Understanding the interplay between hydrological flushing and biogeochemical cycling in streams is now possible owing to advances in high‐frequency water quality measurements with in situ sensors. It is often assumed that storm events are periods when biogeochemical processes become suppressed and longitudinal transport of solutes and particulates dominates. However, high‐frequency data show that diel cycles are a common feature of water quality time series and can be preserved during storm events, especially those of low‐magnitude. In this study, we mine a high‐frequency dataset and use two key hydrochemical indices, hysteresis and flushing index to evaluate the diversity of concentration‐discharge relationships in 3rd order agricultural stream. We show that mobilisation patterns, inferred from the hysteresis index, change on a seasonal basis, with a predominance of rapid mobilisation from surface and near stream sources during winter high‐magnitude storm events and of delayed mobilisation from subsurface sources during summer low‐magnitude storm events. Using Dynamic Harmonic Regression, we were able to separate concentration signals during storm events into hydrological flushing (using trend as a proxy) and biogeochemical cycling (using amplitude of a diel cycle as a proxy). We identified three groups of water quality parameters depending on their typical c‐q response: flushing dominated parameters (phosphorus and sediments), mixed flushing and cycling parameters (nitrate nitrogen, specific conductivity and pH) and cycling dominated parameters (dissolved oxygen, redox potential and water temperature). Our results show that despite large storm to storm diversity in hydrochemical responses, storm event magnitude and timing have a critical role in controlling the type of mobilisation, flushing and cycling behaviour of each water quality constituent. Hydrochemical indices can be used to fingerprint the effect of hydrological disturbance on freshwater quality and can be useful in determining the impacts of global change on stream ecology.

中文翻译：

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淡水质量的水文和生物地球化学驱动因素的指纹图谱

由于使用原位传感器进行高频水质测量的进步，现在可以了解水文冲洗和河流中生物地球化学循环之间的相互作用。通常假设风暴事件是生物地球化学过程受到抑制并且溶质和颗粒的纵向传输占主导地位的时期。然而，高频数据表明，昼夜循环是水质时间序列的一个共同特征，并且可以在风暴事件期间保存下来，尤其是那些低强度的风暴事件。在本研究中，我们挖掘了一个高频数据集，并使用滞后和冲洗指数这两个关键水化学指标来评估三阶农业河流中浓度-排放关系的多样性。我们表明，从滞后指数推断的动员模式随季节变化，冬季高强度风暴事件期间地表和附近河流源的快速动员占优势，夏季低强度风暴事件期间地下源的动员延迟。使用动态谐波回归，我们能够将风暴事件期间的浓度信号分为水文冲刷（使用趋势作为代理）和生物地球化学循环（使用昼夜循环的幅度作为代理）。我们根据典型的 c-q 响应确定了三组水质参数：冲洗主导参数（磷和沉积物）、混合冲洗和循环参数（硝酸氮、比电导率和 pH 值）和循环主导参数（溶解氧、氧化还原电位）和水温）。我们的结果表明，尽管在水化学反应中风暴到风暴的多样性很大，但风暴事件的强度和时间在控制每种水质成分的流动类型、冲洗和循环行为方面起着关键作用。水化学指数可用于确定水文干扰对淡水质量的影响，并可用于确定全球变化对河流生态的影响。