Characterization And Sources Of Water-soluble Ions In Aerosol Fine Particles In Beijing And Surrounding Region.

In recent years, with the high-speed development of economy in our country, urban atmospheric environmental pollution has become a prominent environmental problem affecting human health. Haze gradually aroused widespread concern. The sources of atmospheric fine particles are extremely complex. Water-soluble ions are the major components of fine particles.Therefore, it is of great significance to study the physical and chemical characteristics and sources of water-soluble ions in fine particles.PM2.5 samples were collected by TH-150C sampler from June 2014 to April 2015 in Beijing and surrounding regions (Jiandemen, Dongzhimen,Huairou, Xiangshan, Xianghe, Xinglong and Baoding). The water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+ and Cl-,NO3-,SO42-) were analyzed by ion chromatography (IC). The spatial distribution, concentration level, seasonal and diurnal variation characteristics , the pollution process characteristics of water-soluble ions in Beijing and surrounding region were discussed. We obtain the following conclusions:The concentration level of water-soluble ions is shown as follows:Baoding (61.1 ±37.8μg·m03) >Xianghe (59.4±37.0μg·m-3) >Jiandemen(51.7±45.0μg·m-3),Dongzhimen (49.6±38.5μg·m-3).>Xiangshan (47.1± 36.9μg·m-3 ) > Huairou ( 44.1±42.2μg·n-3) > Xinglong ( 39.9 ±38.5μg·m-3) . In Beijing and surrounding region, PM2.5 concentrations in the southern were higher than in the northern. The concentrations of water-soluble ions in city sites were higher than in the suburban sites, and the concentrations of water-soluble ions in suburban sites were higher than in the background sites. Water-soluble ions in city sites have obvious seasonal variation. In suburban sites, however the seasonal variation of water-soluble ions is not obvious. SO42-,NO3- and NH4- were the major components of water-soluble ions in the four seasons. From clean days to heavy haze days, the concentration of SO42- , NO3- and NH4+ were significantly increased. The concentration of water-soluble ions increased more in summer and autumn from clean days to heavy haze days. The results of principal component analysis showed that: The main sources of water-soluble ions in Beijing and surrounding region are secondary formation, biomass burning emission and dust.