Earth Science Department Seminar

Tuesday, December 18, 2018 3:00 pm - 3:00 pm EST (GMT -05:00)

Microbe-mineral-fluid interactions: Case studies from natural environments, industrial problems and arctic biogeochemical processes 

Presented by Dr. Jenine McCutcheon, School of Earth and Environment, University of Leeds

Abstract: Microbial processes influence geochemical reaction pathways in a range of natural and engineered environments. These processes often result in the precipitation, alteration, or dissolution of mineral phases, thereby also altering the chemistry of the surrounding fluid. By characterizing the structure and chemistry of biomineralization products, it becomes possible to use these processes to solve environmental challenges. This will be demonstrated through case studies highlighting the biogeochemistry of three dissimilar environments. First, the role of cyanobacteria in beachrock cementation was studied in carbonate beachrock on Heron Island (Great Barrier Reef, Australia). These field and laboratory studies used synchrotron-based microscopy to characterize beachrock microbialites and cements, and have applications to reef island stabilization. Next, cyanobacteria carbonate precipitation reactions were applied to mineral carbonation of ultramafic mine tailings, for the purposes of carbon sequestration and mine waste remediation. Finally, while microbe-mineral interactions occur on the scale of nanometers to micrometers, they can have large-scale implications for global biogeochemical processes. This will be demonstrated in the third case study, exploring the role of mineral dust and ice algae in darkening the Greenland Ice Sheet. These pigmented ice algae ‘bloom’ during the summer melt season, thereby lowering the ice sheet albedo and accelerating melting. These case studies from dissimilar natural and industrial systems demonstrate the chemical and structural complexity of microbe-mineral interactions. The final part of this presentation will highlight emerging and future research directions in the field of geomicrobiology, with a focus on rethinking how we analyze biofilm structures and processes. The anticipated work will utilize novel microscopic and spectroscopic techniques to provide a better understanding of biofilm architecture and microbially mediated mineral nucleation reactions. Industrial applications of this work include enhanced resource recovery from low grade ores or mine waste materials, bioremediation of mine sites and contaminated soils, and carbon sequestration in mineral products. This work will better our understanding of microbial nutrient acquisition in extreme environments, as well as microfossil preservation in the rock record.