Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China.
BayCEER, Department of Hydrology, University of Bayreuth, D-95440 Bayreuth, Germany.
Sci Total Environ. 2022 Apr 10;816:151574. doi: 10.1016/j.scitotenv.2021.151574. Epub 2021 Nov 16.
Rapid industrialization and urbanization have resulted in elevated concentrations of contaminants in the groundwaters and subsurface soils, posing a growing hazard to humans and ecosystems. The transformation of most contaminants is closely linked to the mineralogy of ferric (hydr)oxides. Sulfidation of ferric (hydr)oxides is one of the most significant biogeochemical reactions in the anoxic environments, causing reductive dissolution and recrystallization of ferric (hydr)oxides and further affecting the transformation of iron-associated contaminants. This paper provides a comprehensive review on the sulfidation process of ferric (hydr)oxides and the transformation of relevant contaminants. This review presents detailed reaction mechanisms between ferric (hydr)oxides and dissolved sulfide, and elucidates the factors (e.g. crystallinity of ferric (hydr)oxides, the ratio of sulfide concentration to the surface area concentration of ferric (hydr)oxides) that control the formation of surface associated Fe(II), iron sulfide minerals, as well as transformation of secondary minerals. Then, we summarized the transformation mechanisms of a variety of typical environmentally relevant contaminants existing in groundwater and subsurface soils, including heavy metals, metal(loid) oxyanions (arsenic, antimony, chromium), radionuclides (uranium, technetium), organic contaminants and phosphate/nitrate species. The general mechanisms of contaminant transformation involve a combination of release, reduction and re-adsorption/incorporation processes, the specific pathway of which is highly dependent on the properties of the contaminant itself and the extent of sulfidation. Moreover, the challenge of extending our knowledge towards in situ remediation, as well as further research needs are identified.
快速的工业化和城市化导致地下水和地下土壤中污染物浓度升高，对人类和生态系统构成了越来越大的威胁。大多数污染物的转化与铁（氢）氧化物的矿物学密切相关。铁（氢）氧化物的硫化作用是缺氧环境中最重要的生物地球化学反应之一，导致铁（氢）氧化物的还原溶解和再结晶，并进一步影响与铁相关的污染物的转化。本文对铁（氢）氧化物的硫化过程和相关污染物的转化进行了全面综述。本文详细介绍了铁（氢）氧化物与溶解态硫化物之间的反应机制，并阐明了控制表面结合态 Fe(II)、铁硫化物矿物形成以及次生矿物转化的因素（如铁（氢）氧化物的结晶度、硫化物浓度与铁（氢）氧化物表面积浓度之比）。然后，我们总结了地下水和地下土壤中存在的各种典型环境相关污染物的转化机制，包括重金属、金属（类）含氧阴离子（砷、锑、铬）、放射性核素（铀、锝）、有机污染物和磷酸盐/硝酸盐。污染物转化的一般机制涉及释放、还原和再吸附/掺入过程的结合，具体途径高度依赖于污染物本身的性质和硫化程度。此外，确定了将我们的知识扩展到原位修复以及进一步研究需求的挑战。
