硫磺对土壤镉有效性动态调控及超富集植物镉吸收累积的影响研究

Effects of Sulfur Amendment on the Dynamic Regulation of Cadmium Availability in Soil and Its Uptake by Hyperaccumulator Plants

    摘要
  • 摘要:
    目的 土壤硫素的氧化还原过程与重金属环境行为密切相关，探究硫对镉（Cd）在土壤－超积累植物中迁移的影响，并揭示其主控因素，为农田土壤植物修复体系构建提供方法和理论支撑。
    方法 采用室内模拟结合田间验证的方法，分析了不同添加量的硫磺（0%、0.1%、0.25%、0.5%、1%）对土壤Cd生物有效性的动态调控过程，并探究了硫磺施加对典型Cd超积累植物叶芽鼠耳芥及东南景天Cd吸收、累积的影响。
    结果 土壤pH随硫磺施用后时间的延长而降低，处理28 d后土壤pH降低幅度减小，且pH的降低幅度与硫磺施加量成正相关。土壤中溶解性有机碳（Dissolved Organic Carbon，DOC）的浓度随硫磺施用后时间的延长有增大的趋势，0.5%和1%的硫磺处理112 d后，土壤DOC浓度分别比对照组升高1.08和1.78倍。土壤有效Cd浓度随硫磺施用后时间的延长而增大，其中112 d后0.25%的硫磺处理组DGT提取态Cd浓度最高，较对照组提高了5.97倍，施用1%的硫磺处理组DTPA提取态Cd浓度最高，较对照组升高了70.4%。盆栽实验与田间实验进一步证明硫磺的施用促进了超积累植物对土壤Cd的吸收，且在一定范围内随着硫磺添加量的增大，东南景天植株中Cd的累积量也在增大。
    结论 施用硫磺能够降低土壤pH值，28 d后降低幅度变小，硫磺的添加可缓慢促进土壤Cd向有效态转变，适量添加硫磺（0.5%）可有效提高超积累植物对土壤Cd的提取效率。

     

    Abstract:
    Objective The oxidation - reduction processes of sulfur in soil are closely related to the environmental behavior of heavy metals. Investigating the influence of sulfur on cadmium (Cd) migration in hyperaccumulator plants and revealing the dominant controlling factors can provide methodological and theoretical support for the construction of phytoremediation systems in agricultural soils.
    Method By conducting both pot and field experiments, the dynamic regulation of soil Cd bioavailability by different rates of sulfur (0%, 0.1%, 0.25%, 0.5%, and 1%) in Cd contaminated agricultural soils was investigated and the impact of sulfur application on the accumulation of Cd in Arabidopsis thaliana and Sedum alfredii Hance was revealed.
    Result Soil pH decreased with the addition of sulfur and the decrease of pH slowed down about 28 d. The concentration of dissolved organic carbon (DOC) in the soil showed a trend of increase with the addition of sulfur, and the concentration of DOC in soil increased by 1.08-fold and 1.78-fold respectively compared with that of the control group after soil treated with 0.5% and 1% sulfur for 112 d. The concentration of bioavailable Cd in soil increased with the addition of sulfur, with the highest concentration of DGT-extractable Cd in soil treated with 0.25% sulfur for 112 d, which was 5.97 times higher than that of the control group, and the highest concentration of DTPA-extractable Cd in soil treated with 1% sulfur for 112 d, which was 70.4% higher than that of the control group. Pot and field experiments further confirmed that sulfur addition promoted Cd uptake by hyperaccumulator plants. Within a certain range, the Cd accumulation in Sedum alfredii increased with higher sulfur application rates.
    Conclusion Sulfur application can reduce soil pH, with a slower decline after 28 days. The addition of sulfur gradually promotes the transformation of soil Cd into bioavailable forms. An appropriate sulfur application rate (0.5%) can effectively enhance the Cd extraction efficiency of hyperaccumulator plants.

     

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