Storm-Induced Dynamics of Particulate Organic Carbon in Clear Creek, Iowa: An Intensively Managed Landscape Critical Zone Observatory Story
Storm-Induced Dynamics of Particulate Organic Carbon in Clear Creek, Iowa: An Intensively Managed Landscape Critical Zone Observatory Story
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DOI：
10.3389/frwa.2020.578261
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
Jieun Kim;N. Blair;A. Ward;K. Goff
中科院分区：
文献类型：
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作者：
Jieun Kim;N. Blair;A. Ward;K. Goff
河流整合和传输颗粒有机碳（POC）从不同的成岩历史的多个来源。大量的POC在风暴事件期间被输送到河流中，但动员的材料的来源和命运往往是不清楚的。为了衡量输入源的可变性，本研究使用了生物标志物的方法，广泛的有机物的特征在分子水平上。2015年10月，在美国爱荷华州沿Clear Creek的三个沿着嵌套采样位置，在风暴期间收集了悬浮沉积物。通过补充大量元素和C-同位素测量，获得了生物标志物分析，以确定POC的来源和成岩状态的变化。富含脂肪酸的有机物是由于动员藻类垫在流通道在风暴的早期阶段作为降水开始和水的速度开始增加。一个显着的贡献，富含木质素的材料发生在峰值降水和升高排放标志着土壤来源。部分氧化木质素和土壤有机质的示踪剂表明，这是一个部分时间分辨的新鲜和降解材料的混合物。风暴引起的生物标志物的变化，观察在整个流域的三个采样站。混合模式变得更加复杂的风暴脉冲下游移动，由于添加剂的贡献，多个支流和假设的重要性越来越多的冲积银行侵蚀。这种侵蚀的增加是由于在流域地貌从上游的V形到下游的一个更广泛的箱形山谷系统的过渡。尽管生物标志物浓度测量结果显示，随着时间的推移，来源的多样性，与峰值放电相关的POC的复杂混合物占主导地位的材料下游的流量。这项研究突出了风暴引发的C-运输的复杂性和需要在未来的高时空分辨率的广谱示踪剂研究。
Rivers integrate and transport particulate organic carbon (POC) from multiple sources with varied diagenetic histories. A significant amount of POC is delivered to rivers during storm events, but the sources and fates of the mobilized material are often unclear. To gauge the variability of input sources, this study uses a biomarker approach that broadly characterizes organic matter at the molecular level. Suspended sediment was collected during a storm in October 2015 at three nested sampling locations along Clear Creek in Iowa, U.S.A. Supplemented with bulk elemental and C-isotopic measurements, biomarker analyses were obtained to identify changes in sources and the diagenetic state of the POC. Fatty acid-rich organic matter was attributed to the mobilization of algal mats in the stream channel at the early stage of the storm as precipitation initiated and water velocities began to increase. A significant contribution of lignin-rich material occurred at peak precipitation and elevated discharge signifying soil sources. Tracers for partially oxidized lignin and soil organic matter suggested that this was a partially time-resolved mixture of fresh and degraded material. Storm-induced variations of biomarkers were observed at the three sampling stations located throughout the watershed. The mixing patterns became more complex as the storm pulse moved downstream due to the additive contributions of multiple tributaries and the hypothesized increasing importance of alluvial bank erosion. This erosional increase is attributed to a systematic transition in basin geomorphology from a V-shape in the upper reach to a wider box-shaped valley in the lower reach. Even though biomarker concentration measurements revealed a diversity of sources over time, the complex mixture of POC associated with peak discharge dominated the flux of material downstream. This study highlights the complexity of storm-initiated C-transport and the need for high spaciotemporal resolution broad spectrum tracer studies in the future.