UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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Author: search.filters.author.Brose, DominicSubject: search.filters.subject.Chemistry, Agricultural

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    Oxidation-Reduction Transformations of Chromium in Aerobic Soils and the Role of Electron-Shuttling Quinones in Chemical and Microbiological Pathways
    (2008-05-05) Brose, Dominic; James, Bruce R; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Soils from three toposequences in Maryland with minimal heavy metal contamination were sampled to investigate oxidation-reduction transformations of chromium in whole soil samples. Chromium (VI) reduction to Cr(III) was observed in all 18 samples, and 11 demonstrated enhanced reduction with the electron shuttle anthraquinone-2,6-disulfonate (AQDS). Oxidation of Cr(III) to Cr(VI) was observed in 12 samples, and 7 samples demonstrated diminished oxidation with AQDS. Lactate was added to the Watchung series to enhance biological activity, and high salt concentration was added to inhibit it. Both treatments reduced Cr(VI) to below detection limits by 11 d, suggesting abiotic reduction. The control treatment demonstrated reduction of Cr(VI) without soil. To further investigate, increasing lactate concentrations were added to Cr(VI) and AQDS. Reduction increased with increasing concentration; 60 mM lactate reduced all Cr(VI) within 1 hr. Other organic acids were tested for similar interactions; tartrate and citrate reduced Cr(VI), which was enhanced with AQDS.