Smart tracers and distributed sensor networks for quantifying the metabolic activity in streambed reactivity hotspots

智能示踪剂和分布式传感器网络，用于量化河床反应热点的代谢活动

• 批准号: NE/I016120/1
• 负责人: Stefan Krause
• 金额: $ 6.67万
• 依托单位: Keele University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI016120%2F1
• 关键词: Smart; tracers; distributed; sensor; networks

There are major concerns amongst regulators and river managers that at locations where rivers are well connected to the surrounding aquifer, the up-welling of contaminated groundwater can represent a severe risk to the surface water quality and the ecological conditions in the river and cause significant economical damage. For assessing the environmental risks associated with the discharge of contaminated groundwater into surface waters, regulators and river managers urgently require detailed information of the natural attenuation potential of groundwater aquifers and aquifer-river interfaces. While the natural attenuation potential in groundwater aquifers is often limited due to a lack organic carbon and microbial activity, the mixing of groundwater and surface water in streambeds can provide higher concentrations of organic carbon and thus, stimulate enhanced metabolic activity and increase natural attenuation. Initial research of the investigator indicated that aquifer-river interfaces of lowland rivers may contain hotspots of metabolic activity in anoxic, high carbon pockets underneath peat and clay structures in the streambed. This project is designed to identify such locations and quantify the metabolic activity of these streambed reactivity hotspots in order to provide regulators and river managers with the knowledge urgently required for assessing the natural attenuation potential of aquifer-river interfaces. This study therefore applies fibre-optic Distributed Temperature Sensing (FO-DTS) to monitor streambed temperature patterns in high detail (0.01 C accuracy, 2 m spatial resolution) along a fibre-optic cable deployed in the streambed. It will identify locations with intensive groundwater up-welling (cold spots) against areas with inhibited groundwater up-welling (warm spots) during summer months when groundwater and surface water temperatures differ by 6 - 10 C. Streambed multi-level mini-piezometers will be installed in identified warm spots, where the delayed up-welling of cold groundwater is expected to indicate potential reactivity hotspots with increased metabolic activity underneath streambed peat structures. For comparison, piezometers will also be installed in identified cold spots caused by intensive groundwater up-welling, indicating high groundwater-surface water connectivity with low residence times and potentially low natural metabolic activity. A smart tracer, combining the reactive (resazurine) and non-reactive (NaCl) compounds will be injected at the bottom (150 cm depth) of the piezometers and breakthrough curves will be analysed at 15 cm intervals along the multi-level piezometers. NaCl breakthrough curves will be used to calculate groundwater up-welling rates and residence times whereas the reduction of resazurine to the strongly fluorescent substance resorufin will be used in a reactive decay simulation to indicate the microbial metabolic activity at the respective depths. Metabolic activity and residence times will be compared to nitrate concentrations, redox-potential, dissolved oxygen and organic carbon content at the piezometers locations to proof that metabolic activity hotspots increase the natural attenuation potential. The result of this project will provide regulators and river basin managers with the urgently required understanding of the natural attenuation potential of streambed reactivity hotspots of enhanced microbial activity. The knowledge provided by this project is of great importance for a range of related scientific disciplines as well as regulators and river basin managers. Thermal conditions are an integral part of the ecosystem health of hydrological systems. The improved understanding of heat flow in streambeds will directly benefit aquatic ecologists and eco-hydrologists while advanced knowledge on metabolic activity hotspots will greatly benefit future research of multi-contaminant reactive transport and biogeochemical cycling at aquifer-river interfaces.

监管机构和河流管理人员主要关注的是，在河流与周围含水层连接良好的地方，受污染地下水的上涌可能对地表水质量和河流生态条件构成严重风险，并造成重大经济损失。为了评估受污染地下水排入地表沃茨的环境风险，监管机构和河流管理人员迫切需要关于地下水蓄水层和蓄水层-河流界面自然衰减潜力的详细信息。由于缺乏有机碳和微生物活动，地下水含水层的自然衰减潜力往往有限，但河床中地下水和地表水的混合可提供更高浓度的有机碳，从而刺激代谢活动的增强，增加自然衰减。调查人员的初步研究表明，低地河流的蓄水层-河流界面可能包含河床中泥炭和粘土结构下缺氧高碳袋中的代谢活动热点。该项目旨在确定这些位置，并量化这些河床反应热点的代谢活动，以提供监管机构和河流管理人员迫切需要的知识，评估含水层-河流界面的自然衰减潜力。因此，本研究采用光纤分布式温度传感（FO-100）监测河床温度模式的高度详细（0.01 C精度，2米的空间分辨率）沿着部署在河床中的光纤电缆。它将确定在夏季地下水和地表水温度相差6 - 10 ℃时，地下水上涌强烈的地区（冷点）与地下水上涌受到抑制的地区（暖点）。将在确定的温暖地点安装河床多级微型测压计，在那里，预计冷地下水的延迟上涌将表明潜在的反应热点，河床泥炭结构下的代谢活动增加。为了进行比较，还将在地下水强烈上涌造成的已确定的冷点安装压力计，这表明地下水-地表水连通性高，停留时间短，自然代谢活动可能较低。将在压力计底部（150 cm深）注入一种智能示踪剂，将活性（刃天青）和非活性（NaCl）化合物结合在一起，并沿多级压力计以沿着15 cm的间隔分析穿透曲线。NaCl穿透曲线将用于计算地下水上升速率和停留时间，而刃天青还原为强荧光物质试卤灵将用于反应性衰变模拟，以指示相应深度的微生物代谢活动。代谢活动和停留时间将与压力计位置处的硝酸盐浓度、氧化还原电位、溶解氧和有机碳含量进行比较，以证明代谢活动热点增加了自然衰减潜力。该项目的结果将为监管机构和流域管理人员提供迫切需要的理解，提高微生物活性的河床反应热点的自然衰减潜力。该项目提供的知识对于一系列相关科学学科以及监管机构和流域管理人员都非常重要。热条件是水文系统生态系统健康的一个组成部分。对河床热流的深入了解将直接使水生生态学家和生态水文学家受益，而对代谢活动热点的深入了解将极大地有利于未来含水层-河流界面多污染物反应输运和水地球化学循环的研究。

项目成果

The method controls the story - Sampling method impacts on the detection of pore-water nitrogen concentrations in streambeds.

该方法控制了故事 - 采样方法对河床孔隙水氮浓度检测的影响。

• DOI: 10.1016/j.scitotenv.2019.136075
• 发表时间: 2020
• 期刊: The Science of the total environment
• 作者: Comer-Warner S

Is the Hyporheic Zone Relevant beyond the Scientific Community?

• DOI: 10.3390/w11112230
• 发表时间: 2019-11-01
• 期刊: WATER
• 影响因子: 3.4
• 作者: Lewandowski, Joerg;Arnon, Shai;Wu, Liwen
• 通讯作者: Wu, Liwen

Instream wood increases riverbed temperature variability in a lowland sandy stream

河内木材增加了低地沙质河流的河床温度变化

• DOI: 10.1002/rra.3698
• 发表时间: 2020
• 期刊: River Research and Applications
• 影响因子: 2.2
• 作者: Klaar M

Identification of floodplain and riverbed sediment heterogeneity in a meandering UK lowland stream by ground penetrating radar

利用探地雷达识别英国蜿蜒低地溪流中的漫滩和河床沉积物异质性

• DOI: 10.1016/j.jappgeo.2019.103863
• 发表时间: 2019
• 期刊: Journal of Applied Geophysics
• 影响因子: 2
• 作者: Dara R