RAPID: Collaborative Research: Sediment and Contaminant Mobilization by Extreme Flooding Associated with Hurricane Florence

高强度的河流洪水是一个逐渐被认识到的塑造景观、移动沉积物和污染物以及建立地层记录的过程。热带气旋是带来极端降水和产生高强度河流洪水的主要机制。2018年9月14日，飓风“佛罗伦萨”在北卡罗来纳州登陆，并在那里停下来，造成了强降水，大西洋下游沿海平原的河流发生了历史性的洪水。这些洪水重塑了洪泛区，并从该地区的工业中动员了一系列污染物，为研究极端洪水的地貌和环境影响提供了独特的机会。pi将系统地收集洪水在美国东南部最大的流域之一皮迪河系统下游沉积的沉积物，以调查飓风登陆引起的洪水后沉积物和相关污染物沉积的横向和纵向模式。这项研究将阐明极端洪水事件是如何将沉积物和污染物从陆地带到海洋的，这是一个影响沿途人类健康和生态系统的过程。确定和量化流入温亚湾的污染物对沿海生态系统管理和公众健康具有重要意义。调查结果将传达给当地的利益相关者和决策者。该项目将资助一个多学科团队，包括不同职业阶段的地球科学家、环境科学家和环境工程师。来自卡罗来纳海岸大学和东北大学的本科生和研究生将参加拟议的活动，以获得研究经验，并开展研究活动，这些活动可以融入他们的学术课程。登陆的飓风在大西洋沿岸平原造成河流洪水的危险，影响了数百万地区居民。该项目利用罕见的极端洪水来观察这种类型的事件如何塑造冲积河系统的洪泛区，并将沉积物和污染物从陆地和点源输送到沿海海洋。在其他过程去除或侵蚀洪水产生的沉积物之前，pi将收集洪水沉积物样本。他们将分析沉积物特征，对沉积物进行7Be测年以确定沉积时间，并测量洪水沉积物中有机（多环芳烃；多环芳烃）和微量金属（V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Sn, Hg， Pb和Bi）污染物的浓度。就像哈维飓风（2017年）引发的洪水和污染物研究一样，这项工作具有高度相关性，并说明了将污染物扩散作为公共卫生问题进行跟踪的必要性。同时使用多环芳烃和选定的痕量金属将为多环芳烃化合物提供更强有力的来源识别，例如，从道路、停车场的煤或与煤炭燃烧有关的径流。拟议的活动建立在一个活跃的NSF项目（EAR-1804799）的基础上，该项目支持PIs Munoz和Shen，通过提供极端洪水沉积沉积的现代模拟，开发冲积河流（古洪水）的洪水沉积记录。数据将有助于理解景观和生态系统对极端洪水的反应，并改善人口稠密沿海地区过去风暴活动和周期性的古洪水和古风暴重建。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

High magnitude riverine floods are an increasingly recognized process shaping landscapes, mobilizing sediment and contaminants and building stratigraphic records. Tropical cyclones are the dominant mechanism that delivers extreme precipitation and produces high magnitude riverine flooding. Hurricane Florence made landfall in North Carolina on Sep 14, 2018 where it stalled and generated heavy precipitation and historic flooding on rivers across the lower Atlantic coastal plain. These floods reshaped floodplains and mobilized a range of contaminants from industries in the region, providing a unique opportunity to study the geomorphic and environmental effects of an extreme flood. The PIs will systematically collect sediment deposited by the flood in the lower reaches of the Pee Dee River system, one of the largest watersheds in the southeastern US, to investigate the lateral and longitudinal patterns of sediment and associated contaminant deposition immediately following flooding caused by a landfalling hurricane. This research will clarify how extreme flood events carry sediments and contaminants from land to sea, a process affecting the health of people and ecosystems along the way. Identifying and quantifying contaminant inputs to Winyah Bay has critical implications for coastal ecosystem management and public health. Findings will be communicated to local stakeholders and decision makers. The project will fund a multidisciplinary team that encompasses geoscientists, environmental scientists, and environmental engineers across a range of career stages. A diverse group of undergraduate and graduate students from Coastal Carolina University and Northeastern University will participate in the proposed activities to gain research experience and develop research activities that can be built into their academic programs.Landfalling hurricanes generating riverine flooding hazards on the Atlantic Coastal Plain affect millions of area residents. This project takes advantage of a rare extreme flood to observe how this type of event shapes the floodplain of an alluvial river system and transports sediment and contaminants from land and point sources to the coastal ocean. The PIs will collect floodwater sediment samples before other processes remove or erode the flood-born deposits. They will analyze sediment characteristics, conduct 7Be dating of sediment to confirm timing of deposition, and measure concentrations of organic (Polycyclic aromatic hydrocarbons; PAHs) and trace metal (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Sn, Hg, Pb, and Bi) contaminants in the floodwater sediments. Like flood and contaminant research resulting from Hurricane Harvey (2017), the work is highly relevant and illustrative of the need to track contaminant dispersal as a public health issue. Using both PAHs and the selected trace metals will provide stronger source identification for PAH compounds, e.g., run-off from roads, parking lot sealcoat, or associated with coal combustion. The proposed activities build on an active NSF project (EAR-1804799) supporting PIs Munoz and Shen that develops sedimentary records of flooding on alluvial rivers (paleofloods) by providing a modern analogue of sediment deposition by an extreme flood. Data will aid in understanding landscape and ecosystem responses to extreme flooding and improve paleoflood and paleo-tempestological reconstructions of past storm activity and periodicity in heavily populated coastal regions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.