Dynamic hydrologic exchange flows in river beds and banks are important for many ecosystem functions throughout river corridors. Here we test whether the exchanges and the associated mixing between a flooding river and groundwater within the river’s bank can be effectively traced by Radon‐222 (²²²Rn), a naturally occurring, inert, radiogenic, and radioactive gas that can be analyzed and monitored in situ. The assessment was done by simulation of groundwater flow and reactive transport of ²²²Rn in the bank following a single, relatively rapid (hours long) flood wave and auxiliary field observations of ²²²Rn, temperature and total dissolved solids (a surrogate for any ionic conservative tracer). Results illustrate that ²²²Rn is more effective than temperature and total dissolved solids in tracing dynamic hyporheic exchange. ²²²Rn variations in space and time are larger than the analytical uncertainty of common measurement methods. The individual effects of aquifer hydraulic conductivity, dispersivity, river water ²²²Rn concentration, and bank topography were analyzed through sensitivity analysis. Larger hydraulic conductivity and dispersivity, lower ²²²Rn concentration in river water relative to groundwater, and gentler bank slopes resulted in a more prominent and traceable ²²²Rn signal. The transport and residence time of exchanged water may be estimated and interpreted using reactive transport models such as those implemented here. However, such application is sensitive to fluctuations in river water ²²²Rn, requiring it to be well characterized. The assessment provides guidance for using ²²²Rn as a tracer for groundwater and surface water interactions in dynamic settings.

中文翻译：

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使用222Rn跟踪银行存储和亲水交换动力学：虚拟和现场测试以及与其他示踪剂的比较

河床和河岸的动态水文交换流量对于整个河道中的许多生态系统功能都很重要。在这里，我们测试是否可以通过Radon-222（²²² Rn）来有效地追踪洪水河与河岸内地下水之间的交换以及相关的混合，Radon-222（²²² Rn）是可以分析和监控的天然存在的惰性气体，放射性气体和放射性气体原地。通过模拟一个相对较快（数小时）的洪水波和辅助场观测到的²²² Rn，温度和总溶解固体（模拟的任何离子替代物的替代物），通过模拟银行中²²² Rn的地下水流量和反应性输运来进行评估。示踪剂）。结果表明²²²在追踪动态流变交换中，Rn比温度和总溶解固体更有效。²²² Rn在空间和时间上的变化大于常规测量方法的分析不确定性。通过敏感性分析，分析了含水层水力传导率，分散性，河水²²² Rn浓度和河岸地形的各个影响。较大的水力传导率和分散性，相对于地下水，河水中的²²² Rn浓度较低，较缓的河岸坡度导致²²²更加突出和可追踪Rn信号。可以使用诸如在此实现的反应性传输模型来估计和解释交换水的传输和停留时间。然而，这种应用对河水²²² Rn的波动敏感，要求对其进行良好的表征。该评估为使用²²² Rn作为动态环境中地下水和地表水相互作用的示踪剂提供了指导。