Phytoextraction: The Use of Plants To Remove Heavy Metals from Soils

摘要

A small number of wild plants that grow on metal-contaminated soil accumulate large amounts of heavy metals in their roots and shoots. This property may be exploited for soil reclamation, if an easily cultivated, high biomass crop plant able to accumulate heavy metals is identified. Therefore, the ability of various crop plants to accumulate Pb in shoots and roots was compared. While all crop Brassicas tested accumulated Pb, some cultivars of Brassica juncea (L.) Czern. showed a strong ability to accumulate Pb in roots and to transport Pb to the shoots (108.3 mg of Pb/g DW in the roots and 34.5 mg of Pb/g DW in the shoots). B. juncea was also able to concentrate Cr~(6+) Cd, Ni, Zn, and Cu in the shoots 58-, 52-, 31-, 17-, and 7-fold, respectively, from a substrate containing sulfates and phosphates as fertilizers. The high metal accumulation by some cultivars of B. juncea suggests that these plants may be used to clean up toxic metal-contaminated sites in a process termed phytoextraction.