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Published on: July 10, 2015
Stoichiometric characteristics and economic implications of water-soluble ions in PM2.5 from a resource-dependent
Haoji Wang1, Xianghao Wang1, Haijun Zhou2
1Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China; Institute of Environmental Geology, Inner Mongolia University, Hohhot, 010021, China.
Abstract:
The stoichiometric characteristics of water-soluble ions (WSIs) in PM2.5, which can be used as an indicator socioeconomic development level, are mostly depending on the sources and formation mechanism of PM2.5. This work presents the stoichiometric characteristics and socioeconomic linkage of WSIs in PM2.5 from a resource-dependent city. The relationship between NO3-/SO42- and car parc indexes the contribution of mobile emission source. The equivalent ratio of WSIs suggested that aerosol particles were weak acidic due to the deficiency of cations in PM2.5, which was consistent with the average annual pH (6.27) of precipitation in Wuhai in 2015. NH4+ neutralizes PM2.5 acidity in clean and polluted days, while Ca2+ and NH4+ in dust storm days. Furthermore, the PCA analysis indicated the multi-sources pollution characteristics from Spring to Fall, which was related the small build-up area (only 62.30 km2) and the close-set of various industrial enterprises in Wuhai. The ratios of NO2/SO2 may not work effectively to identify the importance of mobile versus stationary pollution emission sources when the heavy emission from the secondary industry, especially the proportion of secondary industry higher than 65% and the ratios of NO2/SO2 lower than 0.4. This work contributes to more effective control strategies for PM2.5 in resource-dependent areas.
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