Cadmium uptake by the water hyacinth: Effects of root mass, solution volume, complexers and other metal ions1

Abstract

At a fixed Cd2+ concentration water hyacinth () plants with greater root mass (dry weight) take up more metal ions as a function of time, and more metal ions are taken up by a plant as the solution volume is increased. Experiments in which several different metal ion complexers were present suggest that (1) the roots possess sites which initially reversibly bind free Cd2+, (2) some added complexers can compete with these root sites for free Cd2+, and (3) with time Cd2+ bound to the roots is translocated into into the root tissues effectively removing it from the equilibrium processes in solution. Many metal ions are taken up by the plant but only the micronutrient Zn2+ competes well with Cd2+ for uptake. Thus, there may be binding sites on the roots for specific metal ions.