贵阳大气降水化学特征及来源分析

对贵阳地区2008年10月1日～2009年9月30日降水样品的pH值和主要阴阳离子组成的进行测定,并运用TrajStat软件模拟后向气团轨迹,分析了贵阳地区降水中离子来源以及影响离子浓度的因素.结果表明,2008～2009全年降水pH值加权平均值为4.23;SO42-是主要阴离子,加权平均值为265.63μeq/L,占总阴离子的69.29%.Ca2+和NH4+是主要的阳离子,加权平均值分别为182.90和112.79μeq/L,分别占总离子的47.10%和29.05%.并且NH4+、Ca2+与SO42-之间存在明显的相关性,说明贵阳大气中可能主要存着(NH4)2SO4、NH4HSO4、CaSO4等物质.总离子浓度季节差异性大,冬季高、夏季低,主要受到降水量、污染物来源等多方面的影响.海相和土壤富集系数表明,Ca2+、Mg2+、K+主要来自地壳源,而SO42-、NO3-主要来自人为源.贵阳后向轨迹表明春季气团轨迹较为杂乱,夏季气团主要来自沿海,秋冬季则主要受中国内陆的影响.

Chemical characteristics and source apportionment of precipitation in Guiyang

This study analyzed the concentrations of cation and anion, and pH in precipitation taken in Guiyang throughout one year from October 1, 2008 to September 30, 2009. Using the software-TrajStat to simulate backward trajectory of air mass, we examined the source of ions and impact factors on ion concentrations. The results indicated that the volume-weighted average of pH in one year was 4.23. SO42- was the major anion and volume-weighted average was 265.63μeq·L-1, accounting for 87.19% of total anions. And Ca2+ and NH4+ were the major cations and their volume-weighted means were 182.90μeq/L and 112.79μeq/L, accounting for 47.10% and 29.05% of total cations, respectively. Good correlations between NH4+, Ca2+ and SO42- were observed, which imply the (NH4)2SO4, NH4HSO4 and CaSO4 being exist in the atmosphere in Guiyang. Significant seasonal variations in total ion concentration, as high in winter and low in summer, showed that the ion concentration was affected by many factors such as precipitation amount and pollutant sources. Enrichment factor relative to seawater and soil indicated that Ca2+, Mg2+ and K+ were mainly from crustal source, but SO42- and NO3- from the anthropogenic source. The backward trajectories in Guiyang showed that the air mass from various directions in spring, from sea in summer, and from northeastern inland in autumn and winter.