中文摘要：

为了探讨兰州市大气细颗粒物中水溶性无机组分的污染特征及来源,采集了2012年冬季和2013年夏季PM_（2.5）样品共40个,并利用离子色谱法对其中的无机离子进行了分析.分析结果显示,兰州市PM_（2.5）中无机离子冬季平均值为39.59μg·m~（-3）,夏季平均值为10.71μg·m-3,冬季污染程度远高于夏季,SO_4~（2-）、NH_4~＋和NO_3~-是3种最主要的水溶性离子;阴阳离子当量回归分析表明,冬季兰州PM2.5组分偏酸性,夏季偏碱性,离子间的结合方式主要以NH_4NO_3、（NH_4）_2SO_4、NH_4HSO_4和NH_4Cl的形式为主,冬季还有少量KNO_3、NaNO_3、K_2SO_4、Na_2SO_4、KCl和Na Cl存在;[NO_3~-]-/[SO_4~（2-）]比值的均值冬季为0.58±0.22,夏季为0.49±0.20,说明兰州市的冬季大气污染虽然呈现燃煤源等固定源和机动车尾气等流动源并存的复合污染类型,但仍然以煤烟型污染为主,而夏季NO_3~-受高温条件影响比较大,机动车尾气污染仍需引起重视.

英文摘要：

Forty PM2.5 samples were collected during winter 2012 and summer 2013 in Lanzhou city to investigate the chemical characteristics and sources of WSIN （Water Soluble Inorganic ）. The concentrations of WSIN were measured using ion chromatography. The levels of WSIN in winter were much higher than those in summer and the average concentrations of WSIN of PM2.5 were 39.59 μg.m-3 in winter and 10.71 μg.m-3 in summer in Lanzhou, respectively. SO24-, NH4 and NO3- were the three major WISN. Regression analysis of WSIN equivalent between total cations and total anions showed that PM2.5 was slightly acidic in winter and alkaline in summer in Lanzhou. Water-soluble ions of PM2.5 mainly existed in the forms of NH4NO3, （ NH4 ） 2SOa, NH4HSO4 and NH4Cl, with a few of KNO3, NaNO3, K2SO4, Na2SO4, KCl and NaCl in winter; The average values of [ NO3]/[SO24-] were 0.58±0.22 in winter and 0.49±0.20 in summer, respectively, suggesting sources contributed to WISN could be divided into stationary sources （such as coal combustions）, and mobile sources （such as motor vehicles） in winter. But the sources of WISN in summer are more complex, particularly at high temperatures. Motor vehicle emissions should be paid more attentions to.