第六届青年地学论坛

1578 / 2019-08-21 17:51:36

Fractionation of rare earth elements (REEs) in a soil–plant system during the phytoextraction of ionic REE mine tailings by using Phytolacca americana L.

17、土壤科学与环境健康 > 专题7：土壤重金属迁移转化及其环境效应

Background and Aims: Phytolacca americana L. is a high-biomass hyperaccumulating plant for rare earth elements (REEs). However, the effects of remediation practices involving this plant on the soil properties of REE mine tailings and REE fractionation in a soil-plant system remain poorly understood.
Methods: P. americana was grown on three treatments, namely, bare tailings (B), tailings amended with organic matter (BA), and amended tailings planted with P. americana (BAPA). The properties of the soils and soil solutions of B, BA, and BAPA and the related REE fractionation in the soil-plant system were analyzed.
Results: The physicochemical properties of the soil solution and the rhizospheric soil significantly improved compared with the bare tailings. The concentration of total REEs in leaves reached 2197 mg kg−1. In this soil-plant system, the ratios of light REEs (LREEs) to heavy REEs (HREEs) (LREE/HREE) during REE transfers from soil solution to roots, from roots to stems, and from stems to leaves were 6.25, 0.35, and 0.41, respectively.
Conclusions: The combination of amendments with P. americana could be potentially used for the phytoextraction of REE mine tailings. HREEs had a higher migration ability than that of LREEs in the soil-plant system, where P. americana preferred to absorb REEs via ion channels and translocate them through ligand chelation. A conceptual model was proposed to depict REE fractionation in this soil-plant system.