平顶山矿区丘陵坡地土壤重金属分布及污染特征

对平顶山矿区周边丘陵坡地土壤进行采样,分析了Cu、Zn、Cr、Ni、Pb在不同海拔与矿区下风向不同距离处的分布特征及污染水平。结果表明:①矿区丘陵坡地土壤存在不同程度的重金属累积,以Ni、Cr、Cu累积较重。②五种元素均在矿区、坡底附近及近坡顶含量较高,而在矿区下风向以50 m内含量最高,之后呈递减趋势。③Cu、Cr、Pb随坡度减小而含量增大,Zn、Ni在坡度5°~15°时含量最大;土地利用对坡面土壤重金属的分布不产生明显影响,林地、草地、坡耕地之间重金属含量也无显著差别。④五种元素均在矿区附近产生污染,矿区以下存在Cu、Ni、Pb污染,而矿区以上只有Ni出现轻度污染;矿区下风向Cu、Ni污染且迁移距离较远,Cr、Pb仅在100 m内出现轻度污染,Zn尚未达到污染水平。⑤Ni、Cu、Pb以人为活动源为主,Cr和Zn以自然源为主。

Distribution and pollution of soil heavy metals in hilly upland around Pingdingshan coal mining area

An attempt was made to investigate the influence of mining activities upon the hilly upland soil around Pingdingshan coal mining area. Topsoil samples were collected from this area. Subsequently, the contents of five heavy metals, including Cu, Zn, Cr, Ni and Pb, were determined by means of the standard analysis methods of soil chemical composition. We analyzed their distribution characteristics at different altitudes and at different distances off the wind direct from the mining area, and evaluated the conditions of soil heavy metal pollution by adopting geo-accumulation index. The results are shown as follows. 1) The accumulations of heavy metals mentioned above were different from each other at different extents in the hilly upland soil around Pingdingshan coal mining area, in which Ni was the most significant, followed by Cr, Cu and Pb in turn. 2) The higher concentrations of five heavy metals at different altitudes were found in the mining zone, near slope bottom and slope top respectively. On the other hand, the highest concentrations were found within a distance of 50 m off the wind direct from the mining area, and contents of five heavy metals decreased as the distance increase. 3) Contents of Cu, Cr and Pb increase with the slope reduction, while the lowest contents of Zn and Ni were found in soils of slope from 5° to 15°. However, land use patterns showed no effects on the distributions of heavy metals in the upland soil around Pingdingshan coal mining area. Moreover, the contents of five heavy metals between forest land, grassland and arable land were not significantly different. 4) Cu, Zn, Cr, Ni and Pb pollutions were all found in the mining zone, and Cu, Ni and Pb pollutions were also found on the slopes below the mining zone, yet soils in slopes above the mining zone were only lightly polluted by Ni. Cu and Ni were the main pollution elements in downwind direction, with light to intermediate pollutions at different distances. Cr and Pb showed light pollutions within a distance of 50 m off the wind. Otherwise, Zn still kept clean in downwind direction. 5) Ni, Cu and Pb contaminations in the hilly upland soil around Pingdingshan coal mining area were caused mainly by human activities. In contrast, Zn and Cr were chiefly from natural sources.