Response of Alternanthera philoxeroides to heavy metals and its sorption effectiveness for heavy metals

The phytoremediation is an effective way to solve more and more heavy metal problems and becomes an important field in ecological and environmental sciences, in which the response of plant to heavy metals and its sorption effectiveness for heavy metals are the scientific basis. A pot experiment with different ratio of sludge to soil (0, 5%, 10%, 20% sludge) was carried out to determine the response of Alternanthera philoxeroides to heavy metals and its sorption effectiveness by measuring the chlorophyll content, peroxidase (POD) activity, and superoxidedismutase (SOD) in the leaves of A. philoxeroides after three, four, five and six months treatment, and the metals content (Cd，Cr，Mn，Ni，Pb，Cu, and Zn) in the leaves, roots, and stems of A. philoxeroides after six months treatment. This study showed that the chlorophyll content, POD and SOD activity in the leaves of A. philoxeroide increased as the sludge volume increased; however, they decreased when A. philoxeroide grew in the soil containing heavy metals for six months. This study also showed that the Mn, Ni, Cr, Pb, Cu, and Zn content of the leaves and the stems were higher than those of the roots in different treatments. These results indicated that although A. philoxeroides was useful for phytoremediation of heavy metals in sludge due to its good growth ability, strong tolerance to the heavy metals, and higher transfer coefficient for Mn, Ni, Cr, Pb, Cu, and Zn.