Wen Bing, Zhou Weiqing, Liu Peng, Zhang Yuanzheng, Jia Xiaocen, Gao Shang, Zhang Fan, Zhou Jianwei, Huang Jianbo
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, 210042 Nanjing, People's Republic of China.
School of Environmental Studies, China University of Geosciences, 430074 Wuhan, People's Republic of China.
Sci Total Environ. 2024 Jul 10;933:172972. doi: 10.1016/j.scitotenv.2024.172972. Epub 2024 May 10.
Antimony (Sb) isotopes hold immense promise for unraveling Sb biogeochemical cycling in environmental systems. Mn oxides help control the fate of Sb via adsorption reactions, yet the behavior and mechanisms of Sb isotopic fractionation on Mn oxides are poorly understood. In this study, we examine the Sb isotopic fractionation induced by adsorption on β-MnO in different experiments (kinetic, isothermal, effect of pH). We observe that adsorption on β-MnO surfaces preferentially enriches lighter Sb isotopes through equilibrium fractionation, with ΔSb of 0.55-0.79 ‰. Neither the pH or surface coverage affects the fractionation magnitude. The analysis of extended X-ray absorption fine structure (EXAFS) demonstrates that the enrichment of light isotope results from the adsorption of inner-sphere complexation on solids. Our finding of this study enhances our comprehension of the impact of β-MnO on Sb isotopic fractionation behavior and mechanism and facilitate the applicability of Sb isotopes as effective tracers to elucidate the origins and pathways of Sb contamination in environmental systems, as well as provide a new insight into forecasting the isotopic fractionation of other similar metals adsorbed by manganese oxides.
锑（Sb）同位素在揭示环境系统中锑的生物地球化学循环方面具有巨大潜力。锰氧化物通过吸附反应帮助控制锑的归宿，然而，人们对锰氧化物上锑同位素分馏的行为和机制了解甚少。在本研究中，我们在不同实验（动力学、等温、pH值影响）中研究了β -MnO吸附诱导的锑同位素分馏。我们观察到，通过平衡分馏，β -MnO表面的吸附优先富集较轻的锑同位素，ΔSb为0.55 - 0.79‰。pH值和表面覆盖率均不影响分馏程度。扩展X射线吸收精细结构（EXAFS）分析表明，轻同位素的富集是由于内球络合在固体上的吸附。我们这项研究的发现增强了我们对β -MnO对锑同位素分馏行为和机制影响的理解，并促进了锑同位素作为有效示踪剂在阐明环境系统中锑污染的来源和途径方面的应用，同时为预测锰氧化物吸附的其他类似金属的同位素分馏提供了新的见解。
