State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan University, Chengdu, 610065, China; Tianfu Yongxing Laboratory, Chengdu, 610217, China.
State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan University, Chengdu, 610065, China.
Environ Res. 2023 Dec 1;238(Pt 2):117232. doi: 10.1016/j.envres.2023.117232. Epub 2023 Oct 2.
Fe and Mn release from sediments promotes the release of other chemicals and jointly affects downstream water safety, especially in drinking water reservoirs. Quantitative research on release processes and flux estimation methods for endogenous Fe and Mn in reservoirs is still limited. Static incubation experiments were designed to systematically explore the effects of water temperature (WT), dissolved oxygen (DO), pH, carbon sources, and microbial activity on Fe and Mn release. The results showed that increased WT and carbon source addition promoted the release of acid-extractable Fe and Mn from the sediments; hypoxia and acidification promoted the dissolution of reducible sediment Fe and Mn; and microorganisms participated in the cycling of Fe and Mn. Based on the experimental results, first-order kinetic equations for sediment Fe and Mn release to overlying water were proposed, and the relationships between release rate and environmental factors were mathematically represented by a surface equation (R = 0.88 and 0.86, respectively). A diffusion gradients in thin films (DGT) device based on the diffusion model was used in situ to obtain the diffusion fluxes of Fe (J = 13.93 mg m d) and Mn (J = 3.48 mg m d). When environmental factors obtained in the field were introduced into the established mathematical model, the modeled release fluxes of Fe and Mn were R = 20.92 mg m d and R = 13.12 mg m d, respectively. The established model filled gaps in the diffusion model, which does not account for differences in release fluxes under changing physicochemical water conditions. This work serves as a reference for studying the release fluxes of endogenous chemicals in sediments.
铁和锰从沉积物中的释放促进了其他化学物质的释放，并共同影响下游的水安全，尤其是在饮用水水库中。对于水库中内源性铁和锰的释放过程和通量估算方法，定量研究仍然有限。本研究设计了静态培养实验，系统地探讨了水温（WT）、溶解氧（DO）、pH 值、碳源和微生物活性对铁和锰释放的影响。结果表明，升高 WT 和添加碳源促进了沉积物中酸可提取铁和锰的释放；缺氧和酸化促进了可还原沉积物铁和锰的溶解；微生物参与了铁和锰的循环。基于实验结果，提出了沉积物铁和锰释放到上覆水中的一级动力学方程，并通过曲面方程（分别为 R = 0.88 和 0.86）数学表示了释放速率与环境因素之间的关系。基于扩散模型的扩散梯度薄膜（DGT）装置原位获得了铁（J = 13.93 mg m d）和锰（J = 3.48 mg m d）的扩散通量。当将野外获得的环境因素引入建立的数学模型时，铁和锰的模拟释放通量分别为 R = 20.92 mg m d 和 R = 13.12 mg m d。所建立的模型填补了扩散模型在不同理化水条件下释放通量差异方面的空白。这项工作为研究沉积物中内源性化学物质的释放通量提供了参考。
