Engineering Research Center of Groundwater Pollution Control and Remediation of Ministry of Education of China, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.
Engineering Research Center of Groundwater Pollution Control and Remediation of Ministry of Education of China, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.
Chemosphere. 2022 Aug;300:134524. doi: 10.1016/j.chemosphere.2022.134524. Epub 2022 Apr 6.
The groundwater in many aquifers contains elevated concentrations of iron (Fe). Although much of this Fe is from its release from water-bearing sediments under natural environmental conditions, sufficient evidence is lacking to clarify whether anthropogenic pollutants, such as dissolved organic matter (DOM), can increase this natural release. In this time series and comparative analysis study, an Fe increasing effect was verified through laboratory leaching tests. The influences of the aqueous environmental conditions, such as pH, were also investigated. DOM can promote the release of Fe from sediments and increase the concentration of Fe in groundwater. In addition, lower or higher pH and temperature can enhance the release of Fe to some extent. Higher concentrations of DOM provided a more thorough release of Fe from the sediment; additional ions such as Cu also affected Fe release. It is possible that complexation between DOM and Fe occurs through ligand dissolution and reduction, thus promoting the release of Fe. The findings indicate that DOM imported through anthropogenic activities can increase the release of Fe from aquifer sediments into groundwater, thus worsening Fe pollution in groundwater. This study explored the mechanism by which different types of DOM release Fe from aquifer sediments and investigated the factors that influence this process. The findings provide insights into the geochemical processes of Fe in the groundwater.
许多含水层中的地下水含有较高浓度的铁 (Fe)。尽管其中大部分铁是在自然环境条件下从含水沉积物中释放出来的，但缺乏足够的证据来阐明溶解有机质 (DOM) 等人为污染物是否可以增加这种自然释放。在这项时间序列和对比分析研究中，通过实验室浸出试验验证了 Fe 的增加效应。还研究了 pH 等水环境保护条件的影响。DOM 可以促进沉积物中 Fe 的释放，并增加地下水 Fe 的浓度。此外，较低或较高的 pH 值和温度可以在一定程度上增强 Fe 的释放。较高浓度的 DOM 使 Fe 从沉积物中更彻底地释放出来；Cu 等额外的离子也会影响 Fe 的释放。DOM 和 Fe 之间可能通过配体溶解和还原发生络合，从而促进 Fe 的释放。研究结果表明，通过人为活动输入的 DOM 可以增加含水层沉积物中 Fe 的释放到地下水中，从而加剧地下水的 Fe 污染。本研究探讨了不同类型的 DOM 从含水层沉积物中释放 Fe 的机制，并研究了影响这一过程的因素。研究结果为地下水 Fe 的地球化学过程提供了深入了解。
