کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6341202 | 1620394 | 2013 | 10 صفحه PDF | دانلود رایگان |
- The concentrations of water-soluble ions in the Jing-Jin-Ji urban agglomeration.
- The spatial variability of those compounds was discussed.
- The seasonal variations and size distributions of those compounds were discussed.
- The sources and formation mechanisms of secondary water-soluble ions were discussed.
To investigate the characteristics of aerosols in north China, the samples of water-soluble ions, including anions (Fâ, Clâ, NO2â, NO3â, SO42â) and cations (NH4+, K+, Na+, Ca2+, Mg2+) in 8 size-segregated particle fractions, are collected using a sampler from Sep. 2009 to Aug. 2010 at four sites in urban areas (Beijing, Tianjin and Tangshan) and a background region (Xinglong) in the Jing-Jin-Ji urban agglomeration. High spatial variability is observed between the urban areas and the background region. The results of chemical composition analysis showed that secondary water soluble ions (SO42â + NO3â + NH4+) (SWSI) composed more than half the total ions, and are mainly found in fine particles (aerodynamic diameters less than 2.1 μm), while Mg2+ and Ca2+ contributed to a large fraction of the total water-soluble ions in coarse particles (aerodynamic diameters greater than 2.1 μm and less than 9.0 μm). The concentrations of SO42â, NO3â and NH4+ are higher in summer and winter and lower in spring and autumn. Mg2+ and Ca2+ are obviously abundant in winter in Beijing, Tianjin and Tangshan. In contrast, Mg2+ and Ca2+ are abundant in autumn in Xinglong. The SWSI showed a bimodal size distribution with the fine mode at 0.43-1.1 μm and the coarse mode at 4.7-5.8 μm, and had different seasonal variations and bimodal shapes. NH4+ played an important role in the size distributions and the formations of SO42â and NO3â. Heterogeneous reaction is the main formation mechanism of SO42â and NO3â, which tended to be enriched in the coarse mode of aerosol. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) indicated high photochemical oxidation property over the whole Jing-Jin-Ji urban agglomeration.
Journal: Atmospheric Environment - Volume 77, October 2013, Pages 250-259