Mihalevich Bryce A, Horsburgh Jeffery S, Melcher Anthony A
Department of Civil and Environmental Engineering and Utah Water Research Laboratory, Utah State University, 8200 Old Main Hill, Logan, UT, 84322-8200, USA.
Environ Monit Assess. 2017 Oct 30;189(11):593. doi: 10.1007/s10661-017-6310-y.
Stormwater runoff in urban areas can contribute high concentrations of dissolved organic matter (DOM) to receiving waters, potentially causing impairment to the aquatic ecosystem of urban streams and downstream water bodies. Compositional changes in DOM due to storm events in forested, agricultural, and urban landscapes have been well studied, but in situ sensors have not been widely applied to monitor stormwater contributions in urbanized areas, leaving the spatial and temporal characteristics of DOM within these systems poorly understood. We deployed fluorescent DOM (FDOM) sensors at upstream and downstream locations within a study reach to characterize the spatial and temporal changes in DOM quantity and sources within an urban water conveyance that receives stormwater runoff. Baseflow FDOM decreased over the summer season as seasonal flows upstream transported less DOM. FDOM fluctuated diurnally, the amplitude of which also declined as the summer season progressed. During storms, FDOM concentrations were rapidly elevated to values orders of magnitude greater than baseflow measurements, with greater concentrations at the downstream monitoring site, revealing high contributions from stormwater outfalls between the two locations. Observations from custom, in situ fluorometers resembled results obtained using laboratory methods for identifying DOM source material and indicated that DOM transitioned to a more microbially derived composition as the summer season progressed, while stormwater contributions contributed DOM from terrestrial sources. Deployment of a mobile sensing platform during varying flow conditions captured spatial changes in DOM concentration and composition and revealed contributions of DOM from outfalls during stormflows that would have otherwise been unobserved.
城市地区的雨水径流会向受纳水体输送高浓度的溶解有机物（DOM），这可能会损害城市溪流和下游水体的水生生态系统。森林、农业和城市景观中暴雨事件导致的DOM成分变化已得到充分研究，但原位传感器尚未广泛应用于监测城市化地区的雨水贡献情况，导致对这些系统中DOM的时空特征了解不足。我们在一个研究河段的上游和下游位置部署了荧光DOM（FDOM）传感器，以表征接收雨水径流的城市输水系统中DOM数量和来源的时空变化。夏季基流FDOM下降，因为上游季节性水流输送的DOM较少。FDOM呈昼夜波动，随着夏季的推进，波动幅度也有所下降。暴雨期间，FDOM浓度迅速升高，达到比基流测量值高几个数量级的值，下游监测点的浓度更高，这表明两个位置之间的雨水排放口贡献很大。定制的原位荧光计的观测结果与使用实验室方法识别DOM源物质获得的结果相似，表明随着夏季的推进，DOM转变为微生物来源更多的成分，而雨水贡献则来自陆地来源的DOM。在不同水流条件下部署移动传感平台，捕捉到了DOM浓度和成分的空间变化，并揭示了暴雨径流期间排放口的DOM贡献，否则这些贡献是无法观测到的。
