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V. G. Alexandratos, T. Behrends, P. Van Cappellen
V. G. Alexandratos, T. Behrends, P. Van Cappellen


This study investigates possible redox transformations of uranium under Ntransient redox conditions. NSpecific focus lies on the fate of U as reductive dissolution of iron oxyhydroxides by S(-II) is initiated. In batch experiments sulfide was incrementally added to a lepidocrocite suspension containing adsorbed U(VI). The partitioning of uranium was monitored during the progressing transformation of lepidocrocite into FeS. Synchrotron-based X-ray absorption spectroscopy was used to resolve the oxidation state of uranium.Upon addition of sulfide intermediate release of U from the solid to the solution was observed. The mobilization of U was followed by immobilization in later stages. XAS reveals that this immobilization coincides with reduction of NU(VI) to U(IV). Consequently, reduction of U(VI) and precipitation of U(IV) solids, due to a shift from oxic to sulfate reducing conditions is possible. NHowever, kinetic effects might lead to an intermediate mobilization of U that should be considered for the risk assessment of nuclear waste repositories and the remediation of sites, contaminated with radionuclides.


uranium mobilization; reductive dissolution; iron mineral transformation; redox transitions; iron sulfides; X-ray absorption spectroscopy;

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Afornso, M., dos Santos and Stumm Werner, 1992. Reductive Dissolution of Iron(III) (Hydr)oxides by

Hydrogen Sulfide. Langmuir, 8, 1671-1675.

Anderson, RF, Fleisher, MQ., LeHuray, AP., 1989. Concentration, oxidation state and particulate flux of

uranium in the Black Sea. Geochim. Cosmochim. Acta, 53, 2215-2224.

Bargar, J. R., Reitmeyer, R., Lenhart, J. J and Davis, J.A., 2000. Characterization of U(VI)-carbonato ternary

complexes on hematite: EXAFS and electrophoretic mobility measurements. Geochimica et

Cosmochimica Acta, 64, No. 16, pp. 2737–2749, 2000.

Behrends, T. and Van Cappellen, P., 2005. Competition between enzymatic and abiotic reduction of ura-

XLIII, No 5 – 2316

Fig. 5: Chart with U(VI) percentages remaining in association with the solid from two suspensions reacted with 8

mM S(-II) in “C” and 5 mM S(-II) in “D”. Results are derived using coordination numbers from EXAFS fitting.

nium(VI) under iron reducing conditions. Chemical Geology 220, pp. 315-327.

Canfield, D.E., 1989. Reactive iron in marine sediments. Geochim. Cosmochim. Acta 53, 619–632

Chaillou, G., Anschutz, P., Lavaux, G., Schäfer, J. and Blanc, G., 2002. The distribution of Mo, U, and

Cd in relation to major redox species in muddy sediments of the Bay of Biscay. Marine Chemistry 80:


Charlet, L., Silvester, E., and Liger, E., 1998c. N-compound reduction and actinide immobilisation in

surficial fluids by Fe(II): the surface Fe(III)OFe(II)OH degrees species, as major reductant. Chemical

geology, vol.151 iss.1-4, pg.85 -93.

De Pablo, J., Casas, I., Gimenez, J., Molera, M., Rovira, M., Duro, L., and Bruno, J., 1999. The oxidative

dissolution mechanism of uranium dioxide. I. The effect of temperature in hydrogen carbonate

medium. Geochim. Cosmochim. Acta 63, 3097-3103.

Duff, M.C. and Amrhein, C., 1996. Uranium(VI) adsorption on goethite and soil in carbonate solutions.

Soil Sci. Soc. Am. J. 60, 1393.

Fredrickson, J.K., Zachara, J.M., Kennedy, D. W., Duff, M. C., Gorby, Y. A., Li, S. M. W., and Krupka,

K.M., 2000. Reduction of U(VI) in goethite (alpha-FeOOH) suspensions by a dissimilatory metal-reducing

bacterium. Geochim. Cosmochim. Acta 64, 3085-3098.

Gabriel, U., Gaudet, J. P., Spadini, L., and Charlet, L., 1998. Reactive transport of uranyl in a goethite column:

an experimental and modeling study. Chem. Geol., 151, 107-28.

Giammar, D.E and Herring, J.G., 2001. Time scales for sorption-desorption and surface precipitation of

uranyl on goethite. Environ. Sci. Thechnol. 35, 3332-3337

Hsi C.-K. D. and Langmuir, D., 1985. Adsorption of uranyl onto ferric oxyhydroxides: Application of the

surface complexation site-binding model. Geochim. Cosmochim. Acta 49, 1931–1941.

Ho, C. H. and Miller, N. H., 1986. Adsorption of uranly species from bicarbonate solution onto hematite

particles. J. Colloid Interf. Sci. 110, 165–171.

Jørgensen, B. B., 1977. The sulfur cycle of a coastal marine sediment (Limfjorden, Denmark). Limnol.

Oceanogr. 5, 814–832.

Krom, M. D., Mortimer, R. J. G., Poulton, S. W., Hayes, P., Davies, I. M., Davison, W., and Zhang, H.,

In-situ determination of dissolved iron production in recent marine sediments. Aquatic Sciences

, 282-291.

Langmuir, D., 1978. Uranium solution-mineral equilibria at low temperatures with application to sedimentary

ore deposits. Geochim. Cosmochim. Acta 42, 547–569.

Liger, E., Charlet, L. and Van Cappellen, P., 1999. Surface catalysis of uranium (VI) reduction by iron(II).

Geochim. Cosmochim. Acta, 63, 2939-2955.

Lloyd, J. R., Chesnes, J., Glasauer, S., Bunker, D. J., Livens, F. R., and Lovley, D. R., 2002. Reduction of

actinides and fission products by Fe(III)-reducing bacteria. Geomicrobiology Journal 19(1), 103-120.

Lovely, D. R., Phillips, E. J. P., Gorby, Y. A., and Landa, E. R., 1991. Microbial reduction of uranium. Nature

, 413-416.

Lovley, D. R., Roden, E. E., Phillips, E. J. P., and Woodward, J. C., 1993. Enzymatic Iron and Uranium

Reduction by Sulfate-Reducing Bacteria. Mar. Geol. 113, 41–53.

Mohagheghi, A., Updegraff, D. M., Goldhaber, M. B., 1984. The role of sulfate-reducing bacteria in the

deposition of sedimentary uranium ores. Geomicrobiology Journal. 4(2): 153-173

Morrison, S. J., Spangler, R. R., and Tripathi, V. S., 1995a. Adsorption of U(VI) on Amorphous Ferric

Oxyhydroxide at High-concentrations of Dissolved Carbon (IV) and sulphur (VI). Journal of Contaminant

Hydrology 17, 333-346.


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