PM2.5 and PM10-2.5 chemical composition and source apportionment near a Hong Kong roadway--颗粒学报PARTICUOLOGY

Cheng, Y., Lee, S., Gu, Z., Ho, K., Zhang, Y., Huang, Y., Chow, J. C., Watson, J. G., Cao, J., & Zhang, R. (2015). PM2.5 and PM10-2.5 chemical composition and source apportionment near a Hong Kong roadway. Particuology, 18, 96–104. https://doi.org/10.1016/j.partic.2013.10.003

PM_2.5 and PM_10-2.5 chemical composition and source apportionment near a Hong Kong roadway

Yan Cheng ^{a b c *}, Shuncheng Lee ^c, Zhaolin Gu ^a, Kinfai Ho ^d, Yunwei Zhang ^a, Yu Huang ^c, Judith C. Chow ^{a b e}, John G. Watson ^{a b e}, Junji Cao ^b, Renjian Zhang ^f

a Department of Environmental Science and Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
b State Key Laboratory of Loess Quaternary Geology, Institute of Earth and Environment, Chinese Academy of Sciences, Xi’an 710075, China
c Department of Civil and Structural Engineering, Research Center for Environmental Technology and Management, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
d School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China
e Division of Atmospheric Sciences, Desert Research Institute, NV 89512-1095, USA
f Key Laboratory of Regional Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China

10.1016/j.partic.2013.10.003

Volume 18, February 2015, Pages 96-104

Received 7 August 2013, Revised 24 October 2013, Accepted 29 October 2013, Available online 25 December 2013.

E-mail: chengyan@mail.xjtu.edu.cn

Highlights

• PM_2.5 and PM₁₀ samples were collected simultaneously at a roadside site in Hong Kong.

• PM_10-2.5 showed different chemical composition and potential sources from PM_2.5.

• OC, EC, SO₄²⁻, NH₄⁺, and K⁺ were more abundant in the fine fraction.

• Cl⁻, Al, Si, Ca, Ti, and Fe were enriched in the coarse fraction.

• Potential source apportionments were estimated for PM_10-2.5.

Abstract

Twenty-four-hour PM_2.5 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 PM_2.5, PM_10-2.5 (defined as PM₁₀ − PM_2.5), 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 PM_2.5 and PM_10-2.5. The annual average mass concentrations were 55.5 ± 25.5 and 25.9 ± 15.7 μg/m³ for PM_2.5 and PM_10-2.5, respectively. EC, OM (OM = OC × 1.4), and ammonium sulfate comprised over ∼82% of PM_2.5, accounting for ∼29%, ∼27%, and ∼25%, respectively, of the PM_2.5 mass. Low OC/EC ratios (less than 1) for PM_2.5 suggested that fresh diesel-engine exhaust was a major contributor. Seven sources were resolved for PM_2.5 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 PM_10-2.5. The average OC/EC ratio of PM_10-2.5 was 7.8 ± 14.2, suggesting that sources other than vehicular exhaust were important contributors. The sources for PM_10-2.5 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.

Graphical abstract

Keywords

PM_2.5; PM_10-2.5; Roadside; Chemical composition; Source apportionment; Hong Kong

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