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Full-Text Articles in Engineering
Bacterial Reduction Of Crystalline Fe3+ Oxides In Single Phase Suspensions And Subsurface Materials, John M. Zachara, James K. Fredrickson, Shu-Mei Li, David W. Kennedy, Steven C. Smith, Paul L. Gassman
Bacterial Reduction Of Crystalline Fe3+ Oxides In Single Phase Suspensions And Subsurface Materials, John M. Zachara, James K. Fredrickson, Shu-Mei Li, David W. Kennedy, Steven C. Smith, Paul L. Gassman
US Department of Energy Publications
Microbiologic reduction of synthetic and geologic Fe3+ oxides associated with four Pleistocene- age, Atlantic coastal plain sediments was investigated using a dissimilatory Fe reducing bacterium (Shewanella putrefaciens, strain CN32) in bicarbonate buffer. Experiments investigated whether phosphate and anthraquinone-2, 6-disulfonate, (AQDS, a humic acid analogue) influenced the extent of crystalline Fe3+ oxide bioreduction and whether crystalline Fe3+ oxides in geologic materials are more or less reducible than comparable synthetic phases. Anaerobic incubations (108 organisms/mL) were performed both with and without PO4 and AQDS that functions as an electron repository and shuttle. The production of …
Biogenic Iron Mineralization Accompanying The Dissimilatory Reduction Of Hydrous Ferric Oxide By A Groundwater Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Hailang Dong, Tullis Onstott, Nancy Hinman, Shu-Mei Li
Biogenic Iron Mineralization Accompanying The Dissimilatory Reduction Of Hydrous Ferric Oxide By A Groundwater Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Hailang Dong, Tullis Onstott, Nancy Hinman, Shu-Mei Li
US Department of Energy Publications
Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens, strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic …
Chemical Information On Tank Supernatants, Cs Adsorption From Tank Liquids Onto Hanford Sediments, And Field Observations Of Cs Migration From Past Tank Leaks, R. J. Serne, John M. Zachara, D. S. Burke
Chemical Information On Tank Supernatants, Cs Adsorption From Tank Liquids Onto Hanford Sediments, And Field Observations Of Cs Migration From Past Tank Leaks, R. J. Serne, John M. Zachara, D. S. Burke
US Department of Energy Publications
Borehole gamma-logging profiles beneath the SX-Tank Farm suggest that contamination from Cs-137 extends to at least a depth of 40 m (130 ft), and may extend even deeper. What is presently not known is the pathway that Cs-137 has taken to reach these depths. In this report we provide an analysis of the chemistry of tank supernates with emphasis on the REDOX waste stream disposed in SX tanks, Cs chemistry in aqueous solutions and adsorption properties onto minerals, available data on Cs adsorption onto Hanford sediments, and information on Cs migration from other Hanford tank leaks that have been studied. …
Influence Of Iron Oxide Inclusion Shape On Coii/Iiiedta Reactive Transport Through Spatially Heterogeneous Sediment, James E. Szecsody, Ashley Chilakapati, John M. Zachara, Amanda Garvin
Influence Of Iron Oxide Inclusion Shape On Coii/Iiiedta Reactive Transport Through Spatially Heterogeneous Sediment, James E. Szecsody, Ashley Chilakapati, John M. Zachara, Amanda Garvin
US Department of Energy Publications
Multisolute reactive transport was investigated in chemically heterogeneous systems to determine the influence of the shapes of the reactive heterogeneities (iron oxide inclusions) by comparison of two-dimensional heterogeneous experiments with spatially averaged models that had differing inclusion characterization. Eleven reactions were considered in this system, starting with absorption of the initial solute (CoIIEDTA) to Fe oxides, followed by two competing surface reactions: oxidation forming CoIIIEDTA and Fe dissolution forming FeIIIEDTA and Co2+. Spatial moments of the eight mobile species were compared between data and models. One spatially averaged model (homogenous equivalent), which incorporated inclusion …