植物修复以其资源可回收、成本低、低碳绿色等优点逐渐成为土壤重金属污染原位修复的首选方式.然而石灰性土壤中重金属的生物有效性低,限制了植物修复技术的应用.为了探讨活化剂强植物修复技术对石灰性土壤重金属污染的修复效果,以大豆为模式植物,通过盆栽培养试验,研究添加不同浓度草酸、乙二胺四乙酸(ED-TA)和柠檬酸等活化剂对石灰性土壤中大豆生长及其富集Cd的影响.结果表明:添加低、中浓度的活化剂对大豆生长无显著影响,而高浓度活化剂在一定程度上会抑制大豆的发芽、生长及营养成分累积.添加活化剂可以促进大豆对Cd的吸收,其中添加 1.0 μmol·g-1 EDTA和 3.0 μmol·g-1草酸的促进效果最显著,Cd去除率分别是对照组的 3.99倍和 3.96 倍.添加活化剂降低了土壤pH值,改变了土壤中Cd的赋存形态,添加草酸和低浓度的EDTA能使土壤中的Cd从较稳定形态转化为植物易吸收态,从而促进大豆对土壤Cd的去除,而添加柠檬酸可以促进Cd的茎向传输从而提高大豆对Cd的去除率.此研究结果为石灰性土壤重金属污染植物修复技术的应用及推广提供参考.
With advantages of resource recyclability,low-cost,low carbon emissions and environmental friendliness,phytoremediation is gradually replacing other methods for in situ treatment of heavy metal pollution in the soil.However,the low biological effectiveness of heavy metals in the calcareous soil limits the application of phytoremediation technology.In order to investigate the efficiency of activator-strengthened phytoremediation tech-nology on the remediation of heavy metal contamination in the calcareous soil,effects of different concentrations of activators such as oxalic acid,ethylenediaminetetraacetic acid(EDTA)and citric acid on the soybean growth and their Cd enrichments were investigated by pot culture tests using soybean as the model plant.Results show that the addition of low and medium concentrations of activators has no significant effect on the soybean growth,while high concentrations of activators can,to a certain extent,inhibit the germination,growth and nutrient accumulation of soybean.The addition of activators promotes the uptake of Cd by soybean,with the most significant promotion effect achieving via adding 1.0 μmol·g-1 of EDTA and 3.0 μmol·g-1 of oxalic acid,and the Cd removal rate is 3.99 and 3.96 times higher than those of control group,respectively.The addition of activators lowers the soil pH and chan-ges the form of Cd in the soil.The addition of oxalic acid and a low concentration of EDTA can convert Cd in the soil from a stable form to a plant-absorbable state,thus promoting the removal of Cd in the soil by soybeans,while the addition of citric acid can promote the root-to-stem transport of Cd and thus improve the removal of Cd by soy-bean.Results of the research provide a scientific reference for the application and promotion of phytoremediation techniques toward heavy metal contamination in the calcareous soil.