SGER: Seabed and Geochemical Deltaic Changes Induced by Hurricane Katrina

东卡罗莱纳大学的研究人员将利用探索性研究小额基金的资助，评估卡特里娜飓风对密西西比河三角洲近海沉积物再分布的影响。2005年8月29日，这场强飓风直接通过密西西比河鸟足三角洲，为评估与一次特大气象事件相关的泥沙扰动和沉积/输出提供了一个独特的机会。“伊万”飓风之后的快速反应研究的最新结果表明，与大型飓风相关的跨货架和下货架运输是巨大的。此外，与伊万飓风有关的管道损坏表明，在这些事件中，群众运动可能是一个重要的运输代理。在过去的24个月里，研究小组在大陆架和密西西比河三角洲附近的峡谷收集了一系列时间序列的岩心，以了解短期沉积动力学。基于这项工作和其他人的研究，他们假设重大天气事件，如飓风，在密西西比河边缘沉积物和相关生物地球化学重要成分的不稳定和重新分配中具有不成比例的重要作用，特别是通过大规模运动。他们计划重新占领密西西比边缘的11个站点，这些站点位于卡特里娜飓风（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射线摄影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，并将有助于针对这一事件制定更准确的沉积物输送性质的概念框架。通过对这一重大事件的快速反应，并与俄勒冈州立大学和杜兰大学的同事密切合作，研究小组希望对卡特里娜飓风后的跨大陆架运输和物质沉积提供定量估计。就更广泛的影响而言，该项目解决了大风暴在沿海系统沉积物扩散中所起作用的基本问题。海床的扰动可能加强沉积物的再加工过程，因此对发生在沉积物中的成岩反应、埋藏物质的组成以及上覆水域的营养物质和氧气的可用性有直接影响。这项研究的结果也应该提供一个更好的理解动力学和历史的粒子在河流主导的陆架环境。这个项目的时间、持续时间和性质为几个高年级本科生和研究生提供了一个极好的机会，让他们接触海上科学。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，研究的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拨款单独资助），旨在教育公众了解沉积物和溶质从源头到汇的转移。

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.