Remediation of a Multi-metal Contaminated Soil under Quinoa Cultivation by Green Synthesized Zinc, Copper and Iron Nanoparticles

Abstract One of the sustainable approaches to remove heavy metals (HMs) is the use of green metal nanoparticles. In this study, zinc (Zn), copper (Cu) and iron (Fe) nanoparticles were prepared by green synthesis method as an environmentally friendly method using Arizona cypress leaf extract and nitrate salts of Zn, Cu, and Fe. The nanoparticles at two rates of 0.5 and 1% were added to a soil contaminated with 100 mg kg -1 of each Zn, nickel (Ni), lead (Pb) and cadmium (Cd) to investigate and compare their influence on the uptake of the HMs by quinoa. According to the results, the lowest shoot and root uptakes of all four HMs were observed following the application of Cu nanoparticles (1%). The lowest metal uptake belonged to Ni in shoot and Pb in roots which were 19.06 and 20.82 (μg pot -1 ), respectively. Most likely due to the lowest specific surface area observed (11.42 m 2 g -1 ), the highest uptake of Ni, Pb and Cd by the plant was occurred after the application of Fe nanoparticles. Likewise, as a good accumulator, the quinoa was able to absorb considerable quantities of Ni in the root (144.94 μg pot -1 ) and Zn in the shoot (452.1 μg pot -1 ). The findings of this study showed that the synthesized Cu nanoparticles had the highest adsorption capability of HMs compared to other tested nanoparticles, which was most probably due to having the highest specific surface area (147.66 m 2 g -1 ) and the smallest particle size (32.26 nm).