Screening the importance of soil micro-organisms on radionuclides mobility

Abstract. In surface soils, the native physical and chemical properties of the abiotic components control most of the sorption-desorption processes. Moreover, micro-organisms may significantly modify the speciation of trace elements and/or radionuclides and subsequently determine their fate, to a large extent. Micro-organisms, mainly bacteria and fungi, develop many strategies that may affect indirectly or directly the behaviour of trace elements. Due to their activity, changes in the pore-water composition, e.g. pH, redox-potential, may occur in relation with organic acid production or solid phase alteration, reduction or oxidation of metallic oxi-hydroxides, and mineralization of organo-metallic complexes. Micro-organisms may also directly modify the speciation of radionuclides as a result of bio-accumulation in living cells, biosorption on cellular components, direct reduction or oxidation, biomethylation, etc. Each one of these microbial processes may either increase or decrease radionuclide mobility, depending on the element, the soil reactivity and the environmental conditions. The resulting effect of these processes is still poorly known. This literature review intends to present a comprehensive overview of the role of micro-organisms on radionuclide mobility. It aims at classifying these elements, regarding to their potential sensitivity to these microbial processes. It summarizes the theoretical effect of these mechanisms, resulting in a potential increase or decrease of the solid-liquid distribution. The environmental significance of such processes for various biogeochemical radionuclides cycles still remains to be confirmed by experiments. (This study is part of a research program supported by Andra)

Screening the importance of soil micro-organisms on radionuclides mobility

In surface soils, the native physical and chemical properties of the abiotic components control most of the sorption-desorption processes. Moreover, micro-organisms may significantly modify the speciation of trace elements and/or radionuclides and subsequently determine their fate, to a large extent. Micro-organisms, mainly bacteria and fungi, develop many strategies that may affect indirectly or directly the behaviour of trace elements. Due to their activity, changes in the pore-water composition, e.g. pH, redox-potential, may occur in relation with organic acid production or solid phase alteration, reduction or oxidation of metallic oxi-hydroxides, and mineralization of organo-metallic complexes. Micro-organisms may also directly modify the speciation of radionuclides as a result of bio-accumulation in living cells, biosorption on cellular components, direct reduction or oxidation, biomethylation, etc. Each one of these microbial processes may either increase or decrease radionuclide mobility, depending on the element, the soil reactivity and the environmental conditions. The resulting effect of these processes is still poorly known. This literature review intends to present a comprehensive overview of the role of micro-organisms on radionuclide mobility. It aims at classifying these elements, regarding to their potential sensitivity to these microbial processes. It summarizes the theoretical effect of these mechanisms, resulting in a potential increase or decrease of the solid-liquid distribution. The environmental significance of such processes for various biogeochemical radionuclides cycles still remains to be confirmed by experiments. (This study is part of a research program supported by Andra)

Effectiveness of Vetiver Grass (Vetiveria Zizanioides L. Nash) for phytoremediation of endosulfan in two cotton soils from Burkina Faso

ISI Document Delivery No.: 217LO Times Cited: 1 Cited Reference Count: 38 Abaga, Norbert Ondo Zue Dousset, Sylvie Munier-Lamy, Colette Billet, David CORUS II project; Gabonese Government The authors thank the CORUS II project and the Gabonese Government for financial support and the Botanical Garden of Montet (Villers-les-Nancy, 54 France) for material support and for providing the vetiver plants. We also thank Paul Savadogo (INERA, Ouagadougou, Burkina-Faso) for providing the studied soils, Regine Mosser-Ruck (G2R, Nancy) for the clay mineralogical compositions and Geraldine Kitzinger (LIMOS, Nancy) for the organic acid analyses. Taylor & francis inc PhiladelphiaThe influence of vetiver grass (Vetiveria zizanioides) on the fate of endosulfan was studied using a vertisol and a lixisol soils from cotton-growing areas of Burkina Faso. Endosulfan adsorption isotherms were prepared for planted and unplanted soils. Pot experiments were then conducted for six months. For both soils, endosulfan adsorption was higher on planted soils (K-f= 6.53-9.73mg(1-n)L(n)kg(-1)) than on unplanted soils (6.27-7.24mg(1-n)L(n)kg(-1)). In unplanted soils, vertisol adsorbed more endosulfan than lixisol. From the pot experiments, the estimated half-lives of endosulfan in unplanted soils (40.6 to 43.1days) were higher than in planted soils (34.5 to 40.6days) containing a greater number of endosulfan-degrading microorganisms. Six months after treatment, endosulfan was not detected in soils. The effectiveness of vetiver in promoting adsorption and the disappearance of endosulfan in both studied soils should be validated on the cotton plot scale in Burkina Faso

Comportement de l'uranium dans les pédogenèses tempérées

An important soil sampling was done according to the principal types of pedogenesis of temperate zones and has allowed to define geochemical profiles of uranium and to determine its behaviour in relation with the pedogenesis : progressive and increasing leaching of U with weathering in brown forest soils ; similar redistribution of U, Fe and organic compounds in podzols ; accumulation of U in organic or placic horizons of hydromorphic soils. More detailed analytical studies, based on physical and chemical separations has permitted to define repartition of uranium in the different soil fractions and the nature of some soil constituents as preferential sites of fixation : iron oxihydroxides (cryptocrystal-lines and amorphous forms), humic and fulvic compounds.L'échantillonnage de nombreux profils représentatifs des grands types de sols rencontrés dans la zone tempérée a permis de définir les profils géochimiques de l'uranium et de déterminer son comportement en relation avec la pédogenèse : lessivage de l'uranium progressif et croissant avec l'altération dans les sols bruns, redistribution parallèle de Fe, U et matières organiques dans les sols podzolisés, accumulation dans les horizons holorganiques et/ou placiques des sols hydromorphes . Une étude analytique plus approfondie, fondée sur des fractionnements physiques et chimiques précise la répartition de l'uranium dans les différents compartiments du sol et la nature de certains constituants en tant que sites préférentiels de fixation : oxyhydroxydes de fer (plutôt cryptocristallins ou amorphes) et composés humiques ou fulviques.Gueniot B., Munier-Lamy C., Berthelin J., Guillet B., Souchier Bernard. Comportement de l'uranium dans les pédogenèses tempérées. In: Pétrologie des altérations et des sols. Vol. III : Pédologie. Pétrologie appliquée aux substances utiles. Colloque international du CNRS, Paris 4-7 juillet 1983. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1983. pp. 133-142. (Sciences Géologiques. Mémoire, 73

Comportement de l'uranium dans les pédogenèses tempérées

An important soil sampling was done according to the principal types of pedogenesis of temperate zones and has allowed to define geochemical profiles of uranium and to determine its behaviour in relation with the pedogenesis : progressive and increasing leaching of U with weathering in brown forest soils ; similar redistribution of U, Fe and organic compounds in podzols ; accumulation of U in organic or placic horizons of hydromorphic soils. More detailed analytical studies, based on physical and chemical separations has permitted to define repartition of uranium in the different soil fractions and the nature of some soil constituents as preferential sites of fixation : iron oxihydroxides (cryptocrystal-lines and amorphous forms), humic and fulvic compounds.L'échantillonnage de nombreux profils représentatifs des grands types de sols rencontrés dans la zone tempérée a permis de définir les profils géochimiques de l'uranium et de déterminer son comportement en relation avec la pédogenèse : lessivage de l'uranium progressif et croissant avec l'altération dans les sols bruns, redistribution parallèle de Fe, U et matières organiques dans les sols podzolisés, accumulation dans les horizons holorganiques et/ou placiques des sols hydromorphes . Une étude analytique plus approfondie, fondée sur des fractionnements physiques et chimiques précise la répartition de l'uranium dans les différents compartiments du sol et la nature de certains constituants en tant que sites préférentiels de fixation : oxyhydroxydes de fer (plutôt cryptocristallins ou amorphes) et composés humiques ou fulviques.Gueniot B., Munier-Lamy C., Berthelin J., Guillet B., Souchier Bernard. Comportement de l'uranium dans les pédogenèses tempérées. In: Pétrologie des altérations et des sols. Vol. III : Pédologie. Pétrologie appliquée aux substances utiles. Colloque international du CNRS, Paris 4-7 juillet 1983. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1983. pp. 133-142. (Sciences Géologiques. Mémoire, 73

A laboratory study of the mineralization and binding of 14C-labeled herbicide rimsulfuron in a rendzina soil

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