Multitracer Field Fluorometry: Accounting for Temperature and Turbidity Variability During Stream Tracer Tests
Multitracer Field Fluorometry: Accounting for Temperature and Turbidity Variability During Stream Tracer Tests
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DOI：
10.1002/2017wr020815
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发表时间：
2017-11-01
影响因子：
5.4
通讯作者：
Krause, Stefan
中科院分区：
文献类型：
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作者：
Blaen, Phillip J.;Brekenfeld, Nicolai;Krause, Stefan
在水文科学中，多示踪野外荧光法的使用正在增加。然而，考虑到河流生态系统内环境条件的变异性，获得高质量的荧光测量是具有挑战性的。在这里，我们进行了一系列的河流示踪剂测试，以检验在现实的野外条件下，多示踪剂现场荧光法在多大程度上能够可靠地估计示踪剂浓度。使用常用的保守的(乌拉宁)和反应性的(重天青-间苯二酚)荧光示踪剂的例子，我们表明，示踪剂穿透曲线的现场测量可能与实验室条件下分析的相应样品显著偏离。为了研究关键环境变量对荧光测量的影响，我们表征了现场荧光仪测量对温度、浊度和示踪剂浓度变化的响应。结果表明，温度对所有示踪剂的荧光测量都有显著的负对数线性影响，通常在较低的示踪剂浓度下观察到更强的影响。我们还观察到浊度对荧光测量的线性影响，这种影响可以预测地随示踪剂浓度而变化。基于我们的发现，我们提出了校正现场荧光计测量这些参数变化的方法。我们的结果表明，不断变化的环境条件如何在荧光示踪剂穿透曲线的分析中引入大量的不确定性，并强调了考虑这些变化的重要性，以防止对支持观察到的模式的物理和生物地球化学过程做出不正确的推断。
The use of multitracer field fluorometry is increasing in the hydrological sciences. However, obtaining high-quality fluorescence measurements is challenging given the variability in environmental conditions within stream ecosystems. Here, we conducted a series of stream tracer tests to examine the degree to which multitracer field fluorometry produces reliable estimates of tracer concentrations under realistic field conditions. Using frequently applied examples of conservative (Uranine) and reactive (Resazurin-Resorufin) fluorescent tracers, we show that in situ measurements of tracer breakthrough curves can deviate markedly from corresponding samples analyzed under laboratory conditions. To investigate the effects of key environmental variables on fluorescence measurements, we characterized the response of field fluorometer measurements to changes in temperature, turbidity, and tracer concentration. Results showed pronounced negative log-linear effects of temperature on fluorescence measurements for all tracers, with stronger effects observed typically at lower tracer concentrations. We also observed linear effects of turbidity on fluorescence measurements that varied predictably with tracer concentration. Based on our findings, we present methods to correct field fluorometer measurements for variation in these parameters. Our results show how changing environmental conditions can introduce substantial uncertainties in the analysis of fluorescent tracer breakthrough curves, and highlight the importance of accounting for these changes to prevent incorrect inferences being drawn regarding the physical and biogeochemical processes underpinning observed patterns.