Accumulation and Distribution of Rare Earth Elements (REEs) and Non-REEs With Vetiver Grass in The Abandoned Ion-Absorbed Rare Earth Mine

Overexploitation of rare earth elements (REEs) has caused serious desertification and environmental pollution, and ecological restoration of mines has attracted increasing national attention. In this paper, experiments involved land plowing, organic fertilizer broadcasting and vetiver cultivation were carried out to repair abandoned ion-absorbed rare earth mines (REM). Toxic metals content and pH in mining soil, distribution and transportation of toxic metals in the soil – vetiver grass system were investigated in detail.Results revealed that the abandoned REM soil was weakly acidic (pH=4.09) and rich in various toxic metals composed of REEs (La, Ce, Nd, Y, Gd, Dy) of 657.57mg/kg and Non-REEs (Pb, Cu, Se, As, Cd) of 109.98mg/kg. The distribution pattern in vetiver grass illustrated that toxic metals accumulation was mainly concentrated in the roots instead of shoot, and then the cumulative concentration of REEs in roots were much greater than that of Non-REEs. Furthermore, vetiver grass exhibited preferential accumulation of Cd, Se and REEs during the absorption process (from soil to root) and preferential accumulation of Pb, Cu and As during the translocation process (from root to leaf). The adsorption behavior of toxic metals by vetiver was confirmed due to these observed irregular particles in the scanning electron microscopy.