Heavy Metal Absorption and Phytoremediation Capacity of Macrophytes of Polachira Wetland of Kollam District, Kerala, India

Abstract

The current research was carried out to estimate the concentration of heavy metals in water and aquatic macrophytes (Hydrilla verticillata, Salvinia minima and Eichornia crassipes) collected from the Polachira wetland of Kollam district, Kerala during the summer season of the year 2020. The water from the Polchira wetland was used for irrigating the agricultural land. Water and plant samples were collected from four different sites and were analyzed for heavy metals like Zn, Cu, Pb, Fe, Cd and Cr using AAS. The results indicated that the mean heavy metal contents in aquatic macrophytes were in the order of Fe>Zn>Pb>Cu>Cr>Cd. It was also highlighted that among the three aquatic macrophytes, Salvinia minima was observed to be the hyperaccumulator of zinc, copper, lead and cadmium whereas Hydrilla verticillata shows the hyperaccumulation of iron and chromium. The highest metal bioaccumulation factor was obtained for zinc, lead and iron by Salvinia minima and chromium accumulation by Hydrilla verticillata. The bioaccumulation factor for different metals in macrophytes followed a decreasing order as Salvinia minima >Hydrilla verticillata > Eichhornia crassipes. The level of heavy metals studied in water samples showed that copper, cadmium and chromium exceeded the maximum limit prescribed by irrigation standards. Our results manifest the capability of these aquatic macrophytes to act as bio accumulators and bioindicators.