Effects of Lead on Chlorophyll Content, Total Nitrogen, and Antioxidant Enzyme Activities in Duckweed (Lemna minor)

Abstract

The aim of this study was to investigate the effects of lead on the biochemical and physiological processes in duckweed (Lemna minor L.), a free-floating aquatic macrophyte known for its phytoremediating properties. Duckweed was treated with 1, 10 and 100 mg L-1 of lead for five days and Pb effects were compared to control. Lead accumulation in duckweed fronds increased with metal concentrations; at 1, 10 and 100 mg L-1 it was 6.5, 42.6 and 136.3 times greater than in control plants, respectively. In turn, its bioconcentration factor decreased as the applied Pb concentrations increased. Lead exposure decreased the level of chlorophylls and total nitrogen in a dose-dependent manner. Activity of antioxidant enzymes was exchanged by Pb supply in L. minor fronds. These results showed that ascorbate peroxidase and glutathione reductase were significantly correlated with the applied Pb concentration, while catalase showed a negative correlation. Therefore, it can be concluded that Pb-toxicity provoked oxidative stress, which is confirmed by altered enzyme activities. (C) 2013 Friends Science Publishers