Graphene Oxide Promoted Cadmium Uptake by Rice in Soil

Graphene oxide (GO) has shown enormous potential in applications for improving crop yield and soil cultivation quality. However, in heavy metal contaminated soil, the effect of GO on heavy metals and the indirect toxicity of GO to plants remain unclear. In this work, we reveal the GO-promoted cadmium (Cd) uptake by rice in a Cd-contaminated soil system. The oxygen-rich functional groups and the large specific surface area of monolayer GO result in strong Cd(II) adsorption (with a maximum adsorption capacity of 265.8 mg/g), which significantly change the existing forms of Cd(II) in the soil. In particular, GO converts the inorganic-bound form Cd(II) that is not readily absorbed by plants into the exchangeable form that is more available for plant absorption. As a result, Cd(II) content in rice seedlings is increased by 12.5% with the application of GO. Therefore, it can be concluded that GO exhibited indirect toxicity to plants in heavy metal-enriched soil.