粤东铅锌尾矿区四种莎草的重金属富集特性研究

Investigation on the heavy metal-enrichment characteristics of four sedges in Pb-Zn tailings,Eastern Guangdong

从梅州丙村铅锌尾矿区近污水排放区采集了土壤与四种优势植物样品,分别测定和分析了Zn、Pb、Ni、Cu、Cr、Cd、Mn七种重金属含量。结果表明,该矿区土壤污染严重且为强酸性。Cd、Pb、Zn、Mn、Cu的污染指数均大于3,且综合污染指数为319.16,Zn、Pb、Cd均超出国家土壤环境质量(GB15618-1995)的二级标准,也远超过广东土壤背景值,有很大的潜在生态风险,重金属单因子生态风险指数大小排序为Cd>Pb>Zn>Mn>Cu>Ni>Cr。两歧飘拂草(Fimbristylis dichotoma)、细辐射枝藨草(Scirpus filipes)、多枝扁莎(Pycreus polystachyus)地下部分的Pb含量均超过超富集植物临界含量标准,因此这三种植物有作为Pb富集植物的潜力。贝壳叶荸荠(Heleocharis chaetaria)对镍的富集系数超过1,细辐射枝藨草对Mn的转移系数大于1。这四种植物对土壤的重金属污染有很强的耐性,与非矿区土壤中生长相比,长势并无显著差异,且地下部分重金属含量都很高,说明对它们土壤中的重金属有一定的固定作用,可作为这些区域植被恢复的先锋植物。

The samples of soil and four dominant plants were collected near the sewage discharge area in Pb-Zn Tailings ofBingcun,Meizhou.The contents of Zn,Pb,Ni,Cu,Cr,Cd,Mn were then determined and analyzed comparatively.The soil inthe tailings was seriously polluted and strongly acidic.The pollution indexes of Cd,Pb,Zn,Mn and Cu were all above3,andthe comprehensive pollution index was319.16.The content of Pb,Zn and Cd not only exceeded the secondary standard of thenational soil environmental quality standard(GB15618-1995)in China,but also greatly exceeded the soil background value inGuangdong.The descending order of single factor potential ecological risk indexes for heavy metals were Cd,Pb,Zn,Mn,Cu,Ni and Cr.The Pb content in underground parts of Fimbristylis dichotoma,Scirpus filipes and Pycreus polystachyus was abovethe critical content standard for hyperaccumulators,so the three plants had the potential to be used as Pb enrichment plant.Theenrichment factor of Ni for Heleocharis chaetaria was above1,and the biological transfer coefficient of Mn for Scirpus filipeswas also above1.The four plants had a strong tolerance to heavy metal pollution,and there were no significant difference ofgrowth between them and those distributed in non-mining area,and heavy metal contents of the ground part of the measuredwere relatively high,which indicated that they had a certain effect on the heavy metals in the soil and could be used as pioneerplants in the vegetation restoration in these mining areas.