Abstract This study was aimed at developing a water erosion tracer from montmorillonite (MMT) chemically modified with rare earth elements (REE) as chemical signatures to understand the landscape sediment mobilization dynamics. A new route of development involving the use of an industrial residue from the REE extraction process was evaluated for its REE incorporation efficiency in the clay mineral to enable further tracer applications on a field scale. This industrial residue-modified MMT tracer was compared with a reference tracer based on the chemical modification of MMT with a commercial REE precursor. These REE-modified MMT tracers were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence spectroscopies, inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffractometry, scanning electron microscopy (SEM), and N2 physisorption measurements were performed to verify whether the MMT tracer modified with the industrial residue had the same chemical signature (REE) content and chemical stability as those of the commercial REE precursor-based tracer. Chemical stability tests under different pH conditions were carried out to evaluate possible REE content variations in the tracers, mainly over the targeted soil pH range (pH = 4.0–7.7). The clay modified with the industrial residue was further submitted to laboratory horizontal mobility tests using a soil flume. The chemical modification method was effective in producing a chemically stable MMT-based tracer that also displayed multi-chemical signature due to the use of the ClLa40-INB solution, which will potentially enhance the tracer detection in sediments. The mobility tests confirmed the suitability of the modified clay as a tracer.

中文翻译：

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以工业残渣作为稀土元素来源的水蚀示踪剂的开发

摘要 本研究旨在开发一种以稀土元素 (REE) 化学修饰的蒙脱石 (MMT) 作为化学特征的水蚀示踪剂，以了解景观沉积物动员动力学。一种新的开发途径涉及使用 REE 提取过程中的工业残留物，评估了其在粘土矿物中的 REE 掺入效率，从而能够在现场规模上进一步应用示踪剂。将该工业残留改性的 MMT 示踪剂与基于用商业 REE 前体对 MMT 进行化学改性的参考示踪剂进行比较。这些 REE 修饰的 MMT 示踪剂通过傅里叶变换红外光谱 (FTIR) 和 X 射线荧光光谱、电感耦合等离子体质谱 (ICP-MS)、X 射线衍射、进行扫描电子显微镜 (SEM) 和 N2 物理吸附测量以验证用工业残留物改性的 MMT 示踪剂是否具有与商业 REE 前体示踪剂相同的化学特征 (REE) 含量和化学稳定性。进行了不同 pH 条件下的化学稳定性测试，以评估示踪剂中可能的 REE 含量变化，主要是在目标土壤 pH 范围内（pH = 4.0-7.7）。用工业残留物改性的粘土进一步进行了使用土壤水槽的实验室水平流动性测试。由于使用 ClLa40-INB 溶液，化学修饰方法可有效产生化学稳定的基于 MMT 的示踪剂，该示踪剂也显示出多化学特征，这将有可能增强沉积物中的示踪剂检测。