Collaborative Research: RAPID: Extreme disturbances/perturbations to coastal deposition systems

合作研究：RAPID：对沿海沉积系统的极端干扰/扰动

• 批准号: 2205277
• 负责人: Shaily Rahman
• 金额: $ 12.33万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-15 至 2023-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2205277&HistoricalAwards=false
• 关键词: Collaborative; Research; RAPID; Extreme; disturbances

This project will take advantage of the passage of Hurricane Ida across the northern Gulf of Mexico shelf in August, 2021 to study important aspects of the cycling of silica in coastal sediments. In coastal systems, water column primary productivity is dominated by diatoms, a group of phytoplankton which produce a shell of amorphous biogenic silica. This biogenic silica can either be buried in its original unaltered form or undergo chemical reactions that convert it to aluminosilicate minerals (e.g. marine clays). This latter process is important in global chemical budgets for many elements, including carbon. One of the factors that influences whether silicon is buried as biogenic silica or converted to aluminosilicates may be the amount of oxygen in the sediments. Storms mix the ocean waters and can add oxygen to sediments in shallow water, potentially changing the silica balance. The investigators collected sediment samples in early August, 2021, two weeks before Hurricane Ida. Sampling through the year after the storm will allow them to test whether storms affect silica cycling. This project will support an early-career investigator and undergraduate student researchers.Tropical and subtropical coastal deposition systems sequester 25-40% of the global silica sink, a disproportionately large impact relative to their area. In the northern Gulf of Mexico seasonal water column stratification may impact how sedimentary biogenic silica is processed and preserved by limiting oxygen injections into the benthos, seasonally driving biogenic silica burial efficiency. Hurricane Ida moved through the Mississippi Delta and adjacent Louisiana shelf at the end of August 2021. Thirteen days prior to Hurricane Ida’s landfall in Port Fourchon, LA, in August 2021, the team collected sediment cores at 3 sites in the topset delta sediment between the Southwest Pass (major Mississippi River distributary) and Cocodrie, LA; all sites experienced Category 4 hurricane conditions from Ida with maximum sustained winds of 130 knots (67 m/s). Ida, a much stronger storm than either Hurricanes Harvey or Nate in 2017, likely introduced oxygen into the sediment of the proximal coastal zone, perhaps enough to turn most of the top meter or so of the sediment column oxic. The investigators hypothesize that the storm-induced change in redox and diagenetic conditions initially favored burial of biogenic silica rather than an authigenic aluminosilicate. Using a multi-proxy approach, this project will analyze how this major storm event altered biogenic silica burial over the course of ten months.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.

该项目将利用IDA飓风在2021年8月通过墨西哥货架北部货架上的通过，研究沿海沉积物中二氧化硅循环的重要方面。在沿海系统中，水柱的主要生产力由硅藻（Diotoms）主导，硅藻是一组浮游植物，产生了无定形生物二氧化硅的外壳。这种生物二氧化硅可以以其原始的未改变形式建造，也可以经历化学反应，将其转化为铝硅酸盐矿物质（例如海洋粘土）。对于包括碳在内的许多元素，此后的过程在全球化学预算中很重要。影响硅是作为生物二氧化硅建造还是转化为铝溶剂的因素之一可能是沉积物中的氧气量。风暴混合海水，可以在浅水中的沉积物中添加氧气，从而有可能改变二氧化硅平衡。调查人员于2021年8月上旬（飓风IDA）在2021年8月初收集了沉积物样品。在暴风雨后的一年中进行采样将使他们能够测试风暴是否会影响二氧化硅循环。该项目将支持早期的研究员和本科生研究人员。热带和亚热带沿海沉积系统隔离了全球二氧化硅水槽的25-40％，这是相对于其地区的不成比例的影响。在墨西哥北部的季节性水柱分层可能会影响沉积物生物二氧化硅的处理和保存方式，通过将氧气注射限制为底栖动物，从季节性驱动生物硅酸盐的埋葬效率。艾达飓风在2021年8月底穿过密西西比三角洲和路易斯安那州的相邻架子。2021年8月，飓风艾达在洛杉矶飓风登陆洛杉矶港口的登陆前十三天，该团队在西南山谷（Southwest Pass Pass）中的最高式三角洲（Missipsippi River Distriblect）中的3个地点收集了三个地点的沉积物核心，所有站点都经历了IDA的4类飓风状况，最大持续风为130节（67 m/s）。艾达（Ida）比2017年的飓风哈维（Harvey）或内特（Harvey）更强烈，可能将氧气引入了近端沿海地区的沉积物，也许足以将大部分顶部仪表左右造成沉积物柱氧气的氧气。研究人员假设风暴引起的氧化还原和诊断状况的变化最初有利于埋葬生物二氧化硅，而不是身份化的铝硅酸盐。该项目使用多种方法的方法分析了这一重大风暴事件如何在十个月的时间内改变生物二氧化硅的埋葬。该奖项反映了NSF的法定任务，并通过评估该基金会的知识分子优点和更广泛的影响审查标准，被视为通过评估而被视为珍贵的支持。