摘要
于2007年1月至2008年1月间,系统采集西安市区及咸阳郊区大气降水样品70个,对其主成分进行了分析,以期获得大气降水组成特征及其物质来源信息。研究结果显示,Ca2+是最主要的阳离子,分别占西安和咸阳降水中阳离子总量的77.4%和79.6%,其次是Na+。SO42-是最主要的阴离子,分别占西安和咸阳降水中阴离子总量的83.2%和81.4%,NO3-次之。两地降水中各组分含量年内变化趋势具同步性,均显示冬季远高于夏季的特征,且西安降水中各组分含量均高于咸阳。说明两地降水化学组成具同源性,咸阳大气污染物主要来自西安大气污染物的扩散。海相贡献比例计算结果显示,两地降水中SO42-和Ca2+海相输入比例很小,SO42-主要来自工业生产释放的SO2,而雨水中高浓度的Ca2+和Mg2+则是由于酸性物质对大气颗粒物的强化溶解造成。西安和咸阳雨水SO42-/NO3-值分别为12.89和11.11,属于燃煤型大气污染。
Major ions in precipitation samples collected in the period from January 2007 to January 2008 in the Xi＇an and Xianyang districts, Shaanxi Province, were determined to investigate their chemical composition and potential sources. The results showed that Ca^2＋ , which accounts for about 77.4% and 79.6% of total cations in the Xi＇an and Xianyang districts, respectively, is the principal cation in the precipitation. Na^＋ is the ion whose concentrations are the second highest. SO4^2- is the principal anion, which accounts for about 83.2 % and 81.4% in the precipitation from the Xi＇an and Xianyang districts, respectively.The anion whose concentrations are the second higheston is NO3^-. Annual variation of the concentrations of major ions showing higher levels in the winter than in the summer are quite coincident in precipitation samples from the Xi＇ an and Xianyang districts, although the concentrations of ions are higher in the former than in the latter. This indicates that major ions in precipitation samples from the Xi＇an and Xianyang districts have the same compositions and same potential sources. Relatively high concentrations of the corresponding ions in precipitation samples from the Xi＇ an than Xiangyang districts imply that air contamination in the Xianyang district is diffused from the Xi＇ an city. The estimation result indicated that the potential sources of ions from marine salt have only made limited contributions. SO4^2- comes mainly from the transition of atmospheric SO2 resultant from industrial release. The high concentrations of Ca^2＋ , Mg^2＋ and other major cations in precipitation samples from the Xi＇an district are attributed to strong acid--base reactions on the atmospheric particles. The SO4 ^2-/NO3^- concentration ratios are 12. 89 and 11.11 in precipitation samples from the Xi＇an and Xianyang districts, respectively, which are high relative to the other cities of China, indicating that the air pollution is caused by coal consumption （burning） there.
出处
《地球与环境》
CAS
CSCD
北大核心
2008年第4期289-297,共9页
Earth and Environment
基金
中国科学院创新团队国际合作伙伴计划项目(刘丛强)
中国科学院“西部之光”联合学者项目(王中良)
关键词
化学组成
来源
降水
主离子
西安
chemical composition
potential source
precipitation
major ions
Xi＇an
