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Solid Earth An interactive open-access journal of the European Geosciences Union

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Solid Earth, 8, 845-855, 2017
https://doi.org/10.5194/se-8-845-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
23 Aug 2017
Mineral-leaching chemical transport with runoff and sediment from severely eroded rare-earth tailings in southern China
Huizhong Lu1,2, Longxi Cao1, Yin Liang1, Jiuqin Yuan1,2, Yayun Zhu1,2, Yi Wang1,2, Yalan Gu1,2, and Qiguo Zhao1 1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
2University of Chinese Academy of Sciences, Beijing 100049, China
Abstract. Rare-earth mining has led to severe soil erosion in southern China. Furthermore, the presence of the mineral-leaching chemical ammonium sulfate in runoff and sediment poses a serious environmental threat to downstream water bodies. In this paper, the characteristics of mineral-leaching chemicals in surface soil samples collected in the field were studied. In addition, NH4+ and SO42− transport via soil erosion was monitored using runoff and sediment samples collected during natural rainfall processes. The results demonstrated that the NH4+ contents in the surface sediment deposits increased from the top of the heap (6.56 mg kg−1) to the gully (8.23 mg kg−1) and outside the tailing heap (13.03 mg kg−1). The contents of SO42− in the different locations of the tailing heaps ranged from 27.71 to 40.33 mg kg−1. During typical rainfall events, the absorbed NH4+ concentrations (2.05, 1.26 mg L−1) in runoff were significantly higher than the dissolved concentrations (0.93, 1.04 mg L−1), while the absorbed SO42− concentrations (2.87, 1.92 mg L−1) were significantly lower than the dissolved concentrations (6.55, 7.51 mg L−1). The dissolved NH4+ and SO42− concentrations in runoff displayed an exponentially decreasing tendency with increasing transport distance (Y = 1. 02 ⋅ exp( − 0. 00312X); Y = 3. 34 ⋅ exp( − 0. 0185X)). No clear trend with increasing distance was observed for the absorbed NH4+ and SO42− contents in transported sediment. The NH4+ and SO42− contents had positive correlations with the silt and clay ratio in transported sediment but negative correlations with the sand ratio. These results provide a better understanding of the transport processes and can be used to develop equations to predict the transport of mineral-leaching chemicals in rare-earth tailings, which can provide a scientific foundation for erosion control and soil management in rare-earth tailing regions in southern China.

Citation: Lu, H., Cao, L., Liang, Y., Yuan, J., Zhu, Y., Wang, Y., Gu, Y., and Zhao, Q.: Mineral-leaching chemical transport with runoff and sediment from severely eroded rare-earth tailings in southern China, Solid Earth, 8, 845-855, https://doi.org/10.5194/se-8-845-2017, 2017.
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