Bioaccumulation and phytotoxicity of ZnO nanoparticles in soil-grown Brassica chinensis and potential risks
Abstract A pot-culture experiment was carried out to explore the phytotoxicity and accumulation of ZnO nanoparticles (ZnO NPs) in pakchoi (Brassica chinensis), as well as its potential risk. Zn was mainly accumulated in the shoots of pakchoi and showed the order of cell wall fraction > soluble fraction > organelles fraction. Endosomes were observed in roots cell by transmission electron microscope (TEM) and it is proving that endocytosis is a possible way for NPs to enter the cells. The results showed that higher concentration of ZnO NPs treatments resulted in an increase in the content of photosynthetic pigments and malondialdehyde (MDA), Catalase (CAT) and ascorbate peroxidase (APX) activity, while the activity of superoxide dismutase (SOD) and guaiacol peroxidase (G-POD) decreased significantly compared with the control. These changes suggest that the mechanism of ZnO NPs phytotoxicity may induce strongly oxidative stress and damage biomembrane. Generally, ZnO NPs had a similar impact on the growth and absorption of Zn in pakchoi with Zn2+. Simultaneously, the treatment of ZnO NPs affected the nutritional quality and food safety of pakchoi at high concentration.