Enhanced Phytoextraction for Co-contaminated Soil with Cd and Pb by Ryegrass (Lolium perenne L.)

A pot experiment was conducted to investigate the effect of three additives - citric acid (CA), polyaspartic acid (PASP), and FeCl3 - on the phytoextraction efficiency of cadmium (Cd) and lead (Pb) by ryegrass (Lolium perenneL.) from artificially contaminated soils with different heavy metal concentrations. The results showed that as the concentration of pollutants increased, the TI (tolerance index) and BCF (bio-concentration factor) of ryegrass gradually increased only when FeCl3 was applied. FeCl3 also exhibited the most significant biomass enhancement and heavy metal accumulation of ryegrass, as well as the highest phytoextraction efficiency in heavily-polluted soils. The overall orders of the optimal phytoextraction efficiency for the three additives in terms of their MER (metal extraction ratio) were: FeCl3>PASP>CA. Therefore, FeCl3 can be used to improve the Cd and Pb phytoextraction efficiency of ryegrass in heavily-polluted soils.