SGER: Mobilization and Deposition of Organic Matter along the Louisiana Coast following Hurricane Katrina

SGER：卡特里娜飓风过后路易斯安那州海岸有机物的流动和沉积

• 批准号: 0553090
• 负责人: Miguel Goni
• 金额: $ 12.89万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-10-15 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0553090&HistoricalAwards=false
• 关键词: SGER; Mobilization; Deposition; Organic; Matter

ABSTRACTOCE-0553090Hurricanes and large storms play a critical but often unpredictable role in the transport and redistribution of sediments and organic matter in the coastal ocean. Previous work on the effects of Hurricane Lili, a much smaller storm than Hurricane Katrina, revealed large seaward transport and deposition of fine sediments onto the shelf region west of the storm track. Furthermore, massive deposition of organic carbon and nitrogen associated with these fine sediments was observed throughout the region, vastly exceeding the long-term accumulation of these materials in this area. Based on earlier findings following Hurricane Lili and given its much larger magnitude and intensity, Hurricane Katrina (~ 4m storm surge, 135-160 mph winds) may have potentially mobilized and redistributed much larger amounts of sediment and associated organic matter over a much wider area. The majority of the offshore transport likely occurred in the western region of the storm track, where winds were predominantly in the offshore direction. The impacted area ranges from the more distal Atchafalaya River subaqueous delta to the more proximal Mississippi River delta and associated canyon. With funding from this Small Grant for Exploratory Research, investigators at the Oregon State University will collect samples and carry out analyses of seabed sediments from the region affected by Hurricane Katrina to evaluate its effects on the mobilization and deposition of sediment and organic matter along the Louisiana Shelf. The immediacy of the proposed work is to sample the storm deposits before they are eroded and mixed and while they retain their unique chemical (e.g. short-lived isotopes, organic carbon contents) characteristics. In cooperation with colleagues at East Carolina University and Tulane University, he research team will sample the seabed at several locations along the Louisiana Shelf that have been previously sampled and for which the sediment accumulation rates and sedimentary organic matter have been characterized. These observations will provide baseline information that will be compared to the findings from samples collected after the Katrina event. The Oregon State group will analyze the sediments collected at these sites to determine the concentration and composition of organic matter in the storm layer. The chemical analyses of the organic matter (e.g. stable isotopes, radiocarbon concentrations, terrigenous and marine biomarkers) will help characterize the sources of the organic matter, which will yield information on the ultimate source of the mobilized materials. These results will yield novel insights into the effects of such large storms on the sedimentology and biogeochemistry of this region. Specifically, it will provide detailed information on the role of large storms as a mechanism for the export of terrigenous materials from the inshore regions of the shelf to the more offshore regions, such as the Mississippi Canyon and the prograding Atchafalaya subaqueous-delta clinoform.The broader impacts of the proposed work include the collection and analyses of seabed samples impacted by a major hurricane in a coastal system that has a well-developed baseline of information. Collaboration with other research groups will enhance the understanding of sediment and organic matter cycling in coastal systems during such stochastic events. The proposal will also include involvement by undergraduate students in the field and laboratory aspects of the work.

飓风和大风暴在沿海海洋沉积物和有机物的迁移和再分布中起着至关重要但往往不可预测的作用。 以前对飓风莉莉（比卡特里娜小得多的风暴）影响的研究显示，大量的细沉积物向海迁移并沉积到风暴路径以西的大陆架地区。 此外，在整个区域观察到与这些细沉积物有关的有机碳和氮的大量沉积，大大超过了这些物质在这一地区的长期积累。 根据飓风莉莉之后的早期发现，并考虑到其更大的规模和强度，卡特里娜飓风（约4米的风暴潮，135-160英里/小时的风速）可能已经在更广泛的地区动员和重新分配了大量的沉积物和相关的有机物质。 大部分离岸输送可能发生在风暴路径的西部地区，那里的风主要是离岸方向。 受影响的区域范围从更远的Atchafalaya河水下三角洲到更近的密西西比河三角洲和相关的峡谷。 利用这一探索性研究小额赠款的资金，俄勒冈州州立大学的研究人员将从受卡特里娜飓风影响的地区收集样本并对海底沉积物进行分析，以评估其对路易斯安那大陆架沿着沉积物和有机物的动员和沉积的影响。 拟议工作的紧迫性是在风暴沉积物被侵蚀和混合之前对其进行取样，同时保留其独特的化学特性（例如，短寿命同位素、有机碳含量）。 他的研究小组将与东卡罗莱纳大学和杜兰大学的同事合作，在沿着路易斯安那大陆架的几个地点对海底进行取样，这些地点以前已经取样，沉积物积累率和沉积有机物已经得到表征。 这些观测结果将提供基线信息，并与卡特里娜飓风事件后收集的样本结果进行比较。 俄勒冈州小组将分析在这些地点收集的沉积物，以确定风暴层中有机物的浓度和成分。 对有机物的化学分析（例如稳定同位素、放射性碳浓度、陆源和海洋生物标志物）将有助于确定有机物来源的特征，从而获得关于流动物质最终来源的信息。 这些结果将产生新的见解，这样的大风暴对该地区的沉积学和地球化学的影响。 具体来说，它将提供有关大风暴作为将陆源物质从大陆架近岸地区输出到更近海地区的机制的作用的详细信息，如密西西比峡谷和阿查法拉亚水下三角洲斜坡。拟议工作的更广泛影响包括收集和分析沿海系统中受大飓风影响的海底样本，制定信息基线。 与其他研究小组的合作将增进对这种随机事件期间沿海系统中沉积物和有机物循环的了解。 该提案还将包括本科生参与实地和实验室方面的工作。