Cadmium transfer in contaminated soil-rice systems: Insights from solid-state speciation analysis and stable isotope fractionation

Initial Cadmium (Cd) isotope fractionation studies in cereals ascribed the retention of Cd and its light isotopes to binding sulfur (S). To better understand relation S soils plants, we combined XAS speciation analyses soil-rice systems that were rich S. The included distinct water management (flooded vs. non-flooded) rice accessions with (excluder) without (non-excluder) functional membrane transporter OsHMA3 transports into root vacuoles. Initially, 13% soil was bound Through flooding, proportion increased 100%. Soil flooding enriched plants towards heavy (?114/110Cd = ?0.37 ?0.39%) compared grew on non-flooded ?0.45 ?0.56%) suggesting preferentially precipitated sulfides. Isotope compositions CaCl2 extracts indicated surface contributed shift between plant during flooding. In roots, fully all treatments. roots excluder strongly retained lights while transported shoots (?114/110Cdshoot-root 0.16–0.19‰). non-excluder accumulated apparent difference composition smaller than ?0.02 0.08‰). We ascribe transport by and/or chelating Cd–S complexes vacuole. major form flooded partly immobilization systems.