【摘要】 为了探索西安市大气降水的水溶性化学组分浓度水平及来源,在春季和夏季采集了西安市降水样品,测定了样品中的水溶性无机离子和溶解性有机碳(DOC)的浓度,并对其来源进行了初步探讨.结果显示:春、夏季降水样品的平均pH值分别为5.85和5.83,表明西安市春、夏季降水酸度偏高,但尚未达到酸雨范畴;SO24-、Ca2+、NH+4和NO-3是降水中最主要的无机离子,在春季它们分别占总离子数的35.8%、28.2%、18%、9.1%,在夏季占总离子数的34%、25%、19%、8%.利用相关分析和富集因子法对降水中水溶性化学组分的来源进行了解析,结果表明,西安市春、夏季降水中水溶性化学组分主要来自燃煤、机动车尾气、建筑活动和生物质燃烧等人为因素.SO24-、NO-3当量比值变化揭示了机动车的快速增长、能源结构和燃烧方式的改变使得NO-3对降水酸度的贡献有相对增大的趋势.更多还原

【Abstract】 Atmospheric precipitation samples collected in Xi′an in spring and summer were analyzed to determine the concentration levels of water-soluble inorganic ions and dissolved organic carbon(DOC).The average pH values in the precipitation were 5.85 in spring and 5.83 in summer,indicating that the precipitation samples were acidic but did not form acid rain.SO2-4,Ca2+,NH+4,and NO-3 were dominant in the water-soluble ions in the precipitation samples with the ion concentration of 35.8%,28.2%,18%,and 9.1% in spring and 34%,25%,19%,and 8% in summer,respectively.The analysis on the water-soluble components with the correlations and Enrichment factor shows that they are mainly from coal burning,vehicle exhaust emissions,construction activities,and biomass burning.In addition,The variation of SO2-4/NO-3 ratio confirms that the contribution of NO-3 to the precipitation’s acidity rises with the rapid growth of motor vehicles and the changes of energy structure and combustion methods.更多还原