XVI International Botanical Congess

Green plants are now becoming increasingly popular as a means of restoring environmental contamination and phyto remediation. In a study undertaken by us on some of the aquatic macrophytes, it was found that Pistia stratiotes, and Eichhornia crassipes had a tremendous capacity to remove metal ions from the aquatic environments. Ceratophyllum was also effective in removing the metal ion contaminations from aquatic environments but to a lesser extent. These plants have a unique feature to absorb the metal ions through their physiological mechanisms and transport them to the leaves where they are stored in the starch granules and are unavailable for the plant=s metabolic activity. The metal uptake activity by the plants was determined by clipping small portions of the plant parts and determining the metal concentration by atomic absorption spectroscopy after acid digestion of the samples. About 75-95% of the metals like copper, cadmium, chromium, nickel, zinc, lead and mercury could be easily removed by these plants. The biological process interacting with the abiotic processes in nature could be seen by various microscopic methods. Biochemical estimations of various parameters like protein, chlorophyll, and nucleic acid content showed variations, as determined by standard methods, however visible damage to the plants was not apparent. The development of engineering systems for phyto remediation and scale-up for their utilization is suggested.