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dc.contributorDepartment of Civil and Environmental Engineeringen_US
dc.creatorLi, Hongyi-
dc.identifier.urihttps://theses.lib.polyu.edu.hk/handle/200/10867-
dc.languageEnglishen_US
dc.publisherHong Kong Polytechnic Universityen_US
dc.rightsAll rights reserveden_US
dc.titleTrends of summer PM₂.₅ and its components during 2013-2017 in China: the effects of meteorological changes and emission reductionsen_US
dcterms.abstractChinese government released the Air Pollution Prevention and Control Action Plan in 2013, summertime PM₂.₅ and its components concentration decreased significantly in the latter five years. Here, we utilized the latest regional chemical transportation model (WRF-CMAQ) to investigate the effects of meteorological changes and anthropogenic emission reductions on summertime PM₂.₅ and its components from 2013 to 2017. The anthropogenic emission reductions are the main elements that significantly reduced PM₂.₅ and its components concentration in summer. Nevertheless, meteorological changes also play a vital role in changes in PM₂.₅ and its components. The variations in summertime PM₂.₅ and its components caused by meteorological changes had obvious regional characteristics, which showed that summer PM₂.₅ concentration increased in Central, East and South China, while that in other regions declined. Changes in temperature and specific humidity caused a decline trend in summer PM₂.₅ and its components in Beijing-Tianjin-Hebei and Sichuan-Chongqing, while wind speed changes markedly increased summer PM₂.₅ and its components concentration in Yangtze River Delta. Variations in Planetary boundary layer height, cloud fraction and precipitation had little effect on summer PM₂.₅ and its components concentration. The influence of changes in biogenic emissions and boundary conditions on the summertime PM₂.₅ concentration was negligible during the five-year period. After the implementation of the emission control, in addition to the ascent in VOCS emissions, the emissions of particulate matter, EC, OC, CO, NOX, SO₂ and NH3 all decreased, with particulate matter and SO₂ emissions reducing the most. The reduction of SO₂ and particulate matter reduced the summertime PM₂.₅ and its components concentration considerably, especially in Beijing-Tianjin-Hebei, Yangtze River Delta and Sichuan-Chongqing. Compared with rural areas, the downward trend in urban areas was more obvious in summer. Our outcomes indicated that the role of meteorological changes on summertime PM₂.₅ concentration cannot be ignored and reducing SO₂ and PM₂.₅ emissions is an efficient measure to control PM₂.₅ pollution.en_US
dcterms.extentix, 98 pages : color illustrationsen_US
dcterms.isPartOfPolyU Electronic Thesesen_US
dcterms.issued2020en_US
dcterms.educationalLevelM.Sc.en_US
dcterms.educationalLevelAll Masteren_US
dcterms.LCSHAir quality -- Standards -- Chinaen_US
dcterms.LCSHAir -- Pollution -- Chinaen_US
dcterms.LCSHClimatic changesen_US
dcterms.LCSHAir -- Pollution -- Law and legislation -- Chinaen_US
dcterms.LCSHHong Kong Polytechnic University -- Dissertationsen_US
dcterms.accessRightsrestricted accessen_US

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Please use this identifier to cite or link to this item: https://theses.lib.polyu.edu.hk/handle/200/10867