新疆准东煤田土壤重金属来源分析及风险评价

为研究准东矿区土壤重金属来源及生态风险,分析了阜康市至准东矿区中间的3个缓冲区共27个土壤样方的As,Hg,Pb,Cr,Cu,Zn元素重金属含量状况,并利用因子分析、污染指数法、地累积指数法和潜在生态风险指数法对各缓冲区土壤重金属进行了污染来源及风险分析。结果表明:除Cr的总体平均值高于新疆土壤背景值外,其余重金属含量均低于背景值。基于土壤重金属空间分布图显示,除Cu,Hg含量高值分布于C区域土壤外,其余重金属高值均出现在准东矿区(A区域)附近土壤,3个区域各重金属所占比例基本一致,距离矿区越远,变异系数呈减少趋势;污染源分析可知,准东矿区89.3%的Hg来源于煤炭燃烧,40.1%的Pb来源于交通运输,19.65%的As来源于大气降尘,Cu和Cr的主要来源为煤尘,其贡献率分别为60.23%和81.57%,其中29.7%的Cu来源于土壤母质,75.1%的Zn来源于土壤母质;基于污染指数法、地累积指数法和潜在生态危害指数法对不同缓冲区土壤污染风险进行了评价,得出土壤整体呈轻度-中度污染水平,距离矿区越远重金属污染状况越轻。As,Hg,Pb和Cr元素生态风险均呈现缓冲区区域A区域B区域C的趋势,距离矿区越远,生态风险越低。潜在生态风险指数与重金属单因子生态风险的大小顺序一致。

Soil heavy metal sources analysis and risk evaluation of Zhundong coal mine in Xinjiang

Abstract: During the process of opencast and underground coal mining, a variety of rock types with different compositions are exposed to atmospheric conditions and undergo accelerated weathering. These materials are often deposited nearby as mine waste rocks and mine dust. Heavy metal pollution is the representative environmental pollution which is caused by heavy metals or their compounds. It has wide range, long duration, non-degradability, and some other features. The accumulation of heavy metals in soil will destroy the physical and chemical properties of soil, cause irreversible pollution of environment, and further threaten human health. For mining area, influenced by human exploitation, the top soil is thin and is easily affected by atmospheric dust fall. To study the origin of heavy metals in soils and ecological risk in Zhundong area, we analyzed heavy metal (As, Hg, Pb, Cr, Cu and Zn) content with 27 soil samples in three buffers (every 42 km from Zhundong Diggings to Fukang City was divided into a area, area A, area B and area C). The risk analysis of heavy metals was carried out by means of pollution index method, land accumulation index method and potential ecological risk index method. The results showed that: 1) In addition to the overall average value of Cr is 53.03 mg/kg, which is higher than the background value of soil (49.3 mg/kg) in Xinjiang, the contents of other heavy metals are lower than their background values. The figures of spatial distribution of soil heavy metals indicate that: High values of Cu and Hg content was distributed in the area C, high values of other heavy metal content appeared in soils near Zhundong mining area (area A), the heavy metal content in the three buffers are basically the same, the coefficient of variation decreased with the increasing of distance to the mining area. 2) Through the analysis of pollution sources, in Zhundong area, 89.31% of Hg comes from coal burning, 40.1% of Pb comes from transportation, 19.65% of As comes from atmospheric dust. The main source of Cu and Cr is coal dust and its contribution rates are 60.23% and 81.6% , respectively, 29.7% of Cu comes from the soil parent material, and 75.1% of Zn comes from the soil parent material. There are still unknown sources of heavy metals in soil except Zn. 3) The soil pollution risk in the study area was evaluated by means of pollution index method, land accumulation index method and potential ecological hazard index method. The pollution level of soil in Zhundong area is mild-moderate, single element pollution degree from high to low is Hg>As>Pb>Cr>Cu>Zn. The farther away from the mining area, the lighter the heavy metal pollution is. The rank of Regional ecological risks of As, Hg, Pb and Cr elements was A >B >C, the farther away from the mining area, the lower the ecological risk is. The potential ecological risk index is consistent with the order of single factor ecological risk of heavy metals. The mining of coal results in the pollution of heavy metals in the surrounding soil, which seriously affects people undefined cultivation and life, and also affects the ecological environmental system. Therefore, it is necessary to establish a system of environmental protection and strictly manage of mining in mining areas.