Shi, Jiyan , Silk, Wendy K. , Kennedy, Ian , Hristova, Krassimira R. .
Comparing the toxicity of CuO nanoparticles and soluble Cu affecting Spirodela polyrrhiza.
Metal oxide nanoparticles are increasingly released into the environment; however, the potential toxicity of these materials is not known. In this study CuO nanoparticles and comparable doses of ionic Cu were applied to duckweed (Spirodela polyrrhiza),a floating aquatic, monocotyledonous plant found in ponds and sloughs. CuO nanoparticles were synthesized in a hydrogen diffusion flame. Particle size (mean diameter of 43nm) and morphology were characterized using a scanning mobility particle sizer and transmission electron microscopy. Effects of the nanoparticles on plant growth, Cu uptake and pigment concentration were determined and compared to the effect of ionic Cu. Duckweeds were grown in Hoaglands solution for nine days, corresponding to 3.8 frond doubling times for controls. The solubility of CuO nanoparticles varies with both pH and the presence of other ions. Approximately 3.7% of nanoparticles dissolved in water at pH 6.0, while 65% dissolved at pH 3.2 in Hoaglands solution. Nanoparticulate CuO inhibits growth more than can be accounted for by the soluble Cu present in the nanoparticulate suspension. Compared to controls, the frond growth was inhibited 50% by either 0.60 ppm soluble copper or by 10 ppm CuO nanoparticles that release only 0.16 ppm soluble Cu in the growth medium. A significant decrease of chlorophyll a and b was observed in plants stressed by 1 ppm CuO nanoparticles. In contrast, a slight increase of pigments was found in the comparable 0.2 ppm soluble Cu treatment. The Cu in duckweeds exposed to 1 ppm CuO nanoparticles is more than twice as as concentrated than those in 0.2 ppm soluble Cu treatments. Our results suggest that the potential toxicity of CuO nanoparticles to aquatic plants is mediated not only by the release of soluble Cu, but also by some aspect of the nanoparticulate structure.
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1 - Zhejiang University, Department of Environmental Engineering, HangZhou, 310029, People’s Republic of Chin
2 - University of California at Davis, Land, Air, and Water Resources, One Shields Ave., Davis, CA, 95616-8627, USA
3 - University of California Davis, Department of Mechanical and Aeronautical Engineering, Biomedical Engineering Graduate Group , Davis, CA, 95616, USA
4 - University of California Davis, Land, Air, and Water Resources, Davis, CA, 95616, USA
heavy metal phytotoxicity.
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Wasatch B/Cliff Lodge - Level C
Date: Tuesday, July 28th, 2009
Time: 10:30 AM