EAR-PF:Seasonal Variation in Suspended Sediment Source and Chemistry in a Shale Watershed

Diana Karwan博士被授予美国国家科学基金会地球科学博士后奖学金，在特拉华大学实施一项研究和教育计划。这项研究将在关键区域天文台网络的多个站点之间进行。具体而言，本研究旨在量化悬浮沉积物组成，并将水系沉积物的地球化学差异与其不同的流域来源以及沉积物从景观到溪流的水文路径联系起来。首先，将分析河流和流域沉积物的组成，特别强调元素矿物含量、稳定同位素（如碳-13和氮-15）和放射性同位素（如碳-14、铯-137、铅-210）。这些数据将与统计模型和流域水文学知识结合使用，以评估河流沉积物的可能来源以及这种来源如何随季节和降水而变化。了解沉积物来源和组成的变化将有助于了解沉积物到达河流的不同机制的相对重要性，如河岸崩塌、地表侵蚀和河岸渗漏。这种认识反过来又将有助于设计更有效和更有针对性的流域管理和恢复战略。大量的环境问题围绕着悬浮物的流域输出，例如饮用水质量、河流生境健康、生物地球化学循环以及河口和三角洲功能。除了研究沉积物输送背后的机制外，Karwan博士还将与一个已建立的环境教育项目合作，以提高学龄儿童的流域素养。通过将她的流域研究添加到现有的“我的流域模型”项目中，城市和郊区的学生将能够在一个互动的在线模拟游戏中探索森林和溪流之间的联系。

Dr. Diana Karwan is awarded an NSF Earth Sciences Postdoctoral Fellowship to implement a research and education program based at the University of Delaware. The research will be conducted between multiple sites in the Critical Zone Observatory network. Specifically, this study aims to quantify suspended sediment composition and link geochemical differences in stream sediment to their distinct watershed sources and the hydrologic paths by which sediments move from the landscape to the stream. First, the stream and watershed sediments will be analyzed for their composition with particular emphasis on elemental mineral content, stable isotopes, such as Carbon-13 and Nitrogen-15, and radioisotopes, such as Carbon-14, Cesium-137, Lead-210. This data will be used in combination with statistical models and knowledge of the watershed hydrology to assess the likely source of stream sediments and how this source varies seasonally and with precipitation. Understanding variations in sediment source and composition will lend valuable insights into the relative importance of different mechanisms by which sediment reaches the stream, such as bank collapse, surface erosion, and bank seepage. This insight will, in turn, allow for the design of more effective and targeted watershed management and restoration strategies.Considerable environmental concerns surround the watershed export of suspended sediment, such as drinking water quality, stream habitat health, biogeochemical cycles, and estuarine and delta function. In addition to studying the mechanisms behind sediment delivery, Dr. Karwan will work with an established environmental education program to increase the watershed literacy of school-aged children. By adding her study watershed to the existing Model My Watershed project, urban and sub-urban students will be able to explore the links between forests and stream water flows in an interactive, online simulation game.