|Ming, Li Li
|Fine atmospheric particles (PM₂.₅) in large city clusters, China : chemical compositions, temporal-spatial variations and regional transport
|Li, X. D. (CEE)
|Hong Kong Polytechnic University -- Dissertations
Air -- Pollution -- China
Air -- Pollution -- Measurement
|Department of Civil and Environmental Engineering
|xvi, 200 pages : color illustrations
|With the aggravation of atmospheric environment, fine atmospheric particle (PM₂.₅) pollution has become one of the top environmental issues in China, due to its adverse impact on human health and climate. This project is aimed to investigate the current pollution statuses and pollution characteristics of PM₂.₅ in three large city clusters of China: the Pearl River Delta (PRD), the Yangtze River Delta (YRD) and North China. PM₂.₅ samples were simultaneously collected in the three regions over a one-year period to measure their chemical compositions (e.g., trace metals, organic carbon and elemental carbon, lead isotopic compositions and water-soluble inorganic ions). The temporal-spatial and seasonal variations, sources and long-range transport of PM₂.₅, the formation mechanism and regional transport of PM₂.₅ during pollution events, and the bioaccessibility and health risks of airborne trace metals in PM₂.₅ have been studied in this research. In the three regions, the concentrations and chemical compositions of PM₂.₅ showed a decreasing trend in the order of urban > rural > remote site, and clear seasonal variations. Among the urban sites, PM₂.₅ pollution was most serious in North China (Beijing), followed by the YRD region (Shanghai, Nanjing and Hangzhou) and the PRD region (Guangzhou). Source appointment of chemical compositions of PM₂.₅ demonstrated that anthropogenic sources including coal combustion, heavy industries and traffic emissions were the major contributors to PM₂.₅ in the three regions. Long-range transport pathways and potential source regions of PM₂.₅ in the three regions were seasonally dependent. Different characteristics in the temporal-spatial and seasonal variations of PM₂.₅ among the three regions were driven by their local emissions, meteorological conditions and long-range transport pathways. Trans-boundary transport of PM₂.₅ over the three regions was demonstrated by the PSCF model and the NAQPMS model. Meteorological conditions and regional transport play an important role in the formation of the three pollution events occurred in Shanghai during autumn and winter. Secondary aerosols contributed the largest fraction to PM₂.₅ during the pollution events, suggesting the importance of secondary aerosol formation in driving PM₂.₅ pollution. The results indicated that the formation of PM₂.₅ pollution is related to emission sources, meteorological conditions and long-range transport of air pollutants. High bioaccessibility for V, intermediate bioaccessibility for Mn, Cr and Ni, and low bioaccessibility for Pb and Zn were investigated in Guangzhou (GZ), Shanghai (SH) and Nanjing (NJ). Seasonally, the bioaccessibility of Mn, Pb and Zn were highest in winter. Compared with non-pollution days, the bioaccessibility of Mn, Pb, V and Zn in GZ, and Zn in SH and NJ were higher on pollution days. Carcinogenic and non-carcinogenic risks posed by airborne trace metals via inhalation exposure to children and adults were significantly higher on pollution days than those on non-pollution days during winter.
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