title: Toxicity of iron-based nanoparticles to green algae: Effects of particle size, crystal phase, oxidation state and environmental aging.
abstract: 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 Fe2O3NPs of different crystal phases, and 1 type of Fe3O4NPs 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 > Fe3O4NPs > Fe2O3NPs, and α-Fe2O3NPs presented significantly higher toxicity than γ-Fe2O3NPs. 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.
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Lei
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Luqing
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China.
authors.forename: Lizhong
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China. Electronic address: lindaohui@zju.edu.cn.
authors.forename: Daohui
authors.initials: D
authors.lastname: Lin
mesh_terms: D002708:Chlorella / Q000187:drug effects*; D007501:Iron / Q000737:chemistry / Q000633:toxicity*; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010084:Oxidation-Reduction; D010316:Particle Size; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water; D007501:Iron
keywords: Algal toxicity; Environmental aging; Nanomaterial; Oxidation; Zero-valent iron