Uptake of heavy metals by living and dead Cladonia thalli

Uptake of Pb, Cu and Zn by thalli of Cladonia convoluta (Lam.) and Cladonia rangiformis (Hoffm.) from different concentrations of solutions of Pb(NO3)(2), CuCl2 and ZnCl2 was studied. Zinc accumulation was higher in living than in dead thalli, but the opposite occurred for Pb and Cu. Further study with a solution containing all three metals revealed that at higher concentrations, uptake of Zn was very low compared with that for the single-metal solution. Long term exposure of Cladonia living thalli in double deionised water and also in a 10(-6) M ZnCl2 solution resulted in leaching of Zn. Leaching of Zn from the thalli was also observed after uptake of Pb or Cu from a single-metal solution. No effects were observed on naturally accumulated Pb with uptake of Cu or Zn and on naturally accumulated Cu with uptake of Pb or Zn from a single-metal solution. It can be concluded that Pb, Cu and Zn ions were more strongly bound in C. convoluta than in C. rangiformis. (C) 1997 Elsevier Science B.V.