9753072 Axe Hydrous Fe and Mn oxides are ubiquitous in natural aquatic systems. Because of their high surface areas, affinity for trace metals, and tendency to form coatings on other mineral surfaces, they can control the transport and fate of metals in aqueous systems. Unfortunately, predicting contaminant transport has been unsuccessful. In this research enhancement proposal, advanced methods in x-ray absorption spectroscopy (XAS) will be learned and applied under the direction of Professor Grant Bunker, Illinois Institute of Technology. Access to the Advance Photon Source at Argonne National Laboratory will be provided through the Biological Collaborative Access Team (BiocAT) sector 18 undulator beamline of which Professor Bunker is director and the Materials Research Collaborative Access Team (MR-CAT) undulator beamline (sector 10) through IIT's membership in MR-CAT. XAS studies will be conducted to develop mechanistic, microscopic models of a metal interaction at Fe and Mn oxide surfaces. Previous studies have been limited to relatively high concentrations (in the range of 1 mM) with respect to typical contaminant concentrations found in the environment. With the higher flux available at the Advanced Photon Source, it is theoretically possible to obtain valuable measurements from samples at least two orders of magnitude lower in concentration. Techniques developed here will be used in future spectroscopic studies of complex, natural substrates. Results from this work will enhance further complimentary laboratory studies in understanding and modeling contaminants in the environment. ***
