Nutrient and heavy metal removal capacity of Pistia Stratiotes L. from a freshwater wetland at Kelaniya

Abstract

Performance of Pistia stratiotes collected from Iriyawetiya wetland at Kelaniya, in removing nitrite, nitrate, phosphate and heavy metals, chromium, copper, lead and cadmium was monitored for a period of eight weeks from April to June 2003. Three (plastic) experimental tanks (replicated) and a control tank kept insidea polythene tunnel were used for the purpose within eight weeks. Pistia stratiotes was able to remove 61.05% of the chromium, 52% of copper, 57.16% of lead and 63.66% of cadmium present in the water collected from the middle portion of Iriyawetiya wetland. Also removed 19% of nitrite, 60% of nitrate and 87% of phosphate present in wetland water, indicating that Pistia stratiotes is a potential candidate species for bioremediation. The plants retained more heavy metals, in roots i.e. 0.09 g/kg/day of chromium, 0.01 g/kg /day of copper, 0.094 g/kg/day of lead and 0.01g/kg of cadmium than in the shoots, i.e. 0.005 g/kg/day of chromium, 0.003 g/kg/day of copper, 0.008 g/kg/day of lead and 0.001 g/kg/day of cadmium.