Uptake and Transformation of Silver Nanoparticles and Ions by Rice Plants Revealed by Dual Stable Isotope Tracing.
Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag+ ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag+ ions in hydroponic rice Oryza sativa L. is assessed in modified Hewitt (with Cl ions, HS(Cl) and Hogland solutions (without Cl ions, HS) using dual stable isotope tracing (107AgNO3 and 109AgNPs) After coexposure to 107Ag+ ions and 109AgNPs at 50 mg L 1 (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively) Most of the Ag+ ions (from 107Ag+ ions and 109AgNPs) were retained on the root surface, while the occurrence of AgNPs (from 109AgNPs and 107Ag+ ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag+ ions. Higher fractions of Ag+ ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag+ ions and AgNPs and the role of AgNPs as carriers and sources of Ag+ ions in organisms, which is helpful for understanding the fate and toxicology of Ag.
Environmental science technology