This study assessed the feasibility of iron oxide nanoparticles impregnated with biochar (INPBC), derived from woody biomass, as a stabilizing agent for the stabilization of farmland soil in the vicinity of an abandoned mine through pot experiments with 28 days of lettuce growth. The lettuce grown in the INPBC amended soils increased by more than 100% and the concentrations of inorganic elements (Cu, Ni, Zn) decreased by more than 40%. As, Cd and Pb were not transferred properly from the soils to the lettuce biomass. The bioavailability of arsenic and heavy metals in the INPBC amended soils were decreased by 26%~50%. It seems that the major mechanisms of stabilization were arsenic adsorption on iron oxides, heavy metal precipitation by soil pH increasing and heavy metal adsorption on organic matter. These results revealed that the lower bioavailability of the inorganic pollutants in the soils stabilized using INPBC induced lower transfer to the lettuce. Thus, INPBC could be used as an amendment material for the stabilization of farmland soils contaminated by arsenic and heavy metals. However, a pre-review of the chemical properties of the amended soil must be performed prior to applying INPBC in farmland soil because the concentration of the nutrients in the soil such as available phosphates and exchangeable cations (Ca, Mg, K) could be decreased due to adsorption on the surface of the iron oxides and organic matter

Keywords: Stabilization, Biochar, Iron nanoparticle, Arsenic, Heavy metal