三峡库区消落带土壤金属污染特征的研究进展

三峡库区蓄水后的生态环境问题受到人们和政府的高度重视,库区消落带是水库生态环境的重要组成部分。近年来,针对库区消落带土壤金属环境问题,国内外相关学者开展了大量的研究工作。基于近十年相关研究成果,本文对三峡库区消落带土壤金属含量、时空分布特征及生态环境风险进行了梳理、归纳和分析。结果表明,三峡库区消落带土壤金属含量总体呈现库区上游及下游较高,库区中游较低的空间格局,不同水位高程不同土壤层中各金属元素的分布特征存在一定差异。与蓄水前期相比,库区消落带土壤金属含量随干湿交替周期的增加呈现动态变化,且存在向江水中迁移的环境风险。由土壤环境质量评价结果可知,研究区域土壤总体上为二类土,处于轻度污染等级,存在轻微生态风险,主要风险元素为Cd,其次为As和Hg,但目前其含量并未影响人体生命健康。针对库区消落带的研究现状,本文提出今后相关研究的着眼方向,以期为三峡库区消落带土壤重金属污染防控及库区水生态环境保护提供参考。

Reviews on soil metal pollution in water-level fluctuation zone of Three Gorges Reservoir area

At present, the eco-environmental problem in the Three Gorges Reservoir (TGR) area is highly concerned by government and people. The water-level fluctuation zone (WLFZ) is a significant component of ecological environment in the TGR. In recent decades, the heavy metal pollution in soils in WLFZ has attracted much attention from researchers all over the world. However, the comprehensive analysis on heavy metal pollution in soils in WLFZ remains scarce. Through literature review (the last ten years), this study summarizes the content, spatial and temporal distribution characteristics and ecological environmental risks of heavy metal in soils in WLFZ in TGR. The results show that in general, the concentrations of heavy metal in soils in WLFZ are higher in the upper and lower reaches than those in the middle reaches in the TGR. Meanwhile, the distribution characteristics of heavy metal vary with soil layer and elevation. Compared with soils before submergence, the metals concentration in soils in WLFZ exhibit dynamic change with the increase of dry/wet alternation cycle, and heavy metal in soils has the potential to transform into river water. The environmental risk assessment suggested that the studied soil generally belongs to the second-class soil, which is slightly polluted and shows slow ecological risk. The main heavy metals with ecological risks are Cd,followed by As and Hg. However,these metals do not influence human health at present. Finally, this review summarizes future research perspectives on the basis of current research status, which will provide a basis for the development of strategies to prevent soil heavy metal pollution in WLFZ and conserve water ecological environment in the TGR.