三峡库区消落区表层土壤重金属污染评价及源解析

三峡库区是我国重要的水源地, 研究库区水陆交错带消落区内土壤重金属污染程度并解析其来源,对水库的水环境和土壤环境具有重要意义。本研究采用地质累积指数, 对三峡库区消落区175 m 水位蓄水前12 个采样区表层68 个土样的土壤重金属Cu、Pb、Zn、Cd、Hg、As 和Cr 污染进行评价, 结果表明: 整个研究区不受Cr 污染, 研究区70%以上面积不受Pb、Cu 和Zn 污染; 研究区As 污染最严重, 其次为Cd 和Hg。利用因子分析法对这7 种重金属来源进行解析的结果表明, 库区消落区土壤重金属源可分为2 大类别:“自然因子”类别元素(Cr、Pb、Cu 和Zn)和“工业污染因子”类别元素(Hg、As 和Cd)。消落区表层土壤重金属污染评价及源解析可为消落区生态环境的综合治理提供参考。

Sources and assessment of heavy metal contamination in water-level fluctuation zone of the Three Gorges Reservoir, China

The Three Gorges Reservoir is one of the most important water resources in China. Understanding the degree of soil contamination in the water-level fluctuation zone is critical for water/soil conservation in the region. A total of 68 soil samples were collected at 12 sites in the reservoir region and analyzed before the water level rose to 175 m above mean sea level. The degrees of Cu, Pb, Zn, Cd, Hg, As and Cr contamination were determined via the geo-accumulation index (Igeo) method. The study showed that soils in the reservoir region were severely contaminated with As, Cd and Hg. While there was no Cr contamination in the reservoir region; Pb, Cu and Zn contamination was not significant in about 70% of the region. Further Factor Analysis on sources of heavy metals revealed that Cr, Pb, Cu and Zn contamination in the water-level fluctuation zone were caused by natural factors, and that of Hg, As and Cd by industrial factors. The findings of sources and the evaluation of surface soil heavy metal contamination were critical for sustainable environmental management in especially the water-level fluctuation zone in the Three Gorges Reservoir.