开封市秋冬季大气细颗粒物化学成分及来源解析

Chemical composition and source apportionment of atmospheric fine particulate matter in autumn and winter in Kaifeng City

为研究开封市秋冬季大气细颗粒物(PM_(2.5))的化学组分及主要来源,分别于2017、2018年秋冬季在开封市设置了3个点位采集大气PM_(2.5)样品。采用X射线荧光法(XRF)、离子色谱法(IC)与热光反射法(TOR)分别测定了PM_(2.5)中元素、水溶性离子及碳质组分特征,并运用正定矩阵因子分解(PMF)模型解析PM_(2.5)来源。结果表明,2017、2018年秋冬季开封市大气PM_(2.5)平均质量浓度分别为124.38、111.48μg/m_(3),水溶性离子平均质量浓度为分别为54.48、58.16μg/m_(3),其中3种二次无机离子(NO^(-)_(3)、NH_(4)^(+)、SO_(4)^(2-))是主要组分。2017、2018年秋冬季NO^(-)_(3)与SO_(4)^(2-)质量比分别为1.91、2.56,表明PM_(2.5)受移动源影响增大。二次有机碳(SOC)是PM_(2.5)中有机碳(OC)的主要来源,2017、2018年分别占OC的93.70%、73.20%。开封市PM_(2.5)主要来源于二次无机源、机动车排放源、扬尘源和燃煤源,与2017年相比,2018年秋冬季二次无机源、扬尘源贡献率分别下降15.2百分点、8.3百分点,燃煤源和机动车排放源的贡献率分别上升8.0百分点、5.9百分点。开封市2018年采取的多项大气污染防治措施有效降低了二次无机源、扬尘源等对PM_(2.5)浓度的贡献。

To explore the chemical composition and main sources of atmospheric fine particulate matter(PM_(2.5))in autumn and winter in Kaifeng City,PM_(2.5)samples were collected at three sites from autumn to winter in 2017 and 2018.X-ray fluorescence(XRF),ion chromatography(IC)and thermo-optical reflection(TOR)were applied to test elements,water-soluble ions and carbonaceous components in PM_(2.5).Source apportionment of PM_(2.5)was conducted by using the positive matrix factor(PMF)model.Results showed that the average concentrations of atmospheric PM_(2.5)in Kaifeng City were 124.38 and 111.48μg/m_(3)in 2017 and 2018,respectively.The average concentrations of water-soluble ions were 54.48 and 58.16μg/m_(3)in 2017 and 2018 respectively,and 3 secondary inorganic ions(NO^(-)_(3),NH_(4)^(+),SO_(4)^(2-))accounted for most of the water-soluble ions.The average mass ratios of NO^(-)_(3)to SO_(4)^(2-)in 2017 and 2018 were 1.91 and 2.56 respectively,indicating that PM_(2.5)was greatly affected by mobile sources.Secondary organic carbon(SOC)was the main source of OC in PM_(2.5),which accounted for 93.70%and 73.20%of OC in 2017 and 2018.PM_(2.5)mainly came from secondary inorganic source,motor vehicles emission source,fugitive dust and coal-fired sources.Compared with 2017,the contribution of secondary inorganic and fugitive dust sources in 2018 decreased by 15.2 percent points and 8.3 percent points,while the contribution of coal-fired and motor vehicle sources increased by 8.0 percent points and 5.9 percent points.It meant that air pollution control measures adopted in Kaifeng City in 2018 had effectively reduced the contributions of secondary inorganic source and fugitive dust source to PM_(2.5).