Chemical component of Particle Matter (PM) at Hong Kong-PolyU roadside

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Chemical component of Particle Matter (PM) at Hong Kong-PolyU roadside


Author: Sun, Jian
Title: Chemical component of Particle Matter (PM) at Hong Kong-PolyU roadside
Degree: M.Sc.
Year: 2012
Subject: Automobiles -- Motors -- Exhaust gas -- Measurement.
Air quality -- Measurement.
Air -- Pollution -- China -- Hong Kong -- Measurement.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Civil and Structural Engineering
Pages: 82 leaves : ill. (chiefly col.) ; 30 cm.
Language: English
InnoPac Record:
Abstract: With the rising environmental and resultant health awareness, there are increasing concerns on particulate emissions due to the continuously growing vehicle numbers and kilometers driven in Hong Kong. Thus, investigation on particulate emissions related to vehicles is needed in order to improve urban air quality. This thesis is aimed to explore the chemical compositions and sources of airborne particles in PM₁ (Dp<1 μm),PM₂.₅ (Dp<2.5 μm), and PM₁₀ (Dp<10 μm) size ranges in the urban roadside environment. Researches on chemical compositions of PM show distinct difference between PM₁, PM₂.₅ and PM10 at PolyU roadside which is a typical roadside monitoring site with heavy traffic. The mass concentration of PM are studied in different scenarios (daily circle, weather system and aerosol episodes). The daily variation of mass concentrations in three diameters show the same trends and in addition, big Dp PM concentrations are higher than that of little Dp PM. Moreover, high number concentrations of PM in three Dp are found in winter and low in summer. The diurnal cycles of PM mass concentrations should be correlated to the vehicle number, on the other hand, the seasonal cycles are influenced by East Asia Monsoons, which bring pollutants from upwind areas. Through experiment analysis, particulate episodes are happened both in winter and summer though in different strength. And the PCSF (Potential Source Contribution Function) receptor model identifies the coastal areas of southeastern China and the PRD (Pearl River Delta) region as the source areas of regional pollution in cold and warm seasons respectively. By comparing the vehicle emission and particle chemical components, the diesel-fueled vehicles have more contribution to the airborne particle. And to better the source identification at PolyU roadside, various methods, such as OC/EC (Organic Carbon and Element Carbon), PMF (Positive Matrix Factorization) and CMB (Chemical Mass Balance) receptor model, are applied in this study. Vehicle exhaust is identified as the major source for both fine particles (PM₁ and PM₂.₅), while resuspensions being the main source for coarse particles. Moreover, regional pollution can contribute to nearly half of the total fine particulate mass when air masses are from Mainland China.

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