Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, N2L 3G1 Waterloo, Canada.
Centre of Sport, Exercise and Life Sciences, Institute for Health and Wellbeing, Coventry University, Priory Street Coventry CV1 5FB, United Kingdom.
Environ Sci Technol. 2022 Jun 21;56(12):7954-7962. doi: 10.1021/acs.est.2c00523. Epub 2022 Jun 1.
Microbially mediated sulfate reduction is a promising cost-effective and sustainable process utilized in permeable reactive barriers (PRB) and constructed wetlands to treat mine wastewater. Laboratory batch experiments were performed to evaluate nickel (Ni) isotope fractionation associated with precipitation of Ni-sulfides in the presence of the sulfate-reducing bacterium (SRB) (DSM-642). Precipitates were collected anaerobically and characterized by synchrotron powder X-ray diffraction (PXRD), scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). Solid-phase analyses showed that the precipitates associated with bacteria attached to the serum bottle walls were characterized by enhanced size and crystallinity. Lighter Ni isotopes were preferentially concentrated in the solid phase, whereas the solution was enriched in heavier Ni isotopes compared to the input solution. This fractionation pattern was consistent with closed-system equilibrium isotope fractionation, yielding a fractionation factor of ΔNi = -1.99‰. The Ni isotope fractionation measured in this study indicates multiple Ni reaction mechanisms occurring in the complex SRB-Ni system. The results from this study offer insights into Ni isotope fractionation during interaction with SRB and provide a foundation for the characterization and development of Ni stable isotopes as tracers in environmental applications.
微生物介导的硫酸盐还原是一种有前途的具有成本效益和可持续性的过程，可用于可渗透反应屏障 (PRB) 和人工湿地处理矿山废水。进行了实验室批量实验，以评估在硫酸盐还原菌 (SRB) （DSM-642）存在下与 Ni-硫化物沉淀相关的镍 (Ni) 同位素分馏。在厌氧条件下收集沉淀物，并通过同步辐射粉末 X 射线衍射 (PXRD)、扫描电子显微镜结合能量色散 X 射线光谱 (SEM-EDS) 和透射电子显微镜 (TEM) 进行表征。固相分析表明，与附着在血清瓶壁上的细菌相关的沉淀物具有增强的尺寸和结晶度。较轻的 Ni 同位素优先浓缩在固相中，而与输入溶液相比，溶液中富含较重的 Ni 同位素。这种分馏模式与封闭体系平衡同位素分馏一致，产生分馏因子 ΔNi = -1.99‰。本研究中测量的 Ni 同位素分馏表明，在复杂的 SRB-Ni 体系中发生了多种 Ni 反应机制。本研究的结果提供了对与 SRB 相互作用过程中 Ni 同位素分馏的深入了解，并为 Ni 稳定同位素作为环境应用中的示踪剂的表征和开发提供了基础。
