• 关键词：汽车站  地表灰尘  重金属  来源  生物有效性

• 基金项目：国家自然科学基金资助项目(No40771090,40471064)

• 章明奎
• 1. 浙江大学 环境与资源学院 土水资源与环境研究所, 杭州 310029; 2. 浙江省亚热带土壤与植物营养重点研究实验室, 杭州 310029

• 摘要：为了解不同区域城市汽车站地表灰尘重金属的积累、有效性及其可能来源,在浙江省范围内选择了73个城市汽车站,采样并分析了地表灰尘颗粒组成及Pb、Zn、Cu、Cd、Cr、Ni、Hg、As、Se、Al、Fe、Mn和Co等元素的含量,用连续提取程序研究了地表灰尘中主要污染元素的化学形态.同时,应用相关分析、主成分分析和聚类分析等方法探讨了城市汽车站地表灰尘中重金属的可能来源及各城市汽车站地表灰尘组成的差异.颗粒组成分析结果表明,浙江省城市汽车站地表灰尘以粗颗粒组成为主,地表灰尘主要来源于车站附近的土壤、建筑、垃圾等,大气沉降对地表灰尘的贡献相对较小.与浙江省土壤背景值相比,Pb、Zn、Cu、Cd、Cr、Ni、Hg、As和Se等元素均有不同程度的污染,其平均含量分别为287.1、424.0、172.8、1.21、122.3、54.4、0.71、16.00和2.07mg·kg^-1.因子分析将13个元素变量压缩为3个因子,可解释浙江省城市汽车站地表灰尘元素的来源:Pb、Zn、Cu、Cd、Cr和Ni主要与交通活动、工业污染等有关;Al、Fe、Mn和Co与当地成土母质等地质背景有关;Hg、As和Se等元素受交通污染、居民生活污染和工业污染等多重影响.根据地表灰尘元素组成的差异,可把城市汽车站分为5类.重金属元素化学形态研究表明,城市汽车站地表灰尘中不同元素的化学形态有较大的差异,有效性较高的元素为Zn、Mn和Cd,其次为Cu、Ni和Hg,而Pb、Cr和Fe的活性相对较低.

• Abstract：Contaminated surface dust is a world wide problem,and concentration and mobilization of contaminants in the surface dust are among the most critical issues in environmental risk assessment.Urban coach stations are one of the most important public places where surface dust has a direct effect on people's health as a result of respiration,because of the small size of the particles and the effect of heavy metals on biochemical mechanisms,and especially because the metals can be bio-accumulated.In order to investigate the accumulation,possible sources and availability of heavy metals in the surface dust at different types of urban coach stations,73 surface dust samples were collected from each of 73 coach stations in Zhejiang Province for characterization of the particle composition and accumulation of Pb,Zn,Cu,Cd,Cr,Ni,Hg,As,Se,Al,Fe,Mn,and Co.Chemical forms of Pb, Zn,Cu,Cd,Cr,Ni,Hg,Fe,Mn,and Co in representative samples were also characterized by a sequential extraction technique.Multivariate statistical techniques,including correlation analysis,principal component analysis (PCA),and cluster analysis,were applied to identify possible sources of heavy metals in the surface dusts and classify the coach stations in term of chemical components of the surface dusts.The particle analysis showed that coarse particles with size of > 100μm composed the majority of the surface dusts in the urban coach stations in Zhejiang Province,and suggested that the surface dusts mostly originated from soil,construction materials,and garbage near the coach stations,and atmospheric deposition made little contribution to the surface dusts.The mean total concentrations of Pb,Zn,Cu,Cd,Cr,Ni,Hg,As,and Se in the surface dusts were 287.1,424.0,172.8,1.21,122.3,54.4,0.71,16.00,and 2.07 mg·kg^-1,respectively,and were significantly higher than background values of the elements in the soils of the Zhejiang,indicating that the surface dusts were heavily contaminated with the heavy metals.Three significant components were extracted by PCA, explaining 89.77% of total variance of the 13 elements.Aluminium,Fe,Mn,and Co were associated with lithogenic components and originated from soil particles (natural source).Lead,Zn,Cu,Cd,Cr,and Ni were possibly related to traffic exhaust and industrial pollution.Mercury,As,and Se were originated from multiple activities including coal combustion,traffic exhaust,and industrial pollution.Based on the chemical components of the surface dusts,the 73 coach stations could be classified into 5 groups.Chemical speciation results showed that the chemical forms of the metals in surface dusts varied with the elements,and the potential availability of the metals decreased in the sequence Zn,Mn,and Cd > Cu,Ni,and Hg > Pb,Cr,and Fe.

• Key words：coach station  surface dust  heavy metals  source  availability

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