| 摘要: |
| 稀土被称为“工业维生素”。随着稀土元素使用日益增加，导致其在土壤广泛分布并不断积累。土壤中稀土元素的地球化学过程已成为全球关注的热点。本文通过检索土壤环境稀土元素方向研究文献，综述土壤稀土元素迁移-富集机制的研究进展，识别土壤稀土元素主要来源，探讨土壤稀土元素的含量分布、分馏特征和赋存相态，以及稀土元素迁移富集和分馏的影响因素，分析稀土元素对土壤理化性质、动物、植物和微生物等产生的生态效应，以及对人体健康的潜在威胁，提出土壤稀土元素未来研究的关键问题和方向。相关认识有助于理解和掌握稀土元素在土壤中的迁移和归趋，并为稀土污染防治提供理论依据。 |
| 关键词: 土壤 稀土元素 迁移-富集 生态效应 健康风险 |
| DOI：10.7515/JEE221024 |
| CSTR： |
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| 基金项目:国家自然科学基金项目（41771024） |
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| Migration enrichment mechanism and ecological effects of rare earth elements in soil |
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LIN Zhuoling, HUANG Guangqing
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1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou 510070, China
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| Abstract: |
| Background, aim, and scope Rare earth elements (REEs) are known as “industrial vitamins”. The increasing use of REEs has led to their widespread distribution and accumulation in the soil, and they are considered emerging pollutants. Southern China contains granite bodies in which ion-adsorption-type REE deposits have formed due to surface weathering. REEs are highly soluble and prone to migrate by leaching into the surrounding soil environment, a process affected by the weathering crust medium, climatic conditions and geomorphic characteristics of the natural environment. REE pollution is believed to pose a long-term ecological risk in China. As both an important “source” and “sink” of pollutants, the soil environment is an important window through which to study the migration and enrichment processes of REEs. To make efficient use of REE resources, while controlling associated pollution, geochemists and environmental scientists worldwide have investigated the geochemical processes of REEs in soil. This paper presents an analysis of the sources, processes and ecological risks relating to soil REE pollution based on a review of research on REEs in soil surface environments, and proposes future research and development directions and key problems relating to soil REEs. The paper will provide a reference to support further exploration of the migration and enrichment of REEs in soil and the evaluation of the associated ecological risk. Materials and methods Based on the literature on REEs in soil environments in China and beyond, this paper summarizes the progress of research into the migration, enrichment mechanism and ecological effects of REEs in soil. Results The main sources of REEs in soil are the natural leaching of ion-adsorption-type REE ores, mining of REEs, agricultural application of fertilizer, and vehicular and dust emissions. Differences in soil texture and utilization type lead to differences in the content and spatial distribution of REEs. Generally, REEs exist in either an inorganic-bound state, an organic-bound state or an iron manganese oxide-bound state. Depending on the pH value, redox conditions, soil texture and other factors, REEs undergo migration and enrichment at a range of scales. These processes have an adverse impact on the physical and chemical properties of soil and on animals, plants and microorganisms, and pose varying degrees of risk to human health through respiratory exposure and the food chain. Studies have revealed the potential health risks of REEs at the molecular, cellular and individual levels. Discussion The migration and enrichment of REEs are restricted by multiple factors. The occurrence phases of REEs in soil affect their content, migration behavior and bioavailability. Specifically, REEs form complexes with inorganic oxyacid anions and organic ligands, and are mainly distributed in the soil in the form of inorganic-bound, organic-bound or iron manganese oxide-bound phases. The distribution of these phases results in marked differences in the content and migration rate of REEs in the soil. Meanwhile, the migration, enrichment and fractionation of REEs in soil can be understood as a series of complex chemical processes, including weathering-leaching, oxidation-reduction, dissolution-precipitation, adsorption-desorption and others. These processes are affected by the soil pH value, redox conditions, soil texture and other factors, resulting in variations in the migration and enrichment of REEs and corresponding changes in their geochemically driven fractionation behavior. REEs differ in their abundance distribution patterns and environmental migration potential. Future research is expected to focus on further tracking and investigating the sources and contributors of REEs in soil from the perspective of multiple temporal and spatial scales and land-use types, revealing the dynamic mechanism of their release and migration, evaluating the dose-biological response behavior of REE compounds as pollutants and the corresponding health risks, exploring the response strategies of microorganisms to REE-rich environments and developing new technologies for resource utilization of REEs. Conclusions Through field monitoring, experimental simulations and theoretical model calculations, researchers have conducted in-depth investigations of the abundance, differential activation and migration mechanisms, morphology and influencing factors of REEs. Due to the complexity of soil pollution profiles and the diversity of sources of REEs, the behavior of REEs in soil and the associated risks are not yet clearly understood. The differentiation and occurrence forms of REEs significantly affect their migration process and environmental effects in the soil, in turn affecting the biological, ecological and human health risks these elements pose. Recommendations and perspectives Relevant knowledge is helpful for understanding and managing the migration and fate of REEs in soil, and providing a theoretical basis for the prevention and control of REE pollution. |
| Key words: soil rare earth elements migration and enrichment ecological effect health risk |
