A flow-through cell (FTC) experiment was conducted to identify mechanisms of Ni removal by calcite through study of changes in Ni speciation and Ni isotope signature during the treatment of simulated Ni-contaminated groundwater. Synthetic Ni-contaminated groundwater was pumped through a FTC packed with crushed natural calcite. Effluent samples were collected to determine concentrations of anions, cations, and for Ni isotope-ratio measurement. X-ray absorption spectroscopy (XAS) was performed on chosen spots of the solid phase along the FTC length. Isotope data indicated multiple mechanisms affected Ni removal in the FTC system. Ni adsorption to and coprecipitation with calcite dominated the early part of the experiment yielding a fractionation factor of ε = −0.5 ‰. Subsequently, Ni precipitation as a Ni-hydroxide phase became the major process controlling Ni removal, resulting in a fractionation factor ε = −0.4 ‰. XAS analysis confirmed the presence of both Ni(OH)₂ and (Ni, Ca)CO₃ types of Ni local structural environments. Results from this study highlight the potential of Ni isotopes as auxiliary tools to determine the processes involved in Ni attenuation from the environment. The characterization of mechanisms involved in Ni removal from solution is necessary to evaluate potential impacts to the environment and to develop effective remediation strategies.

通过研究模拟 Ni 污染地下水处理过程中 Ni 形态和 Ni 同位素特征的变化，进行了流通池 (FTC) 实验，以确定方解石去除 Ni 的机制。合成的受镍污染的地下水被泵入装有碎天然方解石的 FTC。收集流出物样品以确定阴离子、阳离子的浓度，并用于 Ni 同位素比测量。X 射线吸收光谱 (XAS) 沿 FTC 长度在固相的选定点上进行。同位素数据表明多种机制影响 FTC 系统中的 Ni 去除。Ni对方解石的吸附和与方解石的共沉淀在实验的早期部分占主导地位，产生的分馏因子为 ε = -0.5 ‰。随后，作为镍氢氧化物相的镍沉淀成为控制镍去除的主要过程，导致分馏因子 ε = -0.4 ‰。XAS 分析证实了 Ni(OH)₂和 (Ni, Ca)CO ₃类型的 Ni 局部结构环境。这项研究的结果强调了镍同位素作为辅助工具来确定镍从环境中衰减的过程的潜力。从溶液中去除 Ni 所涉及的机制的表征对于评估对环境的潜在影响和制定有效的修复策略是必要的。