Collaborative Research: Continuous vs. episodic fluviodeltaic sedimentation: Implications for carbon sequestration and coastal restoration

合作研究：连续与间歇性河流三角洲沉积：对碳封存和海岸恢复的影响

• 批准号: 1148005
• 负责人: Torbjorn Tornqvist
• 金额: $ 33.24万
• 依托单位: Tulane University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1148005&HistoricalAwards=false
• 关键词: Collaborative; Research; Continuous; vs.; episodic

Collaborative Research: Continuous vs. episodic fluviodeltaic sedimentation: Implications for carbon sequestration and coastal restorationbyZhixiong Shen, EAR-1148005, Tulane UniversityWonsuck Kim, EAR-1148247, Univ. Texas, AustinABSTRACTPIs will investigate patterns and rates of late Holocene fluviodeltaic sedimentation with the aid of optically stimulated luminescence (OSL) dating, and explore the potential of land building and organic carbon (OC) sequestration using field data collected from one of the largest clastic depocenters: the Mississippi Delta. This research is not only important scientifically, but also for coastal restoration in the Mississippi Delta that suffers continuous wetland loss.PIs will collect stratigraphic and geochronologic data from overbank deposits along a recently abandoned major distributary of the Mississippi River to test the hypothesis that the clastic stratigraphic record in fluviodeltaic settings consists of a patchwork of discrete sediment bodies that accumulate in an episodic fashion over relatively short time periods. This hypothesis is rooted in a long-standing geological debate that traces back to the early 19th century, centering on the question whether the Earth's stratigraphic record primarily reflects gradual deposition or catastrophic events. This debate is important because understanding the nature of the preserved sedimentary record is critical to interpret changes in the Earth system over geological timescales. Furthermore, they will measure the content and age spectra of OC within fluviodeltaic deposits. The OC content will be used, in combination with the chronologic data, to calculate rates of OC sequestration to test the hypothesis that rates of OC sequestration by clastic overbank deposition can equal or exceed those by swamp peat accretion. Consequently, floodplains and delta plains may constitute an important OC pool that is to date poorly quantified and commonly ignored. The age spectra of the OC will be compared with the OSL dating results to investigate the effect of human activity on OC transport by large rivers. Finally, stratigraphic data will be used to estimate the sediment trapping efficiency of crevasse-splay deposition, a natural analog to artificial river diversions that are currently proposed for coastal restoration. Studying sediment trapping efficiency in the Mississippi Delta, in concert with numerical modeling, will provide critical information to assist in the better estimation of land-building potential by Mississippi River diversions. In addition, the OC sequestration data will provide new insights about potential ecosystem services of restored wetlands.

合作研究：连续与间歇河流三角洲沉积：研究人员将利用光激发发光（OSL）测年技术研究晚全新世河流三角洲沉积的模式和速率，并利用从最大的碎屑沉积中心之一——密西西比三角洲收集的野外数据，探索陆地构造和有机碳（OC）封存的潜力。该研究不仅具有重要的科学意义，而且对持续遭受湿地损失的密西西比三角洲的海岸恢复具有重要意义。pi将从最近废弃的密西西比河主要支流的河岸沉积物中收集地层学和地质年代学数据，以验证河流三角洲环境中的碎屑地层记录是由分散的沉积物体拼凑而成的，这些沉积物体在相对较短的时间内以偶发性的方式积累。这一假设源于19世纪早期的一场长期地质学争论，争论的焦点是地球的地层记录主要反映的是渐进沉积还是灾难性事件。这场争论很重要，因为了解保存下来的沉积记录的性质对于解释地球系统在地质时间尺度上的变化至关重要。此外，他们将测量河流三角洲沉积物中OC的含量和年龄谱。将使用有机碳含量，结合年代学数据，计算有机碳封存速率，以验证碎屑河岸沉积的有机碳封存速率等于或超过沼泽泥炭沉积的有机碳封存速率的假设。因此，洪泛平原和三角洲平原可能构成一个重要的OC库，但迄今为止，这一库的量化很差，而且通常被忽视。将OC的年龄谱与OSL定年结果进行比较，探讨人类活动对大河OC输送的影响。最后，地层数据将用于估计裂缝-张开沉积的沉积物捕获效率，这是目前提出的用于海岸恢复的人工河流改道的自然类比。研究密西西比河三角洲的沉积物捕获效率，结合数值模拟，将提供关键信息，以帮助更好地估计密西西比河改道的造陆潜力。此外，碳封存数据将为恢复湿地潜在的生态系统服务提供新的见解。