长沙市夏季大气颗粒物中重金属的形态及其源解析

Research on source and extraction characterization of heavy metals on atmospheric particles in Changsha in summer

对长沙市高开区、经开区、开福区以及马坡岭4个采样点夏季的大气颗粒物（TSP）浓度以及颗粒物中的重金属元素Cu、Zn、Mn、Pb和Cd的浓度和形态分布进行了研究分析,利用污染因子（Cf）对重金属元素的可保持能力进行了评价,并利用因子分析方法（PCA）分析TSP中重金属元素的主要来源。结果显示长沙市夏季TSP平均浓度为220.7μg/m3,表明长沙市颗粒物污染较严重。TSP中重金属元素浓度大小顺序为：Zn〉Pb〉Cu〉Mn〉Cd。从形态分布来看,大约63.3%~89.0%的Cu主要存在于可氧化态（F3）,而Mn在这一态中分布最少。元素Zn、Cd则主要分布在弱酸提取态,分别占了70%和35%。Pb主要分布在残渣态,大约为24%~43%。由污染因子计算可知Cu、Cd和Zn比Mn、Pb有更高的迁移性。

In the present study,BCR 3-step sequential extraction procedure was applied to determine the fractionation of heavy metals in TSP samples collected from four locations in Changsha,China.The average TSP concentration in Changsha in May was 220.7 μg/m3 showing that the particle pollution is serious in Changsha.The distributions of heavy metals（Cu,Zn,Mn,Pb,Cd） in different spots were evaluated and the total concentration of heavy metals can be listed in the following order： ZnPbCuMnCd.From the percentage distribution of species,approximately 63.3%～89.0%of total Cu present in oxidizable fraction（F3）,whereas Mn has the lowest concentration in oxidizable fraction.While Zn and Cd mainly appears in the exchangeable and weak acid soluble fraction（70% and 35%,respectively）,Pb prevails in residual fraction（24%～43%）.Contamination factors showed Cu,Cd and Zn had higher values indicating a high mobility and Mn and Pb having comparatively low Cf values.Principal component analysis（PCA） was applied to evaluate the analytical results and to identify the possible pollution sources of metals.