| Facing the serious problem of atmospheric particles pollution, Dongguan, an industrial city in South China, has accumulated some successful experiences ensuring both environmental protection and coordinated development of economy. These experiences provide an important reference for Wuhan, a major industrial city in Central China which has been implementing its double-growth industrial plan. Based on the national requirement of further improvement of environmental air quality, the author of this dissertation has made a study of the physical and chemical properties of atmospheric particles in the urban areas of Dongguan and Wuhan. The research focus is on the examination of pollution features of nine water soluble ions and elementary constituents in PM1.0, PM2.5 and PM10, sixteen polycyclic aromatic hydrocarbons (PAHs) and C10?C36 n-alkanes, as well as on the exploration of the similarities and differences of atmospheric particles pollution between the two cities and the reasons for the differences. The purpose of the present study is to provide a theoretical basis for improvement of environmental air quality in both cities, especially for seeking the methods to control the atmospheric particles pollution. The major research findings in the dissertation are as follows:(1) The mathematic statistical method was used to analyze some parameters such as the concentration level of particles, the total annual emision of pollutants and meteorology in the urban areas of Dongguan and Wuhan. The findings showed that the particle pollution as a whole in Wuhan was more serious than in Dongguan. The annual average concentration of PM1.0 in Wuhan was 82?g/m3, which was 1.86 times that in Dongguan. The averages of PM1.0/PM2.5 and PM1.0/PM10 were 0.81 and 0.67, which were, respectively, 1.25 times and 1.59 times those in Dongguan. One of the reasons for the difference is that the particle emission in Wuhan was much larger than in Dongguan and the atmospheric diffusion condition in Whan was poorer than in Dongguan.(2) The time-space distribution research on the physicochemical characteristics of atmospheric particles showed that the concentrations of particles and water soluble ions, elemetary constituents and organic elements in the urban areas of Wuhan and Dongguan were all chracterizeed by different seasonal distributions in which the concentration of particles, water soluble ions, PAHs and n-alkanes was high in winter and low in summer, while the elemental concentration was characterized by an opposite distribution. However, the specific value of PM1.0/PM2.5 and PM1.0/PM10 in urban Dongguan reached the highest in winter and second highest in autumn. In Wuhan, the value arrived at the highest in summer and second highest in winter. The main reason for the seasonal difference in the physicochemical characteristics in both cities is that subtropical oceanic monsoon climate and subtropical temperate monsoon climate gave rise to their seasonal differences in the meteorological condition, input of sea salt coarse particles and input of northern dust.(3) Based on the theory of zwitter-ion electric charge balance on particle and analysis of linear regression, this disseration showed that the acidity features of particles and ion occurrence modes in Wuhan and Dongguan were quite different. The water soluble ions SO42- and NH4+ in Dongguan mainly existed in the form of NH4HSO4, while the ions in Wuhan existed in(NH4)2SO4, which resulted in acidic PM1.0 and PM2.5 in Dongguan and alkaline PM1.0 and PM2.5 in Wuhan. The reason for this difference mgiht be due to the larger rural area around Wuhan, which resulted in more emission of NH3 into atmospheric particles to produce NH4+.(4) This dissertation conducted research on the mass closure of the chemical component quality of particles, which resulted in a discovery of the differences in the main chemical components of atmospheric particles in Dongguan and Wuhan, particularly in the fine particle PM1.0. the primary matter of the chemical component in Dongguan's rural area was probably of organic matter, while the matter in Wuhan was SO42-/NO3-/NH4+(SNA for short). The huge disparity of industrial structure in both cities might be the significant reason for the difference in the main chemical composition in atmospheric particles.(5) Research on the size distribution feature of particles showed that the same distribution feature was found with the water soluble ions, crustal elements and organic components in atmospheric particles in Dongguan and Wuhan. That is to say, SNA, K+ and Cl- mainly distributed in the fine particle PM1.0, while Ca2+, Mg2+ and F- mainly in the coarse particle PM2.5?10. Meanwhile, the heavy metal elements, PAHs and n-alkanes, mainly distributed in the submicron particle PM1.0. Therefore, as far as human health is concerned, more attention should be given to the pollution control of PM1.0.(6) An analysis of the concentration of WSIIs and elemental components gave a hint that the concentrations of the components in the urban ambient particles in Dongguan and Wuhan were quite different. The concentrations of Na+ and Mg2+ in Dongugan's urban PM1.0 were, respectively,1.23 and 1.35 times those in Wuhan's urban PM1.0, and the concentration of K+ in Wuhan's urban PM1.0 was 1.81 times that in Dongguan's urban PM1.0. Moreover, apart from Na, Mg and Ca, the concentrations of other elements in Wuhan's urban PM1.0 were as a whole higher than those in Dongguan, espeically cadmium (Cd) and arsenic (As). The concentrations of Cd and As in Wuhan's urban PM1.0 were 16.3 and 5.1 times those in Dongguan. The analysis of organic components in the different function areas in Dongguan showed that the concentration distribution of different n-alkanes in particles in different functions area were quite similar, but the distribution of PAHs was quite different.The results based on the specific ratio method suggested that the higher concentrations of Na+ and Mg2+ in Dongguan's urban PM1.0 were mainly caused by the input of marine aerosol and the higher concentration of K+ in Wuhan's urban PM1.0 was mainly affected by the biomass burning in and around Wuhan. The results based on the enrich factor and pricinpal component analysis indicated that the main reason for the higher concentration of Cd and As in Wuhan's PM1.0 was the serious emisison of steel works and power-coal plants in Wuhan. Based on the analysis of the carbon maximum number, carbon preference index and the contribution of wax n-alkanes, it had been found that fossil fuel burning was the main contributor of PM1.0 n-alkane both in the industrial and living areas in Dongguan. It contributed 84.1% and 83.6% to the n-alkanes in PM1.0 from the industrial and living areas, respectively. But the contributors to the PM1.0 PAHs in Dongguan's different functions areas were quite different.(7)The source apportionment of urban ambient particulate matter in Dongguan and Wuhan by the method of principal component analysis were also performed. The results indicated that secondary inorganic source, coal burning, motor vehicle emission and construction/soil mixed dust were both resovled in Dongguan and Wuhan. But there were also steel works, glass/cement industry mixed emission, biomass burning, and motor vehicle mechanical friction, which contributed, respectively,12.63,8.45,7.64 and 1.96 to PM1.0 mass concentration in Wuhan. And there were also industrial emission and marine source, which contributed 8.76 and 1.19 to PM1.0 mass concentration in Dongguan. Although the main sourcres of differen particles were similar, the contributions of the same type to the particles varied from size to size.(8)Through comparing the chemical characteristics of ambient particles in haze and no-haze days of different seasons in Dongguan and Wuhan, the results indicated the different chemical characteristics and meteological characteristics of different seasons in these two cities. Furthermore, the method of the positve matrix factorization and K-mean cluster analysis were performed to do the source apportionment of urban ambient PM2.5 during the 2013 Chinese Spring Festival air pollution episode in Wuhan. Seven sources were resolved, and they were respectively motro vehicle exhuast, coal combustion, lcoal steel works, secondary inorganic source, fireworks burning, local glass/cement industry emission, and traffic road dust. Their contributions to PM2.5 mass were, respectively, 20.7%,17.9%,13.8%,13.2%,9.2%,9.0% and 5.4%. In addition, the lead in PM2.5 during the study period mainly came from the source of coal burning.In summary, compared with PM2.5, PM1.0 is exactly the particle which could reflect more about the charateristics of anthropogenic particles. And there were significant differences between the chemical characteristics and emission sources of urban ambient particles in Dongguan and Wuhan. Therefore, specific conditions should be taken into consideration in borrowing the experiences of atmospheric particles treatment and then some pertinent countermeasures suitable for the local conditions should be taken. |
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