Climate-driven fluxes of organic-bound uranium to an alpine lake overthe Holocene

Autor: Anne-Lise Develle, Arnaud Mangeret, Jean-Louis Reyss, Pierre Le Pape, Jérôme Gaillardet, Olivier Diez, Charlotte Cazala, Guillaume Morin, Pierre Lefebvre, Alkiviadis Gourgiotis, Pascale Louvat, Pierre Sabatier
Přispěvatelé: 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), 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), 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), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-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), 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), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), PSE-ENV/SEDRE/LELI, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Minéralogie Environnementale (MinEnv)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Science of the Total Environment
Science of the Total Environment, 2021, 783, pp.146878. ⟨10.1016/j.scitotenv.2021.146878⟩
Science of the Total Environment, Elsevier, 2021, 783, pp.146878. ⟨10.1016/j.scitotenv.2021.146878⟩
ISSN: 0048-9697
1879-1026
Popis: International audience; Uranium (U) isotopic signatures and concentration in sediments are widely used as paleo-redox proxies, as the behavior of U is often controlled by bottom water oxygenation. Here, we investigated the processes controlling U accumulation in the sediments of Lake Nègre (Mediterranean Alps, South-East France) over the past 9200 years. Exceptionally high natural U concentrations (350-1250 μg.g-1) allowed the measurement of U along with other elements by high-resolution X-Ray Fluorescence core-scanning. Weathering and erosion proxies (Ti content, Zr/Al and K/Ti ratios) indicate that sedimentary inputs were controlled by Holocene climatic variations. After a period of low erosion during the Holocene Climatic Optimum, a major regime shift was recorded at 4.2 kyr BP when terrigenous fluxes consistently increased until present with high sensitivity to centennial-scale climatic events. Sedimentary organic matter (OM) inputs were dominated by terrigenous OM from the catchment soils until 2.4 kyr BP, as attested by carbon to nitrogen (C/N) and bromine to organic carbon (Br/TOC) ratios. From 2.4 kyr BP to present, lake primary production and soils equally contributed to sedimentary OM. Uranium fluxes to the sediments were well correlated to terrigenous OM fluxes from 7 kyr BP to present, showing that U supply to the lake was controlled by U scavenging in the soils of the watershed followed by transport of U bound to detrital organic particles. Higher U/OM ratios before 7 kyr BP likely reflect the development of the upstream wetland. The fluctuations of U sedimentary inputs appear to be independent of bottom water oxygenation, as estimated from constant Fe/Mn ratios and δ238U isotopic signatures, and rather controlled by the production, erosion and sedimentation of terrigenous OM. This finding confirms that the use of U (and potentially other metals with high affinity to OM) concentrations alone should be used with caution for paleo-redox reconstructions.
Databáze: OpenAIRE
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