Characteristics and Mechanism of Hematite Dissolution and Release on Arsenic Migration in Heterogeneous Materials.

IF 3.9 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Toxics Pub Date : 2024-09-23 DOI:10.3390/toxics12090687

Zheying Li, Huimei Shan, Wanyue Rong, Zhicheng Zhao, Kexin Ma, Sanxi Peng, Song Wei

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Abstract

The migration of arsenic in groundwater is influenced by the heterogeneity of the medium, and the presence of iron minerals adds complexity and uncertainty to this effect. In this study, a stratified heterogeneous sand column with an embedded hematite lens at the coarse-to-medium sand interface was designed. We introduced an arsenic-laden solution and controlled groundwater flow to investigate the spatiotemporal characteristics of arsenic migration and the impact of hematite dissolution. The results showed that the medium structure significantly influenced the arsenic migration and distribution within the lens-containing sand column. The clay layers directed the lateral migration of arsenic, and the arsenic concentrations in deeper layers were up to seven times greater than those on the surface. The extraction experiments of solid-phase arsenic revealed that the main adsorption modes on quartz sand surfaces were the specific adsorption (F2) and adsorption on weakly crystalline iron-aluminum oxides (F3), correlating to the specific and colloidal adsorption modes, respectively. Monitoring the total iron ions (Fe(aq)) revealed rapid increases within the first 14 days, reaching a maximum on day 15, and then gradually declining; these results indicate that hematite did not continuously dissolve. This study can aid in the prevention and control of arsenic contamination in groundwater.

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赤铁矿溶解和释放对异质材料中砷迁移的影响特征和机制

砷在地下水中的迁移受介质异质性的影响，铁矿物的存在增加了这种影响的复杂性和不确定性。在这项研究中，我们设计了一个分层异质砂柱，在粗砂到中砂的界面上有一个嵌入式赤铁矿透镜。我们引入含砷溶液并控制地下水流，以研究砷迁移的时空特征和赤铁矿溶解的影响。结果表明，介质结构极大地影响了砷在含透镜砂柱中的迁移和分布。粘土层引导砷的横向迁移，深层的砷浓度是表层的七倍。固相砷的萃取实验表明，石英砂表面的主要吸附模式为比吸附（F2）和弱结晶铁铝氧化物吸附（F3），分别与比吸附和胶体吸附模式相关。对总铁离子（Fe(aq)）的监测显示，在最初的 14 天内，铁离子迅速增加，在第 15 天达到最大值，然后逐渐下降；这些结果表明赤铁矿并没有持续溶解。这项研究有助于预防和控制地下水中的砷污染。

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来源期刊

Toxics Chemical Engineering-Chemical Health and Safety

CiteScore

4.50

自引率

10.90%

发文量

681

审稿时长

6 weeks

期刊介绍： The Journal accepts papers describing work that furthers our understanding of the exposure, effects, and risks of chemicals and materials in humans and the natural environment as well as approaches to assess and/or manage the toxicological and ecotoxicological risks of chemicals and materials. The journal covers a wide range of toxic substances, including metals, pesticides, pharmaceuticals, biocides, nanomaterials, and polymers such as micro- and mesoplastics. Toxics accepts papers covering: The occurrence, transport, and fate of chemicals and materials in different systems (e.g., food, air, water, soil); Exposure of humans and the environment to toxic chemicals and materials as well as modelling and experimental approaches for characterizing the exposure in, e.g., water, air, soil, food, and consumer products; Uptake, metabolism, and effects of chemicals and materials in a wide range of systems including in-vitro toxicological assays, aquatic and terrestrial organisms and ecosystems, model mammalian systems, and humans; Approaches to assess the risks of chemicals and materials to humans and the environment; Methodologies to eliminate or reduce the exposure of humans and the environment to toxic chemicals and materials.