Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China.

Lingqing Wang,Tao Liang

doi:10.1038/srep12483

Abstract

Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 104 mg·kg−1 with an average value of 4.67 × 103 mg·kg−1, which was significantly higher than the average value in China (181 mg·kg−1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.

Highlights

Waring and Watling (1990)[8] and Pairon et al (1995)[9] have documented that some inhaled Rare earth elements (REEs) tend to accumulate in human lung and lymph nodes
The REE fractions of these soil profiles showed an enrichment of light rare earth elements (LREEs) relative to the heavy rare earth elements (HREEs) (Fig. 4). These results indicate that the REEs patterns of the soils around the mine tailings are consistent with those of Bayan Obo ores reported in the literature[28]
The order of the average concentrations of REEs in surface soils around the Bayan Obo mine region was as follows: Ce > La > Nd > Pr > Sm > Gd > Dy > Er > Yb > Eu > Tb > Ho > Tm > L u, which was similar to that found in Bayan Obo ores, suggesting that the concentration and distribution of REEs are influenced by the mine tailing

Summary

Introduction

Waring and Watling (1990)[8] and Pairon et al (1995)[9] have documented that some inhaled REEs tend to accumulate in human lung and lymph nodes. The mobility of REEs and their possible impacts on ecosystems are still relatively unknown and potential risks for human health and environment cannot be currently estimated. The Bayan Obo mine produces approximately 8.0 million tons of tailings each year[11]. Most of this enormous waste is typically disposed of in open dumps. Tailing is one of the major sources of REE environmental pollution since the tailing is powdery (and potentially mobile) and its quantity is larger than slag. The results presented provide scientific evidence of the ecological risk associated with the excavation of rare earth minerals and advocate the prevention of REE pollution in soil and eco-resumption

Methods

Results

Conclusion