Search

Your search keyword '"Didier Jézéquel"' showing total 87 results
Start Over Author "Didier Jézéquel"
87 results on '"Didier Jézéquel"'

1. Seismic events as potential drivers of the microbial community structure and evolution in a paleo-ocean analog

Author

Adrien Vigneron, Lilian A. Cloarec, Hélène Agogué, Cécile Bernard, Sébastien Duperron, Christophe Leboulanger, Claire Carré, Patrice Got, Cécile Roques, Marc Troussellier, Didier Jézéquel, Alexis Groleau, Magali Ader, Philipe M. Oger, and Mylène Hugoni

Subjects
Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract

Abstract Anthropogenic perturbations profoundly affect aquatic ecosystem microbiomes and associated ecological functions. Comparatively, the effects of geological stresses on microbiome composition and stability remain poorly explored. Here, we monitored the archaeal, bacterial and microeukaryotes community structure over an 8-years period in Lake Dziani Dzaha (Comoros archipelago), that experienced a major earthquake swarm mid-survey, providing a rare opportunity to investigate the aftermaths of seismo-volcanic events on microbiome. Our results revealed the sensitivity of the aquatic microbial community towards seismicity and associated environmental changes, that triggered a major shift in microbiome composition and abundance with persisting consequences on structure and richness of the microbial ecosystem. Our findings suggest that seismological perturbations could be major drivers of the microbial community structure in aquatic environments through cascading effects on environmental conditions. Over geological time scales, such events may have been significant yet underestimated forces driving diversification and evolution of microbial communities.

Published
2024
Full Text
View/download PDF

2. Combined Earth observations reveal the sequence of conditions leading to a large algal bloom in Lake Geneva

Author

Abolfazl Irani Rahaghi, Daniel Odermatt, Orlane Anneville, Oscar Sepúlveda Steiner, Rafael Sebastian Reiss, Marina Amadori, Marco Toffolon, Stéphan Jacquet, Tristan Harmel, Mortimer Werther, Frédéric Soulignac, Etienne Dambrine, Didier Jézéquel, Christine Hatté, Viet Tran-Khac, Serena Rasconi, Frédéric Rimet, and Damien Bouffard

Subjects
Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract

Abstract Freshwater algae exhibit complex dynamics, particularly in meso-oligotrophic lakes with sudden and dramatic increases in algal biomass following long periods of low background concentration. While the fundamental prerequisites for algal blooms, namely light and nutrient availability, are well-known, their specific causation involves an intricate chain of conditions. Here we examine a recent massive Uroglena bloom in Lake Geneva (Switzerland/France). We show that a certain sequence of meteorological conditions triggered this specific algal bloom event: heavy rainfall promoting excessive organic matter and nutrients loading, followed by wind-induced coastal upwelling, and a prolonged period of warm, calm weather. The combination of satellite remote sensing, in-situ measurements, ad-hoc biogeochemical analyses, and three-dimensional modeling proved invaluable in unraveling the complex dynamics of algal blooms highlighting the substantial role of littoral-pelagic connectivities in large low-nutrient lakes. These findings underscore the advantages of state-of-the-art multidisciplinary approaches for an improved understanding of dynamic systems as a whole.

Published
2024
Full Text
View/download PDF

3. Transcriptomic insights into the dominance of two phototrophs throughout the water column of a tropical hypersaline-alkaline crater lake (Dziani Dzaha, Mayotte)

Author

Sébastien Duperron, Sébastien Halary, Jean-Pierre Bouly, Théotime Roussel, Myléne Hugoni, Maxime Bruto, Philippe M. Oger, Charlotte Duval, Anthony Woo, Didier Jézéquel, Magali Ader, Christophe Leboulanger, Hélène Agogué, Vincent Grossi, Marc Troussellier, and Cécile Bernard

Subjects
Limnospira platensis, Picocystis salinarum, metatranscriptomics, photosynthesis, fermentation, transcriptomics, Microbiology, QR1-502
Abstract

Saline-alkaline lakes often shelter high biomasses despite challenging conditions, owing to the occurrence of highly adapted phototrophs. Dziani Dzaha (Mayotte) is one such lake characterized by the stable co-dominance of the cyanobacterium Limnospira platensis and the picoeukaryote Picocystis salinarum throughout its water column. Despite light penetrating only into the uppermost meter, the prevailing co-dominance of these species persists even in light- and oxygen-deprived zones. Here, a depth profile of phototrophs metatranscriptomes, annotated using genomic data from isolated strains, is employed to identify expression patterns of genes related to carbon processing pathways including photosynthesis, transporters and fermentation. The findings indicate a prominence of gene expression associated with photosynthesis, with a peak of expression around 1 m below the surface, although the light intensity is very low and only red and dark red wavelengths can reach it, given the very high turbidity linked to the high biomass of L. platensis. Experiments on strains confirmed that both species do grow under these wavelengths, at rates comparable to those obtained under white light. A decrease in the expression of photosynthesis-related genes was observed in L. platensis with increasing depth, whereas P. salinarum maintained a very high pool of psbA transcripts down to the deepest point as a possible adaptation against photodamage, in the absence and/or very low levels of expression of genes involved in protection. In the aphotic/anoxic zone, expression of genes involved in fermentation pathways suggests active metabolism of reserve or available dissolved carbon compounds. Overall, L. platensis seems to be adapted to the uppermost water layer, where it is probably maintained thanks to gas vesicles, as evidenced by high expression of the gvpA gene. In contrast, P. salinarum occurs at similar densities throughout the water column, with a peak in abundance and gene expression levels which suggests a better adaptation to lower light intensities. These slight differences may contribute to limited inter-specific competition, favoring stable co-dominance of these two phototrophs.

Published
2024
Full Text
View/download PDF

4. Biogeochemical Niche of Magnetotactic Cocci Capable of Sequestering Large Polyphosphate Inclusions in the Anoxic Layer of the Lake Pavin Water Column

Author

Cécile C. Bidaud, Caroline L. Monteil, Nicolas Menguy, Vincent Busigny, Didier Jézéquel, Éric Viollier, Cynthia Travert, Fériel Skouri-Panet, Karim Benzerara, Christopher T. Lefevre, and Élodie Duprat

Subjects
magnetotactic bacteria (MTB), magnetosomes, redox and chemical gradients, morphotype diversity, P sequestration, electron microscopy, Microbiology, QR1-502
Abstract

Magnetotactic bacteria (MTB) are microorganisms thriving mostly at oxic–anoxic boundaries of aquatic habitats. MTB are efficient in biomineralising or sequestering diverse elements intracellularly, which makes them potentially important actors in biogeochemical cycles. Lake Pavin is a unique aqueous system populated by a wide diversity of MTB with two communities harbouring the capability to sequester not only iron under the form of magnetosomes but also phosphorus and magnesium under the form of polyphosphates, or calcium carbonates, respectively. MTB thrive in the water column of Lake Pavin over a few metres along strong redox and chemical gradients representing a series of different microenvironments. In this study, we investigate the relative abundance and the vertical stratification of the diverse populations of MTB in relation to environmental parameters, by using a new method coupling a precise sampling for geochemical analyses, MTB morphotype description, and in situ measurement of the physicochemical parameters. We assess the ultrastructure of MTB as a function of depth using light and electron microscopy. We evidence the biogeochemical niche of magnetotactic cocci, capable of sequestering large PolyP inclusions below the oxic–anoxic transition zone. Our results suggest a tight link between the S and P metabolisms of these bacteria and pave the way to better understand the implication of MTB for the P cycle in stratified environmental conditions.

Published
2022
Full Text
View/download PDF

5. Nitrogen Isotope Discrepancy Between Primary Producers and Sediments in an Anoxic and Alkaline Lake

Author

Pierre Cadeau, Magali Ader, Didier Jézéquel, Carine Chaduteau, Gérard Sarazin, Cécile Bernard, and Christophe Leboulanger

Subjects
nitrogen isotopes, Dziani Dzaha, ammonium assimilation, pH, basic condition, alkaline lake, Science
Abstract

Nitrogen isotope compositions (δ15N) in sedimentary rocks are extensively used to investigate the biogeochemical nitrogen cycle through geological times. This use relies on the observation that, in modern continental platforms and anoxic basins, surface sediments faithfully record the δ15N of primary producers, assuming that it was similar in the past. Over Earth’s history, however, surface environments experienced profound changes, including the transition of ammonium-dominated to nitrate-dominated waters and the transition from exclusively microbial ecosystems to ecosystems including multicellularity, which make modern environments significantly different compared to earlier ones, potentially invalidating the fundamental assumption that surface sediments faithfully record the δ15N of primary producers. In order to improve our understanding of the nitrogen isotopic information contained in the early Earth’s sedimentary rock record, we investigate here the nitrogen isotope systematics in a microbial, nitrate free and ammonium-rich modern system, the Dziani Dzaha Lake. In this modern system, the δ15N of the reduced dissolved inorganic nitrogen (i.e., NH4+ and NH3) in the water column is close to ∼7‰ . δ15N of suspended particulate matter (SPM) show a similar average value in surface waters (i.e., where SPM is massively composed of active primary producers), but increases up to 14‰ in the deeper part of the water column during periods when it is enriched in dissolved reduced species (i.e., CH4, H2S/HS− and NH4+/NH3). Surface sediments δ15N, with values comprised between 10 and 14 ‰, seem to preferentially record these positive isotopic signatures, rather than those of active primary producers. We propose here that the observed isotopic pattern is mainly linked to the assimilation of ammonium strongly enriched in 15N by isotope exchange with ammonia under basic conditions. Although ammonium assimilation seems here to be responsible for a significant isotopic enrichment due to the basic conditions, in neutral anoxic environments inhabited by similar microbial ecosystems, this process may also significantly impact the δ15N of primary producers towards more negative values. This would have strong implications for our interpretation of the Precambrian sedimentary record as this finding challenges one the fundamental hypotheses underlying the use of sedimentary δ15N in paleo-oceanographic reconstructions, i.e. that surface sediments faithfully record the δ15N of active primary producers in the photic zone.

Published
2021
Full Text
View/download PDF

6. Two-dimensional ammonium distribution in sediment pore waters using a new colorimetric diffusive equilibration in thin-film technique

Author

Edouard Metzger, Anthony Barbe, Florian Cesbron, Aubin Thibault de Chanvalon, Thierry Jauffrais, Didier Jézéquel, and Aurélia Mouret

Subjects
Environmental technology. Sanitary engineering, TD1-1066
Abstract

This study presents a new gel based technique to describe the pore water ammonium distribution through the sediment-water interface in two dimensions at a millimeter scale. The technique is an adaptation of the classical colorimetric method based on the Berthelot's reaction. After the thin film of the gel probe was equilibrated by diffusion either in standard solutions or in pore waters, a colorimetric reagent gel was set on the gel probe, allowing development of the characteristic green color. A flatbed scanner and subsequent densitometry image analysis allowed to determine the concentration distribution of ammonium. The gel probe was tested in the laboratory for two media, deionized water and seawater, within the range 0–3000 μM in NH4+. Detection limit is about 20 μM and accuracy about ±25 μM. The field validation was realized in a tidal mudflat of the French Atlantic coast by comparison with conventional pore water extraction and colorimetric analysis. The large range of concentrations and its applicability in continental and marine sediments suggest a wide range of applications of the technique for a reasonable cost. Keywords: Biogeochemistry, High-resolution, Porewater, DET, Densitometry

Published
2019
Full Text
View/download PDF

7. Microbial diversity involved in iron and cryptic sulfur cycling in the ferruginous, low-sulfate waters of Lake Pavin.

Author

Jasmine S Berg, Didier Jézéquel, Arnaud Duverger, Dominique Lamy, Christel Laberty-Robert, and Jennyfer Miot

Subjects
Medicine, Science
Abstract

Both iron- and sulfur- reducing bacteria strongly impact the mineralogy of iron, but their activity has long been thought to be spatially and temporally segregated based on the higher thermodynamic yields of iron over sulfate reduction. However, recent evidence suggests that sulfur cycling can predominate even under ferruginous conditions. In this study, we investigated the potential for bacterial iron and sulfur metabolisms in the iron-rich (1.2 mM dissolved Fe2+), sulfate-poor (< 20 μM) Lake Pavin which is expected to host large populations of iron-reducing and iron-oxidizing microorganisms influencing the mineralogy of iron precipitates in its permanently anoxic bottom waters and sediments. 16S rRNA gene amplicon libraries from at and below the oxycline revealed that highly diverse populations of sulfur/sulfate-reducing (SRB) and sulfur/sulfide-oxidizing bacteria represented up to 10% and 5% of the total recovered sequences in situ, respectively, which together was roughly equivalent to the fraction of putative iron cycling bacteria. In enrichment cultures amended with key iron phases identified in situ (ferric iron phosphate, ferrihydrite) or with soluble iron (Fe2+), SRB were the most competitive microorganisms, both in the presence and absence of added sulfate. The large fraction of Sulfurospirillum, which are known to reduce thiosulfate and sulfur but not sulfate, present in all cultures was likely supported by Fe(III)-driven sulfide oxidation. These results support the hypothesis that an active cryptic sulfur cycle interacts with iron cycling in the lake. Analyses of mineral phases showed that ferric phosphate in cultures dominated by SRB was transformed to vivianite with concomitant precipitation of iron sulfides. As colloidal FeS and vivianite have been reported in the monimolimnion, we suggest that SRB along with iron-reducing bacteria strongly influence iron mineralogy in the water column and sediments of Lake Pavin.

Published
2019
Full Text
View/download PDF

8. Key Role of Alphaproteobacteria and Cyanobacteria in the Formation of Stromatolites of Lake Dziani Dzaha (Mayotte, Western Indian Ocean)

Author

Emmanuelle Gérard, Siham De Goeyse, Mylène Hugoni, Hélène Agogué, Laurent Richard, Vincent Milesi, François Guyot, Léna Lecourt, Stephan Borensztajn, Marie-Béatrice Joseph, Thomas Leclerc, Gérard Sarazin, Didier Jézéquel, Christophe Leboulanger, and Magali Ader

Subjects
stromatolites, alkaline lake, Pleurocapsales, Mg-silicate, Alphaproteobacteria, anoxygenic phototrophic bacteria, Microbiology, QR1-502
Abstract

Lake Dziani Dzaha is a thalassohaline tropical crater lake located on the “Petite Terre” Island of Mayotte (Comoros archipelago, Western Indian Ocean). Stromatolites are actively growing in the shallow waters of the lake shores. These stromatolites are mainly composed of aragonite with lesser proportions of hydromagnesite, calcite, dolomite, and phyllosilicates. They are morphologically and texturally diverse ranging from tabular covered by a cauliflower-like crust to columnar ones with a smooth surface. High-throughput sequencing of bacterial and archaeal 16S rRNA genes combined with confocal laser scanning microscopy (CLSM) analysis revealed that the microbial composition of the mats associated with the stromatolites was clearly distinct from that of the Arthrospira-dominated lake water. Unicellular-colonial Cyanobacteria belonging to the Xenococcus genus of the Pleurocapsales order were detected in the cauliflower crust mats, whereas filamentous Cyanobacteria belonging to the Leptolyngbya genus were found in the smooth surface mats. Observations using CLSM, scanning electron microscopy (SEM) and Raman spectroscopy indicated that the cauliflower texture consists of laminations of aragonite, magnesium-silicate phase and hydromagnesite. The associated microbial mat, as confirmed by laser microdissection and whole-genome amplification (WGA), is composed of Pleurocapsales coated by abundant filamentous and coccoid Alphaproteobacteria. These phototrophic Alphaproteobacteria promote the precipitation of aragonite in which they become incrusted. In contrast, the Pleurocapsales are not calcifying but instead accumulate silicon and magnesium in their sheaths, which may be responsible for the formation of the Mg-silicate phase found in the cauliflower crust. We therefore propose that Pleurocapsales and Alphaproteobacteria are involved in the formation of two distinct mineral phases present in the cauliflower texture: Mg-silicate and aragonite, respectively. These results point out the role of phototrophic Alphaproteobacteria in the formation of stromatolites, which may open new perspective for the analysis of the fossil record.

Published
2018
Full Text
View/download PDF

9. Stratification of Archaea in the deep sediments of a freshwater meromictic lake: vertical shift from methanogenic to uncultured archaeal lineages.

Author

Guillaume Borrel, Anne-Catherine Lehours, Olivier Crouzet, Didier Jézéquel, Karl Rockne, Amélie Kulczak, Emilie Duffaud, Keith Joblin, and Gérard Fonty

Subjects
Medicine, Science
Abstract

As for lineages of known methanogens, several lineages of uncultured archaea were recurrently retrieved in freshwater sediments. However, knowledge is missing about how these lineages might be affected and structured according to depth. In the present study, the vertical changes of archaeal communities were characterized in the deep sediment of the freshwater meromictic Lake Pavin. For that purpose, an integrated molecular approach was performed to gain information on the structure, composition, abundance and vertical stratification of archaeal communities thriving in anoxic freshwater sediments along a gradient of sediments encompassing 130 years of sedimentation. Huge changes occurred in the structure and composition of archaeal assemblages along the sediment core. Methanogenic taxa (i.e. Methanosaeta and Methanomicrobiales) were progressively replaced by uncultured archaeal lineages (i.e. Marine Benthic Group-D (MBG-D) and Miscellaneous Crenarchaeal Group (MCG)) which are suspected to be involved in the methane cycle.

Published
2012
Full Text
View/download PDF

13. The hidden role of dissolved organic carbon in the biogeochemical cycle of carbon in modern redox-stratified lakes

Author

Robin Havas, Christophe Thomazo, Miguel Iniesto, Didier Jézéquel, David Moreira, Rosaluz Tavera, Jeanne Caumartin, Elodie Muller, Purificación López-García, and Karim Benzerara

Abstract

The dissolved organic carbon (DOC) reservoir plays a critical role in the C cycle of marine and freshwater environments because of its size and implication in many biogeochemical reactions. Although it is poorly constrained, its importance in ancient Earth's C cycles is also commonly invoked. Yet DOC is rarely quantified and characterized in modern stratified analogues. In this study, we investigated the DOC reservoirs of four redox-stratified alkaline crater lakes in Mexico. We analyzed the concentrations and isotopic compositions of DOC throughout the four water columns and compared them with existing data on dissolved inorganic and particulate organic C reservoirs (DIC and POC). The four lakes have high DOC concentrations with great variability between and within the lakes (averaging 2 ± 4 mM; 1 SD, n=28; i.e., from ∼ 15 to 160 times the amount of POC). The δ13CDOC signatures also span a broad range of values from −29.3 ‰ to −8.7 ‰ (with as much as 12.5 ‰ variation within a single lake). The prominent DOC peaks (up to 21 mM), together with their associated isotopic variability, are interpreted as reflecting oxygenic and/or anoxygenic primary productivity through the release of excess fixed carbon in three of the lakes (Alberca de los Espinos, La Preciosa, and Atexcac). By contrast, the variability of [DOC] and δ13CDOC in the case of Lake Alchichica is mainly explained by the partial degradation of organic matter and the accumulation of DOC in anoxic waters. The DOC records detailed metabolic functions such as active DIC-uptake and DIC-concentrating mechanisms, which cannot be inferred from DIC and POC analyses alone but which are critical to the understanding of carbon fluxes from the environment to the biomass. Extrapolating our results to the geological record, we suggest that anaerobic oxidation of DOC may have caused the very negative C isotope excursions in the Neoproterozoic. It is, however, unlikely that a large oceanic DOC reservoir could overweigh the entire oceanic DIC reservoir. This study demonstrates how the analysis of DOC in modern systems deepens our understanding of the C cycle in stratified environments and helps to set boundary conditions for the Earth's past oceans.

Published
2023

14. A comparative isotopic study of the biogeochemical cycle of carbon in modern stratified lakes: the hidden role of DOC

Author

Robin Havas, Christophe Thomazo, Miguel Iniesto, Didier Jézéquel, David Moreira, Rosaluz Tavera, Jeanne Caumartin, Elodie Muller, Purificación López-García, and Karim Benzerara

Abstract

The carbon cycle is central to the evolution of biogeochemical processes at the surface of the Earth. In the ocean, which has been redox-stratified through most of the Earth’s history, the dissolved organic carbon (DOC) reservoir holds a critical role in these processes because of its large size and involvement in many biogeochemical reactions. However, it is rarely measured and examined in modern stratified analogs and yet commonly invoked in past C cycle studies. Here, we characterized the C cycles of four redox-stratified alkaline crater lakes from Mexico. For this purpose, we analyzed the concentrations and isotopic compositions of DOC together with dissolved inorganic and particulate organic C (DIC and POC). In parallel we measured physico-chemical parameters of the water columns and surficial bottom sediments. The four lakes have high DOC concentrations (from ~ 15 to 160 times the amount of POC, averaging 2 ± 4 mM; 1SD, n=28) with an important variability between and within the lakes. All lakes exhibit prominent DOC peaks (up to 21 mM), found in the oxic and/or anoxic zones. δ13CDOC signatures also span a broad range of values from -29.3 to -8.7 ‰ (with as much as 12.5 ‰ variation within a single lake), while δ13CPOC and δ13CDIC varied from -29.0 to -23.5 ‰ and -4.1 to +2.0 ‰, respectively. The DOC peaks in the water columns and associated isotopic variability seem mostly related to oxygenic and/or anoxygenic primary productivity through the release of excess fixed C in three of the lakes (Atexcac, La Preciosa and La Alberca de los Espinos). By contrast, the variability of [DOC] and δ13CDOC in Lake Alchichica could be mainly explained by partial degradation and accumulation in anoxic waters. Overall, DOC records metabolic reactions that would not have been clearly detected if only DIC and POC reservoirs had been analyzed. For example, DOC analyses evidence an active DIC-uptake and use of a DIC-concentrating mechanism by part of the photosynthetic plankton. Despite the prominent role of DOC in the C cycle of these lakes, variations of [DOC]/δ13CDOC and associated reactions are not reflected in the sedimentary organic carbon record, hence calling for special care when considering sediments as reliable archives of metabolic activities in stratified water columns. Overall, this study brings to light the need of further investigating the role of DOC in the C cycles of modern stratified analogs.

Published
2022

16. DEEP-C Consortium: Carbon sink or methane source – local to global scale assessment of lentic waters’ role in the climate system

Author

Jean-Philippe Jenny, Laurent Millet, Ronny Lauerwald, Fanny Colas, Hélène Masclaux, Yves Prairie, Pierre Regnier, Adam A. Ali, Fabien Arnaud, Nuno Carvalhais, Vincent Chanudet, Emmanuel Chapron, Patrick Durand, Isabelle Domaizon, Etienne Dambrine, Mathieu Dellinger, David Etienne, Jérome Gaillardet, Didier Galop, David Gateuille, Charline Giguet-Covex, Olivia Itier-Desgué, Didier Jezequel, Emilie Lyautey, Laurent Marquer, Florence Mazier, Théo Mazure, Erwan Messager, Jérôme Poulenard, Damien Rius, Pierre Sabatier, Georges-Marie Saulnier, Anaëlle Simonneau, Laura Soares, Viet Tran-Khac, Valérie Verneaux, and Philippe Ciais

Subjects
Land to ocean aquatic continuum, lentic waters, la, Science
Abstract

Lentic waters are biogeochemical reactors, producing and receiving carbon (C) originally fixed by the terrestrial and aquatic biosphere, which is then buried in sediments or respired back to the atmosphere in the forms of carbon dioxide (CO2) and one of the more potent greenhouse gas (GHG) methane (CH4). Additionally, lakes serve as archives of terrestrial and aquatic carbon processes within their sediments, enabling the reconstruction of historical changes spanning thousands of years. These changes encompass alterations in land cover, indicated by pollen records, soil carbon erosion and shifts in lake productivity resulting from changes in land use and climate. Both the burial of C in lakes and the emissions of GHGs are recognised as important components of Earth's climate system, yet they remain poorly understood and constrained due to inadequate quantities and qualities of observations. In the case of GHG emissions from lakes, observations are often sporadic, failing to capture the significant spatial and temporal variations in emissions across diverse lentic systems. To address this challenge, process-based models that incorporate the interconnected biogeochemical processes occurring within lakes and their watersheds would arguably be the best tool to extrapolate from site-level observations to regional and finally global scales, to quantify the anthropogenic impact on these fluxes and to reconstruct long-term shifts in emissions and burial due to changes in land cover and climate. However, the development and evaluation of such models is hampered by the lack of observations in sufficient quality. In this project, we bring together a unique consortium of specialists in aquatic ecology, biogeochemistry, palynology, sedimentology and modelling of terrestrial and aquatic biogeochemistry. This project will put forth a national programme of systematic, long-term observations of lake GHG and C cycling processes of unmet detail, consistency and quality. First, at 40 pilot sites spanning typological and environmental gradients, there will be a comprehensive data acquisition endeavour to evaluate biological processes and mesological factors influencing the sequestration or recycling of organic carbon. This effort will be complemented with a synthesis of existing data (WP1). Second, based on well-dated sediment records, which include both newly-acquired and synthesised existing data, variability of lake C burial and their climate and land-use controls will be reconstructed over the past 150 years (WP2). For 15 of these pilot sites, reconstruction will go back until the mid-Holocene (5,000 years BP), allowing us to shed light on the anthropogenic perturbation of the C cycle in this earlier part of human history, which is commonly excluded from this type of research due to lack of information. The activities of these first two WPs will result in an open-source national database, guaranteeing valorisation of our research far beyond this project. In WP3, we will use the land surface model (LSM) ORCHIDEE C-lateral to assess C cycling in the terrestrial biosphere and the mobilisation of biospheric C into lakes, which is possible due to an explicit representation of soil C leaching and erosion processes and a downscaling scheme permitting us to assess C exports from watersheds at sub-grid scale. While LSMs are used to assess evolution of biospheric C budgets from the beginning of the Industrial Period, we will use it to hindcast the evolution since the mid-Holocene, using lake sediment records for model validation. Moreover, we will develop a new process-based lake C model supported by the database established in WPs 1 and 2, which we will couple to ORCHIDEE C-lateral to simulate lake C burial and GHG emissions in response to climate and processes in the lake watershed. This model set-up will first be used to better constrain contemporary large-scale lake GHG emissions and to disentangle the anthropogenic perturbation of these fluxes from the natural background flux. These estimates will be revolutionary, as they will allow attributing part of lake GHG emissions to anthropogenic emissions for national GHG budget reporting. Then, these models will be emulated to reconstruct evolution of lake GHG budgets and C budgets of the whole lake watershed since the mid-Holocene. While simulations will first be performed at the scales of France and Europe, the development of international partnerships to implement observations from other biomes (WP4) will finally support simulations at the global scale.

Published
2024
Full Text
View/download PDF

17. The Dziani Dzaha Lake: A long‐awaited modern analogue for superheavy pyrites

Author

Pierre Cadeau, Pierre Cartigny, Christophe Thomazo, Didier Jézéquel, Christophe Leboulanger, Gérard Sarazin, Magali Ader, 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), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Total Corporate Foundation (project DZAHA C001493), and TOTAL (convention FR00008189), and ANR-13-BS06-0001,Dziani,Ecalairages sur les océans précambriens par l'étude biogéochimique et microbiologique d'un analogue actuel: le lac Dziani Dzaha, Mayotte.(2013)

Subjects
Sulfates, [SDE.MCG]Environmental Sciences/Global Changes, Water, multiple sulfur isotopes, Sulfides, sulfide oxidation, Lakes, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, modern analogue, Sulfur Isotopes, General Earth and Planetary Sciences, microbial sulfate reduction, Ecology, Evolution, Behavior and Systematics, Sulfur, General Environmental Science, superheavy pyrites
Abstract

International audience; Sedimentary records of superheavy pyrites in Phanerozoic and Proterozoic successions (i.e., extremely positive delta S-34(pyrite) values together with higher delta S-34(pyrite) than coeval delta S-34(CAS)) are mostly interpreted as resulting either from secondary postdepositional processes or from multiple redox reactions between sulfate and sulfide in stratified sulfate-poor environments. We report here the first observation of strongly positive delta S-34 values for both dissolved sulfate and sulfide (average delta S-34(diss.sulfate) value of 34.6 parts per thousand and delta S-34(diss.sulfide) values of 36.7 parts per thousand) compared to the present-day seawater delta S-34(diss).(sulfate) (similar to 21 parts per thousand), with a negative apparent fractionation between sulfate and sulfide (Delta S-34(diss.sulfate-diss.sulfide) similar to -2.1 +/- 1.4 parts per thousand), in the sulfate-poor (m) modern thalassohaline lacustrine system Dziani Dzaha (Mayotte, Indian Ocean). Overall, surface sediments faithfully record the water column isotopic signatures including a mainly negative Delta S-34(sed.sulfate-sed.sulfide) (-4.98 +/- 4.5 parts per thousand), corresponding to the definition of superheavy pyrite documented in the rock record. We propose that in the Dziani Dzaha this superheavy pyrite signature results from a two-stage evolution of the sulfur biogeochemical cycle. In a first stage, the sulfur cycle would have been dominated by sulfate from initially sulfate-rich marine waters. Overtime, Raleigh distillation by microbial sulfate reduction coupled with sulfide burial in the sediment would have progressively enriched in S-34 the water column residual sulfate. In a second still active stage, quantitative sulfate reduction not only occurs below the halocline during stratified periods but also in the whole water column during fully anoxic episodes. Sulfates are then regenerated by partial oxidation of sulfides as the oxic-anoxic interface moves downward. These results demonstrate that the atypical superheavy pyrite isotope signature does not necessarily require postdepositional or secondary oxidative processes and can result from primary processes in restricted sulfate-poor and highly productive environments analogous to the Dziani Dzaha.

Published
2022
Full Text
View/download PDF

18. Early Diagenesis of Lacustrine Carbonates in Volcanic Settings: The Role of Magmatic CO2 (Lake Dziani Dzaha, Mayotte, Indian Ocean)

Author

Aurélien Virgone, Gérard Sarazin, François Guyot, Vincent Milesi, Mathieu Debure, Virgile Rouchon, Edouard Bard, Nicolas C.M. Marty, Manuela Capano, Magali Ader, Carl I. Steefel, Patrick Albéric, Eric C. Gaucher, Didier Jézéquel, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), IFP Energies nouvelles (IFPEN), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Biogéosystèmes Continentaux - UMR7327, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), 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), TOTAL-Scientific and Technical Center Jean Féger (CSTJF), TOTAL FINA ELF, CNRS-INSU : INTERRIVECNRS-INSU : ARTEMIS, ANR-13-BS06-0001,Dziani,Ecalairages sur les océans précambriens par l'étude biogéochimique et microbiologique d'un analogue actuel: le lac Dziani Dzaha, Mayotte.(2013), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), 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), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Chaire Evolution du climat et de l'océan, Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), 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), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Collège de France - Chaire Evolution du climat et de l'océan, Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Centre scientifique et Technique Jean Feger (CSTJF)

Subjects
saponite, Atmospheric Science, 010504 meteorology & atmospheric sciences, volcanic crater lake, Geochemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Geochemistry and Petrology, Crater lake, Dissolved organic carbon, magmatic CO2, Dziani Dzaha, 14. Life underwater, Hydromagnesite, rift settings, 0105 earth and related environmental sciences, magnesium phyllosilicates, geography, geography.geographical_feature_category, Mg silicates saponite rift settings pre-salt reactive transport modeling magmatic CO2 volcanic crater lake South-Atlantic early Cretaceous lacustrine carbonates paleoenvironment, Aragonite, Sediment, reactive transport modeling, Diagenesis, isotopy, Volcano, chemistry, kinetics, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, engineering, Carbonate, Geology, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract

International audience; Lacustrine carbonates formed in rift settings are increasingly studied not only as archives of Earth chemical and climatic history but also as potential hydrocarbon source rocks and/or reservoirs. The role of magmatic gases in their formation and diagenetic evolution, hence in their reservoir properties, remains unclear. We studied the first meter of carbonate sediment of the Dziani Dzaha volcanic crater lake (Mayotte Island) and developed a reactive-transport model with CrunchFlow software that allows the quantification of diagenetic reactions by considering depth-dependent burial rates and sediment compaction. The model is constrained by the previously documented solid-phase compositions of the lake sediment and new data consisting of 14C dating of plant macroremains to characterize the sediment age model, chemical composition of sediment pore waters, and chemical and isotopic composition of gases dissolved and bubbling through the lake. These new data reveal a massive magmatic CO2 contribution to the dissolved inorganic carbon of the lake, which fuels the primary productivity and carbonate formation. A pH value of 9 in the surface sediment pore waters induces supersaturation relative to aragonite, hydromagnesite, and saponite. At 1 m depth in the sediment, our model predicts that magmatic CO2 inflows and organic matter degradation account for 22 and 2 mol % dissolved inorganic carbon, respectively. The magmatic CO2 inflows result in a pH decrease at depth, leading to the destabilization of hydromagnesite, while saponite and aragonite remain stable. These results demonstrate the role of magmatic CO2 in fueling carbonate production and controlling the diagenetic evolution of sediment mineralogy.

Published
2020
Full Text
View/download PDF

19. Lake Pavin is a microbial mineralization oasis

Author

Christopher Lefevre, Nicolas Menguy, Karim Benzerara, Vincent Busigny, Camille Mangin, Neha Mehta, Cytnhia Travert, Romain Bolzoni, Cécile Bidaud, François Mathon, Didier Jézéquel, Eric Viollier, Fériel Skouri-Panet, Elodie Duprat, and Caroline Monteil

Published
2022
Full Text
View/download PDF

20. Influence of aphotic haloclines and euxinia on organic biomarkers and microbial communities in a thalassohaline and alkaline volcanic crater lake

Author

Mylène Hugoni, Cécile Bernard, Ingrid Antheaume, Gérard Sarazin, Hélène Agogué, Christophe Leboulanger, Vincent Grossi, Didier Jézéquel, David Sala, Magali Ader, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), 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), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Molécules de Communication et Adaptation des Micro-organismes (MCAM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Microbiologie, adaptation et pathogénie (MAP), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Institut de Physique du Globe de Paris (IPGP), and 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)

Subjects
Biogeochemical cycle, haline and aphotic euxinia, WSA2 methanogenic 69 Euryarchaeota, Thermoplasmata, Haline and aphotic euxinia, Bacteroidetes ML635J-40 aquatic group, syntrophomonadaceae, 03 medical and health sciences, Water column, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, RNA, Ribosomal, 16S, Crater lake, Organic matter, Photic zone, 14. Life underwater, lipid biomarkers, WSA2 methanogenic Euryarchaeota, Phylogeny, Ecology, Evolution, Behavior and Systematics, 030304 developmental biology, General Environmental Science, chemistry.chemical_classification, 0303 health sciences, biology, 030306 microbiology, Microbiota, bacterial and archaeal diversity, 15. Life on land, bacteroidetes ML635J-40 aquatic group, biology.organism_classification, Archaea, Anoxic waters, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, 6. Clean water, Lakes, chemistry, 13. Climate action, Aphotic zone, Environmental chemistry, General Earth and Planetary Sciences, Syntrophomonadaceae, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Biomarkers
Abstract

International audience; Studies on microbial communities, and their associated organic biomarkers, that are found thriving in the aphotic euxinic waters in modern stratified ecosystems are scarce compared to those undertaken in euxinic photic zones. The Dziani Dzaha (Mayotte,Indian Ocean) is a tropical, saline, alkaline crater lake that has recently been presentedas a modern analog of Proterozoic Oceans due to its thalassohaline classification (having water of marine origin) and specific biogeochemical characteristics. Continuous intense photosynthetic production and microbial mineralization keep most of the water column permanently aphotic and anoxic preventing the development of a euxinic (sulfidic and anoxic) photic zone despite a high sulfide/sulfate ratio and the presence of permanent or seasonal haloclines. In this study, the molecular composition of the organic matter in Lake Dziani Dzaha was investigated and compared to the microbial diversity evaluated through 16S rRNA gene amplicon sequencing, over two contrasting seasons (rainy vs. dry) that influence water column stratification. Depth profiles of organic biomarker concentrations (chlorophyll-a and lipid biomarkers) and bacterial and archaeal OTU abundances appeared to be strongly dependent on the presence of aphotic haloclines and euxinia. OTU abundances revealed theimportance of specific haloalkaliphilic bacterial and archaeal assemblages in phytoplanktonic biomass recycling and the biogeochemical functioning of the lake, suggesting new haloalkaline non-phototrophic anaerobic microbial precursors for some of the lipid biomarkers. Uncultured Firmicutes from the family Syntrophomonadaceae (Clostridiales), and Bacteroidetes from the ML635J-40 aquatic group, emerged as abundant chemotrophic bacterial members in the anoxic or euxinic waters and were probably responsible for the production of short-chain n-alkenes, wax esters, diplopterol, and tetrahymanol. Halocline-dependent euxinia also had a strong impact on the archaeal community which was dominated by Woesearchaeota in the sulfide-free waters. In the euxinic waters, methanogenic Euryarchaeota from the Methanomicrobia, Thermoplasmata, and WSA2 classes dominated and were likely at the origin of common hydrocarbon biomarkers of methanogens (phytane, pentamethyl-eicosenes, and partially hydrogenated squalene).

Published
2022
Full Text
View/download PDF

22. Mercury, organic matter, iron, and sulfur co-cycling in a ferruginous meromictic lake

Author

Delphine Tisserand, Stéphane Guédron, Eric Viollier, Didier Jézéquel, Sylvain Rigaud, Sylvain Campillo, Géraldine Sarret, Laurent Charlet, Daniel Cossa, Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), 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), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Détection, évaluation, gestion des risques CHROniques et éMErgents (CHROME) / Université de Nîmes (CHROME), and Université de Nîmes (UNIMES)

Subjects
Redox, Geochemistry and Petrology, Iron, [SDE]Environmental Sciences, Environmental Chemistry, Organic matter, methylmercury, Mercury, Pollution, Sulfur, Lake pavin
Abstract

International audience; Mercury (Hg) speciation in natural waters is controlled by redox conditions and microbiological activity. Water columns of meromictic lakes have large and stable redox chemical and biological gradients that allow the investigation of many Hg chemical transformations. In this study, Hg speciation (elemental Hg = Hg-0, methylated Hg = MeHg) and partitioning between truly dissolved (< 3 kDa), colloidal (< 0.45 mu m and > 3 kDa), and particulate (> 0.45 mu m) fractions, were determined throughout a high-resolution water column profile in the ferruginous meromictic Lake Pavin (Massif Central, France) in July 2018. Total Hg concentrations (THg) in water ranged between 0.4 and 8.8 pmol L-1. The particulate phase represented 10-70% of the THg, with a peak found in the mesolimnion associated with the particulate organic carbon maximum. In the mesolimnion, the colloidal fraction represented 12-68% of THg, and the highest value was found at the top of the sulfidic zone, whereas the truly dissolved Hg species (70 +/- 9%) dominated in all the rest of the sulfidic zone. MeHg ranged from less than 10% of THg in the oxic mixolimnion to more than 90% in the anoxic monimolimnion. The Hg methylation was most active within the suboxic zone where iron and sulfate reduction are occurring. These results, associated with those of the partition of organic matter (OM), sulfur, and iron, in conjunction with thermodynamic calculations, allow us to present a conceptual scheme for the Hg cycle in the lake. Atmospheric Hg deposited onto surface waters of the lake is partially photo-reduced and returned to the air, another part is scavenged by biogenic particulate matter and conveyed at depth by settling organic material. Water stratification and redox changes create a sequence of reactions from oxic to ferruginous waters where Hg is successively (i) desorbed from particulate OM where mineralization occurs, (ii) adsorbed onto iron-oxy(hydr)oxides, (iii) desorbed where they dissolved, (iv) precipitate as HgS, (v) methylated, and (vi) reduced as Hg-0 in the deepest part of the lake. In brief, the (micro)biological uptake, OM, iron and sulfur recycling, through associated microbial consortia, control the Hg cycling in the Pavin waters.

Published
2022
Full Text
View/download PDF

23. Lake Dziani Dzaha (Mayotte, Indian Ocean) : A modern analogue for type I kerogen formation

Author

Edouard Bard, Fabien Arnaud, I. Antheaume, F. Gelin, Manuela Capano, Vincent Grossi, Magali Ader, S. Mignard, F. Baudin, Didier Jézéquel, Pierre Cartigny, Laurent Simon, I. Jovovic, Emmanuel Malet, Pierre Adam, Collège de France - Chaire Evolution du climat et de l'océan, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), 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), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), STMicroelectronics [Crolles] (ST-CROLLES), 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), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Équipe 3 - Écologie, Évolution, Écosystemes Souterrains (E3S), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Total E&P, Centre scientifique et Technique Jean Feger (CSTJF), and TOTAL FINA ELF

Subjects
2HAL, δ18O, Aquatic ecosystem, Geochemistry, BARD Édouard, Anoxic waters, Diagenesis, Texte intégral (accès ouvert), chemistry.chemical_compound, web-evolution-climat-ocean, chemistry, Source rock, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Kerogen, Sedimentary rock, traité, Chaires, Green River Formation, Geology, Document sous DOI (Digital Object Identifier)
Abstract

https://hal.archives-ouvertes.fr/hal-03252301; International audience; Summary In the past, highly productive (hyper)saline and alkaline environments have proved propitious for large accumulation of sedimentary OM that led to the formation of Type I kerogens, such as those of the Green River Formation. A sediment core that covers most of the history of Lake Dziani Dzaha, a hypereutrophic saline, alkaline and mostly anoxic crater lakewhich waspostulatedto be a modern analogue of such environments, has been investigated using several analytical approaches comprising bulk (Rock-Eval and C, N, S elemental analyses), isotopic (δ13,14C, δ15N, δ18O, δ33,34,36S), and sedimentological descriptions. This study revealed that, despite strong environmental changes undergone by the lake since its formation, the conditions prevailing in the lake supported by a continuous high primary production have led to an excellent preservation of OM and to early diagenetic reductive and sulfurization processes which have yielded an exceptionally reduced character of the OM with respect to its short diagenetic history (< 6 ky). The similarities observed between the sediments of Lake Dziani Dzaha and some source rocks associated to Type I kerogens suggest that early diagenetic processes can have a strong and rapid impact on the accumulation of OM in some (semi)closed and highly productive aquatic ecosystems.

Published
2021
Full Text
View/download PDF

24. Biogeochemical niche of phosphorus sequestrating magnetotactic bacteria in Lake Pavin, a freshwater feruginous environment

Author

Caroline L. Monteil, Elodie Duprat, Cécile C. Bidaud, Christopher T. Lefèvre, Fériel Skouri-Panet, Didier Jézéquel, Nicolas Menguy, Eric Viollier, Karim Benzerara, Vincent Busigny, and Cynthia Travert

Subjects
Water column, Magnetotactic bacteria, Chemistry, Environmental chemistry, Population structure, Intracellular
Abstract

Phosphorus (P) is essential to life but a limiting nutrient in many ecosystems. Understanding the role of microorganisms in P cycling, especially the processes of P uptake and storage, is a major environmental issue. Only few models are known to highly sequestrate phosphorus and mostly in marine environments. We thus need to improve our knowledge about other model of sequestration and especially in freshwater environments.Freshwater magnetotactic bacteria (MTB) affiliated to the Magnetococcaceae family have been identified within the water column of Lake Pavin in France [3]. Similarly, to the marine Thiomarguarita and Beggiatoa [1, 2], they accumulate intracellular polyphosphates (PolyP) to a uniquely high extent, up to 90% of their cell volume. In contradiction with the marine Thiomarguarita and Beggiatoa, the Magnetococcaceae accumulate PolyP in anoxic conditions. They represent the major population of MTB and are located right under the oxic-anoxic interface in a zone of strong chemical and redox gradients. These gradients allow the study of the impact of varying chemical conditions on microbial physiology.We aim at characterizing Magnetococcaceae distribution as a function of depth and therefore of different chemical parameters, but also at determining the drivers of PolyP accumulation. Here, we combine a variety of methods to analyse these MTB and their potential appartenance to a specific ecological niche in the water column. We measured the physico-chemical parameters of the water column (O2, pH, redox, conductivity, FDOM, turbidity, etc.). We used a new sampling system that allowed us to reach a better spatial resolution [4], from 1 m to 20 cm. We were therefore able to better estimate the impact of the chemical parameters on the MTB. We then sampled the water to measure the geochemical parameters using ICP-OES and to characterize MTB via optical and electronic microscopy. Optical microscopy helped identify the main populations of MTB and their concentrations, while electronic microscopy permitted the characterization of the different magnetosome organisation and PolyP accumulation capacities. Multivariate statistics were finally performed on all data.Multivariate statistics identified several parameters positively and significantly correlated to the Magnetococcaceae. These parameters are different from the ones correlated to other MTB of the water column. We therefore show that the Magnetococcaceae live into a specific niche with specific biogeochemical parameters. These correlated parameters include dissolved lithium concentration, mass percentage of nitrogen, magnesium and particulate P. Phosporus and magnesium are linked to the formation of PolyP, lithium represent a cofactor for phosphate transport [5] and nitrogen might be linked to nitrate transportation by the MTB [6].Genomic analyses will be done in the future to allow further comprehension on molecular mecanisms and PolyP formation. [1] Brock J, Schulz-Vogt HN. (2011) ISME Journal 5, 497-506. [2] Mubmann M et al. (2007) PLoS Biology 5(9), e230. [3] Rivas-Lamelo S et al. (2017) Geochem. Persp. Let. 5, 35–41. [4] Busigny et al., submitted to Environmental Microbiology. [5] Jakobsson E et al. (2017) J. Membr. Biol. 250,587-604. [6] Li et al. (2020) Geophys. Res. Biogeosciences.

Published
2021
Full Text
View/download PDF

25. Mass collection of magnetotactic bacteria from the permanently stratified ferruginous Lake Pavin, France

Author

Karim Benzerara, Didier Jézéquel, Nicolas Menguy, François P. Mathon, Christopher T. Lefèvre, Jean‐Jacques Bourrand, Eric Viollier, Cécile C. Bidaud, Caroline L. Monteil, Gérard Bardoux, Elodie Duprat, Vincent Busigny, 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), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), 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), French National Research Agency (ANR)SIGMAG: ANR-18-CE31-0003PHOSTORE: ANR-19-CE01-0005CNRS: 'DEFI Instrumentation aux limites' (MAGNETOTRAP project)'Programme National Ecosphere Continentale et Cotiere (EC2CO)' (BACCARAT2 project)13068Frontieres de l'Innovation en Recherche et Education (FIRE) PhD program from the Centre de Recherches Interdisciplinaires (CRI), 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), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), ANR-18-CE31-0003,SIGMAG,SIGNATURE DES MAGNETITES PRODUITES PAR LES BACTERIES MAGNETOTACTIQUES : PERSPECTIVES CHIMIQUES ET ISOTOPIQUES(2018), and ANR-19-CE01-0005,PHOSTORE,Piégeage du phosphore : contribution des bactéries magnétotactiques dans les zones de transition oxique-anoxique(2019)

Subjects
Magnetotactic bacteria, Earth science, Microorganism, Magnetosome, Biology, Microbiology, 03 medical and health sciences, Water column, Crater lake, Ecology, Evolution, Behavior and Systematics, Nansen bottle, Ecosystem, Phylogeny, 030304 developmental biology, 0303 health sciences, Bacteria, 030306 microbiology, Aquatic ecosystem, Sediment, 15. Life on land, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, Lakes, 13. Climate action, Magnetosomes, Metagenomics, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

Obtaining high biomass yields of specific microorganisms for culture-independent approaches is a challenge faced by scientists studying organisms recalcitrant to laboratory conditions and culture. This difficulty is highly decreased when studying magnetotactic bacteria (MTB) since their unique behavior allows their enrichment and purification from other microorganisms present in aquatic environments. Here, we use Lake Pavin, a permanently stratified lake in the French Massif Central, as a natural laboratory to optimize collection and concentration of MTB that thrive in the water column and sediments. A method is presented to separate MTB from highly abundant abiotic magnetic particles in the sediment of this crater lake. For the water column, different sampling approaches are compared such as in situ collection using a Niskin bottle and online pumping. By monitoring several physicochemical parameters of the water column, we identify the ecological niche where MTB live. Then, by focusing our sampling at the peak of MTB abundance, we show that the online pumping system is the most efficient for fast recovering of large volumes of water at a high spatial resolution, which is necessary considering the sharp physicochemical gradients observed in the water column. Taking advantage of aerotactic and magnetic MTB properties, we present an efficient method for MTB concentration from large volumes of water. Our methodology represents a first step for further multidisciplinary investigations of the diversity, metagenomic and ecology of MTB populations in Lake Pavin and elsewhere, as well as chemical and isotopic analyses of their magnetosomes. This article is protected by copyright. All rights reserved.

Published
2021
Full Text
View/download PDF

26. Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years

Author

Mathilde Zebracki, Pascale Louvat, Emmanuel Malet, Pierre Lefebvre, Didier Jézéquel, Pierre Le Pape, Alkiviadis Gourgiotis, John R. Bargar, Pascale Blanchart, Nicolas Menguy, Jean-Louis Reyss, Guillaume Morin, Pauline Merrot, Camille Baya, Charlotte Cazala, Pierre Sabatier, Jérôme Gaillardet, Arnaud Mangeret, Olivier Diez, 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), PSE-ENV/SEDRE/LELI, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), 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]), 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), PSE-ENV/SEDRE/USDR, Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Minéralogie Environnementale (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), United States Department of Energy (DOE)DE-AC02-76SF00515IPGP multidisciplinary program PARIParis-IdF Region SESAME Grant12015908IRSNLS 20942, ANR-18-IDEX-0001,Université de Paris,Université de Paris(2018), Service des déchets radioactifs et des transferts dans la géosphère (IRSN/PSE-ENV/SEDRE), 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), Propriétés des amorphes, liquides et minéraux [IMPMC] (IMPMC_PALM), Laboratoire de recherche sur le devenir des pollutions de sites radioactifs (IRSN/PSE-ENV/SEDRE/LELI), 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), Unité d'expertise des sites et des déchets radioactifs (IRSN/PSE-ENV/SEDRE/USDR), and IMPMC_Minéralogie Environnementale (IMPMC_MINENV)

Subjects
media_common.quotation_subject, lake sediments, chemistry.chemical_element, 010501 environmental sciences, 010502 geochemistry & geophysics, 01 natural sciences, uranium, Coffinite, Organic matter, 0105 earth and related environmental sciences, media_common, chemistry.chemical_classification, Multidisciplinary, Isotopes of uranium, Lability, Authigenic, Uranium, diagenetic aging, noncrystalline species, Diagenesis, Speciation, chemistry, 13. Climate action, Environmental chemistry, Physical Sciences, [SDE]Environmental Sciences, uranium isotopes
Abstract

The long-term fate of uranium-contaminated sediments, especially downstream former mining areas, is a widespread environmental challenge. Essential for their management is the proper understanding of uranium (U) immobilization mechanisms in reducing environments. In particular, the long-term behavior of noncrystalline U(IV) species and their possible evolution to more stable phases in subsurface conditions is poorly documented, which limits our ability to predict U long-term geochemical reactivity. Here, we report direct evidence for the evolution of U speciation over 3,300 y in naturally highly U-enriched sediments (350–760 µg ⋅ g(−1) U) from Lake Nègre (Mercantour Massif, Mediterranean Alps, France) by combining U isotopic data (δ(238)U and ((234)U/(238)U)) with U L(3)-edge X-ray absorption fine structure spectroscopy. Constant isotopic ratios over the entire sediment core indicate stable U sources and accumulation modes, allowing for determination of the impact of aging on U speciation. We demonstrate that, after sediment deposition, mononuclear U(IV) species associated with organic matter transformed into authigenic polymeric U(IV)–silica species that might have partially converted to a nanocrystalline coffinite (U(IV)SiO(4)·nH(2)O)-like phase. This diagenetic transformation occurred in less than 700 y and is consistent with the high silica availability of sediments in which diatoms are abundant. It also yields consistency with laboratory studies that proposed the formation of colloidal polynuclear U(IV)–silica species, as precursors for coffinite formation. However, the incomplete transformation observed here only slightly reduces the potential lability of U, which could have important implications to evaluate the long-term management of U-contaminated sediments and, by extension, of U-bearing wastes in silica-rich subsurface environments.

Published
2021
Full Text
View/download PDF

28. Evolution of noncrystalline uranium in lake sediments over 3,300 years

Author

Mathilde Zebracki, Emmanuel Malet, Jean-Louis Reyss, Didier Jézéquel, Charlotte Cazala, Nicolas Menguy, Alkiviadis Gourgiotis, Pauline Merrot, John R. Bargar, Pierre Le Pape, Guillaume Morin, Pierre Lefebvre, Pascale Louvat, Pascale Blanchart, Pierre Sabatier, Camille Baya, Jérôme Gaillardet, Arnaud Mangeret, and Olivier Diez

Subjects
chemistry, Geochemistry, chemistry.chemical_element, Uranium, Geology
Published
2021
Full Text
View/download PDF

31. Pluri-millenial evolution of uranium speciation in lacustrine sediments

Author

Pierre Sabatier, Emmanuel Malet, Arnaud Mangeret, Didier Jézéquel, Olivier Diez, Mathilde Zebracki, Pascale Louvat, Pierre Le Pape, Pierre Lefebvre, Jérôme Gaillardet, Charlotte Cazala, Pauline Merrot, Guillaume Morin, Alkiviadis Gourgiotis, Jean-Louis Reyss, Camille Baya, John R. Bargar, 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), PSE-ENV/SEDRE/LELI, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), 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]), 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), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Minéralogie Environnementale (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), and ATHENA, Irsn

Subjects
[SDE] Environmental Sciences, Radionuclide, Environmental remediation, media_common.quotation_subject, Sediment, chemistry.chemical_element, Uranium, Anoxic waters, Deposition (geology), Diagenesis, Speciation, chemistry, Environmental chemistry, [SDE]Environmental Sciences, Environmental science, media_common
Abstract

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.

Published
2020

34. Intracellular amorphous Ca-carbonate and magnetite biomineralization by a magnetotactic bacterium affiliated to the Alphaproteobacteria

Author

Béatrice Alonso, Magali Floriani, Camille Garau, Elodie Duprat, Christopher T. Lefèvre, Vincent Busigny, Sufal Swaraj, Caroline L. Monteil, Margot Coutaud, Eric Viollier, Didier Jézéquel, Martin Sachse, Romain Bolzoni, Nicolas Menguy, Karim Benzerara, Emmanuel Michot-Achdjian, Nicolas Ginet, Cécile C. Bidaud, François Guyot, François P. Mathon, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), Institut de Physique du Globe de Paris (IPG Paris), Laboratoire de chimie bactérienne (LCB), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Plateforme BioImagerie Ultrastructurale – Ultrastructural BioImaging Platform (UTechS UBI), Institut Pasteur [Paris] (IP), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), This work was supported by the CNRS: 'Programme national Ecosphère Continentale et Côtière (EC2CO)' (BACCARAT2 – N°13068) and the French National Research Agency (SIGMAG: ANR-18-CE31-0003 and PHOSTORE: ANR-19-CE01-0005-02). CCB was supported by the Frontières de l’Innovation en Recherche et Éducation (FIRE) Ph.D. programme from the Centre de Recherches Interdisciplinaires (CRI). Support for the confocal microscope was provided by the Région Provence Alpes Côte d’Azur, Conseil Général des Bouches du Rhône, French Ministry of Research, CNRS and Commissariat à l’Energie Atomique et aux Energies Alternatives., ANR-18-CE31-0003,SIGMAG,SIGNATURE DES MAGNETITES PRODUITES PAR LES BACTERIES MAGNETOTACTIQUES : PERSPECTIVES CHIMIQUES ET ISOTOPIQUES(2018), ANR-19-CE01-0005,PHOSTORE,Piégeage du phosphore : contribution des bactéries magnétotactiques dans les zones de transition oxique-anoxique(2019), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris, and Institut Pasteur [Paris]

Subjects
Biomineralization, [SDV]Life Sciences [q-bio], Magnetosome, Carbonates, Biology, Microbiology, Article, 03 medical and health sciences, chemistry.chemical_compound, In Situ Hybridization, Fluorescence, Ecology, Evolution, Behavior and Systematics, Alphaproteobacteria, 030304 developmental biology, 0303 health sciences, 030306 microbiology, biology.organism_classification, Ferrosoferric Oxide, Calcium carbonate, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, chemistry, Ultrastructure, Biophysics, Carbonate, Magnetosomes, Intracellular, Bacteria
Abstract

International audience; Bacteria synthesize a wide range of intracellular submicrometer-sized inorganic precipitates of diverse chemical compositions and structures, called biominerals. Their occurrences, functions and ultrastructures are not yet fully described despite great advances in our knowledge of microbial diversity. Here, we report bacteria inhabiting the sediments and water column of the permanently stratified ferruginous Lake Pavin, that have the peculiarity to biomineralize both intracellular magnetic particles and calcium carbonate granules. Based on an ultrastructural characterization using transmission electron microscopy (TEM) and synchrotron-based scanning transmission X-ray microscopy (STXM), we showed that the calcium carbonate granules are amorphous and contained within membrane-delimited vesicles. Single-cell sorting, correlative fluorescent in situ hybridization (FISH), scanning electron microscopy (SEM) and molecular typing of populations inhabiting sediments affiliated these bacteria to a new genus of the Alphaproteobacteria. The partially assembled genome sequence of a representative isolate revealed an atypical structure of the magnetosome gene cluster while geochemical analyses indicate that calcium carbonate production is an active process that costs energy to the cell to maintain an environment suitable for their formation. This discovery further expands the diversity of organisms capable of intracellular Ca-carbonate biomineralization. If the role of such biomineralization is still unclear, cell behaviour suggests that it may participate to cell motility in aquatic habitats as magnetite biomineralization does.

Published
2020
Full Text
View/download PDF

35. Geochemistry of an endorheic thalassohaline ecosystem: the Dziani Dzaha crater lake (Mayotte Archipelago, Indian Ocean)

Author

Marc Bouvy, Emilie Le Floc'h, Marc Troussellier, Didier Jézéquel, Hélène Agogué, Magali Ader, Eric Fouilland, Emmanuelle Gérard, Christophe Leboulanger, Cécile Bernard, Mylène Hugoni, Vincent Grossi, Gérard Sarazin, 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), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN), Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Centre National de la Recherche Scientifique (CNRS), French National Research Agency (ANR)ANR-13-BS06-000Universite Montpellier II (project METTRO)Universite Montpellier II (project MYPROBE)Total Corporate Foundation (project DZAHA), 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), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France, Musée National d'Histoire Naturelle de Luxembourg (MNHN), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Biogeochemical cycle, Thalassohaline lake, 010504 meteorology & atmospheric sciences, Mayotte, 010502 geochemistry & geophysics, Cyanobacteria, 01 natural sciences, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Crater lake, Ecosystem, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Trophic level, geography, Biomass (ecology), geography.geographical_feature_category, Biogeochemistry, 15. Life on land, 6. Clean water, Maar, Oceanography, 13. Climate action, Archipelago, Methane emission, [SDE]Environmental Sciences, General Earth and Planetary Sciences, Environmental science, Endorheic ecosystem
Abstract

International audience; Dziani Dzaha is a maar the age of which is close to 4000 years. While its water is thought to have originated from seawater it is now considered as an extreme environment due to its hypersaline and alkaline characteristics. Those extreme features have led to the simplification of the trophic network. Cyanobacteria account for up to 95% of the photosynthetic biomass. The main biogeochemical processes, i.e. photosynthesis, bacterial sulfate reduction and methanogenesis could explain the current water composition. As far as we know, this ecosystem could be unique on Earth, extending the nature and chemical limits of aquatic inland ecosystems.

Published
2020
Full Text
View/download PDF

36. Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Author

Emilie Le Floc'h, Eric Fouilland, Sophie d’Amore, Vincent Milesi, Pierre Cadeau, Cécile Bernard, Didier Jézéquel, Gérard Sarazin, Christophe Leboulanger, Magali Ader, Carine Chaduteau, Amandine Katz, Julia Guélard, 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), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Molécules de Communication et Adaptation des Micro-organismes (MCAM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), 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), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Methanogenesis, Earth science, lcsh:Medicine, 010502 geochemistry & geophysics, 01 natural sciences, Article, Methane, Carbon cycle, Atmosphere, chemistry.chemical_compound, Limnology, lcsh:Science, 0105 earth and related environmental sciences, Total organic carbon, Multidisciplinary, Proterozoic, lcsh:R, Biogeochemistry, chemistry, 13. Climate action, Isotopes of carbon, Greenhouse gas, [SDE]Environmental Sciences, Environmental science, lcsh:Q, Climate sciences
Abstract

The Proterozoic Era records two periods of abundant positive carbon isotope excursions (CIEs), conventionally interpreted as resulting from increased organic carbon burial and leading to Earth’s surface oxygenation. As strong spatial variations in the amplitude and duration of these excursions are uncovered, this interpretation is challenged. Here, by studying the carbon cycle in the Dziani Dzaha Lake, we propose that they could be due to regionally variable methane emissions to the atmosphere. This lake presents carbon isotope signatures deviated by ~ + 12‰ compared to the modern ocean and shares a unique combination of analogies with putative Proterozoic lakes, interior seas or restricted epireic seas. A simple box model of its Carbon cycle demonstrates that its current isotopic signatures are due to high primary productivity, efficiently mineralized by methanogenesis, and to subsequent methane emissions to the atmosphere. By analogy, these results might allow the reinterpretation of some positive CIEs as at least partly due to regionally large methane emissions. This supports the view that methane may have been a major greenhouse gas during the Proterozoic Era, keeping the Earth from major glaciations, especially during periods of positive CIEs, when increased organic carbon burial would have drowned down atmospheric CO2.

Published
2020
Full Text
View/download PDF

37. Magnetotactic bacteria as a new model for P sequestration in the ferruginous Lake Pavin

Author

Fériel Skouri-Panet, François Guyot, N. Trcera, Didier Jézéquel, Christopher T. Lefèvre, Caroline L. Monteil, Karim Benzerara, Nicolas Menguy, Elodie Duprat, Eric Viollier, Mélanie Poinsot, Jennyfer Miot, Céline Férard, S. Rivas-Lamelo, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Biologie végétale et microbiologie environnementale - UMR7265 (BVME), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Microbiologie Environnementale et Moléculaire (MEM), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), ANR-14-CE33-0003,SRB,Sulfato-Réduction Bactérienne: mécanismes de biominéralisation et préservation de biosignatures d'un métabolisme phare de l'histoire de la Terre(2014), European Project: 307110,EC:FP7:ERC,ERC-2012-StG_20111012,CALCYAN(2013), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
food.ingredient, 010504 meteorology & atmospheric sciences, Magnetotactic bacteria, Microorganism, Context (language use), Beggiatoa, 01 natural sciences, Geochemical cycle, 03 medical and health sciences, food, Water column, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Geochemistry and Petrology, Environmental Chemistry, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 030304 developmental biology, 0105 earth and related environmental sciences, 0303 health sciences, biology, Ecology, Chemistry, Geology, biology.organism_classification, 6. Clean water, Enhanced biological phosphorus removal, Environmental chemistry, Thiomargarita
Abstract

International audience; The role of microorganisms in the geochemical cycle of P has received great interest in the context of enhanced biological phosphorus removal and phosphorite formation. Here, we combine scanning and transmission electron microscopies, confocal laser scanning microscopy and synchrotron-based x-ray microfluorescence to analyse the distribution of P at the oxic-anoxic interface in the water column of the ferruginous Lake Pavin. We show that magnetotactic bacteria of the Magnetococca-ceae family strongly accumulate polyphosphates and appear as P hotspots in the particulate fraction at this depth. This high accumulation may be characteristic of this family and may also relate to the chemical conditions prevailing in the lake. As a result, these magneto-tactic cocci can be considered as new models playing a potentially important role in the P geochemical cycle, similar to sulphide oxidising bacteria such as Thiomargarita and Beggiatoa but thriving in a ferruginous, poorly sulphidic environment.

Published
2017
Full Text
View/download PDF

38. SEQUESTERED CHLOROPLASTS IN THE BENTHIC FORAMINIFERHAYNESINA GERMANICA: CELLULAR ORGANIZATION, OXYGEN FLUXES AND POTENTIAL ECOLOGICAL IMPLICATIONS

Author

Didier Jézéquel, Emmanuelle Geslin, Frans Jorissen, Thierry Jauffrais, Guillaume Mabilleau, Dewi Langlet, Edouard Metzger, Charlotte Le Kieffre, Maria Pia Nardelli, Florian Cesbron, Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Groupe d'Études Remodelage Osseux et bioMatériaux (GEROM), Laboratoire de Planétologie et Géodynamique - Angers (LPG-ANGERS), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Bio-Indicateurs Actuels et Fossiles (BIAF), Groupe Etudes Remodelage Osseux et bioMatériaux (GEROM), Laboratoire de Planétologie et Géodynamique - Bio-Indicateurs Actuels et Fossiles (LPG-BIAF), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, and Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)

Subjects
0106 biological sciences, chemistry.chemical_classification, 010504 meteorology & atmospheric sciences, Ecology, [SDV]Life Sciences [q-bio], 010604 marine biology & hydrobiology, Heterotroph, Paleontology, Biogeochemistry, 15. Life on land, Biology, Photosynthesis, 01 natural sciences, Microbiology, Chloroplast, chemistry, Benthic zone, Botany, Organic matter, Autotroph, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, ComputingMilieux_MISCELLANEOUS, Mixotroph, 0105 earth and related environmental sciences
Abstract

Haynesina germanica is a coastal benthic foraminifer known to sequester chloroplasts from benthic pennate diatoms. This study investigates its cellular organization, as well as the oxygen consumption and production rates under dark and light conditions. The implications of the sequestered chloroplasts are subsequently discussed at an individual and ecological level. Living specimens collected in Arcachon Basin showed well-preserved chloroplasts in the cytoplasm in observations using transmission electron microscopy. Microelectrodes were used to measure oxygen consumption and production rates in incubated specimens in the laboratory. In the dark, oxygen consumption rates ranged from 662 ± 12 to 1082 ± 59 pmol O 2 ind -1 d -1 . Under illuminated conditions (i.e., about 300 μmol photon -1 m -2 s -1 ), we observed and quantified substantial photosynthetic activity, up to 199 pmol O 2 ind -1 d -1 . It appears that H. germanica combines autotrophic and heterotrophic nutritional modes, thereby reflecting a mixotrophic strategy. In Arcachon Basin, H. germanica potentially uses chloroplasts acquired from microphytobenthos to carry out photosynthesis and produce oxygen and organic matter. Stored chloroplasts could constitute an additional food source during impoverished periods, providing substantial competitive advantage to this species. This putative behavior could also affect the biogeochemistry of the sediment at a microscale by creating oxygenated microniches around individual foraminifera.

Published
2017
Full Text
View/download PDF

39. Natural H2in Kansas: Deep or shallow origin?

Author

Magali Ader, Didier Jézéquel, Julia Guélard, Eric Deville, François Guyot, Virgile Rouchon, Valérie Beaumont, K. D. Newell, and Daniel Pillot

Subjects
geography, geography.geographical_feature_category, Radiogenic nuclide, 010504 meteorology & atmospheric sciences, Geochemistry, Mineralogy, Aquifer, Direct reduced iron, 010502 geochemistry & geophysics, 01 natural sciences, Methane, chemistry.chemical_compound, Geophysics, Basement (geology), chemistry, 13. Climate action, Geochemistry and Petrology, Dissolved organic carbon, Sedimentary rock, Gas composition, Geology, 0105 earth and related environmental sciences
Abstract

A geochemical study of gas coming from three wells in northeastern Kansas supplements previous studies from the 1980s and points to a persistent regional phenomenon of H2 production. In 2008, a new well showed, just after drilling, a free gas phase with more than 80 mole % of H2, followed by water production associated with gas. This gas is mainly composed of N2, He, H2, and occasionally CH4, with changing proportions through time. A drastic decrease in H2 at the well was observed since the aquifer is produced, along with occasional recharges in H2 evidenced notably in the early phases of gas sampling. We demonstrate that this evolution of gas composition is closely associated to the well completion story. Accordingly, two distinct origins of H2 are proposed: (1) deep crustal H2: water reduction associated to iron oxidation in the Precambrian basement; (2) reactions occurring in the tubing, primarily attributed to high contents of reduced iron and/or dissolved organic carbon (DOC = 4.1 mg L−1) in the water. The low δD values averaging −760‰ are attributed to a low temperature process, possibly a re-equilibration with water. Furthermore, the suggested origins are supported by the observed gas associations: (a) deep crustal H2 with radiogenic gases (4He and 40Ar) and metamorphic N2 (δ15N averaging +2.5‰); (b) surficial H2 with methane produced in the sedimentary aquifer and the tubing by methanogenic organisms.

Published
2017
Full Text
View/download PDF

40. Formation of magnesium-smectite during lacustrine carbonates early diagenesis: study case of the volcanic crater lake Dziani Dzaha (Mayotte - Indian Ocean)

Author

Vincent Milesi, Emmanuelle Vennin, Eric C. Gaucher, Pierre Cadeau, François Guyot, Gérard Sarazin, Aurélien Virgone, Mathieu Debure, Magali Ader, Francis Claret, Didier Jézéquel, Carine Chaduteau, Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), ASU School of Earth and Space Exploration (SESE), Arizona State University [Tempe] (ASU), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), 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), Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), TOTAL-Scientific and Technical Center Jean Féger (CSTJF), TOTAL FINA ELF, Work supported by IPGP, TOTAL (project FR00008189), Total Corporate Foundation (project 755 DZAHA) and one INSU-INTERRVIE grant (grant number AO2013-785992)., and ANR-13-BS06-0001,Dziani,Ecalairages sur les océans précambriens par l'étude biogéochimique et microbiologique d'un analogue actuel: le lac Dziani Dzaha, Mayotte.(2013)

Subjects
010506 paleontology, saponite, organic matter decomposition, Stratigraphy, Geochemistry, magnesian clays, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, lacustrine carbonates, Volcanic Gases, chemistry.chemical_compound, Crater lake, event, Hydromagnesite, 0105 earth and related environmental sciences, event.disaster_type, volcanic lake, geography, geography.geographical_feature_category, Aragonite, Geology, Authigenesis, Diagenesis, chemistry, Volcano, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, engineering, Carbonate, Carbonate rock, early diagenesis
Abstract

19 pages; International audience; The volcanic crater lake of Dziani Dzaha in Mayotte is studied to constrain the geochemical settings and the diagenetic processes at the origin of Mg‐phyllosilicates associated with carbonate rocks. The Dziani Dzaha is characterized by intense primary productivity, volcanic gases bubbling in three locations and a volcanic catchment of phonolitic/alkaline composition. The lake water has an alkalinity of ca 0·2 mol l−1 and pH values of ca 9·3. Cores of the lake sediments reaching up to one metre in length were collected and studied by means of carbon–hydrogen–nitrogen elemental analyzer, X‐ray fluorescence spectrometry and X‐ray powder diffraction. In surface sediments, the content of total organic carbon reaches up to 20 weight %. The mineral content consists of aragonite and hydromagnesite with minor amounts of alkaline feldspar and clinopyroxene from the volcanic catchment. Below 30 cm depth, X‐ray diffraction analyses of the

Published
2019
Full Text
View/download PDF

41. Two-dimensional ammonium distribution in sediment pore waters using a new colorimetric diffusive equilibration in thin-film technique

Author

Aurélia Mouret, Florian Cesbron, Anthony Barbe, Didier Jézéquel, Thierry Jauffrais, Aubin Thibault de Chanvalon, Edouard Metzger, Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Bio-Indicateurs Actuels et Fossiles (BIAF), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), and Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Materials science, Analytical chemistry, 010501 environmental sciences, Standard solution, 01 natural sciences, lcsh:TD1-1066, Porewater, chemistry.chemical_compound, Pore water pressure, [CHIM]Chemical Sciences, Ammonium, Diffusion (business), lcsh:Environmental technology. Sanitary engineering, Waste Management and Disposal, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Water Science and Technology, Detection limit, Full Paper, 010604 marine biology & hydrobiology, Ecological Modeling, Biogeochemistry, Pollution, DET, 6. Clean water, chemistry, Reagent, Seawater, High-resolution, Colorimetric analysis, Densitometry
Abstract

This study presents a new gel based technique to describe the pore water ammonium distribution through the sediment-water interface in two dimensions at a millimeter scale. The technique is an adaptation of the classical colorimetric method based on the Berthelot's reaction. After the thin film of the gel probe was equilibrated by diffusion either in standard solutions or in pore waters, a colorimetric reagent gel was set on the gel probe, allowing development of the characteristic green color. A flatbed scanner and subsequent densitometry image analysis allowed to determine the concentration distribution of ammonium. The gel probe was tested in the laboratory for two media, deionized water and seawater, within the range 0–3000 μM in NH4+. Detection limit is about 20 μM and accuracy about ±25 μM. The field validation was realized in a tidal mudflat of the French Atlantic coast by comparison with conventional pore water extraction and colorimetric analysis. The large range of concentrations and its applicability in continental and marine sediments suggest a wide range of applications of the technique for a reasonable cost., Graphical abstract Image 1, Highlights • Fast and inexpensive ammonium 2D imaging through the sediment water interface. • Millimetric spatial resolution. • Applicable in marine and fresh aquatic systems.

Published
2019
Full Text
View/download PDF

42. Very Low Phytoplankton Diversity in a Tropical Saline-Alkaline Lake, with Co-dominance of Arthrospira fusiformis (Cyanobacteria) and Picocystis salinarum (Chlorophyta)

Author

Arthur Escalas, Christophe Leboulanger, Nicolas Villeriot, Hélène Agogué, Cécile Bernard, Gérard Sarazin, Patrice Got, Maga Ader, Mylène Hugoni, Didier Jézéquel, Vincent Grossi, Marc Troussellier, Charlotte Duval, Claire Carré, Molécules de Communication et Adaptation des Micro-organismes (MCAM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Vétérinaire de Lyon (ENVL)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Total Corporate Foundation (DZAHA project) C001493, ANR-13-BS06-0001,Dziani,Ecalairages sur les océans précambriens par l'étude biogéochimique et microbiologique d'un analogue actuel: le lac Dziani Dzaha, Mayotte.(2013), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Ecole Nationale Vétérinaire de Lyon (ENVL), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0301 basic medicine, Chlorophyll a, Thalassohaline lake, 030106 microbiology, Soil Science, Chlorophyta, [SDV.BID]Life Sciences [q-bio]/Biodiversity, Biology, Cyanobacteria, 03 medical and health sciences, chemistry.chemical_compound, Water column, Phytoplankton, Spirulina, Environmental Microbiology, Dominance (ecology), Biomass, 14. Life underwater, Picoeukaryote, Indian Ocean, Ecosystem, Ecology, Evolution, Behavior and Systematics, Islands, Diversity, Ecology, Chlorophyll A, Aquatic ecosystem, Biodiversity, 15. Life on land, biology.organism_classification, Lakes, 030104 developmental biology, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, chemistry, Aphotic zone, Extreme environment, [SDE]Environmental Sciences, Seasons
Abstract

Lake Dziani Dzaha (Mayotte Island, Indian Ocean) is a tropical thalassohaline lake which geochemical and biological conditions make it a unique aquatic ecosystem considered as a modern analogue of Precambrian environments. In the present study, we focused on the diversity of phytoplanktonic communities, which produce very high and stable biomass (mean2014–2015 = 652 ± 179 μg chlorophyll a L−1). As predicted by classical community ecology paradigms, and as observed in similar environments, a single species is expected to dominate the phytoplanktonic communities. To test this hypothesis, we sampled water column in the deepest part of the lake (18 m) during rainy and dry seasons for two consecutive years. Phytoplanktonic communities were characterized using a combination of metagenomic, microscopy-based and flow cytometry approaches, and we used statistical modeling to identify the environmental factors determining the abundance of dominant organisms. As hypothesized, the overall diversity of the phytoplanktonic communities was very low (15 OTUs), but we observed a co-dominance of two, and not only one, OTUs, viz., Arthrospira fusiformis (Cyanobacteria) and Picocystis salinarum (Chlorophyta). We observed a decrease in the abundance of these co-dominant taxa along the depth profile and identified the adverse environmental factors driving this decline. The functional traits measured on isolated strains of these two taxa (i.e., size, pigment composition, and concentration) are then compared and discussed to explain their capacity to cope with the extreme environmental conditions encountered in the aphotic, anoxic, and sulfidic layers of the water column of Lake Dziani Dzaha. Electronic supplementary material The online version of this article (10.1007/s00248-019-01332-8) contains supplementary material, which is available to authorized users.

Published
2019
Full Text
View/download PDF

43. Vertical distribution and respiration rates of benthic foraminifera: Contribution to aerobic remineralization in intertidal mudflats covered by Zostera noltei meadows

Author

Frans Jorissen, Didier Jézéquel, M.L. Delgard, Florian Cesbron, Bruno Deflandre, Laurie M. Charrieau, Edouard Metzger, Pierre Anschutz, Emmanuelle Geslin, Bio-Indicateurs Actuels et Fossiles (BIAF), and Université d'Angers (UA)

Subjects
0106 biological sciences, Carbon remineralization, 010504 meteorology & atmospheric sciences, [SDV]Life Sciences [q-bio], Meiobenthos, Intertidal zone, Aquatic Science, Oceanography, 01 natural sciences, Foraminifera, 14. Life underwater, 0105 earth and related environmental sciences, Zostera noltei, biology, Ecology, 010604 marine biology & hydrobiology, Sediment, Biogeochemistry, 15. Life on land, biology.organism_classification, Living benthic foraminifera, Seagrass, Ammonia tepida, Benthic zone, Microhabitat
Abstract

International audience; The present study investigates the influence of seagrass root systems on benthic hard-shelled meiofauna (foraminifera). In February and July 2011, sediment cores were collected at low tide at two sites in Arcachon lagoon, a vegetated site with Zostera noltei and a second site with bare sediments. We used the highly discriminative CellTracker™ Green fluorogenic probe technique to recognize living foraminifera and to describe foraminiferal density and diversity. Three dominant species of foraminifera were observed: Ammonia tepida, Haynesina germanica and Eggerella scabra. The two calcareous species, A.tepida and H.germanica, were preferentially found in the upper half to 1cm of the sediment. At the vegetated site, these two species had a slightly deeper microhabitat. In the literature, both species have been described alive in much deeper sediment layers, possibly due to false positives from the Rose Bengal staining method. These two species also showed 1) higher densities at the site with Z.noltei, 2) a higher density in February when conditions were supposed optimal due to a microphytobenthos bloom, and 3) dissolved calcitic shells in July, probably resulting from a lower pH. The agglutinated species E.scabra was present alive down to at least 7cm depth. E.scabra showed high densities in the anoxic part of the sediment at both the vegetated and bare sites, with a substantially higher density in summer at the site with bare sediments. Its presence at depth may be related to its trophic requirements; this species could be less dependent on labile organic matter than A.tepida and H.germanica. On this intertidal mudflat, the foraminiferal contribution to aerobic carbon remineralization, based on respiration rate measurements, can account for up to 7% of the diffusive oxygen uptake, almost five times more than the maximum contribution recorded in open marine environments (300m depth) in the Bay of Biscay.

Published
2016
Full Text
View/download PDF

44. Simultaneous Nitrite/Nitrate Imagery at Millimeter Scale through the Water–Sediment Interface

Author

Edouard Metzger, Didier Jézéquel, Anthony Barbe, Aurélia Mouret, Florian Cesbron, Patrick Launeau, A. Thibault De Chanvalon, Bio-Indicateurs Actuels et Fossiles (BIAF), and Université d'Angers (UA)

Subjects
Detection limit, Nitrates, Spectral signature, 010504 meteorology & atmospheric sciences, [SDV]Life Sciences [q-bio], Inorganic chemistry, Analytical chemistry, Water, Hyperspectral imaging, General Chemistry, 010501 environmental sciences, 01 natural sciences, chemistry.chemical_compound, Nitrate, chemistry, Reagent, Environmental Chemistry, Vanadium chloride, Colorimetry, Nitrite, Nitrites, Water Pollutants, Chemical, 0105 earth and related environmental sciences, Visible spectrum
Abstract

International audience; The present study describes new procedures to obtain at millimeter resolution the spatial distribution of nitrite and nitrate in porewaters, combining diffusive equilibrium in thin films (DET), colorimetry and hyperspectral imagery. Nitrite distribution can be easily achieved by adapting the well-known colorimetric method from Griess (1879) and using a common flatbed scanner with a limit of detection about 1.7 μmol L–1. Nitrate distribution can be obtained after reduction into nitrite by a vanadium chloride reagent. However, the concentration of vanadium chloride used in this protocol brings coloration with a wide spectral signature that creates interference only deconvolvable by imaging treatment from an entire visible spectrum for each pixel (spectral analysis). This can be achieved by hyperspectral imaging. The protocol retained in the present study allows obtaining a nitrite/nitrate image with micromolar limit of detection. The methods were applied in sediments from the Loire Estuary after different treatments and allowed to precisely describe two-dimensional millimeter features. The present technique adds to the combination of gel-colorimetry and hyperspectral imagery a very promising new application of wide interest for environmental issues in the context of early diagenesis and benthic fluxes.

Published
2016
Full Text
View/download PDF

45. Spatiotemporal variations in microbial diversity across the three domains of life in a tropical thalassohaline lake (Dziani Dzaha, Mayotte Island)

Author

Arthur Escalas, Marc Bouvy, Marc Troussellier, Christophe Leboulanger, Didier Jézéquel, Cécile Bernard, Mylène Hugoni, Gérard Sarazin, Hélène Agogué, Fanny Vazzoler, M. Ader, Sébastien Nicolas, Patrice Got, Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Vétérinaire de Lyon (ENVL)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS), Molécules de Communication et Adaptation des Micro-organismes (MCAM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Ecole Nationale Vétérinaire de Lyon (ENVL), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Total Corporate Foundation [C001493], ANR [ANR-13-BS06-0001], Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), and La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0301 basic medicine, Salinity, Firmicutes, archaea, Microorganism, 030106 microbiology, [SDV.BID.SPT]Life Sciences [q-bio]/Biodiversity/Systematics, Phylogenetics and taxonomy, Comoros, 03 medical and health sciences, Spatio-Temporal Analysis, eukaryotes, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Genetics, Extreme environment, Ecosystem, extreme environment, 14. Life underwater, Photosynthesis, bacteria, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Soda lake, Ecology, Evolution, Behavior and Systematics, geography, biology, Phylum, Ecology, Soda Lakes, Eukaryota, Bacteroidetes, Biodiversity, 15. Life on land, respiratory system, biology.organism_classification, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, [SDE.ES]Environmental Sciences/Environmental and Society, Lakes, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, 030104 developmental biology, thalassohaline lake, geography.geographical_feature, metabarcoding, Seasons, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Water Microbiology, human activities, Extreme Environments, Archaea, [SDV.EE.IEO]Life Sciences [q-bio]/Ecology, environment/Symbiosis
Abstract

International audience; Thalassohaline ecosystems are hypersaline environments originating from seawater in which sodium chloride is the most abundant salt and the pH is alkaline. Studies focusing on microbial diversity in thalassohaline lakes are still scarce compared with those on athalassohaline lakes such as soda lakes that have no marine origin. In this work, we investigated multiple facets of bacterial, archaeal and eukaryotic diversity in the thalassohaline Lake Dziani Dzaha using a metabarcoding approach. We showed that bacterial and archaeal diversity were mainly affected by contrasting physicochemical conditions retrieved at different depths. While photosynthetic microorganisms were dominant in surface layers, chemotrophic phyla (Firmicutes or Bacteroidetes) and archaeal methanogens dominated deeper layers. In contrast, eukaryotic diversity was constant regardless of depth and was affected by seasonality. A detailed focus on eukaryotic communities showed that this constant diversity profile was the consequence of the high predominance of Picocystis salinarum, while nondominant eukaryotic groups displayed seasonal diversity turnover. Altogether, our results provided an extensive description of the diversity of the three domains of life in an unexplored extreme environment and showed clear differences in the responses of prokaryotic and eukaryotic communities to environmental conditions.

Published
2018
Full Text
View/download PDF

46. A multiscale study of mercury transformations and dynamics at the chemocline of the Petit-Saut tropical reservoir (French Guiana)

Author

Didier Jézéquel, Daniel Cossa, Edouard Metzger, Bogdan Muresan, Laboratoire de Planétologie et Géodynamique - Angers (LPG-ANGERS), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Atlantique (IFREMER Atlantique), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre d'Enseignement et de Recherche Eau Ville Environnement (CEREVE), AgroParisTech-École des Ponts ParisTech (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Laboratoire de Planétologie et Géodynamique - Bio-Indicateurs Actuels et Fossiles (LPG-BIAF), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Institut Français de Recherche pour l'Exploitation de la Mer - Nantes (IFREMER Nantes), Université de Nantes (UN), and Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Biogeochemical cycle, Environmental Engineering, 010504 meteorology & atmospheric sciences, chemistry.chemical_element, 010501 environmental sciences, Chemocline, 01 natural sciences, Pollution, Redox, Mercury (element), Nutrient, Water column, chemistry, Environmental chemistry, Epilimnion, Dissolved organic carbon, [SDE]Environmental Sciences, Environmental Chemistry, Waste Management and Disposal, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

This study investigated, on both metric and centimetric scales, mercury (Hg) transformations and dynamics within a water column chemocline of a tropical reservoir. Data collected included conventional measurement of Hg in water samples, diffusive gradients in thin-films (DGT) assessments, and thermodynamic speciation modeling in order to portray the biogeochemical processes that control elemental Hg (EM) and dissolved monomethylated Hg (MeHgD) production. The primary contribution of this study is demonstration that the DGT technique can be successfully implemented to examine labile Hg compound mobilization, and estimation of how local substratum facilitates Hg reduction and methylation reactions. DGT profiles with a resolution of 1 cm revealed a fine sequence of prominent Hg reduction/oxidation reactions at the chemocline level. This is interpreted as a manifestation of both: i) kinetic effects capable of arising inside the diffusive layer of DGT devices, and ii) extremely localized production or consumption of reducible and methylable Hg. Another key result obtained at the metric scale is that EM and MeHgD production at a water column chemocline are intricately linked, as both are fueled by nutrients episodically released during the decomposition of falling epilimnetic organic particles or inhibited by dissolved organic matter and inorganic compounds continuously transported from the deeper monimolimnion. Finally, it is worth noting that the chemocline acts as an accumulation and recycling domain for falling MeHg-loaded organic particles, whereas the high primary productivity layer in the epilimnion represents the principal reactor with respect to Hg methylation and reduction.

Published
2018
Full Text
View/download PDF

47. Key role of Alphaproteobacteria and Cyanobacteria in the formation of stromatolites of lake Dziani Dzaha (Mayotte, Western Indian Ocean)

Author

Laurent Richard, Siham De Goeyse, Lena Lecourt, Emmanuelle Gérard, Magali Ader, Gérard Sarazin, Didier Jézéquel, Christophe Leboulanger, Hélène Agogué, Thomas Leclerc, Stephan Borensztajn, Marie-Béatrice Joseph, Mylène Hugoni, Vincent Milesi, François Guyot, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Vétérinaire de Lyon (ENVL)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Nazarbayev University [Kazakhstan], Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris ( IPGP ), Institut national des sciences de l'Univers ( INSU - CNRS ) -IPG PARIS-Université Paris Diderot - Paris 7 ( UPD7 ) -Université de la Réunion ( UR ) -Centre National de la Recherche Scientifique ( CNRS ), Ecologie microbienne ( EM ), Centre National de la Recherche Scientifique ( CNRS ) -Ecole Nationale Vétérinaire de Lyon ( ENVL ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique ( INRA ) -VetAgro Sup ( VAS ), LIttoral ENvironnement et Sociétés - UMR 7266 ( LIENSs ), Université de La Rochelle ( ULR ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de minéralogie, de physique des matériaux et de cosmochimie ( IMPMC ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique ( CNRS ), MARine Biodiversity Exploitation and Conservation ( UMR MARBEC ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Ecole Nationale Vétérinaire de Lyon (ENVL), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD)

Subjects
0301 basic medicine, Microbiology (medical), Cyanobacteria, lcsh:QR1-502, alkaline lake, Mg-silicate, cyanobactérie, Pleurocapsales, [ SDV.MP.BAC ] Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, engineering.material, Microbiology, aragonite, lcsh:Microbiology, 03 medical and health sciences, chemistry.chemical_compound, stromatolites, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Crater lake, hydromagnesite, Botany, [ SDV.EE.IEO ] Life Sciences [q-bio]/Ecology, environment/Symbiosis, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, 14. Life underwater, Microbial mat, Hydromagnesite, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Original Research, Alphaproteobacteria, Calcite, [ SDE.BE ] Environmental Sciences/Biodiversity and Ecology, microscopie à balayage électronique, biology, Aragonite, biology.organism_classification, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, mayotte, [ SDV.EE.ECO ] Life Sciences [q-bio]/Ecology, environment/Ecosystems, anoxygenic phototrophic bacteria, 030104 developmental biology, chemistry, engineering, minéralisation, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology, [SDV.EE.IEO]Life Sciences [q-bio]/Ecology, environment/Symbiosis
Abstract

International audience; Lake Dziani Dzaha is a thalassohaline tropical crater lake located on the " Petite Terre " Island of Mayotte (Comoros archipelago, Western Indian Ocean). Stromatolites are actively growing in the shallow waters of the lake shores. These stromatolites are mainly composed of aragonite with lesser proportions of hydromagnesite, calcite, dolomite, and phyllosilicates. They are morphologically and texturally diverse ranging from tabular covered by a cauliflower-like crust to columnar ones with a smooth surface. High-throughput sequencing of bacterial and archaeal 16S rRNA genes combined with confocal laser scanning microscopy (CLSM) analysis revealed that the microbial composition of the mats associated with the stromatolites was clearly distinct from that of the Arthrospira-dominated lake water. Unicellular-colonial Cyanobacteria belonging to the Xenococcus genus of the Pleurocapsales order were detected in the cauliflower crust mats, whereas filamentous Cyanobacteria belonging to the Leptolyngbya genus were found in the smooth surface mats. Observations using CLSM, scanning electron microscopy (SEM) and Raman spectroscopy indicated that the cauliflower texture consists of laminations of aragonite, magnesium-silicate phase and hydromagnesite. The associated microbial mat, as confirmed by laser microdissection and whole-genome amplification (WGA), is composed of Pleurocapsales coated by abundant filamentous and coccoid Alphaproteobacteria. These phototrophic Alphaproteobacteria promote the precipitation of aragonite in which they become incrusted. In contrast, the Pleurocapsales are not calcifying but instead accumulate silicon and magnesium in their sheaths, which may be responsible for the formation of the Mg-silicate phase found in the cauliflower crust. We therefore propose that Pleurocapsales and Alphaproteobacteria are involved in the formation of two distinct mineral phases present in the cauliflower texture: Mg-silicate and aragonite, respectively. These results point out the role of phototrophic Alphaproteobacteria in the formation of stromatolites, which may open new perspective for the analysis of the fossil record.

Published
2018
Full Text
View/download PDF

48. Lake Pavin : History, Geology, Biogeochemistry, and Sedimentology of a Deep Meromictic Maar Lake

Author

Télesphore Sime-Ngando, Pierre Boivin, Emmanuel Chapron, Didier Jezequel, Michel Meybeck, Télesphore Sime-Ngando, Pierre Boivin, Emmanuel Chapron, Didier Jezequel, and Michel Meybeck

Subjects
Maars--France, Crater lakes--France
Abstract

This book represents the first multidisciplinary scientific work on a deep volcanic maar lake in comparison with other similar temperate lakes. The syntheses of the main characteristics of Lake Pavin are, for the first time, set in a firmer footing comparative approach, encompassing regional, national, European and international aquatic science contexts. It is a unique lake because of its permanently anoxic monimolimnion, and furthermore, because of its small surface area, its substantially low human influence, and by the fact that it does not have a river inflow. The book reflects the scientific research done on the general limnology, history, origin, volcanology and geological environment as well as on the geochemistry and biogeochemical cycles. Other chapters focus on the biology and microbial ecology whereas the sedimentology and paleolimnology are also given attention. This volume will be of special interest to researchers and advanced students, primarily in the fields of limnology, biogeochemistry, and aquatic ecology.

Published
2016

49. Millimeter-scale alkalinity measurement in marine sediment using DET probes and colorimetric determination

Author

C. Simonucci, Eric Viollier, Edouard Metzger, François Prévot, Didier Jézéquel, Dewi Langlet, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude des Transferts dans les Sols et le sous-sol (DEI/SARG/LETS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Bio-Indicateurs Actuels et Fossiles (BIAF), and Université d'Angers (UA)

Subjects
Geologic Sediments, Environmental Engineering, 010504 meteorology & atmospheric sciences, Calibration curve, Alkalinity, Bromophenol blue, 010501 environmental sciences, 01 natural sciences, Absorbance, chemistry.chemical_compound, Pore water pressure, Seawater, 14. Life underwater, Waste Management and Disposal, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Water Science and Technology, Civil and Structural Engineering, Chemistry, Ecological Modeling, Sediment, Pollution, Anoxic waters, 6. Clean water, Environmental chemistry, Carbonate, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Water Pollutants, Chemical, Environmental Monitoring
Abstract

Constrained DET (Diffusive Equilibration in Thin films) probes equipped with 75 sampling layers of agarose gel (DGT Research(©)) were used to sample bottom and pore waters in marine sediment with a 2 mm vertical resolution. After retrieval, each piece of hydrogel, corresponding to 25 μL, was introduced into 1 mL of colorimetric reagent (CR) solution consisting of formic acid and bromophenol blue. After the elution/reaction time, absorbance of the latter mixture was read at 590 nm and compared to a calibration curve obtained with the same protocol applied to mini DET probes soaked in sodium hydrogen carbonate standard solutions. This method allows rapid alkalinity determinations for the small volumes of anoxic pore water entrapped into the gel. The method was assessed on organic-rich coastal marine sediments from Thau lagoon (France). Alkalinity values in the overlying waters were in agreement with data obtained by classical sampling techniques. Pore water data showed a progressive increase of alkalinity in the sediment from 2 to 10 mmol kg(-1), corresponding to anaerobic respiration in organic-rich sediments. Moreover, replicates of high-resolution DET profiles showed important lateral heterogeneity at a decimeter scale. This underlines the importance of high-resolution spatial methods for alkalinity profiling in coastal marine systems.

Published
2013
Full Text
View/download PDF

50. Lake Pavin Mixing: New Insights from High Resolution Continuous Measurements

Author

Michel Poulin, Céline Bonhomme, Bruno Tassin, Didier Jézéquel, Brigitte Vinçon-Leite, Mohamed Saad, laboratoire Eau Environnement et Systèmes Urbains (LEESU), AgroParisTech-École des Ponts ParisTech (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Centre de Géosciences (GEOSCIENCES), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Télesphore Sime-Ngando, Pierre Boivin, Emmanuel Chapron, Didier Jezequel, Michel Meybeck, MINES ParisTech - École nationale supérieure des mines de Paris-PSL Research University (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), and Mines Paris - PSL (École nationale supérieure des mines de Paris)

Subjects
Hydrology, 010504 meteorology & atmospheric sciences, Geochemistry, Temperature, High resolution, Meromixis, Chemocline, 01 natural sciences, 6. Clean water, 010305 fluids & plasmas, Turbulence, Geography, 13. Climate action, Water mixing, 0103 physical sciences, [SDE]Environmental Sciences, Kz, Mixing (physics), 0105 earth and related environmental sciences
Abstract

International audience; As a meromictic lake, Lake Pavin mixing is very specific. The chemocline located at about 60 m depth separates the mixolimnion (fully or partially mixed according to the year) and the monimolimnion. Deep layers are geothermally heated and stability is ensured at the bottom of the lake by the increasing dissolved substance concentration. The monimolimnion forms a compartment which has its own specific dynamics but that may interact with the mixolimnion at large time scales. Understanding of physical mixing processes is crucial to study further geochemical processes.Temperature and turbulence were investigated in 2006 and 2007 using continuous measurements, a CTD and a high resolution temperature microstructure profiler (SCAMP). Continuous measurements give the evidence of a sublacustrine spring discharging intermittently into the mixolimnion around 55 m depth. This cold water input was observed using thermistor chains at different depths in 2007. Because of its low saline content, the spring water input rises in the water column by saline convection. The use of a simple conceptual model, representing turbulent diapycnal diffusivity and convection shows its role in maintaining the meromixis characteristic of the lake on the intra-annual time scale. The spring also influences seasonal overturns and thus contributes to establish the depth of the mixolimnion–monimolimnion interface on the interannual time scale.Using SCAMP, vertical dispersion coefficients are estimated by different methods. Vertical dispersion coefficients show a high space and time variability. The use of these data in the geochemical model AQUASIM applied to Lake Pavin shows a variability of model outputs directly depending on mixing inputs and their variability.

Published
2016
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results