蚯蚓-香根草联合作用对复垦土壤重金属Cr、Cu、Pb和Zn的影响

    Effect of Earthworm-vetiver Combination on Heavy Metals Cr, Cu, Pb and Zn in Reclaimed Soils

    • 摘要: 为研究蚯蚓-香根草联合作用对复垦土壤重金属Cr、Cu、Pb和Zn总量及有效态含量的影响, 采用土柱模拟试验, 设置50和70 cm 2组厚度覆土, 每组覆土分别设置不种植香根草不添加蚯蚓(CK)、单独种植香根草(V)、单独添加蚯蚓(E)和蚯蚓-香根草联合(VE)4个处理, 分析覆土理化性质以及Cr、Cu、Pb和Zn总量和有效态含量变化特征。结果表明, 与CK相比, V、E和VE处理均能显著降低土壤Cr、Cu、Pb和Zn总含量(P < 0.05), 且VE处理对重金属总量的降低效果优于其他处理, VE处理50和70 cm厚度覆土重金属Cr、Cu、Pb和Zn总含量与CK相比分别降低4.90%、13.12%、10.36%和6.91%以及5.47%、11.20%、10.34%和6.96%。与CK相比, E处理能提高覆土重金属有效态含量; V处理能降低覆土Cu、Pb和Zn有效态含量; VE处理降低覆土Pb有效态含量的效果较弱, 降低Cu和Zn有效态含量的效果较强。同一覆土厚度条件下, 与CK相比, V、E和VE处理均能降低覆土pH值, 提高土壤OM、TN和TP含量。此外, 接种蚯蚓能增加香根草生物量, 且蚯蚓对香根草地下部生物量增加的效果比地上部生物量更显著。相关性及冗余分析结果表明, 接种蚯蚓后, 土壤pH与Cr和Pb有效态含量呈显著负相关(P < 0.05);OM含量与Cr和Pb有效态含量呈显著负相关, 与Zn有效态含量呈显著正相关(P < 0.05);TN和TP含量与Cu和Pb总含量呈显著负相关(P < 0.05), 土壤pH和OM含量是影响土壤重金属含量的关键因子。因此, 蚯蚓-香根草联合能改善土壤理化性质, 降低覆土重金属含量。

       

      Abstract: In order to study the effect of earthworm-vetiver combination on the total and available heavy metals (Cr, Cu, Pb, Zn) in reclaimed soils. The soil column simulation experiment was set up for two groups of overburden soil thickness (50 and 70 cm). Each group was set up with four treatments: no vetiver plant without earthworm addition (CK), vetiver plant alone (V), earthworm alone (E) and the combined earthworm-vetiver (VE). The total and available Cr, Cu, Pb and Zn contents and the physicochemical properties of the overburden soil were analyzed for different treatments. The results show that treatments of V, E and VE significantly reduced the total Cr, total Cu, total Pb and total Zn contents of the soil compared to the control (P < 0.05). The VE was more effectively in reducing the total amounts of heavy metals than other treatments. The reduction rate of total Cr, total Cu, total Pb and total Zn in VE was 4.90%, 13.12%, 10.36% and 6.91% in the 50 cm group and 5.47%, 11.20%, 10.34% and 6.96% in the 70 cm group, as compared with the CK, respectively. In comparison with CK, treatment E increased the available heavy metals contents, treatment V reduced the available contents of Cu, Pb and Zn, treatment VE showed a weaker reduction for available Pb, but a stronger reduction for available Cu and Zn. At the same thickness, treatments of V, E and VE all reduced pH and increased OM, TN and TP compared to CK. In addition, inoculation with earthworm increased the biomass of vetiver grass, and the root biomass was increased more than shoot biomass. Correlation and redundancy analysis for inoculation with earthworms revealed that, soil pH was significantly and negatively correlated with available Cr and Pb (P < 0.05); OM was significantly and negatively correlated with available Cr and Pb and positively correlated with available Zn (P < 0.05); TN and TP were significantly negatively correlated with total Cu and total Pb (P < 0.05). Soil pH and OM are the key factors affecting soil heavy metal content. Therefore, the combination of earthworm-vetiver can improve physicochemical properties and reduce heavy metal concentration in the reclaimed soil, which provides an important method for the remediation of reclaimed soils.

       

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