biostudies-literatureRico CMIntramural EPA1807-1812https://www.ebi.ac.uk/biostudies/studies/S-EPMC9504423biostudies-literatureUnknown5(8)The transformation of cerium oxide nanoparticles (CeO₂-NPs) in soil and its role in plant uptake is a critical knowledge gap in the literature. This study investigated the reduction and speciation of CeO₂-NPs in barley (<i>Hordeum vulgare</i> L.) cultivated in soil amended with 250 mg CeO₂-NPs kg^-1 soil. Synchrotron micro-X-ray fluorescence (μXRF) was employed for spatial localization and speciation of CeO₂-NPs in thin sections of intact roots at the soil-root interface. Results revealed that Ce was largely localized in soil and at the root surface in nanoparticulate form (84-89%). However, a few hot spots on root surfaces revealed highly significant reduction (55-98%) of CeO₂-NPs [Ce(IV)] to Ce(III) species. Interestingly, only roots in close proximity to hot spots showed Ce uptake which was largely CeO₂ (89-91%) with very little amount Ce(III) (9-10%). These results suggest that the reduction of CeO₂-NPs to Ce(III) is needed to facilitate uptake of Ce.Environmental science. NanoCerium oxide nanoparticles transformation at the root-soil interface of barley (<i>Hordeum vulgare</i> L.).PMC9504423EPA999999Marcus MARico CMJohnson MGfalseCerium oxide nanoparticles transformation at the root-soil interface of barley (<i>Hordeum vulgare</i> L.).The transformation of cerium oxide nanoparticles (CeO₂-NPs) in soil and its role in plant uptake is a critical knowledge gap in the literature. This study investigated the reduction and speciation of CeO₂-NPs in barley (<i>Hordeum vulgare</i> L.) cultivated in soil amended with 250 mg CeO₂-NPs kg^-1 soil. Synchrotron micro-X-ray fluorescence (μXRF) was employed for spatial localization and speciation of CeO₂-NPs in thin sections of intact roots at the soil-root interface. Results revealed that Ce was largely localized in soil and at the root surface in nanoparticulate form (84-89%). However, a few hot spots on root surfaces revealed highly significant reduction (55-98%) of CeO₂-NPs [Ce(IV)] to Ce(III) species. Interestingly, only roots in close proximity to hot spots showed Ce uptake which was largely CeO₂ (89-91%) with very little amount Ce(III) (9-10%). These results suggest that the reduction of CeO₂-NPs to Ce(III) is needed to facilitate uptake of Ce.2018-01-01T00:00:00Z2018 Jun2025-04-21T14:19:52.23Z2025-04-21T14:19:52.23ZS-EPMC95044233616126910.1039/C8EN00316E10.1039/c8en00316e