2010年兰州市降雨化学成分特征  

Characteristics of chemical compositions of rainwater in Lanzhou City in 2010

作　　者：郭勇涛[1] 辛金元[2] 李江萍[1] 王式功[1,3] 程一帆[1] 

机构地区：[1]兰州大学大气科学学院,半干旱气候变化教育部重点实验室,兰州730000 [2]中国科学院大气物理研究所,北京100029 [3]成都信息工程大学大气科学学院,成都610103

出　　处：《兰州大学学报（自然科学版）》2015年第4期546-552,共7页Journal of Lanzhou University(Natural Sciences)

基　　金：中国气象局北京城市气象研究所项目(基于天气学和数值预报模式的京津冀空气污染气象条件预报系统研发);中央高校基本科研业务费专项资金项目(LZUJBKY-2013-M03,2014-101,2013-110)

摘　　要：为了解兰州市降雨的物理化学特征,在2010年3-11月期间收集了该地的降雨样品,使用离子色谱和电感等离子发生光谱等仪器分析了降雨样品中的p H、电导率、水溶性离子和痕量元素等.结果表明监测期间降雨样品中p H在5.54～8.27之间,平均为7.58,说明兰州的降雨属于碱性,与兰州气溶胶浓度高及其气溶胶中的碱性成分多有关.电导率在21.8～770.0μS/cm,平均值为199.7μS/cm,远高于中国基准站瓦里关的电导值,说明兰州的大气污染很严重.SO2-4和Ca2+是降雨样品中质量分数最高的阴离子和阳离子,分别占整个水溶性离子质量分数的45.9%和25.7%,在一定程度上反映出了人为污染与自然尘的相互混合和作用是导致兰州空气污染的成因;SO2-4/NO-3的比率为3.42,说明固定污染源比移动污染源对兰州的大气污染贡献更大.与20世纪90年代的值相比,本研究的SO2-4/NO-3值要低,反映出近年来随着机动车保有量的增加,大气污染类型正在发生转变,流动源变得越来越重要.由于大气降雨p H值的原因,降雨中微量元素的含量普遍较低,平均质量浓度在0.042～1.17μg/L,富集因子的结果表明Fe、Mn主要来自于地壳来源,除Al以外的其他元素主要来自人类活动的贡献.In order to understand the physical and chemical characteristics of rainwater in Lanzhou City, rainwater samples were collected during 3-11, 2010, their pH value, electrical conductivity, water soluble ions and trace elements were measured by IC, ICP-Ms, et al. The result showed that the average pH of rainwater samples was observed to be 7.58, ranging from 5.54 to 8.27, indicating an alkaline nature, which was apparently due to the high aerosol concentration over the city. The average electrical conductivity was 199.7 μS/cm, varying from 21.8~770 μS/cm, which was much higher than that at the Waliguan Global Baseline Station, suggesting that air pollution in Lanzhou had been a much more serious problem. SO4^2- and Ca^2＋ were the most abundant anion and cation, respectively, accounting for about 45.9% and 25.7% of the total mass of water soluble ions, respectively. This meant that the characteristics of air pollution in Lanzhou were a mixture and interaction of anthropogenic and natural sources. The average SO^2-/NO3^- ratio was 3.42, indicating that stationary sources had considerably contributed to air pollution, though it was much lower than that in 1990＇s, indicating that the mobile sources had become more and more predominant. Due to value, the concentrations of the trace elements were generally low, changing from 0.042 to 1.17 μg/L, with Fe and coming from the crust source and other elements except A1 mainly originating from the anthropogenic source by enrichment factor.

关 键 词：降雨 水溶性离子 痕量元素 富集因子 兰州市 

分 类 号：X517[环境科学与工程—环境工程]