Effect of nutrient uptake by plant roots on the fate of REEs in soil

摘要

Concentrations of rare earth elements (REEs) and major ions in soil solutions were observed under different growth stages of soybean in order to evaluate the effect of nutrient uptake by plant roots on the mobility of REEs in soil-plant systems. Soybean plants were grown in pots, which were kept in a greenhouse for 84 days. The concentrations of major nutrient cations (K and Ca) in the soil solution decreased with the soybean growth. On the other hand, the concentrations of Al, Y, La, Ce, Nd, Gd, Dy, Er and Yb increased. Although no decrease of pH was observed, it was assumed that the REEs and Al were dissolved from the soil solid phase due to H~+ release from the plant roots for K~+ and Ca~(2+ )uptake. Subsequently, the bioaccumulation of REEs in the soybean roots was observed in the maturing stage of the soybean. These results showed that the soybean roots could enhance the dissolution of REEs from the soil solid phase and they could also accumulate REEs through plant growth.