Tolerance and bioaccumulation of cadmium by Phragmites australis grown in the presence of elevated concentrations of cadmium, copper, and zinc

14 pages, 5 tables, 2 figures.The effects of cadmium and of combined treatments of cadmium, copper and zinc on growth, tolerance indices, mineral composition (N, P, K, Fe, Zn and Mn) and metal uptake of reed (Phragmites australis [(Cav.) Trin. ex Steudel]) were investigated in hydroponic experiments, with Cd concentrations ranging from 4.4 to 17.6 μM, either alone or combined with different treatments of Cu and Zn. Neither root nor shoot growth were affected by the treatments with 4.4 and 8.8 μM Cd alone. However, root and shoot length were significantly reduced by 17.6 μM Cd. Combined metal treatments significantly decreased shoot length, root number and plant fresh weight further than Cd alone, but not plant dry weight. Cd alone had no effect on tissue concentrations of N, P or K, while Mn concentration decreased in both shoot and root, and Zn concentration increased. As a result of the Cd, Cu and Zn (combined treatment) toxicity, the concentrations of N and K decreased in shoot and root tissues, respectively, and Mn concentration decreased in both shoot and root. Fe concentration increased in roots, leading to a significant relationship between root tissue Fe and Cd concentrations with increasing individual concentration of Cd (log10 basis, P < 0.01) and in all the combined treatments of Cd, Cu and Zn (P < 0.001). Metal bioconcentration (tissue concentration/solution concentration) was higher in roots than in shoots, ranging from 287.5 to 1193 for Cd, 849 to 1554 for Cu and 166 to 915 for Zn. The tolerance level of reed to Cd suggests that reed could be useful in wastewater treatments for the removal of Cd. However, the simultaneous presence of elevated concentrations of Cd, Cu and Zn in the effluents may limit the efficiency.This study has been funded by the CSIC (Spain) and the CNCPRST (Morocco), in the framework of a bilateral scientific collaboration project (Ref.: 2000MA0021), and by a Spanish AECI research grant to Nadia Ait Ali.Peer reviewe