Pollution Characteristics Of PM_2.5 During Haze Periods In Southwest Acid Rain Area

Haze pollution in China has become increasingly serious, mainly concentrated in Beijing-Tianjin-Hebei, the Yangtze River Delta, the Pearl River Delta and the Sichuan basin region, the haze pollution of Southwest of acid rain area Chengdu City is serious, with the development of the economy, the phenomenon of haze gradually appeared in Guiyang City. In this thesis, Guiyang City, Chengdu city as the research area, the atmospheric fine particulate matter(PM_2.5) samples were collected of haze weather. 9 species of ions(including NH₄⁺,K⁺,Ca2+,Na⁺,Mg2+,F^-,Cl^-,NO₃^-,SO₄^2-) were analyzed, 19 kinds of heavy metal elements?Be, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sb, Ba, Tl, Pb? were analyzed by using ICP-MS, micro morphology characteristics of particles were analyzed by using FESEM-EDX, and the sources were analyzed. Scientific basis for air pollution control were provided for Guiyang City by comparing the pollution characteristics of PM_2.5 in two cities. The main results were as follows:?1? The mass concentrations of PM_2.5 in the two cities of haze weather were more than two standards, and fine particulate matter PM_2.5 was seriously polluted. The contents of NH₄⁺, Na⁺, K⁺, NO₃^-, SO₄^2-, Cl^-, F^- in Chengdu were all higher, and the total ions content was significantly higher than that of Guiyang city.?2? The ratio of NO₃^- / SO₄^2- 0.3369 in Guiyang, Chengdu value was 1.053, therefore, coal combustion and other fixed sources to the secondary particles pollution contribution larger in Guiyang, Chengdu was the motor vehicles and other mobile sources to pollution larger, which with Chengdu automobile retain higher amount had a certain relationship.?3? The mass concentrations of Fe, Al, Zn and Pb in the two cities were higher, the content of heavy metal elements in Chengdu City was higher than that of Guiyang City, mass fraction was greater of major pollution elements?Al, Ti, Cr, Mn, Fe, Cu, Zn, As, Ba, Pb? for PM_2.5 mass fraction in Guiyang City, the contribution of heavy metals pollution was higher in PM_2.5 during haze days of Guiyang.?4? PM_2.5 morphology and energy spectrum analysis showed that, mainly particulate types for soot and soot aggregates, coal fly ash, rules of mineral particles, irregular mineral particles, and particles of the same type containing elements were basically the same in two cities. Soot and soot aggregates in the number were the highest in the two cities, followed by irregular mineral particles, high volume percentage of Guiyang city were irregular mineral particles and rules of mineral particles, and Chengdu with the highest was soot and soot aggregates. The number of the main types of particulate matter in Guiyang was concentrated in the particle size range of < 0.7?m. The majority of the main types of particulate matter mainly concentrated in < 0.4?m range in Chengdu, main types of particulate matter concentrated in the small particle size range of the number high frequency in two cities. Irregular mineral particles and rules of mineral particles volume size distribution mainly concentrated in 1-2.5?m, the difference between two cities was the soot and soot aggregates distribution, which was in smaller particle size range mainly in Guiyang.?5? Enrichment factors and correlation analysis of heavy metal elements showed that As, Pb, Cd, Cr and other toxic and harmful heavy metal elements in the two cities had obvious human pollution sources and more complex. The main factor analysis showed that the pollution sources of the two cities were basically the same, but the influence of each pollution source was different. The correlation between ions was poorer in Guiyang; and in Chengdu, the correlation of NH₄⁺ and NO₃^-, SO₄^2-, Cl^-, Fwere higher, the correlation coefficients were above 0.847.