额尔齐斯河流域典型尾矿库区周边土壤重金属污染评价

Evaluation of Heavy Metal Pollution in the Soil Around A Typical Tailing Reservoir in Irtysh River Basin

为了解额尔齐斯河流域典型尾矿库区周边土壤中8种重金属元素(Cr、Ni、Cu、Zn、Cd、Pb、Mn、As)的富集特征,采用调查分析方法,以额尔齐斯河流域土壤背景值和国家土壤环境Ⅱ级标准作为参比值,利用单因子污染指数(Contamination Factor,CF)、污染负荷指数(Pollution Load Index,PLI)、潜在生态风险指数(Potential Ecological Risk Index,RI)和生态风险预警指数(Ecological Risk Warning Index,I_(ER))对尾矿库区周边土壤重金属污染程度以及生态风险进行评价,旨在保护尾矿库区周边土壤环境安全,为土壤环境污染治理提供科学依据。结果表明,(1)尾矿库区周边土壤中Cr、Ni、Cu、Zn、Cd、Pb、Mn和As的含量平均值分别超出该区域土壤背景值的7.53、36.08、31.45、0.68、35.32、1.76、0.76和0.65倍。其中,Cd、Ni、Cu和Cr属于重度污染,Pb、Mn、Zn和As属于轻度污染。(2)尾矿库区周边土壤中重金属元素Ni、Cu和Zn主要来自于尾矿库区,Cr、Cd和Pb与交通运输以及矿业生产活动有关,As和Mn主要受土壤地球化学作用的控制。(3)以额尔齐斯河流域土壤背景作为参比值,研究区土壤PLI平均值为4.04,呈现重度污染,土壤RI平均值为1511.40,呈现很强生态风险态势;土壤IER平均值为115.02,属于重度预警水平。(4)基于国家土壤环境Ⅱ级标准,研究区内调查样点处于强度生态风险和很强生态风险的占比分别为18.52%、81.48%,处于重度预警水平的样点占比为100%。因此,从污染程度和恢复时间的角度来看,尾矿堆存都造成了巨大的环境足迹,急需针对尾矿库周边的土壤重金属污染采取修复措施。

This study investigated the rich characteristics of eight heavy metal elements(Cr,Ni,Cu,Zn,Cd,Pb,Mn,As)in the soil surrounding the typical tailings reservoir of the Irtysh River Basin.The soil background value of the Irtysh River Basin and the national soil environment standard(GradeⅡ)were used as reference values.To provide scientific basis for controlling the soil environmental pollution surrounding the tailings reservoir,the level of heavy metal pollution in the soil around the tailings reservoir and ecological risks were evaluated by the contamination factor(CF),the pollution load index(PLI),the potential ecological risk index(RI),and the ecological risk warning index(IER).The main results showed that(1)the average contents of Cr,Ni,Cu,Zn,Cd,Pb,Mn and As in the soil around the tailings reservoir exceeded the soil background by 7.53,36.08,31.45,0.68,35.32,1.76,0.76 and 0.65 times,respectively.Among them,Cd,Ni,Cu and Cr belonged to high pollution,and Pb,Mn,Zn and As belonged to light pollution.(2)The heavy metal elements of Ni,Cu and Zn in the soil around the tailings reservoir area mainly came from the tailings reservoir area.Cr,Cd and Pb were related to transportation and mining production activities.As and Mn were mainly controlled by soil geochemistry.(3)Taking the soil background of the Irtysh River basin as the reference value,the average soil PLI in the study area was 4.04,showing high pollution;the average soil RI was 1511.40,showing strong ecological risks;and the average soil I_(ER) was 115.02,a severe warning level.(4)Based on the national soil environment standard(GradeⅡ),the proportions of survey sites in the study area that were of high ecological risks and serious ecological risks were 18.52%and 81.48%,respectively,and the proportion of the sites at the severe warning level was 100%.Therefore,based on the pollution degree and recovery time,tailings stockpiling had caused a huge environmental threat,so it is urgent to take remediation measures to control the soil heavy metal pollution around the tailings pond.