邯郸市PM_(2.5)中水溶性无机离子污染特征及来源解析

本研究通过对邯郸市环境空气中PM2.5样本进行采集和成分检测,分析了该地区PM2.5中水溶性无机离子的污染特征,并结合气象要素(风速、温度)、气态污染物(O3、NO2、SO2、CO)、SOR(硫氧化率)、NOR(氮氧化率)对其主要来源进行了解析.研究结果表明:总水溶性无机离子(TWSII)浓度季节变化特征明显,秋、冬季高于春、夏季.SO2-4、NO-3、NH+4是PM2.5中主要的水溶性无机离子,在TWSII中所占的比例为夏(93.2%)冬(85.6%)秋(85.5%)春(84.0%).春、夏、秋三季PM2.5呈酸性,冬季显碱性.此外还分析得到,SO2-4在四季中均以(NH4)2SO4的形式存在.NO-3在冬季以NH4NO3的形式存在,其余季节中以NH4NO3、HNO3等共存.绝大部分Cl-在冬季以NH4Cl的形式存在,其它季节中以NH4Cl、KCl等的形式存在.均相反应是SO2-4的主要生成途径,夏、冬季也伴随有非均相反应.NO-3的生成以均相反应为主(春、夏、秋),在冬季均相反应与非均相反应同时存在.应用因子分析法解析出4个主因子,其中,工业、燃煤、交通、生物质燃烧等综合源是PM2.5中水溶性无机离子的主要来源.

Pollution characteristics and source apportionment of water soluble inorganic ions in PM2.5 in Handan City

Daily PM_2.5 samples were analyzed to study the pollution characteristics of WSII(Water Soluble Inorganic Ions) in Handan City. Meanwhile, by combining the meteorological factors(wind speed, temperature), gaseous pollutants(O₃, NO₂, SO₂, CO), SOR(Sulfur Oxidation Ratio) and NOR(Nitrogen Oxidation Ratio), and the main sources of WSII were apportioned. The results show that TWSII(Total Water Soluble Inorganic Ions) presented obvious seasonal trend with higher values in autumn and winter, lower values in spring and summer. SO₄^2-, NO₃^-, NH₄⁺(SNA) were the dominant ions in TWSII, which accounted for 93.2%(Summer), 85.6%(Winter), 85.5%(Autumn), 84.0%(Spring) of TWSII. PM_2.5 samples were acidic in spring, summer, autumn, and alkaline in winter. In addition, SO₄^2- existed in the form of(NH₄)₂SO₄ in four seasons. NO₃^- existed in the form of NH₄NO₃ in winter, but in other seasons, NH₄NO₃, HNO₃ coexisted in PM_2.5. In winter, most Cl^- existed in the form of NH₄Cl, while in other seasons NH₄Cl and HCl were the dominant form of Cl^-. SO₄^2- was formed via the homogeneous gas-phase reaction between ammonia and sulfuric acid in four seasons, and heterogeneous transformation processes such as metal catalyzed or H₂O₂/O₃ oxidation of sulfur and in-cloud process also occurred in summer and winter. NO₃^- was formed via homogeneous gas-phase reaction, while in winter, heterogeneous process exists at the same time. Results of principal component analysis(PCA) show that the major sources of WSII are the mixture of coal combustion, vehicle exhaust, industrial sources and biomass burning.