印度芥菜和香根草对Pb污染土壤的修复效能及作用途径

为探究印度芥菜(Brassica juncea)和香根草(Vetiveria zizanioides L.)对Pb污染土壤的修复效能和作用途径，采用Pb污染土壤〔w(Pb)为400~2 000 mg/kg〕进行为期30 d的盆栽试验，分析植物对Pb的耐受性、积累能力和固定效果.结果表明:① 印度芥菜和香根草对Pb的积累主要集中在根部，两种植物根部累积的w(Pb)分别为206.62~902.40和288.42~1 102.47 mg/kg，单株植物的Pb积累量分别为70.75~138.31和99.09~220.49 μg，香根草对Pb污染土壤的修复效能高于印度芥菜. ② 印度芥菜和香根草对Pb的去除率随土壤中w(Pb)的增加而降低，对Pb的固定率则随土壤中w(Pb)的增加而增加，二者对Pb的去除率最大值分别为1.02%和1.78%，对Pb的固定率可达11.22%和16.78%，两种植物对Pb污染土壤修复的主要途径为植物固定. ③ 主成分分析表明，w(脯氨酸)对植物Pb积累过程具有重要作用.研究显示，相比于印度芥菜，香根草更适用于Pb污染土壤的植物修复. 

Remediation Efficiency and Pathways of Brassica juncea and Vetiveria zizanioides L. for Pb-Contaminated Soil

Considering the serious pollution of lead (Pb) in soil, it is urgent to effectively select Pb-tolerant plant species. Pot experiments were conducted to investigate the remediation efficiency of Brassica juncea and Vetiveria zizanioides L. for Pb-contaminated soil through phytoextraction and phytostabilization, with Pb concentrations of 400, 800, 1200, 1600 and 2000 mg/kg respectively and the experiment cycle as 30 d. The tolerability, accumulation and immobilization capacity of these two plants for Pb were compared. The results showed: (1) Pb was mainly accumulated in the roots, and the accumulation capacity of V.zizanioides L. was higher than that of B.juncea, with the concentrations of B.juncea and V.zizanioides L. reaching 206.62-902.40 mg/kg and 288.42-1102.47 mg/kg in roots respectively, and accumulation amounts as 70.75-138.31 μg/plant and 99.09-220.49 μg/plant respectively. This indicated that V.zizanioides L. displayed a better remediation efficiency than B.juncea. (2) The Pb removal rates of V.zizanioides L. and B.juncea decreased with the increase of Pb content in soil, while the immobilization rates increased with the increase of Pb content in soil. The maximum removal rates were as low as 1.02% and 1.78% respectively, and the immobilization rates reached 11.22% and 16.78% respectively. The remediation pathway of the two plants was identified as phytostabilization rather than phytoextraction. (3) The results of principal component analysis showed that proline played an important role in accumulating Pb. V.zizanioides L. could be used as an alternative plant for phytoremediation of Pb-contaminated soil.