摘要
探究内蒙古西部露天矿排土场土壤重金属污染状况及其来源对类似矿区排土场土壤重金属污染治理具有重要意义。本文以乌海市棋丰露天矿排土场土壤为研究对象,选择阳坡、半阳坡和阴坡的沙打旺+沙生冰草+披碱草样地、黑沙蒿+紫花苜蓿+沙打旺+黄芥样地、柠条+沙打旺+沙生冰草+黑麦草样地,以自然修复边坡为对照共10类样地。通过测定分析As、Hg、Pb、Cr、Cd、Cu、Zn7种重金属元素含量,利用单因子污染指数、内梅罗综合污染指数、潜在生态危险指数对排土场土壤重金属污染水平和潜在生态风险进行评价,并结合相关性分析和主成分分析探索排土场土壤重金属污染来源。结果表明:(1)棋丰露天矿排土场土壤重金属含量与植物群落配置类型、坡向影响不大,人工配置样地的Cr元素含量较自然修复边坡大幅减少;Hg和Pb含量超土壤Ⅰ级标准,Cd超过Ⅱ级标准,与内蒙古土壤背景值相比,排土场的As、Hg、Pb和Cd含量均超标,排土场土壤存在一定程度重金属积累。(2)单因子污染指数从大到小依次为:Cd>As>Pb>Cr>Hg>Cu>Zn,且排土场样地均受到Cd的污染;从内梅罗综合指数可以看出,排土场土壤重金属处于中度及中度污染水平;单个重金属潜在生态风险指数大小为:Cd>As>Hg>Pb>Cr>Cu>Zn,Cd介于108.650-180.600,为最主要的潜在生态风险因子;综合潜在生态风险指数为114.665-188.792,轻微和中等潜在生态风险样地各占50%。不同评价方法的结果都认为棋丰排土场受到重金属污染,Cd的污染程度和生态风险远高于其它重金属元素,应及时对Cd采取控制措施。(3)相关分析和主成分分析表明,Hg、Pb和Cd来源于道路煤尘扩散及尾气排放,Cu、Zn和Cr来源于交通运输与农业生产活动,As来源于煤炭燃烧污染。
Exploring the status and sources of heavy metal pollution in the soil of the dump in Wuhai City,western Inner Mongolia,is of great significance.This study selected a sunny slope,a half-sunny slope and shady slope with plots of(A)Astragalus adsurgens+Agropyron desertorum+Elymus,(B)Caragana korshinskii+Astragalus adsur-gens+Agropyron desertorum+Lolium,and(C)Medicago sativa+Artemisia ordosica+Astragalus adsurgens+Brassica juncea,and a naturally repaired slope for comparison,yielding a total of 10 types of sample plots.The soil heavy metal pollution levels and the potential ecological harm were assessed by the process of measuring the contents of seven heavy metal elements(As,Hg,Pb,Cr,Cd,Cu and Zn)in dump soil as a single factor pollution index,and then the comprehensive pollution index,potential ecological risk index and the mine soil heavy metal pollution sources were explored by correlation analysis and principal component analysis.The results showed three important aspects of the pollution levels,impacts and sources in this dump.(1)The heavy metal contents in Qifeng dump had little influence on the plant community composition type and no clear relationship with the slope direction,but the Cr content in the manually configured sample was significantly reduced compared with that in the naturally restored slope.The contents of Hg and Pb exceed their soil grade I standards,and Cd exceeds the National Grade II standard compared with the soil background values of Inner Mongolia.The As,Hg,Pb and Cd levels of the dump exceed their standards,so there is a certain degree of heavy metal accumulation in the soil of the dump.(2)The single factor pollution index in descending order is Cd>As>Pb>Cr>Hg>Cu>Zn,and all the dump samples are polluted by Cd.According to the Nemerow composite index,the heavy metals in the soil of the dump are at mid-dlingor moderate pollution levels.The potential ecological risk index values of the individual heavy metals were in the order of Cd>As>Hg>Pb>Cr>Cu>Zn,so Cd was the most important potential ecological risk factor ranging from 108.650 to 180.600.The comprehensive potential ecological risk index ranged from 114.665 to 188.792,in-dicating that 50%of the plots were at slight or moderate potential ecological risks,respectively.According to the different evaluation methods,Qifeng dump is polluted by heavy metals,and the pollution degree and ecological risk associated with Cd are much higher than those of the other heavy metals.Therefore,timely control measures should be taken for Cd.(3)The correlation analysis and principal component analysis showed that Hg,Pb and Cd came from road coal dust diffusion and exhaust emissions,while Cu,Zn and Cr came from transportation and ag-ricultural production activities,and As came from coal combustion pollution.
作者
刘瑞瑶
秦儒
斯庆
许丽
王涵
丛龙宇
刘泽蒙
LIU Ruiyao;QIN Ru;SI Qing;XU Li;WANG Han;CONG Longyu;LIU Zemeng(College of Desert Control Science and Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China;Key Laboratory of State Forest Administration for Desert Ecosystem Protection and Restoration,Hohhot 010018,China;Qiongzhong County Environmental Protection Monitoring Station,Qiongzhong,Hainan 572931,China;Ordos Forestry and Grassland Development Center,Ordos,Inner Mongolia 017000,China)
基金
The Inner Mongolia Autonomous Region Science and Technology Major Project(2020ZD0020-2)
The National Key Research and Development Program of China(2017YFC0504402)。
关键词
露天矿区
矿山排土场
重金属污染
open-pit mining area
waste dump of mine
heavy metal pollution
