Phytoremediation of Lead and Copper by Sainfoin (Onobrychis vicifolia): Role of Antioxidant Enzymes and Biochemical Biomarkers

This experiment was done in order to evaluate the species ability in absorption and recognizability the plant resistant Sainfoin, (Onobrychis vicifolia) to heavy metals lead and copper in 2009. The experimental treatments were arranged as factorial experiment in randomized complete design with four replicates. The first treatment was four lead Pb(NO ) levels 0, 200, 400, 800 and the second treatment was four copper Cu(SO ) 3 2 4 2 levels 0, 150, 300 and 450 mg/kg soil. The results showed significant effects on lead and copper absorption by the sainfoin roots and aerial parts ( P>0.01). The results also demonstrated that sainfoin had the same ability in lead and copper absorption into root at the highest level of of copper and lead alone where 7.68 and 7.34 mg/kg dry weight of these elements were absorbed by roots respectively. In addition, the plant ability in absorbing copper into aerial parts (40.40 mg/kg DW) and was greater than that of lead absorption (15.62 mg/kg DW). Increasing soil lead and copper concentrations and absorption of the elements, showed a significan t increase in the contents of each biomarkers Malondialdehyde (MDA), Dityrosine (D-T) and 8-hydroxy-2- deoxyguanosine (8-2-OH-DG) (P<0.01). The maximum decrease in chlorophyll a, chlorophyll b and total chlorophyll (a+b) contents were observed at the highest level of soil lead (800 mg/kg) and copper (450 mg/kg) levels (P<0.01). The activities and functions of three enzymes Superoxide dismutase (SOD), Catalase (CAT) and Glutathione peroxidase (GPX) showed a significant increase (P<0.01) In general the maximum responses of these enzymes were also observed at the highest level of lead and copper in the soil.