Aaron Packman, Northwestern University
January 14, 2016
11:00 AM - 12:00 PM
810 South Clinton Street, Chicago, IL 60612
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Dynamics of fine particles and microbes in rivers: Transport, retention, and remobilization
Hosted by: Brian Chaplin
Historically, surface waters and groundwaters have been considered to represent distinct systems with little hydrologic connectivity. However, coupling between hydrodynamic and geomorphic processes causes surface and subsurface waters to be highly connected over a wide range of scales. A wide range of processes cause exchange of water and suspended matter between rivers and underlying sediments. Recent observations have demonstrated that fine particles and suspended microorganisms show complex dynamics in rivers, including continuous deposition and resuspension in streambed sediments. This provides substantial opportunity for interaction of stream-borne material with underlying sediments, and this interaction is expected to alter the hydrogeological properties of fluvial deposits, increase the opportunity for metabolism of terrestrial particulate organic matter in rivers, and mediate the migration, persistence, and growth of microorganisms. In this presentation, I will briefly review current understanding of surface-groundwater exchange processes, develop a conceptual model for deposition and resuspension of fine particles and microorganisms in rivers, and present a stochastic modeling framework for these processes. I will close by discussing the limits of current understanding and prospects for future development of more general models for coupled hydrologic, geomorphic, and microbial processes in watersheds.
About the Speaker:
The main focus of my work is the study of environmental transport processes, including both hydrodynamic transport processes and reactive transport processes. A lot of this work involves sediments, including transport processes in sediment beds, the implications of physicochemical particle-particle interactions for fine sediment transport, and the role of sediments in contaminant transport. I also teach classes related to environmental fluid mechanics, transport, and modeling. My research group is applying fundamental, interdisciplinary methods to a variety of environmental problems in streams and other aquatic systems. Generally we start by examining fundamental transport processes in the laboratory, but we are also working to apply this knowledge directly to natural systems. In addition, we are applying fundamental knowledge about transport, chemical reactions, and biological processes to understand the mobility and fate of a fairly wide range of environmentally-relevant substances, including sediments, metals, and pathogens. Because this work is interdisciplinary, it is also highly collaborative and we have a number of very close working relationships with other research groups throughout the U.S. and Europe. Information on all of these topics can be found by following the links in the menu bar.
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