Isotopic fractionation and transport mechanisms of Zn in plants

We have analyzed by MC-ICP-MS the Zn isotopic composition of different components (seeds, leaves, and rhizome, stem and leaves) of lentils (Lens culinaris) and bamboos (Phyllostachys aurea), respectively. Zn isotopes are systematically fractionated between seeds and leaves of lentil and between stem and leaves of bamboos. Leaves are enriched in light Zn isotopes compared to the other parts of plants. The range of the fractionation is up to 0.52 parts per thousand per amu and is clearly mass dependent. The observed Zn isotopic fractionation is consistent with that occurring during both diffusive processes and cross-cell membrane transport. Our study also shows a clear interspecies variability for Zn isotopic fractionation. We conclude that the Zn could be used as a tracer for biological activities. (C) 2008 Elsevier B.V. All rights reserved.