太原市夏季降水中溶解态重金属特征及来源

Characteristics and Sources of Dissolved Heavy Metals in Summer Precipitation of Taiyuan City,China

为了解太原市大气降水中溶解态重金属污染特征及来源,采用干湿沉降自动采样器采集了太原市2013~2015年夏季61场降水样品,使用ICP-MS测定了其中12种溶解态重金属,并对其浓度水平、湿沉降通量及来源进行分析.结果表明,太原市2013~2015年夏季降水p H值范围为4.34~7.95,降水量加权平均值为5.37.溶解态重金属平均浓度为236.931μg·L-1(范围66.324~1 029.212μg·L-1),主要元素是Zn和Fe,占总浓度的53.39%.12种溶解态重金属的湿沉降总通量为1.735mg·(m2·d)-1.降水中Ba、Cu、Sr、Zn、As、Cd和Pb的富集因子大于100,受到严重的人为源影响.PMF模型分析表明太原市夏季降水中重金属的主要来源为钢铁冶金、燃煤源、机动车源和地面扬尘,贡献率分别为38.34%、23.06%、20.45%和18.15%.气团的后向轨迹分析表明西南气团和东南气团对太原市夏季降水贡献最大,分别达到38%和35%,运城-临汾-晋中和晋城-长治-晋中的南部工业源污染应该引起重视.

To investigate the characteristics and sources of dissolved heavy metals in precipitation of Taiyuan,61 precipitation samples were collected using an automated dry and wet sampler from 2013 to 2015 during summertime. The concentrations of 12 dissolved heavy metals were detected using ICP-MS,and wet deposition fluxes and sources were analyzed. The results showed that the p H ranged from4. 34 to 7. 95,with a volume-weighted mean of 5. 37. The mean concentration of the dissolved heavy metals was 236. 931 μg·L-1,with a range of 66. 324 to 1 029. 212 μg·L-1. Zn and Fe were the major components,together accounting for 53. 39% of the total concentrations. The wet deposition fluxes of the 12 dissolved heavy metals reached 1. 735 mg·（ m2·d）-1. The enrichment factors of Ba,Cu,Sr,Zn,As,Cd,and Pb were all in excess of 100,suggesting that these metals were seriously influenced by anthropogenic activities. Results from positive matrix factorization（ PMF） indicated that steel smelting emissions, coal combustion, vehicle emissions,and crustal dusts were the major sources of heavy metals in the precipitation of Taiyuan City,with average contributions of38. 34%,23. 06%,20. 45%,and 18. 15%,respectively. According to backward trajectory analysis,air masses from the southwest and southeast directions contributed the most to precipitation during summer in Taiyuan,with percentages of 38 and 35,respectively.The southern industrial areas located in the Yuncheng-Linfen-Jinzhong and Jincheng-Changzhi-Jinzhong regions should be paid more attention.