煤矿区农田土壤重金属的空间分布及污染评价

Distribution and Pollution Assessment of Heavy metals in Farmland Soil form Coal Mine Area

为深入认识宿州煤矿区土壤重金属的空间分布及污染状况,选择朱仙庄和桃园两矿,在其附近农田采集土壤样品106份,通过实验测试与分析,探讨了矿区土壤重金属元素的赋存含量及空间分布特征,并利用富集因子和潜在生态风险评价法对其污染现状进行了评估。结果发现:重金属元素Pb、Zn、Cr和Cd的平均含量分别为22.72、54.76、66.84、0.336 mg·kg^(-1),除Cd明显超出安徽省土壤背景含量外,其余三种元素均低于背景值;矿区土壤重金属元素含量的空间分布差异明显,各元素的含量高值主要集中在堆积场和塌陷塘附近农田,这是由于煤矸石中微量元素的长期淋溶输出,以及矿区地表水汇集过程中重金属元素不断向地势较低的塌陷塘附近农田土壤迁移所致;富集因子和潜在生态风险评价结果表明,Cd是煤矿区土壤的主要污染元素,其富集因子指数EF和潜在生态危害系数Er分别为3.81和103.84,属中度污染和极强生态风险等级,而Pb、Zn和Cr均为轻微生态风险水平。

In order to recognize the spatial distribution and pollution situation of heavy metals in soils from Suzhou coal mine area,an investigation of 106 samples which have been collected form the farmlands around Zhuxianzhuang and Luling mines was conducted and the contamination levels of four elements（Pb,Zn,Cr and Cd）were assessed,using the index of Enrichment Factor（EF）and the potential ecological risk method.The results showed that：the average concentrations of Pb,Zn,Cr and Cd in soils were 22.72,54.76,66.84 and 0.336 mg·kg^（-1）,respectively.Compared with the background of Anhui soils,Cd was in higher level,while the other three elements were reverse.There were obvious differences in the spatial distrbution of the heavy metal contents,the higher values were mainly concentrated around the gangue dump and collapse pit,and it maight be caused by the prolonged leaching deliquescence of trace elements in gangue and the migratory behaviour of heavy metals in the surface environment of coal mine area.Cd,with the highest values of EF（3.81）and Er（103.84）,was moderately polluted and belonged to the extremely strong potential ecological risk degree,while Pb,Zn and Cr were just slight ecological risk level.