Harnessing Phytodiversity for Decontamination of Aquatic Pollutants in Freshwater Lakes

Abstract

The metal phytoextracting ability of aquatic macrophytes is being widely exploited for phytoremediation of contaminated wetland ecosystems. A study was carried out in Vellayani wetland ecosystem comprising a fresh water lake and surrounding polders lying 8 24' 09'' to 8 26' 30'' N latitude and 76 59' 08'' to 76 59'

47''E longitude at an elevation of 29 m above mean sea level. Water, sediment and plant samples were collected from 15 geocoded sites during different seasons, biomass was recorded and analysed for various

chemical constituents. Fourteen dominant species were identified within the ecosystem. Highest number of plant species was found during pre-monsoon and the lowest during monsoon season. Panicum repens was the most abundantly distributed macrophyte. The biomass production was highest for Pistia stratiotes. Water and sediment properties were significantly influenced by the seasons. Water properties , acidity, EC, BOD, COD, NH₄-N, NO₃-N, Fe, Al, Cd, and Pb contents were at their lowest during monsoon season and highest during pre-monsoon season except for NH₄-N. Sediment also showed almost similar trend with exceptions for NH₄-N, Cd and Pb. With regard to water pollution in Vellayani lake, the entire lake was contaminated with Al and at two sites with Fe, six sites with Cd and eight sites with Pb. Among tested macrophytes, Eichhornea crassipes was the best phytoextractor for Fe and Dryopteris erythrosora and Eichhornea crassipes for Al and Nelumbo nucifera for Cd and Nymphaea odorata,  Nelumbo nucifera  and Pistia stratiotes for Pb.