水培条件下四种植物对Cd、Pb富集特征

Enrichment characteristics of Cd and Pb by four kinds of plant under hydroponic culture

利用水培方法测定了不同浓度下向日葵、蓖麻、紫花苜蓿及芥菜的生物量和植物体内重金属Cd、Pb含量,分析了植物对重金属的富集特征。结果表明:经过5周培养后,4种植物根部与地上部对重金属的富集量随着浓度的增加而增加,Cd浓度为20mg·L-1时,向日葵的根部Cd含量最高,达到237.86mg·kg-1,地上部Cd含量为89.48mg·kg-1;而Pb浓度为200mg·L-1时,芥菜根部对Pb的吸收量较高,达到597.22mg·kg-1,地上部Pb含量最高的则出现在向日葵处理Pb100mg·L-1中,为318.33mg·kg-1。4种植物对Cd、Pb的富集系数随重金属浓度的增加而减小;根部及地上部富集系数与生物量和重金属浓度呈现出一定的相关性;另外,在Cd、Pb复合处理中,一种重金属的存在会在不同程度上影响植物对另一种重金属的吸收。通过比较4种植物根部与地上部的生物量和对Cd、Pb富集特征,认为相对于其他3种植物向日葵对Cd、Pb具有较强的吸收潜力,并可以作为Cd、Pb污染土壤植物修复的备选植物。

A hydroponic experiment with different concentrations of Cd and Pb was conducted to investigate the capabilities of sunflower,ricinus,alfalfa,and mustard in accumulating Cd and Pb. After treated for five weeks,the Cd and Pb contents in the roots and shoots of test plants increased with increasing concentrations of medium Cd and Pb. In treatment 20 mg Cd·L^-1sunflower roots had the highest Cd content （237.86 mg·kg^-1,and its shoots accumulated 89.48 mg·kg^-1of Cd. In treatment 200 mg Pb·L^-1mustard roots showed better capability in enriching Pb （597.22 mg·kg^-1. In treatment 100 mg Pb·L^-1sunflower shoots had the highest content of Pb （318.33 mg·kg^-1. For the test plants,the enrichment coefficients of Cd and Pb decreased with increasing concentrations of medium Cd and Pb,and had definite correlations with plant biomass and the concentrations of medium Cd and Pb. In the treatments with combined application of Cd and Pb,there existed definite antagonism in the Cd and Pb uptake by the plants. Through the comparison of plant biomass and of the enrichment characteristics of Cd and Pd by roots and shoots,it was considered that relative to the other three test plants,sunflower could be selected as a potential candidate for the phytoextraction of soil Cd and Pb.