典型鼓风炉铅冶炼废渣堆场周边优势植物重金属富集特征研究

Study on Enrichment Characteristics of Heavy Metals from Dominant Plants Around the Waste Slag Yard of Lead Smelting in A Typical Blast Furnace

随着长期自然选择,一些野生植物能够适应鼓风炉铅冶炼废渣堆场周边特殊的环境条件,在受重金属污染土壤环境下生存繁殖。若能通过周边覆盖率较高的优势野生植物筛选,找到兼有较好的重金属耐受、重金属富集能力的先锋植物,则可为同类型污染场地的治理修复和生态重建提供重要支持。以个旧北部典型鼓风炉铅冶炼废渣堆场为研究对象,通过实地调查分析废渣堆场周边土壤和三叶鬼针草(Bidens pilosa)、车桑子(Dodonaea viscosa)、夹竹桃(Nerium oleander)、红花八角(Illicium dunnianum)、凤尾蕨(Pteris cretica)等5种野生植物的重金属含量,研究优势植物对重金属的富集特征,筛选出适应该地区生态修复的先锋植物。结果表明,该废渣堆场土壤pH呈酸性,Hg、Cd、As、Zn、Pb、Cu、Cr存在不同程度的富集,以Cd、As、Hg等伴生元素污染最为严重,分别超土壤背景值97.09、33.56、76.00倍。所调查的优势植物对重金属具有一定的耐性,均能适应重金属元素较高的土壤环境。5种优势植物对7种重金属的富集特征差异明显,对Pb、Zn、As、Cd等元素富集量虽然未达到超富集植物规定的临界值,但已远远超过一般植物。其中,鬼针草、车桑子和凤尾蕨对多个重金属生物富集系数大于1,且覆盖率较高,具有较好的富集能力和重金属污染土壤修复潜力,特别是车桑子,其综合富集系数达到9.58,可以作为该地区及同类型地区生态恢复的先锋植物。

With long-term natural selection,some wild plants can adapt to the special environmental conditions around the slag yard of blast furnace lead smelting,and survive and reproduce in the soil polluted by heavy metals.If the pioneer plants with good heavy metal tolerance and heavy metal enrichment ability could be found among the dominant wild plants with high coverage rate in the surrounding area,it can provide important support for the treatment and restoration and ecological reconstruction of the same type of polluted sites.In this study,the typical blast furnace lead smelting waste slag yard in the north of Gejiu was taken as the research object.In order to study the enrichment characteristics of heavy metals in dominant plants,and select the pioneer plants which are suitable for ecological restoration,the heavy metal content in soil and five wild plants around the waste dump site,including Bidens pilosa,Dodonaea viscosa,Nerium oleander,Illicium dunnianum,and Pteris cretica,was investigated through field investigation.The results showed that,the soil pH in this area is acidic,Hg,Cd,As,Zn,Pb,Cu,Cr have varying degrees of excess.The pollution of associated elements such as Cd,As and Hg was the most serious,which were 98.09,34.56 and 76.93 times of Yunnan soil background value,respectively.The dominant plants investigated in this region have a certain tolerance to heavy metals and can adapt to the soil environment with high heavy metal content.The accumulation of seven types of heavy metals by five dominant plants has not reached the critical value of hyper-accumulation plants,but it has far exceeded that of common plants.The bio-concentration factors of Bidens pilosa,Dodonaea viscosa,and Pteris cretica to various heavy metals are all greater than 1,and the coverage rate was relatively high,showing good enrichment ability and remediation potential of heavy metal contaminated soil.Especially,the comprehensive enrichment coefficient of Dodonaea viscosa reached 9.58,which can be used as a pioneer species for ecological restoration in this area and similar areas.