[Influence of PO4(3-) and citrate on REE accumulation and fractionation in wheat]

This paper has studied the influence of phosphate (Pi, one of inorganic ligands) and citrate (Cit, one of organic ligands) on accumulation and fractionation of REEs in wheat based on aqueous culture, added with extraneous mixed REEs (MRE) and ICP-MS analysis technology. The results show that initial phosphate (Pi) solution of different levels followed by exposure to fixed-MRE solution has no significant effects on accumulation of the total concentrations of REEs (sigma REE) in the wheat roots, but it decrease the REE dramatically in the wheat leaves. Simultaneous culture of wheat with mixture of MRE and citrate solution caused obvious decreases of the sigma REE both in wheat roots and leaves. Compared to the control (no Pi or citrate was added), the distribution and fractionation characters of MRE had M-type tetrad effect and MREE enrichment in wheat roots, and W-type tetrad effect and HREE enrichment in wheat leaves. Different levels of Pi had no significant effects on the tetrad effect of MRE, but it notable increased the enrichment of HREE in wheat leaves. Added with citrate of different levels led the fractionation of REE decreasing gradually in wheat roots and leaves, as the concentration of citrate > or = 150 micromol x L(-1), light REE (LREE) enrichment both existed in the roots and leaves.