Subsurface Fe (II) affects concentrations of dissolved O2 in streamwater

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-03-02 DOI:10.1016/j.watres.2025.123368

Silvia Parra Suarez, Romy Wild, Benjamin S. Gilfedder, Juergen Geist, Johannes A.C. Barth, Sven Frei, Stefan Peiffer

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Abstract

The interface between groundwater and surface water is a critical zone influencing ecohydrological and biogeochemical cycles within surface water ecosystems. It is characterized by complex redox gradients, with groundwater-mediated inflow of reduced substances affecting the oxygen budget of stream water. In this study, we have experimentally simulated the inflow of Fe(II)-rich groundwater into the open stream water of a flume system to quantify its effect on dissolved oxygen concentration in both the stream water and the hyporheic zone. The experimental setup consisted of 12 flumes, half used for input of groundwater augmented with Fe(II), while the other half served as a control. We studied the effects of coarse (6% fine sediment content) sediment vs. fine (28 % fine sediment content) sediment as well as and moderate (3 L s^-1) vs. low (0.5 L s-1) flow rate in a fully-crossed, 3-way-replicated design. Weekly sampling campaigns were performed to analyze Fe(II), Fe(III), DOC, and dissolved oxygen (DO) concentrations in the pore water (hyporheic zone) and in the open water over five consecutive weeks. Our results indicate that Fe(II) inflow substantially decreased DO concentrations in both the pore and open waters. Oxygen uptake rates increased from 7.4 up to 8.6 g O₂ m^-2 d^-1 at a moderate flow rate and from 1.7 to 1.9 g O₂ m^-2 d^-1 at a low flow rate. This corresponds to a contribution of the Fe(II) input to the overall oxygen uptake rate in the flumes of 21 and 17%, respectively. Treatment with FeCl₂ also led to a substantial increase in DOC from ∼ 55 mg L^-1 in the control flumes to > 60 mg L^-1 suggesting a linkage between Fe(II) mobilization and the occurrence of DOC. In conclusion, this study highlights the need to consider the effects of hyporheic and riparian redox processes and subsequent inflow of Fe(II) into streams on the oxygen budget and the health of stream ecosystems.

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地下水与地表水之间的界面是影响地表水生态系统生态水文和生物地球化学循环的关键区域。其特点是具有复杂的氧化还原梯度，地下水介导的还原物质流入会影响溪水的氧预算。在这项研究中，我们通过实验模拟了富含铁（II）的地下水流入水槽系统的开放溪流水体的情况，以量化其对溪流水体和下垫面区溶解氧浓度的影响。实验装置由 12 个水槽组成，一半用于输入富含铁（II）的地下水，另一半作为对照。我们研究了粗沉积物（细沉积物含量为 6%）与细沉积物（细沉积物含量为 28%）以及中流量（3 升/秒）与低流量（0.5 升/秒）在完全交叉、3 向重复设计中的影响。在连续五周的时间里，每周取样分析孔隙水（下孔隙带）和开放水体中的铁(II)、铁(III)、DOC 和溶解氧 (DO) 浓度。我们的研究结果表明，铁（II）的流入大大降低了孔隙水和开放水体中的溶解氧浓度。在中等流速下，氧气吸收率从 7.4 g O2 m-2 d-1 增加到 8.6 g O2 m-2 d-1；在低流速下，氧气吸收率从 1.7 g O2 m-2 d-1 增加到 1.9 g O2 m-2 d-1。这相当于在水槽中输入的 Fe（II）对总体氧气吸收率的贡献分别为 21% 和 17%。用 FeCl2 处理还导致 DOC 从对照水槽中的 55 mg L-1 大幅增加到 60 mg L-1，这表明铁（II）迁移与 DOC 的产生之间存在联系。总之，这项研究强调，有必要考虑水体和河岸氧化还原过程以及随后流入溪流的铁（II）对氧预算和溪流生态系统健康的影响。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.