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June 10, 2003 Applications of synchrotron radiation: A pathway to understanding processes in environmental systemsThe tradition of holding an Environmental Sciences Workshop at the National Synchrotron Light Source Users’ Meeting continued with talks by an international array of speakers. This year, in addition to funding by the Users’ Executive Committee, funds were generously provided by the BNL Environmental Sciences Department and the Center for Environmental Molecular Sciences (SUNY Stony Brook/BNL). Presentations focused on three major areas in which synchrotron facilities are used to investigate processes controlling chemical species (usually contaminants) in the environment:
Bruno Lanson (U. of Grenoble, France) presented work exploring the relationship between bioavailability and sorption of Ni, Zn, Pb and Cd onto Birnessite (a Mn oxide) and interlayered Al phases, using a variety of techniques including microbeam x-ray diffraction and XAFS. Mineral and elemental distribution maps coupled metal co-ordination environments with location in the Birnessite interlayer, establishing that Ni associates with the Mn, not the Al, layer. Kathy Dardenne (Research Center Karlsruhe, Germany) presented several applications of synchrotron based techniques including grazing incidence XAS, to assessing interactions of transuranics with Fe-oxyhydroxides by using Lu (III) as a homologue to Am (III). As the Fe mineral aged and recrystalized, Lu was found to be incorporated in a new distorted hematite-like phase. In his animated and interrogative style, Geoffrey Davies (Northeastern U.) gave an overview of metal binding on different sites on humic acids from various sources. XAFS results indicate different binding sites for elements such as Cu (II) and Fe(III) on different humic acids, as suggested by macroscopic isotherm experiments. Two case studies of metal contamination were presented by Rubin Kretzschmar (Swiss Federal Institute of Technology, Switzerland). In the first case, the formation and dissolution of Zn precipitates in column experiments were studied by XAFS. The second used techniques including µ-XRF and µ-XANES to determine the distribution and speciation of Pb around corroding bullets in the soil from a shooting range. Ulrich Neuhäusler (European Synchrotron Radiation Facility, France) gave an overview of x-ray techniques and facilities, especially at the ESRF, for low to medium Z elements. These applications focus on the use of zone plate systems allowing high sensitivity and spacial resolution below 500 nm. The processes by which U associates with calcite were discussed by Evert Elzinga (Center for Environmental Molecular Sciences, SUNY Stony Brook). XAFS and luminescence spectroscopy were used to determine the local structure around U (VI) that was sorbed on the surface of calcite. Four students were invited to give presentations of their work. Sarah Jane White (Princeton U.) spoke about high soil-CO2, resulting from magmatic activity at Mammoth Mountain California, and its effect on survival of plants and the distribution of metals in those plants. Ben Twining (SUNY Stony Brook) presented elemental distributions, by synchrotron XRF at sub-micron resolution, in single cell aquatic protists, including samples taken during field experiments to enhance plankton blooms by adding bioavailable Fe to a section of the southern ocean. Maarten Nachtegaal (U of Delaware), used NEXAFS to observe shifts in relative positions of valence bands of carbon contained in functional groups of humic substances as they reacted with Cu (II) and Mn (II). Charlotte Eng (SUNY Stony Brook) discussed the use of synchrotron infra-red spectroscopy to investigate the association of U with steel and to assess a citric acid method for decontaminating the steel and its corrosion products. We thank the speakers for sharing their work and insights on the use of synchrotron based methods in exploring processes that control distributions of elements within our environment, and we thank the workshop attendees for their participation. FOR MORE INFORMATION |
The National Synchrotron Light Source at Brookhaven National Laboratory in New York, is a national user research
facility funded by the U.S. Department of Energy's Office of Basic Energy Science. The NSLS operates two electron
storage rings: an X-Ray ring and a Vacuum UltraViolet (VUV) ring which provide intense light spanning the electromagnetic
spectrum from the infrared through x-rays. Each year over 2300 scientists from universities, industries and government
labs perform research at the NSLS.
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