黑岱沟露天煤矿复垦区土壤重金属变化及评价

Abstract

为了揭示煤矿复垦区土壤重金属含量随复垦年限的分布变化情况，并进行土壤环境污染的评价，本文以黄土高原区的黑岱沟露天煤矿的排土场复垦区为研究对象，采取不同复垦年限0~40 cm土层土样，对不同复垦年限下土壤重金属含量变化情况进行了分析和评价。结果表明：随着复垦年限的延长，复垦区土壤Pb、Cr、Cd和As含量整体均表现为逐年较少，表层含量高于下层，复垦15 a后含量均低于中国环境质量标准的一级标准。然而土壤Hg含量却整体表现为升高的变化趋势，0~20 cm土层含量增加，含量高于中国环境质量标准的一级标准，但低于中国环境质量标准的二级标，但20~40 cm土层含量减少，含量低于中国环境质量标准的一级标准。矿区复垦时间越长，重金属含量越低，对环境污染越小，而对于Hg含量不降反升的原因建议进一步的深入探究。 To reveal the changes of heavy metals distribution in different reclaimed years in coal mine re-claimed areas, and evaluate the environmental pollution, in this study we chose the reclaimed areas of Heidaigou mining opencast coal mine in loess plateau region as our research object. We sampled from 0 - 40 cm soil depth in different reclaimed areas, analyzed and evaluated the changes of soil heavy metals under different years after reclamation. The results showed that: As the years increased after reclamation, the content of Pb, Cr, Cd and As reduced gradually from a whole respect, and the contents in topsoil were higher than subsoil. After reclamation of 15 years, its contents were lower than the primary standard of the soil environmental quality standards in China. However, the content of Hg followed an increasing trend. It increased in 0 - 20 cm, and the value was higher than the secondary standard of the soil environmental quality standards in China, but lower than the primary standard. But it decreased in 20 - 40 cm soil layer, its value was lower than the primary standard of the soil environmental quality standards in China. The longer of reclamation, the lower contents of heavy metals, and smaller pollution to the environment. As to the phenomenon of Hg content increasing rather than reducing, it needs further study.