| Title: |
Pluri-millenial evolution of uranium speciation in lacustrine sediments |
| Authors: |
Lefebvre, Pierre; Gourgiotis, Alkiviadis; Mangeret, Arnaud; Le Pape, Pierre; Diez, Olivier; Sabatier, Pierre; Louvat, Pascale; Merrot, Pauline; Baya, Camille; Zebracki, Mathilde; Malet, Emmanuel; Jezequel, Didier; Reyss, Jean-Louis; Bargar, John; Gaillardet, Jérôme; Cazala, Charlotte; Morin, Guillaume |
| Contributors: |
Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC); Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement IRD : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS); Laboratoire de recherche sur le devenir des pollutions de sites radioactifs (IRSN/PSE-ENV/SEDRE/LELI); Service des déchets radioactifs et des transferts dans la géosphère (IRSN/PSE-ENV/SEDRE); Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN); Environnements, Dynamiques et Territoires de Montagne (EDYTEM); Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG); Institut de Physique du Globe de Paris (IPGP - UMR_7154); Institut national des sciences de l'Univers (INSU - CNRS)-Institut National de l'Information Géographique et Forestière IGN (IGN)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité); Stanford Synchrotron Radiation Lightsource (SSRL SLAC); SLAC National Accelerator Laboratory (SLAC); Stanford University-Stanford University; Minéralogie Environnementale IMPMC (IMPMC_MINENV); Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement IRD : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement IRD : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS); PF ASNR - Plateforme LUTÈCE - Laboratoire unifié d'expérimentation et de caractérisation |
| Source: |
European Geosciences Union General Assembly 2020, EGU ; https://hal.science/hal-02894361 ; European Geosciences Union General Assembly 2020, EGU, May 2020, VIENNE, Austria |
| Publisher Information: |
CCSD |
| Publication Year: |
2020 |
| Collection: |
Université Savoie Mont Blanc: HAL |
| Subject Terms: |
[SDE]Environmental Sciences |
| Subject Geographic: |
VIENNE; Austria |
| Description: |
International audience ; Uranium (U) is a toxic radionuclide which environmental dissemination must be limited. In this regard, understanding U immobilization mechanisms in reducing environments is essential for improving the management of radioactive waste and the remediation of contaminated sites. In particular, determining the long-term behavior of non-crystalline U(IV) species in (sub-)surface conditions is of growing importance, as these environmentally-relevant species have been recently showed to play a major role in U mobility. For this purpose, we investigated the evolution of U speciation over a pluri-millennial period in naturally U-enriched sediments from Lake Nègre (alt. 2354 m, Mercantour, France) as an analogue of contaminated systems. Several sediment cores were sampled at 24 m of water depth and preserved under anoxic conditions. Bottom sediments were dated back to 8700 cal BP. These organic- and Si-rich sediments display increasing U concentration with depth, from 350 to more than 1000 µg/g. Sequential ultrafiltration of surface waters and uranium isotopic ratios (238U/235U and (234U/238U)) of sediments and waters suggest that the deposition mode of U did not vary significantly with time, thus giving the opportunity to follow the effect of diagenesis on U speciation over more than 1000 years. Uranium LIII-edge X-Ray Absorption Near-Edge Structure (XANES) analysis shows that U is rapidly reduced in the upper sediment layers and is fully reduced at depth. Preliminary Extended X-Ray Absorption Fine Structure (EXAFS) spectroscopy data at the U LIII-edge reveals that U speciation evolved with depth in the sediment core, suggesting an effect of diagenesis in anoxic conditions on U solid speciation. Our results may help to design long-term storage conditions that are able to enhance the formation of poorly soluble U species in U-contaminated soils and sediments. |
| Document Type: |
conference object |
| Language: |
English |
| Relation: |
https://doi.org/10.57876/4tpy-0638 |
| Availability: |
https://hal.science/hal-02894361 |
| Accession Number: |
edsbas.74E478F2 |
| Database: |
BASE |