PHYTOREMEDIATION OF HEAVY METALS BY Ipomoea Aquatica

Abstract- Aquatic plants are well recognized as potential hyperaccumulators of heavy metals. The ability of Ipomoea aquatica (water spinach) to remove lead, chromium, cadmium and nickel from aqueous medium was demonstrated by rhizofiltration, which is a soil-less mechanism of phytoremediation. Plants were cultured in Hoagland medium with desired concentration of heavy metals individually for a period of 8 days. The uptake capacities of the plants were determined by measuring the residual concentration of the aqueous solution. The deposition of heavy metals in root, stem and leaves were investigated by dry ashing procedure. Results revealed that the residual concentration of lead reduced by 95%. Removal of 100% was achieved for low to moderate dosage of chromium, whereas for cadmium above 85% efficiency was achieved for low concentration and it decreased gradually with increasing range of concentrations. Nickel also showed similar trend, but above 70% efficiency was achieved in all the cases. Dry ashing procedure evaluated the shoot, root and stem concentrations, which showed there was a high accumulation of these metals in the plant roots and similarly high distribution in the shoots as well. Bioconcentration factor showed that the plant has good hyperaccumulating potential. Translocation factor showed moderate translocation efficiency to the shoots and very less onto the leaves. Relative growth was good at lower range of concentrations, but decreased sharply at higher ranges. The study showed that the plant can be used effectively for heavy metals removal from contaminated aquatic system.