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Application Of Synchrotron Techniques To Investigate In-Situ Arsenic Speciation
Citation:
SCHECKEL, K. G. Application Of Synchrotron Techniques To Investigate In-Situ Arsenic Speciation. Presented at 20th New Phytologist Symposium: Arsenic: Unravelling It's Metabolism And Speciation In Plants, Aberdeen, UK, June 26 - 27, 2008.
Impact/Purpose:
To provide an introduction to synchrotron techniques available at most synchrotron facilities around the world and steps to become a user of synchrotron research.
Description:
The speciation, or chemical form of elements governs their fate, toxicity, mobility, and bioavailability in contaminated soils, sediments and water as well as food chain transfer mechanisms. To assess these chemical properties and to accurately gauge contaminant impact on human health and the environment we need to characterize metals at the atomic level to explain macroscopic observations. One can employ an array of techniques to address speciation; however, true in-situ analysis is limited to a few options such as advanced synchrotron radiation methods to elucidate metal speciation and distribution. Our ability to determine contaminant speciation in the natural environment enhances efforts to understand the mobility, bioavailability, and fate of contaminants in environmental systems, to assess health risks posed by them, and to develop methods to remediate contaminated sites. To attain in-situ atomic level information on the speciation of contaminants we utilize high-energy synchrotron X-rays to probe the chemical environment. At the Advanced Photon Source (APS) of Argonne National Laboratory (Argonne, IL), we incorporate X-ray absorption (XAS), X-ray fluorescence (XRF), and micro-tomography spectroscopies to analyze environmental samples to determine the true, in-situ speciation of contaminants. XAS determines the speciation of arsenic while XRF illustrates the two-dimensional distribution of arsenic relative to other elements of interest. Micro-tomography can be utilized to produce three-dimensional images of arsenic distribution. These methods are not limited by sample composition and have been successful in examining soils, plants, and microorganisms. These innovative research tools are expanding our ability to directly identify the role of contaminant speciation on many dynamic processes that influence risk. This presentation will provide an introduction to synchrotron techniques available at most synchrotron facilities around the world and steps to become a user of synchrotron research. Included in the presentation will be research highlights of past and current projects related to arsenic in the environment and accumulation in rice accomplished through international collaborations.