不同增强试剂对二维电场下伴矿景天修复镉污染土壤的影响

为探讨添加不同增强试剂对二维电场下伴矿景天（Sedum plumbizincicola）修复镉（Cd）污染土壤的影响，采用室内盆栽试验，通过构建棒状石墨阳极在花盆四周，垂直网状不锈钢阴极在土壤表层的二维电场，研究了硫粉、菌菇渣溶解性有机质（DOM）和柠檬酸等不同增强试剂及固定直流电场和反转电场等不同电场模式对土壤理化性质、Cd迁移转化、伴矿景天生长和Cd吸收的影响。结果表明：无电场条件下，施加硫粉能使土壤pH下降0.5~1.0个单位，整体提高了土壤有效态Cd含量，并且显著提高了伴矿景天根部对Cd的积累，但显著降低了伴矿景天地上部生物量和地上部Cd积累量；施加DOM和柠檬酸可显著促进伴矿景天生长，但对伴矿景天吸收Cd影响较小，植物地上部Cd积累量分别是不添加增强剂的对照的1.43倍和1.60倍。施加固定直流电场使土壤表层总Cd发生迁移，增加了植物根区土壤总Cd含量，但并未使底层土壤总Cd向表层土壤迁移；反转电场缓解了土壤pH和有效态Cd的变化，使表层土壤总Cd向底层迁移。直流电场与DOM和柠檬酸共同作用时，固定直流电场和反转电场均显著抑制了伴矿景天的生长和对Cd的积累，电场对伴矿景天生长和Cd吸收的影响占主导地位；直流电场与硫粉共同作用时，硫粉对伴矿景天生长和Cd吸收的影响起主要作用。整体上，固定直流电场相较反转电场可增加植物对Cd的吸收，反转电场相较固定直流电场能增加植物生物量。固定直流电场与硫粉共同作用可显著增加伴矿景天根系Cd浓度，其对地上部的Cd吸收也有促进作用。研究表明，在利用伴矿景天修复碱性污染土壤时，电场+硫粉处理可作为一种有效的强化措施，但是硫粉的施用量需要进一步优化。

Effects of different enhancing agents on the remediation of cadmium contaminated soil by Sedum plumbizincicola under a two-dimensional electric field

To study the effects of different enhancing agents on the remediation of cadmium(Cd) contaminated soil by Sedum plumbizincicola under a two-dimensional(2D) electric field, the 2D electric field of a graphite rod vertical anode in the four corners of a soil matrix and a vertical, reticular stainless steel cathode on the soil surface was built, and the effects of sulfur powder, mushroom residue dissolved organic matter(DOM) and citric acid, as well as two different electric field modes, i.e., fixed direct current(DC) electric field and electric field reversion, on soil properties, total and bioavailable Cd contents, growth of S. plumbizincicola, and Cd uptake were studied by pot experiment in the laboratory. The study produced several interesting results:Under the condition of no electric field, applying sulfur powder reduced the soil pH by 0.5~1.0 unit, increased the bioavailable Cd content, and significantly increased the accumulation of Cd in roots; however, it significantly reduced the biomass of shoots and Cd accumulation in shoot. The addition of DOM and citric acid significantly promoted the growth of S. plumbizincicola, but it had little effect on Cd uptake by S. plumbizincicola, and the accumulation of Cd in the shoots of the plant was 1.43 times(for DOM) and 1.60 times(for citric acid) the accumulation of the control. The application of the fixed DC electric field caused the total Cd in surface soil to migrate and increased the total Cd content in the root zone soil, but it did not drive total Cd migration from the bottom layer to the soil surface. Electric field reversion alleviated the change of soil pH and bioavailable Cd, but it caused the total Cd in the surface soil to migrate to the bottom layer. Under the condition of the DC electric field with DOM and citric acid, both the fixed DC electric field and the reversed electric field significantly inhibited the growth and Cd uptake of S. plumbizincicola, and the effect of the electric field was dominant. When the electric field and sulfur powder acted together, the sulfur powder played a major role in the growth and Cd uptake of S. plumbizincicola. Overall, the fixed DC electric field increased the uptake of Cd by the plants relative to the reversed electric field, and the reversed electric field increased the biomass of plants relative to the fixed DC electric field. The fixed DC electric field with sulfur powder significantly increased Cd concentration in roots of S. plumbizincicola and also promoted Cd uptake in shoots. Therefore, the electric field plus sulfur powder treatment can be used as an effective strengthening measure in the remediation of alkaline Cd contaminated soil by S. plumbizincicola, but the application concentration of the sulfur powder needs to be optimized further.