9 research outputs found
Remediation of soils contaminated with particulate depleted uranium by multi stage chemical extraction
Contamination of soils with depleted uranium (DU) from munitions firing occurs in conflict zones and at
test firing sites. This study reports the development of a chemical extraction methodology for remediation
of soils contaminated with particulate DU. Uranium phases in soils from two sites at a UK firing range,
MOD Eskmeals, were characterised by electron microscopy and sequential extraction. Uranium rich particles
with characteristic spherical morphologies were observed in soils, consistent with other instances of
DU munitions contamination. Batch extraction efficiencies for aqueous ammonium bicarbonate (42â50%
total DU extracted), citric acid (30â42% total DU) and sulphuric acid (13â19% total DU) were evaluated.
Characterisation of residues from bicarbonate-treated soils by synchrotron microfocus X-ray diffraction
and X-ray absorption spectroscopy revealed partially leached U(IV)-oxide particles and some secondary
uranyl-carbonate phases. Based on these data, a multi-stage extraction scheme was developed utilising
leaching in ammonium bicarbonate followed by citric acid to dissolve secondary carbonate species. Site
specific U extraction was improved to 68â87% total U by the application of this methodology, potentially
providing a route to efficient DU decontamination using low cost, environmentally compatible reagent
Adsorption of radium and barium on goethite and ferrihydrite: A kinetic and surface complexation modelling study
AbstractRadium and barium uptake onto ferrihydrite and goethite have been studied in the concentration range 1nM to 5mM and from pH 4 to 10, to develop a model to predict radium behaviour in legacy uranium mining wastes. For ferrihydrite, uptake of Ra2+ at nM concentrations was strong at pH >7. At higher concentrations, Ba2+ sorption to ferrihydrite was slightly weaker than that of Ra2+. Experiments with goethite showed weaker binding for both metal ions in all systems. The interactions of radium with both ferrihydrite and goethite are fully reversible. The behaviour of radium during transformation of ferrihydrite to goethite has been studied, and no evidence for irreversible incorporation within the goethite lattice was found; radium uptake to goethite was the same, whether or not it was present during its formation. Calcium competed with radium for ferrihydrite sorption only at high calcium concentrations (>10mM). Barium is a more effective competitor, and a concentration of 1mM reduced radium sorption. Sediment samples from a legacy uranium mining site have been analysed, and the in situ Rd values are consistent with radium uptake by surface coatings of ferrihydrite or goethite like phases. Surface complexation models have been developed for radium sorption to ferrihydrite and goethite which simulate the experimental data successfully. In both cases, approaches based on a single surface functional group and tetradentate binding sites simulated the data successfully. These data could be used in underpinning the safety case for legacy mining sites
Determination of depleted uranium using a high-resolution gamma-ray spectrometer and its applications in soil and sediments
Microanalytical X-ray Imaging of Depleted Uranium Speciation in Environmentally Aged Munitions Residues
New insights on the biomineralisation process developing in human lungs around inhaled asbestos fibres
Fine scale measurement and mapping of uranium in soil solution in soil and plant-soil microcosms, with special reference to depleted uranium
Synthesis and characterization of a magnetic adsorbent from negatively-valued iron mud for methylene blue adsorption
Tourismes, patrimoines, identités, territoires
Lâapproche des tourismes prĂ©sentĂ©e dans cet ouvrage qui recueille les communications des participants au colloque Tourismes Patrimoines IdentitĂ©s et Territoires, organisĂ© par lâUniversitĂ© de Perpignan Via Domitia, fait une large place aux facteurs humains souvent nĂ©gligĂ©s au profit dâun raisonnement rĂ©duit Ă lâĂ©conomie. Les territoires y sont pensĂ©s comme des espaces dotĂ©s dâidentitĂ©s que les patrimoines illustrent et les coprĂ©sences liĂ©es aux tourismes permettent en remettant souvent en cause le mythe dâautochtonie ou le « noble mensonge » de Socrate câest Ă dire la croyance des « dirigeants eux-mĂȘmes et (des) militaires, ensuite (du) reste de la citĂ©, quâils avaient Ă©tĂ© modelĂ©s sous la terre et quâune fois que leur fabrication avait Ă©tĂ© terminĂ©e, la terre, qui est leur mĂšre, les avait mis au monde ; et quâĂ prĂ©sent ils doivent dĂ©libĂ©rer au sujet du pays oĂč ils sont, et le dĂ©fendre contre quiconque lâattaque, comme si câĂ©tait lĂ leur mĂšre et leur nourrice, et penser aux citoyens comme Ă des frĂšres nĂ©s comme eux de la terre ». Ils apparaissent comme un compromis entre un aspect affectif et un aspect rationnel : tout Ă la fois espaces fonctionnels, et lieux de pouvoir. Lâouvrage sâadresse aux Ă©tudiants des diffĂ©rentes filiĂšres de formation aux mĂ©tiers du tourisme et Ă lâensemble des acteurs du secteur touristique soucieux de dĂ©veloppement durable, respectueux des identitĂ©s et des patrimoines