Phytoaccumulation of trace elements by wetland plants: II. Water hyacinth

Wetland plants are being used successfully for the phytoremediation of trac e elements in natural and constructed wetlands. This study demonstrates the potential of water hyacinth (Eichhornia crassipes), an aquatic floating pl ant, for the phytoremediation of six trace elements. The ability of water h yacinth to take up and translocate six trace elements-As(V), Cd(LI), Cr(VI) , Cu(II), Ni(II), and Se(VI)-was studied under controlled conditions. Water hyacinth accumulated Cd and Cr best, Se and Cu at moderate levels, and was a poor accumulator of As and Ni. The highest levels of Cd found in shoots and roots were 371 and 6103 mg kg(-1) dry wt., respectively, and those of C r were 119 and 3951 mg kg(-1) dry wt., respectively. Cadmium, Cr, Cu, Ni, a nd As were more highly accumulated in roots than in shoots. In contrast, Se was accumulated more in shoots than in roots at most external concentratio ns. Water hyacinth had high trace element bioconcentration factors when sup plied with low external concentrations of all six elements, particularly Cd (highest BCF = 2150), Cr (1823), and Cu (595). Therefore, mater hyacinth w ill be very efficient at phytoextracting trace elements from wastewater con taining low concentrations of these elements. We conclude that water hyacin th is a promising candidate for phytoremediation of wastewater polluted wit h Cd, Cr, Cu, and Se.