caa a22 4500 378872222 CHVBK 20180305123411.0 cr unu---uuuuu 161128e20031101xx s 000 0 eng 10.1524/ract.91.11.673.23470 doi (NATIONALLICENCE)gruyter-10.1524/ract.91.11.673.23470 Speciation and mobility of uranium(VI) in humic-containing soils [Elektronische Daten] [Pierre Crançon, J. van der Lee] Uranium is known to easily form stable complexes with both organic and inorganic ligands in natural aquatic environments. The potential mobility of U(VI), and particularly the role of humic substances, has been investigated for a sandy podzol. Adsorption of U(VI) at equilibrium was experimentally investigated, comparatively for a pure quartz sand as well as a sandy podzolic soil from Landes Gascony, France, containing 0.6 wt. organic matter. Uranium is strongly retained by the bulk soil, mainly due to organic aggregates (<50μm) and organic coatings on quartz grains. A large fraction of U(VI) is found to be associated to humic colloids in soil, thus forming a potential mobile uranium phase. For the soil, the U(VI) adsorption isotherm is linear for relatively low U(VI) total aqueous concentration, ranging from 15 to 40000μg/L. This indicates that the functional groups of humic matter are far from saturated for aqueous concentrations close to U(VI) solubility in soil pore-water. The speciation of uranium in soil pore water and the interactions between U(VI) species and the reactive sites of the soil material were evaluated using the speciation code CHESS [1]. Comparison between the model and experimental results show that complexation of U(VI) by humic substances tends to immobilise uranium in soils with a pH below 5, when the reactive surface of quartz grains and aggregates are entirely coated by humic matter. In soil pore-water, the presence of mobile organic ligands competing with surface-bound organics for U(VI) complexation must be included in the speciation modelling. Without the mobile organic phase, the model overestimates the actual bound fraction, thus underestimating the actual amount of mobile U(VI). © 2003 Oldenbourg Wissenschaftsverlag GmbH Laboratory techniques, experiments nationallicence Analytical chemistry nationallicence Inorganic chemistry nationallicence Crançon Pierre aut van der Lee J. aut Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 91/11/2003(2003-11-01), 673-679 0033-8230 91:11/2003<673 2003 91 ract https://doi.org/10.1524/ract.91.11.673.23470 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/ract.91.11.673.23470 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Crançon Pierre aut NATIONALLICENCE 700 1- van der Lee J. aut NATIONALLICENCE 773 0- Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 91/11/2003(2003-11-01), 673-679 0033-8230 91:11/2003<673 2003 91 ract CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter