Effect of cadmium and lead on growth, biochemical parameters and uptake in Lemna polyrrhizaL.

Aquatic plants are known to accumulate heavy metals. In this study, Duckweed plants (Lemna polyrrhiza L.) were exposed to different concentrations of Cd and Pb. Various physio-biochemical parameters (fresh weight, chlorophyll content, soluble protein, soluble sugars, proline content and metal absorption) were studied. At lower metal concentrations, an increase in proline, protein and sugar was observed but at higher concentrations (above 30 mg/l) their decrease was noticed. Uptake of the metals was concentration and time dependent. Treatment with 1, 10 and 20 mg/l of Cd and Pb showed synergistic relation while 30 and 40 mg/l treatments showed antagonistic relation during the metal uptake. The results suggest that the L. polyrrhiza can be effectively used as a phytoremediator for wastewater polluted with more than one heavy metal at moderate concentrations.