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首页> 外文期刊>Environmental Science & Technology >Model-Based Interpretation of Groundwater Arsenic Mobility during in Situ Reductive Transformation of Ferrihydrite
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Model-Based Interpretation of Groundwater Arsenic Mobility during in Situ Reductive Transformation of Ferrihydrite

机译：基于模型的地下水砷流动性在原位减少转化过程中的抗磨转换

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摘要

Arsenic (As) release and mobility in groundwater is coupled to the iron (Fe) cycling and the associated transformation of Fe-oxides present in sediments. Recent in situ experiments have provided observations on arsenic mobilization and co-occurring reductive mineral transformation when placing As-loaded ferrihydrite-coated sand for 80 days in wells of an As-contaminated aquifer of Northern China. However, the complex temporal change in solid associated arsenic and the multiple geochemical processes occurring when the flowing groundwater contacts the As loaded ferrihydrite-coated sand hamper a detailed evaluation of the experimental data set. In this study, we develop a modeling approach that allows a quantitative interpretation of arsenic release and ferrihydrite transformation observed during the in situ experiments. The model accounts for the interplay of abiotic and biotic geochemical processes (i.e., surface complexation, reductive dissolution, formation of secondary iron minerals, and arsenic sequestration into the newly formed minerals) involved in the transformation of Fe-oxides and controlling arsenic mobility. The results show the capability of the proposed approach to reproduce the temporal trends of solid arsenic and ferrihydrite concentrations, as well as the spatial variability of mineral transformation, observed in different wells using a common set of surface complexation parameters and kinetic rate constants. The simulation outcomes allowed us to disentangle the specific contribution of the different mechanisms controlling the release of arsenic. It was possible to identify an initial rapid but minor release of As (13-23% of the initial surface concentration) due to desorption from ferrihydrite, as well as the reduction of adsorbed As(V) to As(III) upon contact with the flowing anoxic groundwater. Successively, reductive dissolution of ferrihydrite caused the decrease of the amount of the Fe mineral phase and led to a major depletion of solid-associated arsenic. The produced Fe(II) catalyzed the ferrihydrite conversion into more crystalline Fe(III) oxides (i.e., lepidocrocite and goethite) through Ostwald ripening, and resulted in the formation of siderite and mackinawite upon reaction with carbonates and sulfides naturally present in the groundwater. The model results also showed that, whereas the decrease in surface sites during reductive dissolution of ferrihydrite promoted arsenic mobilization, the mineral transformation limited As release through its sequestration into the newly formed secondary mineral phases.
机译：地下水中的砷（AS）释放和迁移率耦合到铁（Fe）循环和沉积物中存在的Fe氧化物的相关变换。最近的原位实验已经为砷动员和共同发生的还原矿物转化提供了观察结果，当将装载的Ferrihydrite涂层涂层放置80天，在北方北方的AS污染的含水层的井中。然而，当流动地下水接触时，固体相关砷的复杂时间变化和多种地球化学过程发生在载荷的Ferrihydite涂层的沙坑篮下的详细评估实验数据集。在这项研究中，我们开发了一种建模方法，其允许在原位实验期间观察到砷释放的定量解释和在原位实验期间观察到的Ferrihydite转化。该模型占非生物和生物地球化学方法的相互作用（即，表面络合，还原溶解，二次铁矿物的形成，以及砷螯合到新形成的矿物中，参与Fe氧化物的转化和控制砷迁移率。结果表明，使用常见的表面络合参数和动力速率常数在不同的孔中观察到繁殖固体砷和Ferrihydrite浓度的时间趋势的能力，以及矿物转化的空间变异。模拟结果使我们能够解开控制砷释放的不同机制的具体贡献。由于Ferrihydrite的解吸，识别由于从Ferrihydite的解吸而识别为（初始表面浓度的初始表面浓度的13-23％）的初始快速释放，以及在与之接触时被吸附为（v）至（iii）的吸附剂流动的缺氧地下水。连续，减少铁矿石的减少溶解导致Fe矿物相量减少，并导致固体相关砷的主要耗尽。所生产的Fe（ii）通过Ostwald成熟将Ferrihydrite转化为更结晶的Fe（III）氧化物（即鳞片状）氧化物（即，尿道裂霉岩和甲磺酸盐），并导致在与地下水中天然存在的碳酸盐和硫化物反应时形成饱和盐和硫酮。模型结果也表明，而铁磨石的还原溶解期间的表面位点的减少促进了砷动员，而矿物转化限制为通过其螯合到新形成的二级矿物相中的释放。

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  • 来源
    《Environmental Science & Technology》 |2019年第12期|6845-6854|共10页
  • 作者

    Stolze Lucien; Zhang Di; Guo Huaming; Rolle Massimo;

  • 作者单位

    Tech Univ Denmark Dept Environm Engn Bldg 115 DK-2800 Lyngby Denmark;

    China Univ Geosci Sch Water Resources & Environm Beijing 100083 Peoples R China;

    China Univ Geosci Sch Water Resources & Environm Beijing 100083 Peoples R China;

    Tech Univ Denmark Dept Environm Engn Bldg 115 DK-2800 Lyngby Denmark;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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