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Beyond the Black Box: Integrating Advanced Characterization of Microbial Processes with Subsurface Reactive Transport Models

Speaker: Timothy Scheibe, Pacific Northwest National Laboratory, 2010 Darcy Lecturer, NGWA
Series: CEE Departmental Seminars
Location: Bowen Hall Auditorium
Date/Time: Tuesday, November 30, 2010, 4:30 p.m. - 5:30 p.m.


As a hydrogeologist with a geological engineering background, my natural focus has often been on physical processes of flow and transport in heterogeneous aquifers. Over the past decade, however, I have been privileged to have had opportunities to work closely with microbiologists on several projects, and my engineer brain has been highly stretched in the process. In fact, I have found myself on many occasions amazed not only by the microscopic world of subsurface microbes (did you know that some can "breathe" metal, or that others can flourish within ionizing radiation fields that would quickly destroy us?), but also by how technically advanced the science of microbiology has become.
The field of environmental microbiology has taken a quantum leap through developments in molecular biology such as high-throughput multiplex sequencing, high-density microarrays, and environmental proteomics; these technologies provide a deluge of information on the nature and function of microbial communities in natural systems. Importantly, many of these systems are relevant to such pressing issues as contaminant remediation and subsurface sequestration of carbon dioxide.
A key question is: How can we use this information to make quantitative predictions in support of environmental management decisions? Microbial processes are typically represented in subsurface reactive transport models based on relatively simple reaction rate models that do not account for known and important complexities of microbial function and community dynamics. While conventional approaches have been very effective in many settings, an opportunity is now being realized to improve the foundational basis of reactive transport model predictions by integrating newly available microbial characterization data and understanding.
In this talk I will introduce the audience to the amazing world of subsurface microorganisms and present some novel approaches for incorporating new knowledge and data into reactive transport simulations. Particular focus will be given to genome-scale models of microbial cell function, and how these models are being integrated into simulations of contaminant transport and fate in groundwater systems. These will be presented in the context of the application of in situ bioremediation that aims to immobilize uranium in groundwater through microbially mediated metal reduction.


Timothy Scheibe
Photo: Timothy Scheibe

The 2010 Henry Darcy Distinguished Lecturer Timothy "Tim" D. Scheibe, Ph.D., joined Pacific Northwest National Laboratory in September 1992 and is currently a staff scientist in the Hydrology Technical Group. He received his bachelor’s degree in geological engineering from Washington State University, a master's in civil engineering from the University of Washington, and a Ph.D. in civil engineering from Stanford University. At PNNL, he has been responsible for proposal development, project management, and technical contributions in a number of different areas of environmental research and technology development broadly related to the hydrologic sciences.

His primary research focus is on characterization and numerical simulation of natural subsurface heterogeneity, and its impacts on biogeochemically reactive transport in groundwater systems. His research projects include both computational and field experimental elements. Recently, he has worked on problems in the area of subsurface biogeochemistry, including microbial transport in groundwater, and bioremediation of metals and radionuclides. He is currently collaborating with computational scientists and applied mathematicians to simulate coupled flow, transport, and biogeochemical processes at cellular, pore, and continuum scales. His research is supported primarily by the Department of Energy's Office of Science through the Environmental Remediation Science Program and the Scientific Discovery through Advanced Computing Program.

Scheibe is a member of NGWA. He has served on the editorial board of the NGWA journal Ground Water® since 2001 and is active in the American Geophysical Union, in which he currently represents the Hydrology Section on the Joint Assembly Program Committee.