Spéciation et mobilité des éléments chimiques stables associés aux minéralisations uranifères

Cette thèse est sous embargo jusqu’au 26/01/2025.French uranium (U) deposits were exploitedfrom 1948 to 2001 to ensure self-sufficiency for thedevelopment of civilian and military nuclear activities.These U deposits often contain a mixture of primary andsecondary minerals, which also include other tracechemical elements (TEs), potentially toxic. Although Umining and ore processing have ceased in France,environments near mining sites may have been affected,leading to contamination by radionuclides exceedingnatural background geochemical levels. The aim of thisthesis is to study the mobility of TEs associated with Umineralization, particularly in two systems impacted bypast uranium mining activities, to improve theirmanagement.U was studied alongside TEs at two study sites located inAuvergne-Rhône-Alpes: the first site was the artificialreservoir of Saint-Clément, , downstream from the formerBois-Noirs-Limouzat U mine and the former copper-tinmine of Charrier. The second site was a wetlanddownstream from the former U extraction and processingsites of Rophin.For the Saint-Clément site, the results reveal a significantenrichment of copper (Cu), tin (Sn), and bismuth (Bi) inlake sediments, linked to past extraction activities inCharrier. Reoxidation and drying of initially anoxicsediments led to a solid metal speciation dominated byi) inherited sulfide minerals such as chalcopyrite(CuFeS2), ii) metals associated with natural organicmatter (NOM), and iii) refractory cassiterite grains(SnO2). Furthermore, limited remobilization of metalswas observed, confirming the stability of U, Cu, and Biassociated with NOM. For the Rophin site, the results show anthropogenicinputs of U, lead (Pb), and Cu in wetland soils. Thehighest contamination levels are related to the legacydeposit from past uranium mining activities. Along a soilprofile, the solid speciation of Pb is partly linked tostable phosphates (plumbogummite -PbAl3(PO4)(PO3OH)(OH)6). In ancient and recent layersrich in NOM, sorption processes on NOM mainly governTE speciation. In the mining deposit, the solidspeciation of U, Cu, and Pb appears to be influenced byadsorption on particle surfaces and, to a lesser extent,by the precipitation of authigenic phases and/or thedeposition of inherited phases (e.g., U oxides,chalcopyrite, plumbogummite, anglesite - PbSO4- andPb-baryte (Ba,Pb)SO4). Only a small fraction of theseelements is mobilizable (such as Cu and U). Inconclusion, these results highlight contrastingreactivities of diverse TE-bearing phases underoxidizing conditions.Les gisements d’uranium (U) français ont étéexploités de 1948 à 2001 dans le but d’assurerl’autosuffisance pour le développement des activitésnucléaires civiles et militaires. Ces gisements d'uraniumprésentent souvent un mélange de minéraux primaires etsecondaires qui contiennent également d'autreséléments chimiques en traces (ET), potentiellementtoxiques. Bien que l'exploitation et le traitement desminerais d'uranium aient cessé en France, lesenvironnements à proximité des sites miniers ont pu êtreaffectés, entraînant une contamination par desradionucléides dépassant les niveaux naturels de fondgéochimique. L’objectif de la présente thèse est d’étudierla mobilité des ET associés aux minéralisations uranifères,en particulier dans deux systèmes impactés par lesanciennes activités minières d’U, afin d’en améliorer leurgestion.L’U a été étudié conjointement aux ET sur deux sitesd’études localisés en Auvergne-Rhône-Alpes : le premiersite était le réservoir artificiel de Saint-Clément, situé enaval de l'ancienne mine d'U des Bois-Noirs-Limouzat etl'ancienne mine de cuivre-étain de Charrier. Le deuxièmesite était une zone humide située en aval des anciens sitesd'extraction et de traitement de minerais d'U de Rophin.Pour le réservoir de Saint-Clément, les résultats révèlentun enrichissement significatif en cuivre (Cu), étain (Sn) etbismuth (Bi) dans les sédiments lacustres, lié auxanciennes activités d'extraction de la mine de Charrier. Laréoxydation et le séchage des sédiments, initialementanoxiques, ont conduit à une spéciation métallique solidedominée par i) des minéraux de Cuet Bi sulfurés hérités tels que la chalcopyrite (CuFeS2),ii) des métaux associés à la matière organique (MO)naturelle et iii) des grains de cassitérite réfractaire(SnO2). De plus, une remobilisation limitée des métauxa été observée, confirmant ainsi la stabilité de l'U, du Cuet du Bi associés à la MO naturelle.Pour la zone humide de Rophin, les résultats montrentdes apports anthropiques en U, plomb (Pb) et Cu dansles sols de ce site. Les niveaux de contamination les plusélevés sont liés à un dépôt hérité des anciennesactivités minières d’U. Le long d’un profil de sol, laspéciation solide du Pb est en partie liée auxphosphates stables (plumbogummite -PbAl3(PO4)(PO3OH)(OH)6). Dans les couches ancienneset récentes riches en MO, les processus de sorption surcelle-ci régissent principalement la spéciation des ET.Dans le dépôt minier, la spéciation solide de U, Cu et Pbsemble être influencée par l'adsorption à la surface desparticules et, dans une moindre mesure, par laprécipitation de phases authigènes et/ou le dépôt dephases héritées (e.g., oxydes d’U, chalcopyrite,plumbogummite, anglésite - PbSO4, et Pb-Barytine(Ba,Pb)SO4). Seulement une petite partie de ceséléments est mobilisable (tels que Cu et U). In fine,l’ensemble de ces résultats souligne des réactivitéscontrastées des phases porteuses très variées en ET dans des conditions oxydantes

Speciation and mobility of stable chemical elements associated with uranium mineralization

International audienceUranium (U) ores extracted in France until 2001 can be associated to trace elements (TE) mineral phases. These TE can be potentially toxic according to their forms and/or contents. Some TE present in waste rock and tailings can be relatively mobile and redistributed in the various reservoirs of the critical zone such as soils and sediments. In the case of dredging lake sediments contaminated by mining inputs, the cocktail effect of TE presence, on the mobility of U, remains poorly understood.For that purpose, sediments of Saint-Clément Lake (Allier, France) were studied because they are potentially affected by two former mining sites: the U mine of the Bois Noirs Limouzat and the Cu-Snmine of Charrier. The geoaccumulation index and enrichment factor, calculated along a sediment core,highlight significant anthropogenic origin contaminations in Cu and Sn, the highest contamination levels resulting from the rehabilitation of the Charrier tailing pile. The objectives are thus to determine theTE’s solid speciation due to sediments re-oxidation and the geochemical processes governing their mobility.SEM, EPMA analyses and chemical extractions were performed to study the TEs’ bearing phases andleaching tests to understand their stability. First results show that the solid speciation is dominated by cassiterite (SnO2) for Sn and by sulfides e.g., chalcopyrite (CuFeS2) and adsorbed on organic matter for Cu. The standardized TCLP leaching test does not highlight Sn in the leachates but shows Cu concentrations up to 1020 µg/l, higher than the European norm for surface water (1,6 µg/l). These first results suggest a low risk of migration of Sn and a potential instability of Cu

Speciation and mobility of stable chemical elements associated with uranium mineralization

International audienceUranium (U) ores extracted in France until 2001 can be associated to trace elements (TE) mineral phases. These TE can be potentially toxic according to their forms and/or contents. Some TE present in waste rock and tailings can be relatively mobile and redistributed in the various reservoirs of the critical zone such as soils and sediments. In the case of dredging lake sediments contaminated by mining inputs, the cocktail effect of TE presence, on the mobility of U, remains poorly understood.For that purpose, sediments of Saint-Clément Lake (Allier, France) were studied because they are potentially affected by two former mining sites: the U mine of the Bois Noirs Limouzat and the Cu-Snmine of Charrier. The geoaccumulation index and enrichment factor, calculated along a sediment core,highlight significant anthropogenic origin contaminations in Cu and Sn, the highest contamination levels resulting from the rehabilitation of the Charrier tailing pile. The objectives are thus to determine theTE’s solid speciation due to sediments re-oxidation and the geochemical processes governing their mobility.SEM, EPMA analyses and chemical extractions were performed to study the TEs’ bearing phases andleaching tests to understand their stability. First results show that the solid speciation is dominated by cassiterite (SnO2) for Sn and by sulfides e.g., chalcopyrite (CuFeS2) and adsorbed on organic matter for Cu. The standardized TCLP leaching test does not highlight Sn in the leachates but shows Cu concentrations up to 1020 µg/l, higher than the European norm for surface water (1,6 µg/l). These first results suggest a low risk of migration of Sn and a potential instability of Cu

Evaluation of the Anthropogenic Metal Pollution at Osisko Lake: Sediments Characterization for Reclamation Purposes

The anthropogenic pollution of lake ecosystems by human activities (e.g., mining industries) is recognized as a serious issue. The Osisko urban lake located in Rouyn-Noranda (Quebec, Canada) was used partially as a waste disposal facility for many decades, causing a heavy pollution. The main undertakings of this study are (i) assessing the mineralogical and geochemical properties of lake Osisko sediments, and (ii) studying the pollution that occurred within lake water due to the sediments’ reactivity. Water and sediments across the lake were collected in different sensitive locations. Within the sediment samples, two parts were distinguished: a small layer of black vase over grey sediments. The black vase resembled organic matter while the gray sediment seemed close to clean lake sediments. The collected samples were characterized for their physical (particle size distribution, specific gravity and specific surface area), chemical (minor and major elements as well as total sulfur and carbon) and mineralogical (X-ray diffraction and scanning electron microscope) properties. Additionally, the reactivity of sediments was studied using weathering cells to quantify chemical species leaching and their releasing rates. The results showed that the vase was the only contaminated part with high concentrations of sulfur and metals such as copper, zinc and iron. Geochemical data showed that the composite sample and the vase potentially cause contaminated acid drainage if they are exposed to atmospheric conditions. Indeed, the pH values of the leachates from both samples were between 4 and 6, while those corresponding to sediments remained around circumneutral values. Quantitatively, the contaminant release from the tested samples was variable. Indeed, the Fe cumulative concentrations were around 200, 80 and 20 mg/kg for the vase, composite and sediment samples, respectively. Similarly, the Zn cumulative concentrations were around 4500, 4200, and below the detection limit for vase, composite and sediment samples, respectively. The same tendency was observed for Cu, S, and Fe. Thus, sediments within Osisko lake present a risk for water contamination if they are resuspended or dredged out of the lake. Consequently, they should be stabilized before their disposal. The samples’ high Cu contents also offer the possibility of their reprocessing

Speciation of Pb and Cu in a wetland impacted by former uranium mining activities

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J Parkinsons Dis

Evidence shows that altered retinoic acid signaling may contribute to the pathogenesis and pathophysiology of Parkinson's disease (PD). Retinoic acid is the bioactive derivative of the lipophilic vitamin A. Vitamin A is involved in several important homeostatic processes, such as cell differentiation, antioxidant activity, inflammation and neuronal plasticity. The role of vitamin A and its derivatives in the pathogenesis and pathophysiology of neurodegenerative diseases, and their potential as therapeutics, has drawn attention for more than 10 years. However, the literature sits in disparate fields. Vitamin A could act at the crossroad of multiple environmental and genetic factors of PD. The purpose of this review is to outline what is known about the role of vitamin A metabolism in the pathogenesis and pathophysiology of PD. We examine key biological systems and mechanisms that are under the control of vitamin A and its derivatives, which are (or could be) exploited for therapeutic potential in PD: the survival of dopaminergic neurons, oxidative stress, neuroinflammation, circadian rhythms, homeostasis of the enteric nervous system, and hormonal systems. We focus on the pivotal role of ALDH1A1, an enzyme expressed by dopaminergic neurons for the detoxification of these neurons, which is under the control of retinoic acid. By providing an integrated summary, this review will guide future studies on the potential role of vitamin A in the management of symptoms, health and wellbeing for PD patients

Evaluation of the speciation and availability of Cu, Sn, Bi and U from lacustrine sediments influenced by former mining activities

International audienceManaging reservoir sediments remains challenging due to their propensity to significantly sequestrate trace elements. Moreover, many artificial reservoirs were located downstream of former mining sites. However, the knowledge of the exact trace element speciation and its fate in sediments submitted to reoxidation and drying events, such as dredging operations, is still limited.In this study, we examined the degree of contamination and solid speciation of trace elements and radionuclides in case of lake sediments dredging influenced by former mining activities. Finally, to assess the consequences such management i.e., dredging, by mimicking drying and oxidizing conditions, Toxicity Characterizing Leaching Procedure (TCLP) tests combined with parallel chemical extractions and mineralogical analyses were performed.Our results showed enrichments for Cu, Sn and Bi related to the former extractions activities of Charrier Cu–Sn mining site, as well as an enrichment for U partially due to the Bois-Noirs-Limouzat U mining site, in lake sediments. Moreover, the reoxidation and drying of initially anoxic sediments led to metal solid speciation dominated by: (i) Cu and Bi inherited sulfide minerals such as chalcopyrite, (ii) Cu, Bi and U associated with natural organic matter, and (iii) large grain-size refractory cassiterite SnO2 crystals. Additionally, results from the TCLP indicated a limited leachability of the studied elements, confirming the significant stability of U, Cu and Bi associated with natural organic matter. Finally, Cu and U concentrations extracted by TCLP are lower than threshold values indicating that these sediments are not considered as hazardous regarding these elements

Unveiling the origins and transport processes of radioactive pollutants downstream from a former U-mine site using isotopic tracers and U-238 series disequilibrium

International audienceHigh U concentrations (reaching up to 14,850 mg ⋅ kg−1), were determined in soils and sediments of a wetland downstream of a former U mine in France. This study aims to identify the origin of radioactive contaminants in the wetland by employing Pb isotope fingerprinting, (234U/238U) disequilibrium, SEM, and SIMS observations. Additionally, information about U and 226Ra transport processes was studied using U-238 series disequilibrium. The results of Pb fingerprinting highlighted inherited material inputs of different U-mines with mainly two types of U-ores: i) pitchblende (UO2), and ii) parsonsite (Pb2(UO2)(PO4)2). Moreover, significant disequilibrium of (230Th/238U) and (226Ra/230Th) activity ratios highlighted the mobility of 238U and 226Ra in the wetland, primarily driven by the water table fluctuations. Finally, this work uncovered a limitation of Pb isotope fingerprinting in the case of parsonsite materials, as the high natural Pb content of this mineral may hide the uranogenic Pb signature in the samples

Uranium sorption to organic matter and long-term accumulation in a pristine alpine wetland

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