Effects of Ce(III) and CeO2 nanoparticles on soil-denitrification kinetics

摘要

Cerium (Ce)-based compounds, such as CeO2 nanoparticles (NPs), have received much attention in the last several years due to their popular applications in industrial and commercial uses. Understanding the impact of CeO2 NPs on nutrient cycles, a subchronic toxicity study of CeO2 NPs on soil-denitrification process was performed as a function of particle size (33 and 78 nm), total Ce concentration (50-500 mg L-1), and speciation [Ce(IV) vs. Ce(III)]. The antimicrobial effect on the soil-denitrification process was evaluated in both steady-state and zero-order kinetic models to assess particle- and chemical-species specific toxicity. It was found that soluble Ce(III) was far more toxic than Ce(IV)O2 NPs when an equal total concentration of Ce was evaluated. Particle size-dependent toxicity, species-dependent toxicity, and concentration-dependent toxicity were all observed in this study for both the steady-state and the kinetic evaluations. Changes in physicochemical properties of Ce(IV)O2 NPs might be important in assessing the environmental fate and toxicity of NPs in aquatic and terrestrial environments.