Toxic Effects of Nano-CuO, Micro-CuO and Cu²⁺ on Chlorella sp.

Liyan Wang, Mian Wang, Changsheng Peng, Jinfen Pan

Key Lab of Marine Environmental Science and Ecology of the Ministry of Education,College of Environmental Science and Engineering, Ocean University of China, Qingdao, China, 266100.

DOI: 10.4236/jep.2013.41B016                

Abstract

The 96 h acute toxic effects of nano-CuO (N-CuO), micro-CuO (M-CuO) and ²⁺ on Chlorella sp. were investigated in this paper. The results showed that toxicities decreased in an order of Cu²⁺＞N-CuO＞M-CuO. The 96 h EC₅₀ of Cu²⁺ on Chlorella sp. was 1.06 mg /L, and of N-CuO it was 74.61 mg /L, while no pronounced toxicity was observed when the concentration of M-CuO was lower than 160 mg/L. Further experiments were carried out in order to study the toxicity mechanism of nano-CuO on Chlorella sp.. The results of Cu²⁺ release from N-CuO showed less than 0.2 mg/L Cu2+ were released, so the release of Cu²⁺ was not responsible for the toxicity. Further experiments showed N-CuO inhibited formation of Chlorophyll A. Content of Chlorophyll A in the control group was 4.75 mg/10⁸ cells, while it declined to 2.89 mg/10⁸ cells for 160 mg/L N-CuO after 96 h, which indicated that N-CuO could inhibit photosynthesis of Chlorella sp.. Moreover, N-CuO condensed with algal cells. It affected the activity of SOD and POD, indicating that N-CuO could cause oxidant stress to Chlorella sp.. These may be the toxicity mechanism.

Keywords

Nano-CuO; Chlorella sp.; Toxic effects; Photosynthesis; Oxidant stress

Conflicts of Interest

The authors declare no conflicts of interest.

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