三叶草(Trifolium repens)用于土壤镉污染的修复潜力

通过温室盆栽试验法,研究了土壤镉(Cd)污染下三叶草对土壤Cd的富集特征及土壤Cd的净化能力等,以期为三叶草对土壤Cd的生态修复提供依据。结果表明:三叶草具有较好的Cd耐受性,总生物量增加值介于2.0~3.7 g。随着土壤Cd处理浓度增加,三叶草根、茎、叶中Cd含量分别高达178.6、101.3、130.9 mg·kg-1,富集系数(BF)分别介于9.7~17.9、3.0~10.1、3.1~13.1,富集能力大小总体表现为根叶茎,转运系数(TF)值均≥1(除T2处理),表明三叶草有较强的Cd富集能力,且能较好地将Cd转运至地上部位;三叶草根、茎、叶对Cd的吸收量均随着土壤Cd处理浓度的升高而递增,地上部位(茎、叶)吸Cd百分率(占总吸Cd量)最高达87.2%,对土壤Cd净化率最高达6.2%。因此得出三叶草具有作为Cd超积累植物的较好潜力,可以进行污染区域美化改造和Cd污染修复。

Remediation potential of Trifolium repens used in cadmium-contaminated soils

In this study, the enrichment characteristics and purification capacity of Trifolium repens for cadmium in soil were investigated in order to provide a reference for ecological restoration of cadmium. The results showed that the added value of T. repens biomass reached 2.0~3.7 g, indicating that T. repens could have a high tolerance for cadmium. Cadmium accumulation in the roots, stems, and leaves of T. repens reached 178.6, 101.3 mg·kg^-1, and 130.9 mg·kg^-1, respectively, as the concentration of cadmium increased. The bioaccumulation factor values of the roots, stems, and leaves were 9.7~17.9, 3.0~10.1, and 3.1~13.1, respectively, and the ability of cadmium to accumulate in different parts of T. repens was decreased in the order of roots > leaves > stems. The translocation factor values for cadmium in T. repens were all greater than 1(except T2 treatment). These data indicated that T. repens could have a strong capacity for cadmium enrichment and could easily transport cadmium into the soil. The amount of cadmium uptake of T. repens increased diversely with the different cadmium treatments in soils; in particular, the cadmium uptake of the aboveground parts(stems and leaves) of T. repens reached 87.2%, and the purifying rate of cadmium in soils was as high as 6.2%. Based on these findings, T. repens was found to have promising applications in beautifying surroundings and repairing cadmium-contaminated soils.