The toxicity of cerium nitrate to Elodea canadensis: subcellular distribution, chemical forms and physiological effects

The rare earth elements are increasingly being used as trace supplements in different fields. In this study, subcellular distribution, the chemical forms and toxicity of cerium (Ce) were evaluated for Elodea canadensis. The effect of Ce (5-20 mg L-1) applied for 7 days was assessed by measuring changes in the nutrient elements, photosynthetic pigments, malondialdehyde and antioxidant systems. Ce accumulation was greatest in the cell walls, followed by the organelles and the soluble fraction. Ce levels were higher in cellulose and pectin than in other biomacromolecules. The toxic effects caused by Ce were shown by a reduction in photosynthetic pigments, disruption of nutrient elements, and increases in MDA content. E. canadensis shows Ce-induced oxidative stress by modulating antioxidant enzymes, such as guaiacol peroxidase and catalase. Elevated Ce levels may represent a potential risk for aquatic ecosystems.