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，沈志雄，EAR-1148005，杜兰大学Wonsuk Kim，EAR-1148247，大学。德克萨斯州奥斯汀ABSTRACTPI将借助光激发发光(OSL)测年技术研究晚全新世河流三角洲沉积的模式和速率，并使用从最大的碎屑沉积中心之一密西西比三角洲收集的现场数据来探索陆地建设和有机碳(OC)封存的潜力。这项研究不仅具有重要的科学意义，而且对遭受持续湿地损失的密西西比三角洲的海岸恢复也具有重要意义。PI将从密西西比河一条最近被遗弃的主要分流的岸上沉积中收集地层和地质年代学数据，以检验这样一种假设，即河流三角洲环境中的碎屑地层记录是由离散的沉积体拼凑而成的，这些沉积体在相对较短的时间内以插曲的方式积累。这一假设植根于一场长期的地质学争论，这场争论可以追溯到19世纪初，争论的中心是地球的地层记录主要反映的是逐渐沉积还是灾难性事件。这场辩论很重要，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，他们还将测量河流三角洲沉积物中有机碳的含量和年龄谱。利用有机碳含量结合年代学数据计算有机碳的固存速率，以检验碎屑滩面沉积的有机碳固存速率等于或超过沼泽泥炭沉积的有机碳固存速率的假设。因此，泛滥平原和三角洲平原可能构成了一个重要的有机碳储量，到目前为止，该储量的量化程度很低，通常被忽视。将有机碳的年龄谱与OSL测年结果进行比较，以考察人类活动对大江大河有机碳迁移的影响。最后，将使用地层学数据来评估决口淤积的泥沙捕集效率，决口淤积是一种天然的类似于人工改道的河流，目前建议用于海岸恢复。研究密西西比河三角洲的泥沙捕集效率，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地潜力。此外，有机碳固存数据将为恢复的湿地潜在的生态系统服务提供新的见解。

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.