The Department of Chemistry invites you to its departmental seminar today at 4:10 p.m. in Fulmer Hall, room 201.
Dr. Ken Kemner from the Environmental Science and Biogeochemical Process Group, Bioscience Division at Argonne National Lab, will present, Understanding processes that drive heavy metal and radionuclide transformations: Integrating hard x-ray synchrotron radiation into a (Biogeo)chemist’s toolbox.
Abstract: Mineral transformations resulting from the coupling of biological, physical, and chemical processes in the subsurface affect the mobility of contaminants, carbon/nutrient forms and cycling, and the geochemical character of groundwater. Similarly, in situ groundwater remediation or waste storage strategies often have the goal of limiting the mobility of a contaminant by decreasing its solubility in the passing aqueous phase. The chemical or enzymatic reduction of uranium (U), a ubiquitous contaminant at US DOE sites, from U(VI) to U(IV) presents an approach to achieve this goal by exploiting the lower solubility of uraninite (UO2) relative to that of U(VI) species. This property of U has led to extensive research aimed at understanding the mechanism of U(VI) reduction and the stability of uraninite. Characterizing the U and mineral transformations on relevant spatial scales is a major challenge in understanding natural subsurface biogeochemical processes. Synchrotron-based biogeochemistry at the Advanced Photon Source provides an opportunity to characterize and understand these transformations. The Argonne Subsurface Biogeochemical Research Program (SBR) Scientific Focus Area (SFA) integrates synchrotron-based biogeochemistry with “now-generation” DNA sequencing techniques and bioinformatics approaches, microbiology, and molecular biology to pursue the long-term scientific goal of elucidating the interplay, at the molecular level, between specific microbial metabolic activities, solution chemistry, and mineralogy contributing to the transformations of minerals, heavy metals, and radioactive elements in subsurface environments.
One objective of our project is to characterize coupled biotic-abiotic molecular-scale Fe, S, heavy metal, and radionuclide transformations, integrated over different length scales, to provide knowledge that is necessary for understanding subsurface processes and predicting contaminant reactivity and transport. This objective guides the development and optimization of synchrotron methods for molecular-level measurements pertinent to understanding contaminants and the geochemical character of groundwater in subsurface environments. Argonne SBR SFA research addresses many critical knowledge gaps related to understanding these issues. Some of these include (1) an in-depth understanding of molecular processes affecting contaminant speciation; (2) an understanding of the role of biogenic and abiotic redox-active products and intermediates in Fe, S, and contaminant transformations; and (3) an understanding of mass transfer and microenvironment effects on Fe, S, and contaminant transformations. During my presentation, I will provide an introduction to pertinent Biogeochemistry and synchrotron-based x-ray Physics concepts and examples of work performed by our group to address these three knowledge gaps.
This work was supported by the US Department of Energy (US DOE), Office of Science (OS), Biological and Environmental Research, Subsurface Biogeochemical Research Program. The Advanced Photon Source is funded by the US DOE OS Basic Energy Science Division. MRCAT/EnviroCAT is also supported by its member institutions.
