昆明市PM_(2.5)中水溶性无机离子时空变化特征及来源分析

Characteristics and source apportionment of the water soluble inorganic ions in PM_(2.5) of Kunming

为探讨高原城市昆明大气中水溶性无机离子的季节和空间变化特征,选取2013年4月至2014年5月昆明市3个采样点进行了PM2.5样品采集,分析了PM2.5及水溶性无机离子的污染特征,并结合气象因素、硫氧化率、氮氧化率及主成分分析法对其主要来源进行了分析.结果表明:PM_(2.5)质量浓度季节变化为春((105.9±48.0)μg/m^3)>冬((92.7±51.6)μg/m^3)>秋((74.7±41.4)μg/m^3)>夏((72.2±30.3)μg/m^3).总水溶性无机离子质量浓度季节变化特征为夏((38.0±18.3)μg/m^3)>冬((22.0±11.4)μg/m^3)>春((18.4±4.8)μg/m^3)>秋((13.6±3.1)μg/m^3);其中SO^(2-)_4、Ca^(2+)、NO^-_3及NH^+_4为PM_(2.5)中主要的水溶性无机离子,分别占总离子质量浓度的27.7%、17.8%、15.2%和9.5%;二次离子质量浓度之和年均为13.9μg/m^3,占PM_(2.5)质量浓度的16.5%,表明高原城市昆明大气中二次组分较少.NO^-_3/SO^(2-)_4为0.21~0.68之间,表明固定源是主要污染贡献源.主成分分析结果表明水溶性无机离子主要来源于土壤扬尘和建筑扬尘的混合源、燃煤源和工艺过程源.

To investigate the seasonal and spatial variations of WSII in the plateau city of Kunming, the PM2.5 samples have been collected at three sites from April 2013 to May 2014.The PM2.5 and WSII have been analyzed, and the main source of WSII have been apportioned by combining the meteorological factors, sulfur oxidation ratio, nitrogen oxidation ratio and principal component analysis.Results show that the concentration of PM2.5 presents seasonal trend with the highest values in spring（（105.9±48.0） μg/m3） ,followed by winter （（92.7±51.6）μg/ m3） and autumn （（74.7±41.4）μg/m3） ,then summer（（72.2±30.3） μg/m3） .Seasonal variations of TWSII concentration is with higher values in summer followed by winter, and lower in spring and autumn, with concentration of（38.0±18.3） μg/m3, （22.0±11.4） μg/m3, （18.4±4.8） μg/m3 and （ 13.6±3.1 ） μg/m3 respectively. SO4 2- 、 Ca2＋ , NO3-、NH4 are the dominant ions in WSII,which account for 27.7%, 17.8%, 15.2% and 9.5% respectively.Secondary ions concentration is 13.9 μg/m3, accounting for 16.5% of the mass concentration of PM2.5 ,which indicates less secondary ions in the air of plateau Kunming City.The ratio of NO3/SO4 2- is between 0.21 and 0.68 ,indicating that stationary source is the dominant source contribution. The results of principal component analysis suggest that WSII mainly come from mixed source with soil dust and construction dust, coal-fired source and in- dustrial process source.