Cu and Pb accumulation and removal from aqueous medium by Enydra fluctuans Lour. (Asteraceae) - a medicinal plant with potential for phytoremediation.

Abstract

Enydra fluctuans Lour. (Asteraceae) is an edible semi-aquatic floating or trailing herbaceous plant widely distributed in tropical Africa, South and South East Asia, and Australia. Its leaves, which are consumed as a vegetable, are also used in traditional medicine to treat several diseases. The efficacy of this plant in removal of copper and lead from aqueous medium was tested in the present study. The plants were exposed to graded measured concentrations of 0.55-10.2mg Cu L-1 and 11.5-50.2mg Pb L-1 in hydroponic systems. Controls without added Cu and Pb were maintained under identical conditions. Cu and Pb were estimated by atomic absorption spectrometry, and the bioconcentration factor (BCF) and the translocation factor (TF) were calculated for each element at the different concentrations. Accumulation of both Cu and Pb was significantly higher in root than that in leaf and stem. Though all the bioconcentration factor (BCF) values were greater than unity, none of the translocation factor (TF) values was greater than unity, indicating that this plant could not be considered a hyperaccumulator of these metals. Nevertheless, E. fluctuans could remove Cu from aqueous medium at rates ranging from 98.8 to 99.7%, with a mean reduction of 99.2% after 96-h exposure at various concentrations. The removal of Pb ranged from 97.1 to 99.1%, with a mean reduction of 98.2%. Thus, E. fluctuans showed high potential for removal of Cu and Pb from aqueous medium and has the prospect of being used in phytoremediation of these metals.