Accumulation forms of Zn and Pb in Phaseolus vulgaris in the presence and absence of EDTA

The internalized speciation of Zn and Pb in roots and leaves of Phaseolus v ulgaris grown in zinc sulfate, zinc EDTA, lead nitrate, and lead EDTA solut ions were studied by electron microscopy (Zn) and extended X-ray absorption fine structure (EXAFS) spectroscopy (Zn and Pb). Zn was predominantly pres ent as Zn phosphate dihydrate in the roots and leaves of the plant regardle ss of its form in solution. ph was predominantly found in the leaves as cer ussite (lead carbonate) when the plant was grown in Pb nitrate solution and as a mixture of PbEDTA and an undetermined species in contact with PbEDTA solution. Therefore, Phaseolus vulgaris is able to dissociate totally (Zn) or partly(Pb)the two metal-EDTA complexes from the nutrient solution and to bind these metals in other forms.