[Tolerance of Arundo donax to heavy metals]

This paper studied the tolerance of Arundo donax grown in a simulated heavy metals polluted wetland, and determined the biological characters and chlorophyll contents of the plant at its different growth stages as well as the changes of soil heavy metals contents. The results showed that Arundo donax could survive in the wetland when the concentrations of Cu2+, Pb2+, Cd2+, Zn2+, Ni2+ and Hg2+ were 100 mg x kg(-1) and Cr6+ concentration was 50 mg x kg(-1). During 40 days growth period, the chlorophyll content decreased by 20%-56% and the leaf became soft with its tip withered, but the plant still grew. Compared with control, Arundo donax in the polluted wetland was slight and yellow-green, but the impact on plant height was inconspicuous. Arundo donax treated with 100 mg x kg(-1) Cr6+ grew slowly with its root stock rotted, and its leaves withered in a short time, indicating that the plant could not tolerate the pollution of high concentration Cr6+. The concentrations of soil heavy metals declined with the growth of the plant, probably due to the translocation of heavy metals from peripheral soil to rhizosphere and the phytoextraction and phytovolatilization, because the heavy metals contents in rhizosphere were much higher than those in the bulk soil in the test jar. The characters of large biomass, exuberant root and good adaptability of Arundo donax suggested its great potential in remediation of polluted soils. The study on the application of Arundo donax to phytoremediation is of realistic significance.