Cerium Oxide Nanoparticles Affect Heavy Metals Uptake by Pea in a Divergent Way than Their Ionic and Bulk Counterparts

The impact of cerium oxide nanoparticles, bulk cerium oxide and ionic cerium nitrate on the plant development as well as the uptake and further translocation of Cu, Mn, Zn and Fe by sugar pea (Pisum sativum L.) was investigated. Plants were cultivated in the laboratory pot experiments using the modified Hoagland solutions supplemented with cerium compounds at the 200 mg L-1 Ce level. Analysis of variance proved that cerium oxide nanoparticles significantly decreased Cu, Mn, Zn and Fe concentrations in roots and above ground parts of the pea plants. The latter ions are presumably transported via symplastic pathways and may compete with nanoparticles for similar carriers. The lowest impact on the plant growth and the metal uptake was observed under the bulk CeO2 treatment. On the contrary, strongest interactions were observed for supplementation with ionic cerium nitrate. The highly beneficial effect of cerium oxide nanoparticles on the plant growth was not supported by this study. The latter conclusion is of particular relevance when environmental impact of cerium compounds on the waste management, municipal urban low emissions and food production is to be concerned.