Molecular-scale mechanisms of antimony binding to soil organic matter

锑与土壤有机质结合的分子尺度机制

• 批准号: 400878350
• 负责人: Professor Dr. Christian Mikutta
• 金额: --
• 依托单位: Institut für Mineralogie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/400878350?language=en
• 关键词: Molecular; scale; mechanisms; antimony; binding

Antimony (Sb) is a toxic metalloid which is increasingly released into the environment owing to its use in a vast range of industrial and technological products. Antimony compounds are therefore considered as priority pollutants by environmental protection agencies. Despite high Sb inputs to soils (ca. 26,000 t/a) only few studies have examined the speciation of Sb in soils and factors controlling its environmental fate. The low mobility of Sb observed in peat soils suggests that Sb complexation by soil organic matter (OM) represents a key element in the soil Sb cycle. Yet, information on molecular-scale interactions of Sb with inherently complex dissolved and particulate soil OM is missing. Therefore, this project aims at the investigation of molecular-scale mechanisms of Sb binding to soil OM. In the first part of the project we use synchrotron-based Sb K-edge X-ray absorption spectroscopy (XAS) to explore the mechanisms of Sb binding to soil OM under both oxic and anoxic conditions, focusing on Sb binding by carboxyl/hydroxyl and thiol groups as well as organically complexed Fe (ternary Sb complexes). We also elucidate the kinetic stability of the Sb-OM complexes using an enriched stable Sb isotope tracer approach. In the second part of this project, we study the speciation and distribution of Sb in peat soils of the Peak District, U.K. These organic soils have been impacted by long-term atmospheric deposition of Sb and are thus extensively contaminated with Sb. With the help of XAS we explore major Sb sequestration mechanisms operating in these soils. These measurements are complemented by scanning electron microscopy – energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses to study the micro-scale distribution and speciation of Sb and its association with other elements potentially controlling its speciation (e.g., Fe and S). In summary, this project will improve our mechanistic understanding of Sb-OM interactions and clarify the role of OM as a sorbent for Sb in organic soils impacted by anthropogenically released and atmospherically deposited Sb.

锑（Sb）是一种有毒的类金属，由于其在广泛的工业和技术产品中的使用，其越来越多地释放到环境中。因此，锑化合物被环境保护机构视为优先污染物。尽管高锑输入土壤（约。26，000吨/年），只有少数研究探讨了锑在土壤中的形态和控制其环境归宿的因素。Sb在泥炭土中的低流动性表明，Sb络合的土壤有机质（OM）是土壤Sb循环中的一个关键因素。然而，Sb与固有的复杂溶解和颗粒土壤OM的分子尺度相互作用的信息是失踪。因此，本项目旨在研究Sb与土壤有机质结合的分子尺度机制。在该项目的第一部分中，我们使用同步加速器为基础的Sb K边X射线吸收光谱（XAS），探讨在好氧和缺氧条件下Sb结合到土壤OM的机制，重点是Sb的羧基/羟基和巯基结合，以及有机络合的铁（三元Sb络合物）。我们还阐明了动力学稳定性的Sb-OM配合物使用富集稳定的Sb同位素示踪剂的方法。在本项目的第二部分中，我们研究了英国Peak District泥炭土中Sb的形态和分布。这些有机土壤已受到长期的大气沉积的锑，因此广泛的锑污染。与XAS的帮助下，我们探索主要的锑螯合机制在这些土壤中运行。这些测量通过扫描电子显微镜-能量色散X射线光谱（SEM-EDX）和X射线光电子能谱（XPS）分析来补充，以研究Sb的微尺度分布和形态及其与可能控制其形态的其他元素（例如，Fe和S）。总之，该项目将提高我们对Sb-OM相互作用的机械理解，并阐明OM作为Sb在有机土壤中的吸附剂的作用，该有机土壤受大气释放和大气沉积Sb的影响。