Effect of soluble copper released from copper oxide nanoparticles solubilisation on growth and photosynthetic processes of Lemna gibba L

Abstract

Copper oxide nanoparticles (CuO NPs) are used as a biocide in paints, textiles and plastics. Their application may lead to the contamination of aquatic ecosystems, where potential environmental effects remain to be determined. Toxic effects may be related to interactions of NPs with cellular systems or to particles' solubilisation releasing metal ions. In this report, we evaluated CuO NPs and soluble copper effects on photosynthesis of the aquatic macrophyte Lemna gibba L to determine the role of particle solubility in NPs toxicity. When L. gibba plants were exposed 48 h to CuO NPs or soluble copper, inhibition of photosynthetic activity was found, indicated by the inactivation of Photosystem II reaction centers, a decrease in electron transport and an increase of thermal energy dissipation. Toxicity of CuO NPs was mainly driven by copper ions released from particles. However, the bioaccumulation of CuO NPs in plant was shown, indicating the need to evaluate organisms of higher trophic level.

Keywords::

• chlorophyll a fluorescence
• ecotoxicology
• nanotoxicology
• photosystem II

Acknowledgements

The authors thank the staff of the Faculty for Electron Microscopy Research (McGill University) for their assistance. F. Perreault was supported by a NSERC PhD fellowship. D. Dewez acknowledges the financial support provided by the Department of Chemistry and the Faculty of Science (UQAM). This paper is dedicated in memory of professor Radovan Popovic 1940–2012.