Tuesday, Oct. 15, 2013, Noon, 115 EBB
Dr. Paula Mouser, Assistant Professor, Ohio State University
Microorganisms play an important and under-characterized role in the sustainability of unconventional shale energy extraction methods. After being pumped from their native surface water or groundwater environment, aquatic and subsurface microorganisms are then hauled in tanker trucks to a drilling site, mixed at high pressures with sand “proppants” and hydraulic fracturing chemicals, and transported under high fluid velocities and shear stresses into a deep shale formation. Microorganisms are next subjected to harsh physical and chemical conditions while the well is fractured and completed for production – a process that can take anywhere from days to weeks. In situ physicochemical conditions at depths of 2,000 meters include temperatures near 60ºC, pressures approaching 60 MPa, and salinity levels more concentrated than the ocean.
Remarkably, some surface and groundwater organisms survive and even thrive under these conditions; however, rapid and dramatic shifts in the microbial ecology are evident in fluids that return to the surface. Using 454-pyrosequence analysis of nucleic acids that were extracted from flowback samples at a Marcellus site, we deeply profiled the organisms that were injected and returned from three horizontal fracked wellbores. Biomarkers from the 16S rRNA gene indicate that dominant taxa in early and late flowback samples are closely related to bacteria involved in fermentation, hydrocarbon oxidation, and sulfur cycling lifestyles under highly saline conditions. Microorganisms also play an important role in attenuating organic constituents present in hydraulic fracturing fluids that may accidentally escape to the shallow soil and groundwater environment. Indigenous groundwater and soil microorganisms exposed to varying concentrations of fracturing fluids biodegraded 80% (+7%) of added dissolved organic carbon in 25 days under both anaerobic and aerobic conditions, suggesting significant mineralization of fracturing fluid constituents across a range of redox environments.
Dr. Paula Mouser, assistant professor of Civil, Environmental and Geodetic Engineering at Ohio State University, will be the next EBI Seminar speaker in Berkeley on Tuesday, Oct. 15 at noon, when she will discuss "Microorganisms and Shale Energy Development: From Laboratory Experiments to Field–Scale Observations." These results highlight the importance of understanding microbial community dynamics in response to shale energy extraction methods and provide initial insight into biogeochemical processes that may attenuate the migration of hydraulic fracturing fluids under deep and shallow subsurface conditions.
Growing up in western Wyoming, Paula received her B.S. in Environmental Engineering from Utah State University. After graduation, she worked 2 years for the City of Logan managing engineering projects in the Permits and Compliance Division. Paula attended graduate school at the University of Vermont where she received her M.S. and Ph.D. in Environmental Engineering working with Donna Rizzo. Her dissertation examined the use of groundwater microbial communities to detect leaks from municipal landfills. Paula next completed a post-doc with Derek Lovley in the Dept of Microbiology at the University of Massachusetts, Amherst. expanding her knowledge of molecular biology tools to assess the metabolic activity of subsurface bacteria. After her post-doc, Paula worked as a Project Manager for Sanborn, Head & Associates, receiving her Maine P.E. license based on her work related to site characterization and remediation design. In 2011, Paula began as an Assistant Professor at The Ohio State University in the Department of Civil, Environmental & Geodetic Engineering. Paula’s current research is focused on the ecology and metabolic condition of microorganisms that mediate the fate and transport of contaminants in subsurface systems, particularly energy sites.