The oxidative toxicity of Ag and ZnO nanoparticles towards the aquatic plant Spirodela punctuta and the role of testing media parameters

• DOI: 10.1039/c3em00235g
• Publication Date: 2013-07-17T11:02:09Z
• Authors: Melusi Thwala; Ndeke Musee; Lucky Sikhwivhilu; Victor Wepener
• Keywords: Silver; Superoxide Dismutase; Surface Properties; Reactive Nitrogen Species; 01 natural sciences; Antioxidants; Oxidative Stress; Microscopy, Electron, Transmission; 13. Climate action; Araceae; Nanoparticles; Particle Size; Zinc Oxide; Reactive Oxygen Species; Water Pollutants, Chemical; Environmental Monitoring; 0105 earth and related environmental sciences

The toxicity effects of silver (nAg) and zinc oxide (nZnO) engineered nanoparticles (ENPs) on the duckweed Spirodela punctuta were studied to investigate potential risks posed by these ENPs towards higher aquatic plants. influence media abiotic factors stability was also evaluated. Marked agglomeration observed after introduction into testing whereby large particles settled out suspension accumulated at bottom vessels. high ionic strength (IS) promoted because it reduced inter-particle repulsion caused a reduction in their surface charge. Low dissolution for nAg, reaching only 0.015% 1000 mg L−1, whilst improved nZnO, falling below analytical quantification 0.1 L−1 lower. free radicals namely, reactive oxygen nitrogen species (ROS/RNS) hydrogen peroxide (H2O2), indicated induction oxidative stress plants exposed ENPs. A definite dose ROS/RNS volumes nZnO 14 days, response not always observed. total antioxidant capacity (TAC) superoxide dismutase (SOD) activity varying degrees exposure This driven mainly particulates dissolved Zn2+ main driver nZnO. Our findings suggest that nAg could be both forms, as modified properties.