同位素技术是追踪某些污染物来源或提供对环境过程的见解的理想工具。近年来,多收集器电感耦合等离子体质谱(MC-ICP-MS)的出现使各种金属稳定同位素的精确测量成为可能。由于各种环境样本中存在“指纹”属性,金属稳定同位素已被用于有效区分污染物的来源,并进一步了解相应的环境过程。金属元素的环境命运受到吸附的强烈控制,元素在溶解相和颗粒相之间分布的基本过程。金属元素在矿物和有机表面上的吸附显着影响其在环境中的生物地球化学循环。因此,阐明吸附过程中稳定金属同位素的分馏特性至关重要。在这次审查中,选择了三种典型的过渡金属元素,考虑Mo作为阴离子物种的代表,Fe和Zn作为阳离子物种的代表。对于Mo来说,较重的Mo同位素优先吸附在溶液相中,pH值对同位素分馏有更显著的影响,温度和离子强度相对不敏感。吸附过程中溶解和吸附的Mo之间的配位环境差异,即,附着模式(内球或外球)或分子对称性(例如,协调数和失真的幅度),可能是同位素分馏的原因。对于Fe,含水Fe(II)矿物中平衡/动力学Fe同位素分馏的研究并不简单。Fe(II)水溶液和Fe(羟基)氧化物之间的相互作用是复杂的和动态的。同位素效应是由于吸附的Fe(II)之间的电子和原子交换耦合,含水Fe(II),和活性Fe(III)在Fe(羟基)氧化物表面。对于Zn,较重的Fe同位素优先吸附在固相上,pH和离子强度是必不可少的影响因素。配位环境的差异可能是同位素分馏的原因。
Isotope technology is an ideal tool for tracing the sources of certain pollutants or providing insights into environmental processes. In recent years, the advent of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has enabled the precise measurement of various metal stable
isotopes. Due to the presence of \"fingerprint\" properties in various environmental samples, metal stable
isotopes have been applied to distinguish the source of contaminants effectively and further understand the corresponding environmental processes. The environmental fate of metal elements is strongly controlled by adsorption, an essential process for the distribution of elements between the dissolved and particulate phases. The adsorption of metal elements on mineral and organic surfaces significantly affects their biogeochemical cycles in the environment. Therefore, it is crucial to elucidate the fractionation characteristics of stable metal
isotopes during the adsorption process. In this review, three typical transitional metal elements were selected, considering Mo as the representative of anionic species and Fe and Zn as the representative of cationic species. For Mo, the heavier Mo isotope is preferentially adsorbed in the solution phase, pH has a more significant influence on isotope fractionation, and temperature and ionic strength are relatively insensitive. Differences in coordination environments between dissolved and adsorbed Mo during adsorption, i.e., attachment mode (inner- or outer-sphere) or molecular symmetry (e.g., coordination number and magnitude of distortion), are likely responsible for isotopic fractionation. For Fe, The study of equilibrium/kinetic Fe isotopic fractionation in aqueous Fe(II)-mineral is not simple. The interaction between aqueous Fe(II) and Fe (hydroxyl) oxides is complex and dynamic. The isotope effect is due to coupled electron and atom exchange between adsorbed Fe(II), aqueous Fe(II), and reactive Fe(III) on the surface of Fe (hydroxyl) oxide. For Zn, the heavier Fe isotope preferentially adsorbs on the solid phase, and pH and ionic strength are essential influencing factors. The difference in coordination environment may be the cause of isotope fractionation.