Molecular Hysteresis: Hydrologically Driven Changes in Riverine Dissolved Organic Matter Chemistry During a Storm Event
Molecular Hysteresis: Hydrologically Driven Changes in Riverine Dissolved Organic Matter Chemistry During a Storm Event
复制标题
DOI：
10.1029/2018jg004817
复制
发表时间：
2019-04
期刊：
影响因子：
--
通讯作者：
S. Wagner;J. Fair;S. Matt;J. Hosen;P. Raymond;J. Saiers;J. Shanley;T. Dittmar;Aron Stubbins
中科院分区：
文献类型：
--
作者：
S. Wagner;J. Fair;S. Matt;J. Hosen;P. Raymond;J. Saiers;J. Shanley;T. Dittmar;Aron Stubbins
在降雨的驱动下，水文事件控制着通过河网调动的溶解有机物(DOM)的数量和组成。在森林流域，输出的DOM的浓度、组成和活性随着基流向风暴流的转变而变化，对下游的生物地球化学有重大影响。滞后描述了观察到的流中溶质浓度/信号与排放之间的差异。通过研究DOM与河流流量的关系，加深了我们对影响河流DOM数量和质量的环境和水文因素的理解。这项研究的主要目的是跟踪风暴事件期间河流DOM分子组成的滞后变化。样本是从康涅狄格河的一条支流帕斯普西河流域(美国佛蒙特州)内的筑巢地点收集的。对荧光DOM的高分辨率监测(通过现场传感器)和离散样本的自动收集捕获了DOM浓度和组成的短期、水文驱动的变化。超高分辨率质谱仪显示，在风暴开始时，脂肪族化合物的含量较高，而芳香族和多酚类化合物在高峰流量时的含量较高。跨河流顺序的分子滞后模式相似，表明新鲜的陆源DOM在高流量脉冲期间通过河流网络迅速向下游分流。
Hydrological events, driven by rainfall, control the amount and composition of dissolved organic matter (DOM) mobilized through river networks. In forested watersheds, the concentration, composition, and reactivity of DOM exported changes as baseflow transitions to storm flow, with major implications to downstream biogeochemistry. Hysteresis describes an observed difference between in‐stream solute concentration/signal and discharge. By studying the relationship between DOM and stream discharge, we refine our understanding of the environmental and hydrological factors that influence the quantity and quality of stream DOM. The main objective of this study was to track hysteretic changes in riverine DOM molecular composition during storm events. Samples were collected from nested sites within the Passumpsic River catchment (Vermont, USA), a tributary of the Connecticut River. High‐resolution monitoring of fluorescent DOM (via in situ sensors) and automated collection of discrete samples captured short‐term, hydrologically driven variations in DOM concentration and composition. Ultrahigh‐resolution mass spectrometry revealed an enrichment in aliphatic compounds at storm onset, while aromatic and polyphenolic compounds were more enriched at peak discharge. Molecular hysteresis patterns were similar across stream orders, indicating that fresh, terrigenous DOM is quickly shunted downstream, through the river network, during pulses of high discharge.