor vehicle emission factors in Hong Kong

Division of Atmospheric Sciences, Desert Research Institute, Reno, Nevada, USA
Science of The Total Environment (Impact Factor: 4.1). 03/2010; 408(7):1621-1627. DOI: 10.1016/j.scitotenv.2009.11.061
Source: PubMed

ABSTRACT

PM2.5 (particle with an aerodynamic diameter less than 2.5 µm) was measured in different microenvironments of Hong Kong (including one urban tunnel, one Hong Kong/Mainland boundary roadside site, two urban roadside sites, and one urban ambient site) in 2003. The concentrations of organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 40 elements (Na to U) were determined. The average PM2.5 mass concentrations were 229 ± 90, 129 ± 95, 69 ± 12, 49 ± 18 µg m− 3 in the urban tunnel, cross boundary roadside, urban roadside, and urban ambient environments, respectively. Carbonaceous particles (sum of organic material [OM] and EC) were the dominant constituents, on average, accounting for ∼ 82% of PM2.5 emissions in the tunnel, ∼ 70% at the three roadside sites, and ∼ 48% at the ambient site, respectively. The OC/EC ratios were 0.6 ± 0.2 and 0.8 ± 0.1 at the tunnel and roadside sites, respectively, suggesting carbonaceous aerosols were mainly from vehicle exhausts. Higher OC/EC ratio (1.9 ± 0.7) occurred at the ambient site, indicating contributions from secondary organic aerosols. The PM2.5 emission factor for on-road diesel-fueled vehicles in the urban area of Hong Kong was 257 ± 31 mg veh− 1 km− 1, with a composition of ∼ 51% EC, ∼ 26% OC, and ∼ 9% SO4=. The other inorganic ions and elements made up ∼ 11% of the total PM2.5 emissions. OC composed the largest fraction (∼ 51%) in gasoline and liquid petroleum gas (LPG) emissions, followed by EC (∼ 19%). Diesel engines showed higher emission rates than did gasoline and LPG engines for most pollutants, except for V, Br, Sb, and Ba.

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    • "The characteristics of these profiles are identical to those from a Hong Kong tunnel study (Cheng, Lee, et al., 2010) and previous studies on vehicle emissions (Gertler et al., 2002; Norbeck et al., 1998). The second largest contributor, which accounted for ∼27% of PM 2.5 , was characterized by large sulfate, ammonium, nitrate, and soluble sodium contributions, suggesting it was associated with secondary inorganic aerosols. "
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    ABSTRACT: Twenty-four-hour PM2.5 and PM10 samples were collected simultaneously at a highly trafficked roadside site in Hong Kong every sixth day from October 2004 to September 2005. The mass concentrations of PM2.5, PM10-2.5 (defined as PM10 − PM2.5), organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 25 elements were determined. Investigation of the chemical compositions and potential sources revealed distinct differences between PM2.5 and PM10-2.5. The annual average mass concentrations were 55.5 ± 25.5 and 25.9 ± 15.7 μg/m3 for PM2.5 and PM10-2.5, respectively. EC, OM (OM = OC × 1.4), and ammonium sulfate comprised over ∼82% of PM2.5, accounting for ∼29%, ∼27%, and ∼25%, respectively, of the PM2.5 mass. Low OC/EC ratios (less than 1) for PM2.5 suggested that fresh diesel-engine exhaust was a major contributor. Seven sources were resolved for PM2.5 by positive matrix factorization (PMF) model, including vehicle emissions (∼29%), secondary inorganic aerosols (∼27%), waste incinerator/biomass burning (∼23%), residual oil combustion (∼10%), marine aerosols (∼6%), industrial exhaust (∼4%), and resuspended road dust (∼1%). EC and OM comprised only ∼19% of PM10-2.5. The average OC/EC ratio of PM10-2.5 was 7.8 ± 14.2, suggesting that sources other than vehicular exhaust were important contributors. The sources for PM10-2.5 determined by the PMF model included ∼20% traffic-generated resuspension (e.g., tire dust/brake linear/petrol evaporation), ∼17% locally resuspended road dust, ∼17% marine aerosols, ∼12% secondary aerosols/field burning, and ∼11% vehicle emissions.
    Full-text · Article · Dec 2015 · Particuology
    • "However, while this study produced a range of source profiles for PM 10 , the number of profiles for PM 2.5 was relatively limited. In addition to source characterization, previous studies have used other approaches including use of diagnostic tools such as elemental ratios and enrichment factors to identify chemical source markers for PM sources (Artidsoglou and Samara, 2005; Han et al., 2006; Han et al., 2007; Tsai et al., 2007; Cao et al., 2008; Cheng et al., 2010; Kong et al., 2011; Cesari et al., 2012). The key objective of this study was to prepare PM 2.5 source profiles for resuspended dust and vehicular exhaust emission sources for Raipur (India), and a companion paper on other profile categories has recently been published (Matawle et al., 2014). "

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    • "However, while this study produced a range of source profiles for PM 10 , the number of profiles for PM 2.5 was relatively limited. In addition to source characterization, previous studies have used other approaches including use of diagnostic tools such as elemental ratios and enrichment factors to identify chemical source markers for PM sources (Artidsoglou and Samara, 2005; Han et al., 2006; Han et al., 2007; Tsai et al., 2007; Cao et al., 2008; Cheng et al., 2010; Kong et al., 2011; Cesari et al., 2012). The key objective of this study was to prepare PM 2.5 source profiles for resuspended dust and vehicular exhaust emission sources for Raipur (India), and a companion paper on other profile categories has recently been published (Matawle et al., 2014). "
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    ABSTRACT: This paper describes results from a detailed source profile characterization study conducted in Raipur, India to prepare source profiles for traffic and dust-related sources. A companion paper has been published with results for a range of other combustion sources. PM2.5 samples were analyzed for mass, elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, S, Sb, Se, V, Zn), ions (Na+, K+, Mg2+, Ca2+, NH4+, Cl-, F-, NO3-, SO42-) and carbonaceous fractions (OC and EC). All dust profiles were dominated by crustal elements (Al, Ca, Fe and Mg), while carbonaceous species (OC and EC) were most abundant in vehicular emission profiles. Trace element fraction was found to be significantly higher in vehicular exhaust compared to the resuspended dust. Remarkably, sulphur abundance was observed to be several-fold higher in vehicular emission profiles than resuspended dust profiles. Al and Ca were identified as reliable markers for resuspended dust while V, Pb and EC were identified as markers for vehicular exhaust.
    Full-text · Article · Sep 2015 · Aerosol and Air Quality Research
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