The influence of humic acid on the toxicity of nano-ZnO and Zn2+ to the Anabaena sp.

Authors

  • Yulin Tang,

    Corresponding author
    1. State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, People's Republic of China
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  • Shuyan Li,

    1. State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, People's Republic of China
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  • Yao Lu,

    1. State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, People's Republic of China
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  • Qian Li,

    1. State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, People's Republic of China
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  • Shuili Yu

    1. State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, People's Republic of China
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ABSTRACT

This study explored the effects of humic acid (HA) on the toxicity of ZnO nanoparticles (nano-ZnO) and Zn2+ 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 Zn2+ 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 Zn2+ 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 Zn2+ did, which could be proven by the malondialdehyde content in Anabaena sp. cells. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 895–903, 2015.

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