title: Biochemical responses of duckweed (Spirodela polyrhiza) to zinc oxide nanoparticles.
abstract: The present study focuses on the biochemical responses of the aquatic plant duckweed (Spirodela polyrhiza L.) to zinc oxide nanoparticles (ZnO NPs). Laboratory experiments were performed using a 96-h exposure to 25-nm NPs at different concentrations (0, 1, 10, and 50 mg/L). Growth, chlorophyll-to-pheophytin ratio (D665/D665a) and activities of superoxide dismutase, catalase, peroxidase (POD), and Na(+), K(+)-ATPase were determined as indices to evaluate the toxicity of NPs in the culture medium. To understand better whether the Zn(2+) released from the ZnO NP suspensions plays a key role in toxicity of the NPs, we investigated particle aggregation and dissolution in the medium. Furthermore, two exposure treatments for the group with the highest concentration (50 mg/L) were performed: (1) exposure for the full 96 h (50a treatment) and (2) the medium being replaced with culture medium without NPs after 12 h (50b treatment). Our results indicate that ZnO NPs induced adverse effects in S. polyrhiza at the concentration of 50 mg/L in the culture medium. Zn(2+) released from the NPs might be the main source of its toxicity to this species.
authors.affiliation: Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, Linyi University, Linyi, 276000, China.
authors.forename: Changwei
authors.initials: C
authors.lastname: Hu
authors.forename: Yimeng
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiuling
authors.initials: X
authors.lastname: Li
authors.forename: Mei
authors.initials: M
authors.lastname: Li
mesh_terms: D029064:Araceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006128:Growth / Q000187:drug effects; D053758:Nanoparticles / Q000633:toxicity*; D010088:Oxidoreductases / Q000378:metabolism; D018675:Toxicity Tests; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D003470:Culture Media; D010088:Oxidoreductases; D015034:Zinc Oxide