湘江流域土壤重金属元素地球化学背景值与基准值研究

    Geochemical background and baseline values of heavy metals in soils in the Xiangjiang River Basin

    • 摘要: 本研究旨在探讨湘江流域土壤中重金属元素的地球化学背景值和基准值特征,选取表层和深层土壤As、Cd、Cr、Cu、Hg、Pb、Zn、Ni、pH共9项指标,运用迭代法、箱图剔除法、含量—面积分形法等方法,对湘江流域多目标区域地球化学调查完成区的土壤环境背景值进行研究,按不同地层单元及土壤类型对地球化学背景值和基准值影响因素进行讨论。研究结果显示,以上几种计算方法总体差异不大,但不同方法得出的结论均反映研究区内土壤中8种重金属背景值总体高于全国水平,其中Hg和Cd的背景值接近全国背景值的两倍,表明湘江流域是Hg、Cd高背景区;土壤重金属背景值与母岩关系密切,元素富集水平及富集元素数量随着地层年代的由古到今呈增大的趋势,其中Cd的表现尤为明显;湘江流域不同土壤类型的重金属元素地球化学背景值普遍高于基准值。本次研究成果为湘江流域生态环境评价及土地规划提供了重要依据。

       

      Abstract: This study aims to investigate the geochemical background and baseline values of heavy metals in soils in the Xiangjiang River basin. Focusing on nine indicators, i.e., As, Cd, Cr, Cu, Hg, Pb, Zn, Ni, and pH, in both surface and subsurface soils and using methods such as iterative calculations, boxplot-based outlier removal, and content-area fractal analysis, this study investigated the background values in the soil environment within the basin' areas where multi-target geochemical survey had been conducted. Accordingly, the study discussed the factors influencing the geochemical background and baseline values of various stratigraphic units and soil types. The results indicate minimal differences in the results derived using these calculation methods. All methods consistently indicate that the background values of eight heavy metals exceed national averages, with those of Hg and Cd approaching twice the national background levels. This suggests that the Xiangjiang River basin has high geochemical background values of Hg and Cd. The background values of heavy metals in soils within the basin are closely related to parent rock types, with element enrichment levels and the number of elements enriched in soils generally increasing with a decrease in the age of strata, specifically for Cd. Across different soil types within the Xiangjiang River Basin, the geochemical background values of heavy metals are generally higher than their baseline values.The research results of this study provide an important basis for the ecological environment assessment and land planning of the Xiangjiang River Basin.

       

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