Abstract
Stable Zn isotopes are fractionated in roots and leaves of plants. Analyses demonstrate that the heavy Zn isotopes are enriched in the root system of plants with respect to shoots and leaves as well as the host soil, but the fractionation mechanisms remain unclear. Here we show that the origin of this isotope fractionation is due to a chemical isotope effect upon complexation by Zn malates and citrates in the aerial parts and by phosphates in the roots. We calculated the Zn isotope effect in aqueous citrates, malates, and phosphates by ab initio methods. For pH<5, the Zn isotopic compositions of the various parts of the plants are expected to be similar to those of groundwater. In the neutral to alkaline region, the calculations correctly predict that 66Zn is enriched over 64Zn in roots, which concentrate phosphates, with respect to leaves, which concentrate malates and citrates, by about one permil. It is proposed that Zn isotope fractionation represents a useful tracer of Zn availability and mobility in soils.
Highlights
Using XAFS microspectroscopy [1], it was found that Zn is dominantly bound to phosphate in the root system of the pseudometallophyte Arabidopsis halleri and to malate and citrate in the aerial parts
The importance of this observation was strengthened by the remarkable discovery [2] that 66Zn in the root system of plants grown in a controlled environment is enriched over 64Zn by 0.6 permil (%) with respect to the aerial parts of the plant, an observation replicated and confirmed on plants collected in their natural habitat [3,4,5]
Isotope fractionation by hydrated Zn ion, chlorides, sulfides, sulfates, carbonates, and citrates has recently been evaluated by ab initio methods [8,9]
Summary
Using XAFS microspectroscopy [1], it was found that Zn is dominantly bound to phosphate in the root system of the pseudometallophyte Arabidopsis halleri and to malate and citrate in the aerial parts. The importance of this observation was strengthened by the remarkable discovery [2] that 66Zn in the root system of plants grown in a controlled environment is enriched over 64Zn by 0.6 permil (%) with respect to the aerial parts of the plant, an observation replicated and confirmed on plants collected in their natural habitat [3,4,5]. We discuss the implications for plant physiology and soil status
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
