Characteristics of the chemical components of aerosol particles in the various regions over China

In order to obtain the overall chemical "picture" of the aerosol pollution in the various regions of China and discuss the further direction of pollution control, we need to assess and evaluate the concentration level, chemical composition and their sources region-by-region in China. Features of the chemical aerosol particles in China have been obtained, based on the analysis of the six major chemical components (sulfate, nitrate, ammonium, mineral aerosol, organic and element carbon) from the ground-based observation with all having at least one-year-long measurements. The four most hazy regions of the nine regions with characteristics of synchronous changing in visibility within China are also identified, which are the region south of Beijing (also called the Huabei Plain and Guanzhong Plain); the eastern China region with the Yangtze River Delta as its main body; the south China region with the Pearl River Delta as its main body; and also the region of Sichuan Basin. Of the PM10 in China, three major components are accounted for 20%-38% of the total mass for mineral aerosol, 14%-24% for sulfate, and 11%-18% for organic carbon.The heaviest aerosol pollution was found in the Huabei and Guanzhong Plain region, with the annual mean concentrations of 35-47 μg/m3 of sulfate (which was much higher than the urban Beijing level of 13 to 18 μg/m3), 28-45 μg/m3 of organic carbon (about 1.8 factor higher than the Beijing level of 19-22 μg/m3), 19-22 μg/m3 for nitrate (2 times higher than the Beijing level of 9.9-12 μg/m3), 14-16 μg/m3 for ammonium (still one factor higher than the Beijing mean concentration of 6.2-8.4 μg/m3), and the 9.1-12 μg/m3 of elemental carbon which was similar with the level of Beijing. More than 50% mass of nitrate and organic carbon are attributable to coal-combustion, and the agricultural activity is the most important source for ammonium.In the urban areas of eastern, southern and northeastern China, the concentration levels of aerosol chemical components were similar to those in Beijing, but in the urban areas of the Sichuan Basin, the annual mean concentrations were higher than in Beijing, exhibiting heavy aerosol pollution there. In Lanzhou of northwestern China, the urban level concentrations of aerosol chemical components were also similar to that in Beijing, except for much lower concentration in elemental carbon and bit higher concentration of nitrate observed. In the remote desert area of northwestern China, the chemical concentrations of aerosol particles were far lower than in Beijing, while it is also true for the Tibetan and Yuannan-Guizhou Plateau. Coal-combustion, motor vehicle, sources for urban fugitive dust and agricultural activities are found to be the four major pollution sources by the aerosol chemical composition analysis in the different regions. Therefore, the future control countermeasures of atmospheric aerosol pollutants should be directed to the following: strengthening coal desulfurization in addition to the power generation industry, further reducing coal produced emissions of NOx, organic carbon and its precursor gases, and effectively reducing ammonia emissions from agricultural activity with effectively limiting the formation of secondary aerosol, especially for sulfate and nitrate.