Toxicity of zero-valent iron nanoparticles and its fate in Zea mays

Application of nanotechnology has gained remarkable interest in recent years and environmental exposure to nanomaterials is becoming inevitable. Therefore, nanotoxicity problem is gaining more attention. Zero-valent iron nano particles (nZVI) are being used widely for different purposes such as environmental remediation. Excessive amounts of nanomaterials may pose inhibitory effects on growth of plants cultivated in nZVI-affected soils which has been addressed in this research. Moreover, fate of nZVI in plants was investigated in the present study. Plant seeds were exposed to different concentrations of nZVI i.e. 0, 100, 250, 500, 800 and 1000 mg/kg. Z. mays was selected as the model plant in this study and found to be a tolerant plant species in presence of low to moderate levels of nZVI in soil. However, addition of higher doses of nZVI reduced seedling emergence and biomass establishment. Results indicated that the total Fe concentrations in Z. mays treated with nZVI increased compared to the control. Considerably higher accumulation of Fe in roots of Z. mays compared to the shoots in all treatments was found. Results indicated that the total Fe contents in Z. mays treated with nZVI were higher than those in control, with the highest Fe accumulation capacity of 24666.2 µg per pot which was obtained in soil received 500 mg/kg nZVI. Overally, toxic effects of higher doses of nZVI on plants were observed in this study. Intelligent use of nZVI for environmental purposes such as applying low to moderate levels of nZVI in soil remediation activities could remarkably prevent their adverse impacts on plant species, promote plant phytoextraction capability, and reduce nZV emission in the environment.