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Abstract : The Power and Limitations of Synchrotron X-rays in Agro-Environmental Research
( Dean L Hesterberg ) 한국환경농학회 2012 한국환경농학회 워크샵자료 Vol.2012 No.2
High-intensity synchrotron x-rays provide some of the most advanced analytical tools for studying soils. Nevertheless, the extreme complexity of soils across all spatial scales - from landscapes to molecules - challenges our ability to use these advanced measurements in management decisions that optimize crop nutrition while protecting the environment. This presentation will introduce the technique of synchrotron x-ray absorption spectroscopy, and discuss its advantages for analyzing chemical species of trace elements (and nutrients) in soils, and its limitations for such complex systems. Synchrotron x-ray absorption spectroscopy provides chemical-speciation information about average oxidation states and average local molecular coordination environments of individual soil elements, even at part-per-million concentrations. However, in such complex matrices, the specificity of the technique is lost because of the large number of possible (and measured) chemical species present. Technological advances have provided spatially resolving x-ray microprobes that can be applied at smaller and smaller (submicron) spatial scales, which is advantageous for identifying a subset of chemical species within heterogeneous subunits of soils (microsites). A new concept of soil chemistry - the reactive microsite model - proposes that chemical speciation and chemical microenvironments must be understood to predict reactivity. Future developments of chemical-specific analytical tools with high spatial resolution provide opportunities for experimentally assessing real-time transformations of environmental contaminants within soil matrices.