三峡水库蓄水对消落带土壤Cu、Zn、Cr、Cd含量的影响

为揭示水位涨落形成系列淹水梯度对消落带土壤重金属含量的影响,论文采集三峡水库忠县消落带土壤,分析了不同淹水深度土壤Cu、Zn、Cr、Cd含量,并探讨了这些重金属元素物质来源及其与三峡水库水位涨落关系。结果表明：1）不同淹水深度下消落带土壤重金属含量差异较大,长期淹水土壤Cu、Zn、Cd含量远远高于短期淹水和未淹水土壤,Cr则在不同淹水深度略有变化;2）除Cr相对独立外,不同淹水深度下土壤SOM、pH与土壤Cu、Zn、Cd含量密切相关,但pH、SOM间仅有微弱的相关关系;3）因子分析中因子1和因子2对Cu、Zn、Cr、Cd的累计贡献率为93.47%,Cu、Zn、Cd在第一轴载荷值为0.962、0.967、0.925,Cr在第二轴载荷值为0.998。研究发现：1）重金属输入来源和流向异质性是决定不同淹水深度Cu、Zn、Cr、Cd含量差异的重要原因,长期淹水显著增加了土壤Cu、Zn、Cd含量,但对Cr效应并不明显;2）区域土壤内Cr主要来源为自然源的土壤侵蚀和母岩风化,Cu、Zn、Cd来源于人为输入的库岸输入和长江上游来水悬浮颗粒沉积,应引起足够重视。

The Effect of Water Fluctuation on the Contents of Soil Cu,Zn, Cr and Cd at the Riparian Area of Three Gorges Reservoir

To reveal the contents of soil heavy metals that affected by periodic water fluctuation in the riparian soil of Three Gorges Reservoir, the contents of soil Cu, Zn, Cr and Cd in different flooding gradients were analyzed, and the sources of the four heavy metals and the relationship between the contents of those heavy metals and water level fluctuation were further discussed. The results showed that: 1) The contents of soil heavy metal in the riparian area of different flooding gradients were significantly different. The contents of Cu, Zn and Cd were higher in long submerged soil than in short submerged and non-flooded soil, whilst soil contents of Cr had slight change at different water levels. 2) Except Cr, the contents of Cu, Zn and Cd were closely related to values of SOM and pH in soil, but there was only a weak correlation between pH and SOM. 3) PC 1 and PC 2 explained 93.47% of the total variance in soil Cu, Zn, Cr and Cd. Cu, Zn and Cd had the greatest loading of 0.962, 0.967, 0.925 in PC 1, respectively, whilst the load value of Cr in PC 2 was 0.998. The results suggested that: 1) Heterogeneity in the sources and flow directions of heavy metals determined the different heavy mental contents in different submerged soils. Long-term flooding significantly increased the contents of soil Cu, Zn and Cd, but had little effect on Cr. 2) Cr in this region was originally derived from soil erosion and bedrock weathering, while Cu, Zn and Cd originated from the anthropogenic activities on the farmland surface and the sediment of suspended particles from upstream water.