Toxicity of iron-based nanoparticles to green algae: Effects of particle size, crystal phase, oxidation state and environmental aging

Lei, Cheng; Zhang, Luqing; Yang, Kun; Zhu, Lizhong; Lin, Daohui

Toxicity of iron-based nanoparticles to green algae: Effects of particle size, crystal phase, oxidation state and environmental aging

2016

Lei, Cheng | Zhang, Luqing | Yang, Kun | Zhu, Lizhong | Lin, Daohui

With the increasing environmental application and discharge of iron-based nanoparticles (NPs), a comprehensive understanding of their fate and ecotoxicological effect in the aquatic environment is very urgent. In this study, toxicities of 4 zero-valent iron NPs (nZVI) of different sizes, 2 Fe2O3 NPs of different crystal phases, and 1 type of Fe3O4 NPs to a green alga (Chlorella pyrenoidosa) were investigated, with a focus on the effects of particle size, crystal phase, oxidation state, and environmental aging. Results show that the algal growth inhibition of nZVI increased significantly with decreasing particle size; with similar particle sizes (20–30 nm), the algal growth inhibition decreased with oxidation of the NPs with an order of nZVI > Fe3O4 NPs > Fe2O3 NPs, and α-Fe2O3 NPs presented significantly higher toxicity than γ-Fe2O3 NPs. The NP-induced oxidative stress was the main toxic mechanism, which could explain the difference in algal toxicity of the NPs. The NP-cell heteroagglomeration and physical interactions also contributed to the nanotoxicity, whereas the effect of NP dissolution was negligible. The aging in distilled water and 3 surface water samples for 3 months increased surface oxidation of the iron-based NPs especially nZVI, which decreased the toxicity to algae. These findings will be helpful for the understanding of the fate and toxicity of iron-based NPs in the aquatic environment.

اظهر المزيد [+]