Accumulation of Heavy Metals in Cell Walls ofPolygonum cuspidatumRoots from Metalliferous Habitats

摘要

The distribution and accumulation of Cu2+, Zn2+and Cd2+ions in the roots ofPolygonum cuspidatum, collected from metalliferous and non-metalliferous habitats, were examined. About 90%of the metal ions was located in the cell wall fraction of roots of plants grown in either type of habitat. The metal-ion exchange capacity of the cell walls is not specific to the plants from metalliferous habitats, and there were no significant differences among plants from the various habitats. The capacity for Cu2+ions was greater than that for Zn2+or Cd2+ions. Cu2+ions have a high affinity for the cell wall and, thus, it appears that the cell wall is a barrier for the transportation of Cu2+into the cytoplasm.