A Study on Cadmium Phytoremediation Potential of Water Lettuce, Pistia stratiotes L.

Aquatic macrophytes have tremendous potential for remediation of the heavy metal cadmium. The objective of this study was to investigate Cd phytoremediation ability of water lettuce, Pistia stratiotes L. The study was conducted with 5, 10, 15 and 20 mg L-1 CdCl2 in hydroponic system for 21 days and the Cd concentrations in the root and shoot tissues were estimated by atomic absorption spectroscopy. The values obtained were used to evaluate the bioconcentration factor (BCF), translocation factor (TF) and translocation efficiency of this plant. The plant showed high Cd tolerance of up to 20 mg L-1 but there was a general trend of decline in the root and shoot biomass. The maximum BCF values for root and shoot tissues were 2,294 and 870 respectively, obtained for 5 mg L-1 Cd, which indicated that the plant was a Cd hyperaccumulator. The TF maxima was found to be 0.6 and as much as 60 % root to shoot translocation efficiency was observed for 15 mg L-1 Cd which points towards the suitability of water lettuce for removing Cd from surface waters.