title: The influence of humic acid on the toxicity of nano-ZnO and Zn2+ to the Anabaena sp.
abstract: This study explored the effects of humic acid (HA) on the toxicity of ZnO nanoparticles (nano-ZnO) and Zn(2+) to Anabaena sp. Typical chlorophyll fluorescence parameters, including effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse-amplitude modulated fluorometer. Results showed that nano-ZnO and Zn(2+) could inhibit Anabaena sp. growth with the EC50 (concentration for 50% of maximal effect) of 0.74 ± 0.01 and 0.3 ± 0.01 mg/L, respectively. In the presence of 3.0 mg/L of HA, EC50 of nano-ZnO increased to 1.15 ± 0.04 mg/L and EC50 of Zn(2+) was still 0.3 ± 0.01 mg/L. Scanning electron microscopy observation revealed that HA prevented the adhesion of nano-ZnO on the algae cells due to the increased electrostatic repulsion. The generation of intracellular reactive oxygen species and cellular lipid peroxidation were significantly limited by HA. Nano-ZnO had more damage to the cell membrane than Zn(2+) did, which could be proven by the malondialdehyde content in Anabaena sp. cells. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 895-903, 2015.
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
authors: Yulin
authors: Y
authors: Tang
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
authors: Shuyan
authors: S
authors: Li
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
authors: Yao
authors: Y
authors: Lu
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
authors: Qian
authors: Q
authors: Li
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
authors: Shuili
authors: S
authors: Yu
mesh_terms: D017033:Anabaena / Q000187:drug effects*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects; D002614:Chelating Agents / Q000378:metabolism / Q000494:pharmacology*; D004579:Electron Transport / Q000187:drug effects; D006812:Humic Substances; D015227:Lipid Peroxidation / Q000187:drug effects; D053758:Nanoparticles / Q000633:toxicity; D010788:Photosynthesis / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015032:Zinc / Q000633:toxicity*; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D002614:Chelating Agents; D006812:Humic Substances; D017382:Reactive Oxygen Species; D015032:Zinc; D015034:Zinc Oxide
keywords: ZnO nanoparticles; algae; natural organic matter; toxicity; zinc