Fine Particle Migration and Solute Fluxes in Sediment Beds: Analysis of Sediment Structural Dynamics Using 3D Micro-Tomography

这项拟议的工作将通过将大量泥沙运移的详细观测与由此产生的三维沉积结构的精细测量相结合，促进我们对沉积过程的理解。这些过程将在循环水槽中进行研究，以便对水流条件进行控制，并能够直接观察泥沙输送过程。阿贡国家实验室的先进光子源将用于对取自水槽的完整沉积物岩芯进行三维X射线微层析成像和X射线荧光测绘。这些观测的主要目标将是研究块状沉积物结构的演变，特别是非均质沉积结构的发展。沉积物混合也将通过观察示踪剂颗粒的重新分布来确定，示踪剂颗粒将被专门合成，为X射线断层成像提供良好的对比度。一个保守的溶质将被用来评估由河流-地下水流耦合产生的孔隙水通量。基本模型将被用来评估沉积床内细颗粒的迁移以及由此产生的非均匀沉积条件的发展。这项研究将对水文过程和沉积物结构之间的联系提供关键的理解。参与该项目的研究生和本科生将获得详细的、面向过程的、跨学科的环境研究经验。此外，积极的国际合作和学生交换计划将鼓励项目参与者参与全球科学努力。最后，K-12教师的参与和利用项目实验室设施进行教育旅行和示范将向大学预科学生传播项目成果，并鼓励他们继续进行类似的学习。

0310657Packman The proposed work will advance our understanding of sedimentary processes by combining detailed observations of bulk sediment transport with fine-scale measurements of the resulting three-dimensional sedimentary structure. These processes will be studied in a recirculating flume in order to provide control of flow conditions and to allow direct observation of sediment transport processes. The Advanced Photon Source at Argonne National Lab will be used to perform 3D X-ray micro-tomography and X-ray fluorescence mapping on intact sediment cores taken from the flumes. The primary goals of these observations will be to examine the evolution of bulk sediment structure, specifically the development of heterogeneous depositional structures. Sediment mixing will also be determined from observations of the redistribution of tracer particles that will be specifically synthesized to provide good contrast for X-ray tomography. A conservative solute will be used to assess pore water fluxes resulting from stream-subsurface flow coupling. Fundamental models will be applied to assess the migration of fine particles within the sediment bed and the resulting development of heterogeneous sedimentary conditions. This study will provide key understanding of the linkage between hydrologic processes and sediment structure. Graduate and undergraduate students involved in this project will gain experience with detailed, process-oriented, interdisciplinary environmental studies. In addition, active international collaboration and student exchange programs will encourage project participants to engage in global scientific endeavors. Finally, involvement of K-12 teachers and use of project laboratory facilities for educational tours and demonstrations will disseminate project results to pre-college students and encourage them to pursue similar studies.