SGER: Seabed and Geochemical Deltaic Changes Induced by Hurricane Katrina

摘要-0553064利用这项探索性研究的小额赠款，东卡罗莱纳大学的研究人员将评估卡特里娜飓风对密西西比河三角洲地区沉积物再分布的影响。 2005年8月29日，这场强大的飓风直接经过密西西比河的鸟足三角洲，为评估与特大气象事件相关的沉积物扰动和沉积/输出提供了一个独特的机会。 最近在飓风“伊万”之后进行的快速反应研究结果表明，与大型飓风有关的跨大陆和大陆外运输量巨大。此外，与飓风伊万有关的管道损坏表明，在这些事件中，物质运动可能是一个重要的运输代理人。在过去的24个月里，研究小组收集了一个时间序列的核心上的大陆架和峡谷邻近的密西西比三角洲，以了解短期沉积动力学。根据这项工作和其他人的研究，他们假设，主要的天气事件，如飓风，在密西西比边缘的沉积物和相关的地球化学重要成分的不稳定和重新分布中发挥了不成比例的重要作用，特别是通过质量运动。他们计划重新占领位于密西西比边缘的11个站点，这些站点位于卡特里娜飓风作为5级飓风的直接路径上。将对沉积物岩心进行地球化学、放射化学和沉积学分析。X射线照相术也将用于记录结构变化。地球物理调查将把地球化学、放射化学和沉积学观测纳入空间范围，并将有助于为这一事件的沉积物迁移性质制定更准确的概念框架。通过对这一重大事件的迅速反应，并通过与俄勒冈州州立大学和杜兰大学的同事密切合作，研究小组预计将提供卡特里娜飓风后物质跨大陆架运输和沉积的定量估计。就更广泛的影响而言，该项目涉及重大风暴在沿海系统沉积物扩散方面所起作用的基本问题。海床的扰动可能会加强沉积物的改造过程，从而直接影响沉积物中发生的成岩反应和埋藏物质的组成，以及上覆沃茨中的营养物和氧气。 这项研究的结果也应该提供一个更好的了解河流为主的陆架环境中的颗粒的动态和历史。这个项目的时间，持续时间和性质提供了一个很好的机会，让几个高层次的本科生和研究生在海上科学。 通过与教师的沟通，将努力让杜兰大学和新奥尔良大学的学生参与进来。此外，研究见解和观察结果将被纳入一个网站（由现有的国家科学基金会赠款单独资助），目的是教育公众了解沉积物和溶质从源到汇的转移。

ABSTRACTOCE-0553064With funding from this Small Grant for Exploratory Research, researchers at the East Carolina University will assess the impact of Hurricane Katrina on sediment redistribution in the offshore Mississippi River delta region. The passage of this powerful hurricane directly over the birdfoot delta of the Mississippi River on 29 August 2005 offers a unique opportunity to evaluate the sediment disturbance and deposition/export associated with a very large meteorological event. Recent results from rapid-response research following Hurricane Ivan indicate that across- and off-shelf transport associated with major hurricanes is enormous. Also, pipeline damage associated with Hurricane Ivan revealed that mass movement may be an important transport agent during these events.Over the previous 24 months, the research team had collected a time series of cores on the shelf and in the canyon adjacent to the Mississippi delta in order to understand the short-term sediment dynamics. Based on this work and research by others, they hypothesize that major weather events, e.g. hurricanes, have a disproportionately important role in the destabilization and redistribution of sediments and associated biogeochemically-important constituents on the Mississippi margin, particularly via mass movements. They plan to reoccupy 11 stations on the Mississippi margin that were in the immediate path of Hurricane Katrina as a category 5 hurricane. Geochemical, radiochemical and sedimentological analyses of sediment cores will be conducted. X-radiography also will be used to document structural changes. A geophysical survey will put geochemical, radiochemical and sedimentological observations into a spatial context and will help develop a more accurate conceptual framework of the nature of sediment transport in response to this event. By responding rapidly to this major event and through close collaborations with colleagues at Oregon State University and Tulane University), the research team expects to provide quantitative estimates of the cross-shelf transport and deposition of materials following Hurricane Katrina. In terms of broader impacts, this project addresses fundamental issues of the role major storms play in the dispersal of sediments in coastal systems. The disturbance of the sea bed may enhance sediment reworking processes, and therefore have a direct influence on diagenetic reactions that occur in the sediments and on the composition of the buried material, as well as nutrient and oxygen availability in overlying waters. The results of this study should also provide a better understanding of the dynamics and history of particles within river-dominated shelf environments. The timing, duration, and nature of this project offer an excellent opportunity to expose several upper-level undergraduate and graduate students to science at sea. Through communication with faculty, efforts will be made to involve students at Tulane University and University of New Orleans. Additionally, research insights and observations will be incorporated into a web site (funded separately by an existing NSF grant) aimed at educating the public on the source-to-sink transfer of sediment and solutes.