Search

Your search keyword '"Delarue, Frédéric"' showing total 150 results
Start Over Author "Delarue, Frédéric"
150 results on '"Delarue, Frédéric"'

14. New approach to evaluate the intensity of ancient human activities, based on organic matter characteristics using Rock-Eval® thermal analysis.

Author

Aubertin, Marie-Liesse, primary, Malou, Oscar Pascal, additional, Arroyo-Kalin, Manuel, additional, Lombardo, Umberto, additional, Chevallier, Tiphaine, additional, Oliva, Priscia, additional, Delarue, Frédéric, additional, Thiesson, Julien, additional, Quenea, Katell, additional, Sebag, David, additional, and de Saulieu, Geoffroy, additional

Published
2023
Full Text
View/download PDF

15. Multi-elemental and Strontium-Neodymium Isotopic Signatures in Charred Wood: Potential for Wood Provenance Studies

Author

Štulc, Anna Imbert, primary, Poszwa, Anne, additional, Ponton, Stéphane, additional, Dupouey, Jean-Luc, additional, Bouchez, Julien, additional, Bardin, Jérémie, additional, Delarue, Frédéric, additional, Coubray, Sylvie, additional, Lemoine, Michel, additional, Rose, Christophe, additional, Ruelle, Julien, additional, Beuret, Maximilien, additional, Tu, Thanh Thuy Nguyen, additional, and Dufraisse, Alexa, additional

Published
2023
Full Text
View/download PDF

16. Short-Term Modifications in the Chemical Structure of Wood Charcoals: Implications for Anthracological Investigations

Author

Delarue, Frédéric, primary, Ghavidel, Amir, additional, Quénéa, Katell, additional, Gurlet, Ludovic Bellot, additional, Rocha, Eva, additional, Coubray, Sylvie, additional, Baudin, François, additional, SEBAG, David, additional, Lemoine, Michel, additional, Aubry, Emmanuel, additional, Savignac, Florence, additional, and Dufraisse, Alexa, additional

Published
2023
Full Text
View/download PDF

17. Food Web Structure and Energy Flux Dynamics, But Not Taxonomic Richness, Influence Microbial Ecosystem Functions in A Sphagnum-Dominated Peatland

Author

Jassey, Vincent, primary, Petchey, Owen, additional, Binet, Philippe, additional, Buttler, Alexandre, additional, Chiapusio, Geneviève, additional, Delarue, Frédéric, additional, Laggoun-Défarge, Fatima, additional, Gilbert, Daniel, additional, Mitchell, Edward AD, additional, and Barel, Janna, additional

Published
2023
Full Text
View/download PDF

20. Preliminary results on the use of d18O as a climate proxy for charred oak wood

Author

Boisgueheneuc, Diane Du, Delarue, Frédéric, Daux, Valérie, Nguyen Tu, Thanh Thuy, Dufraisse, Alexa, Archéozoologie, archéobotanique : sociétés, pratiques et environnements (AASPE), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDE]Environmental Sciences, [SHS]Humanities and Social Sciences
Abstract

International audience

Published
2022

22. Impact de la carbonisation sur la composition isotopique δ18O du bois de chêne

Author

Boisgueheneuc, Diane Du, Delarue, Frédéric, Daux, Valérie, Nguyen Tu, Thanh Thuy, Dufraisse, Alexa, Archéozoologie, archéobotanique : sociétés, pratiques et environnements (AASPE), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDE]Environmental Sciences
Abstract

International audience

Published
2022

26. Biochemical traits enhance the trait concept in Sphagnum ecology

Author

Sytiuk, Anna, Céréghino, Regis, Hamard, Samuel, Delarue, Frédéric, Dorrepaal, Ellen, Küttim, Martin, Lamentowicz, Mariusz, Pourrut, Bertrand, Robroek, Bjorn J. M., Tuittila, Eeva-Stiina, Jassey, Vincent E. J., Sytiuk, Anna, Céréghino, Regis, Hamard, Samuel, Delarue, Frédéric, Dorrepaal, Ellen, Küttim, Martin, Lamentowicz, Mariusz, Pourrut, Bertrand, Robroek, Bjorn J. M., Tuittila, Eeva-Stiina, and Jassey, Vincent E. J.

Abstract

Sphagnum mosses are key to northern peatland carbon sequestration. They have a range of morphological and anatomical characteristics that allow them to cope with environmental stress. Sphagnum also produces a plethora of biochemicals that may prevent stress-induced cell-damage. However, the linkages between Sphagnum anatomical, morphological and biochemical traits (i.e. metabolites, pigments and antioxidant enzyme activities) are poorly known, neither are their joint responses to environmental change. Here, we quantify and link an array of Sphagnum anatomical, morphological and biochemical traits in five Sphagnum-dominated peatlands distributed along a latitudinal gradient in Europe, covering a range of regional and local environmental conditions. Sphagnum morphological and anatomical traits were intrinsically linked to Sphagnum metabolites and enzyme activities, and these relationships were driven by shared responses to local and regional environmental factors. More particularly, we found that Sphagnum traits can be grouped into four clusters related to growth, biomass, defense and water stress tolerance. We used regional and local environmental conditions data to further show that biochemicals and their specific linkages with some morphological traits describe dimensions of physiology not captured by anatomical and morphological traits alone. These results suggest that Sphagnum morphology and function is rooted in the metabolome, and that incorporating biochemicals into the functional trait space concept can enhance our mechanistic understanding and predictive power in Sphagnum ecology.

Published
2022
Full Text
View/download PDF

27. Predicting the structure and functions of peatland microbial communities from Sphagnum phylogeny, anatomical and morphological traits and metabolites

Author

Sytiuk, Anna, Céréghino, Régis, Hamard, Samuel, Delarue, Frédéric, Guittet, Amélie, Barel, Janna M., Dorrepaal, Ellen, Küttim, Martin, Lamentowicz, Mariusz, Pourrut, Bertrand, Robroek, Bjorn J. M., Tuittila, Eeva-Stiina, Jassey, Vincent E. J., Sytiuk, Anna, Céréghino, Régis, Hamard, Samuel, Delarue, Frédéric, Guittet, Amélie, Barel, Janna M., Dorrepaal, Ellen, Küttim, Martin, Lamentowicz, Mariusz, Pourrut, Bertrand, Robroek, Bjorn J. M., Tuittila, Eeva-Stiina, and Jassey, Vincent E. J.

Abstract

Sphagnum mosses are keystone species in northern peatlands. Notably, they play an important role in peatland carbon (C) cycling by regulating the composition and activity of microbial communities. However, it remains unclear whether information on Sphagnum phylogeny and/or traits-based composition (i.e. anatomical and morphological traits and metabolites) can be used to predict the structure of microbial communities and their functioning. Here we evaluated whether Sphagnum phylogeny and traits predict additional variation in peatland microbial community composition and functioning beyond what would be predicted from environmental characteristics (i.e. climatic and edaphic conditions). We collected Sphagnum and microbial data from five European peatlands distributed along a latitudinal gradient from northern Sweden to southern France. These data allowed us to assess Sphagnum anatomical and morphological traits and metabolites at different sites along changing environmental conditions. Using structural equation modelling (SEM) and phylogenetic distance analyses, we investigated the role of Sphagnum traits in shaping microbial community composition and functioning along with environmental conditions. We show that microbial community composition and traits varied independently from both Sphagnum phylogeny and the latitudinal gradient. Specifically, the addition of Sphagnum traits to climatic and edaphic variables to the SEM allowed it to explain a larger proportion of the explained variance (R2). This observation was most apparent for the biomass of decomposers (+42%) and phototrophs (+19%), as well as for growth yield microbial traits (+10%). As such, that Sphagnum metabolites were important drivers for microbial community structure and traits, while Sphagnum anatomical and morphological traits were poor predictors. Synthesis. Our results highlight that Sphagnum metabolites are more likely to influence peatland microbial food web structure and functioning than Sphagnum

Published
2022
Full Text
View/download PDF

32. Biochemical traits enhance the trait concept in Sphagnum ecology

Author

Sytiuk, Anna, primary, Céréghino, Regis, additional, Hamard, Samuel, additional, Delarue, Frédéric, additional, Dorrepaal, Ellen, additional, Küttim, Martin, additional, Lamentowicz, Mariusz, additional, Pourrut, Bertrand, additional, Robroek, Bjorn J. M., additional, Tuittila, Eeva‐Stiina, additional, and Jassey, Vincent E. J., additional

Published
2022
Full Text
View/download PDF

33. Signification moléculaire du signal S2 de la pyrolyse Rock-Eval

Author

Jacob, Jérémy, Delarue, Frédéric, Copard, Yoann, Le Milbeau, Claude, Brockmann, Patrick, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), 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)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Biogéosystèmes Continentaux - UMR7327, 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), SGF, CNRS, Laboratoire de Géologie de Lyon ou l’étude de la Terre, des planètes et de l’environnement, and Sciencesconf.org, CCSD

Subjects
[SDU] Sciences of the Universe [physics], pyrolyse, carbone organique particulaire, déconvolution, [SDU]Sciences of the Universe [physics], Rock, Eval, matières organiques, S2
Abstract

International audience; La pyrolyse Rock-Eval (RE) est l'une des méthodes permettant d'estimer la qualité et la quantité de matières organiques (MOs) stockées ou transitant entre les différents réservoirs de C (lithosphère, pédosphère, hydrosphère). Seuls quelques paramètres (COT, IH, IO, Tmax) sont utilisés de manière régulière. De nombreux auteurs conviennent que la pyrolyse RE pourrait fournir des informations plus élaborées sur les MOs, à travers les nombreux autres indices délivrés, ou l'étude plus détaillée des signaux de pyrolyse. Parmi ces auteurs, Disnar et al. (2003) et Sebag et al. (2006) ont proposé que la déconvolution mathématique en gaussiennes simples du pic S2 permettait de distinguer les constituants organiques labiles et récalcitrants. Cependant, la nature chimique de ces gaussiennes est mal contrainte. Nous proposons une nouvelle méthode qui permet d'étudier en continu la nature chimique des matières libérées lors de la phase de pyrolyse. Nous avons couplé un pyrolyseur programmable (Pyroprobe 5150) à un spectromètre de masse (ISQ700). L'analyse de standards de sols, roches, tourbe, charbon et MO dissoutes fournit les informations suivantes : (1) les résultats sont reproductibles et quantitatifs; (2) la réponse du spectromètre de masse dépend de la quantité d'échantillon et de sa nature; (3) des températures distinctes sont relevées au pic des courbes de production des m/z; (4) elles sont consistantes entre réplicas et au sein d'une même famille d'échantillons; (5) les températures s'organisent en au moins 4 clusters de m/z de natures chimiques distinctes; (6) des sous-clusters sont identifiés; (7) des effets liés à la matrice minérale et au degré d'organisation des MOs pourraient expliquer les différences mineures observées entre échantillons. Rapide, simple de mise en œuvre et économe en échantillon, cette nouvelle méthode pourrait permettre, à terme, de combler le fossé persistant entre analyses globales et moléculaires.

Published
2021

34. Archaeological charcoal analysis and anthraco-typology. Contribution and limits for the study of firewood exploitation, woodland management and palaeoenvironmental studies

Author

Dufraisse, Alexa, Coubray , Sylvie, Llorenç, Picornell-Gelabert, Alcolea, Marta, Girardclos, Olivier, Tu, Thanh Thuy Nguyen, Delarue, Frédéric, Archéozoologie, archéobotanique : sociétés, pratiques et environnements (AASPE), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Dufraisse, Alexa, Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)

Subjects
[SHS.ARCHEO] Humanities and Social Sciences/Archaeology and Prehistory, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, [SHS.ENVIR] Humanities and Social Sciences/Environmental studies, [SHS.ENVIR]Humanities and Social Sciences/Environmental studies, [SHS] Humanities and Social Sciences, ComputingMilieux_MISCELLANEOUS, [SHS]Humanities and Social Sciences
Abstract

International audience

Published
2021

37. Predicting the structure and functions of peatland microbial communities from Sphagnum phylogeny, anatomical and morphological traits and metabolites

Author

Sytiuk, Anna, primary, Céréghino, Régis, additional, Hamard, Samuel, additional, Delarue, Frédéric, additional, Guittet, Amélie, additional, Barel, Janna M., additional, Dorrepaal, Ellen, additional, Küttim, Martin, additional, Lamentowicz, Mariusz, additional, Pourrut, Bertrand, additional, Robroek, Bjorn J. M., additional, Tuittila, Eeva‐Stiina, additional, and Jassey, Vincent E. J., additional

Published
2021
Full Text
View/download PDF

38. Xenon isotopes in Archean and Proterozoic insoluble organic matter: a robust indicator of syngenecity?

Author

Bekaert, David V., Broadley, M.W., Delarue, Frédéric, Druzhinina, Z., Paris, Guillaume, Robert, François, Sugitani, Kenichiro, Marty, Bernard, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), 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), California Institute of Technology (CALTECH), Graduate School of Environmental Studies [Nagoya], and Nagoya University

Subjects
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU]Sciences of the Universe [physics], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; Insoluble organic materials (kerogens) isolated from ancient sedimentary rocks provide unique insights into the evolution of early life. However, establishing whether these kerogens are indeed syngenetic with the deposition of associated sedimentary host rocks, or contain contribution from episodes of secondary deposition, is not straightforward. Novel geochemical criterions are therefore required to test the syngenetic origin of Archean organic materials. On the one hand, the occurrence of massindependent fractionation of sulphur isotopes (MIF-S) provides a tool to test the Archean origin of ancient sedimentary rocks. Determining the isotope composition of sulphur within kerogens whilst limiting the contribution from associated minerals (e.g., nano-pyrites) is however challenging. On the other hand, the Xe isotope composition of the Archean atmosphere has been shown to present enrichments in the light isotopes relative to its modern composition, together with a mono-isotopic deficit in 129 Xe. Given that the isotopic composition of atmospheric Xe evolved through time by mass dependent fractionation (MDF) until~2.5 to 2.0 Ga, the degree of MDF of Xe isotopes trapped in kerogens could provide a time stamp for the last chemical equilibration between organic matter and the atmosphere. However, the extent to which geological processes could affect the signature of Xe trapped in ancient kerogen remains unclear. In this contribution, we present new Ar, Kr and Xe isotopic data for four kerogens isolated from 3.4 to 1.8 Gy-old cherts and confirm that Xe isotopes from the Archean atmosphere can be retained within kerogens. However, new Xe-derived model ages are lower than expected from the ages of host rocks, indicating that initially trapped Xe components were at least partially lost and/or mixed together with some Xe carried out by younger generations of organic materials, therefore complicating the Xe-based dating method. Whilst non-null Δ 33 S values and 129 Xe deficits relative to modern atmosphere constitute reliable imprints from the Archean atmosphere, using Xe isotopes to provide information on the syngenetic origin of ancient organic matter appears to be a promising-but not unequivocal-tool that calls for further analytical development.

Published
2020
Full Text
View/download PDF

40. Investigation of the Geochemical Preservation of ca. 3.0 Ga Permineralized and Encapsulated Microfossils by Nanoscale Secondary Ion Mass Spectrometry

Author

Delarue, Frédéric, Robert, Francois, Sugitani, Kenichiro, Tartese, Romain, Duhamel, Rémi, Derennes, Sylvie, 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), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), Université Pierre et Marie Curie - Paris 6 (UPMC)-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), 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), Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
Permineralization, [PHYS]Physics [physics], Fossilization, Farrel Quartzite, Nitrogen, Fossils, Palaeontology, Spectrometry, Mass, Secondary Ion, Western Australia, Spectrum Analysis, Raman, Geochemistry and Petrology, Carbonaceous matter, Microscopy, Electron, Scanning, NanoSIMS, Particle Size, Research Articles
Abstract

Observations of Archean organic-walled microfossils suggest that their fossilization took place through both encapsulation and permineralization. In this study, we investigated microfossils from the ca. 3.0 Ga Farrel Quartzite (Pilbara, Western Australia) using transmitted light microscopy, scanning electron microscopy, Raman microspectrometry, and nanoscale secondary ion mass spectrometry (NanoSIMS) ion microprobe analyses. In contrast to previous studies, we demonstrated that permineralized microfossils were not characterized by the micrometric spatial relationships between Si and C-N as observed in thin sections. Permineralized microfossils are composed of carbonaceous globules that did not survive the acid treatment, whereas encapsulated microfossils were characterized due to their resistance to the acid maceration procedure. We also investigated the microscale relationship between the 12C14N- and 12C2- ion emission as a proxy of the N/C atomic ratio in both permineralized and encapsulated microfossils. After considering any potential matrix and microtopography effects, we demonstrate that the encapsulated microfossils exhibit the highest level of geochemical preservation. This finding shows that the chemical heterogeneity of the microfossils, observed at a spatial resolution of a few hundreds of micrometers, can be related to fossilization processes. Key Words: Carbonaceous matter—Farrel Quartzite—Fossilization—NanoSIMS—Nitrogen—Permineralization. Astrobiology 17, 1192–1202.

Published
2017
Full Text
View/download PDF

43. Archean kerogen as a new tracer of atmospheric evolution: Implications for dating the widespread nature of early life

Author

Bekaert, David, Broadley, Michael, Delarue, Frédéric, Avice, Guillaume, Robert, François, Marty, Bernard, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-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), and California Institute of Technology (CALTECH)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Geologic Sediments, Atmospheric Science, Time Factors, Atmosphere, Origin of Life, SciAdv r-articles, Life Sciences, Chemical Fractionation, Spectrum Analysis, Raman, Biological Evolution, Noble Gases, Isotopes, [CHIM]Chemical Sciences, Research Articles, Research Article
Abstract

Abundant ancient air in Archean kerogen reveals temporal atmospheric Xe evolution, providing a dating tool for early organics., Understanding the composition of the Archean atmosphere is vital for unraveling the origin of volatiles and the environmental conditions that led to the development of life. The isotopic composition of xenon in the Archean atmosphere has evolved through time by mass-dependent fractionation from a precursor comprising cometary and solar/chondritic contributions (referred to as U-Xe). Evaluating the composition of the Archean atmosphere is challenging because limited amounts of atmospheric gas are trapped within minerals during their formation. We show that organic matter, known to be efficient at preserving large quantities of noble gases, can be used as a new archive of atmospheric noble gases. Xe isotopes in a kerogen isolated from the 3.0–billion-year–old Farrel Quartzite (Pilbara Craton, Western Australia) are mass fractionated by 9.8 ± 2.1 per mil (‰) (2σ) per atomic mass unit, in line with a progressive evolution toward modern atmospheric values. Archean atmospheric Xe signatures in kerogens open a new avenue for following the evolution of atmospheric composition through time. The degree of mass fractionation of Xe isotopes relative to the modern atmosphere can provide a time stamp for dating Archean kerogens and therefore narrowing the time window for the diversification of early life during the Archean eon.

Published
2017
Full Text
View/download PDF

46. Effects of experimental climate warming on C sink function in a temperate peatland

Author

Laggoun-Défarge, Fatima, Buttler, Alexandre, Delarue, Frédéric, Epron, Daniel, Gilbert, Daniel, Jassey, Vincent, Grasset, Laurent, Guimbaud, Christophe, Huguet, A., Mitchell, E.A.D, 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)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (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), Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, University of Ferrara [Ferrara], 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), Ecologie et Ecophysiologie Forestières [devient SILVA en 2018] (EEF), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Université de Neuchâtel (UNINE), ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), 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)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Università degli Studi di Ferrara = University of Ferrara (UniFE), 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), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Ferrara (UniFE), 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), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -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 ), Ecologie et Ecophysiologie Forestières [devient SILVA en 2018] ( EEF ), Institut National de la Recherche Agronomique ( INRA ) -Université de Lorraine ( UL ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace ( LPC2E ), Centre National de la Recherche Scientifique ( CNRS ) -Université d'Orléans ( UO ) -Institut national des sciences de l'Univers ( INSU - CNRS ), Biogéochimie et écologie des milieux continentaux ( Bioemco ), École normale supérieure - Paris ( ENS Paris ) -Institut National de la Recherche Agronomique ( INRA ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -AgroParisTech-Université Paris-Est Créteil Val-de-Marne - Paris 12 ( UPEC UP12 ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Neuchâtel, and ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes. ( 2007 )

Subjects
[SDU]Sciences of the Universe [physics], [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [ SDU ] Sciences of the Universe [physics]
Abstract

International audience; Global warming induces complex interactions which could have a positive or a negativefeedback on C storage in soils. Peatlands have stored one-third of global C stock of soilsbecause of low rates of plant residue decomposition due to oxygen limitation resulting fromflooding which inhibits microbial activities. Given the multiple possible responses ofpeatlands to global warming, it is presently impossible to predict their future contribution tothe global C cycle. Several approaches have attempted to assess the effect of warming onpeatlands: mesocosms, latitudinal transects, and in situ field experimental warming. Most ofthese studies only assessed the warming impact on vegetation and surface gas emissions, andso far, no study to date has addressed the entire range of biodiversity, community structureand ecosystem function responses to increased temperature, particularly in temperatepeatlands.Within the PEATWARM project (ANR-07-VUL-010), we investigated the response of aSphagnum peatland in the Jura Mountains (France) to climate change using an experimentalsystem (Open Top Chambers – OTC’s) to simulate in situ an increase in average temperature.We examined the effects of temperature increase along a narrow fen-bog gradient on thevegetation, above- and belowground gas fluxes (CO2 and CH4), microbial diversity andactivity in Sphagnum mosses and in peat, CNS interactions between macro- and microorganismsin the peat biota, and the dynamics of labile and recalcitrant peat organic matter.We showed that warming modifies the C and nutrient cycling of the peatland via changes inabove- and belowground interactions. Furthermore, the contrasted responses to warmingbetween the fen and the bog sites suggest that the spatial variability of moisture andhydrochemistry is critical for understanding the impact of global warming on the fate oforganic matter and the C cycle in peatlands.

Published
2016

47. A multiproxy approach of environmental changes in the last millennia reconstructed from an ombrotrophic peat archive (Frasne mire, France)

Author

Laggoun-Défarge , Fatima, Huguet , Arnaud, Delarue , Frédéric, Jassey , Vincent, Mitchell , Edward, Gauthier , Emilie, Le Milbeau , Claude, Grasset , Laurent, Derenne , Sylvie, Gogo , Sébastien, Gilbert , Daniel, Francez , Andre-Jean, Buttler , Alexandre, Richard , Hervé, 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)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), 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)-Université Pierre et Marie Curie - Paris 6 (UPMC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Biology - Laboratory of Soil Biology, Université de Neuchâtel (UNINE), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC), Ecosystèmes, biodiversité, évolution [Rennes] (ECOBIO), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols ( METIS ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), Ecole Polytechnique Fédérale de Lausanne ( EPFL ), Université de Neuchâtel, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Institut de Chimie des Milieux et Matériaux de Poitiers ( IC2MP ), Université de Poitiers-Centre National de la Recherche Scientifique ( CNRS ), Ecosystèmes, biodiversité, évolution [Rennes] ( ECOBIO ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -INEE-Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, POTHIER, Nathalie, Université Pierre et Marie Curie - Paris 6 (UPMC)-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 Chrono-environnement (UMR 6249) (LCE), Université de Poitiers-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; Peatlands have stored ca. one-third of the global soil carbon stock because of low rates of plant residue decomposition due to oxygen limitation resulting from waterlogging which inhibits microbial activities. Thus, thanks to the continuous accumulation organic matter (OM), peatlands are suitable archives for the reconstruction of past environmental changes. The combination of natural climatic variations and human impacts (particularly during the late Holocene) represents a challenge for reconstructing past environmental changes from peat archives, and requires the combination of several proxies. Within the PEATWARM project (ANR-07-VUL-010), we investigated a 4 m peat profile collected in a bog located in Frasne mire (French Jura Mountains) and covering the last 7,400 years BP. We analysed peat OM composition (lignin-derived phenolic monomers, monosaccharides, lipids), testate amoebae, branched glycerol dialkyl glycerol tetraethers (GDGTs) and pollen. Major changes in OM sources and environmental conditions were revealed at 2.5 m depth (ca. 5,000 yrs BP). Below 2.5 m depth, higher contents of lignin-derived phenolic monomers were found suggesting a predominance of vascular plants (e.g. sedges). In this deeper section, the peat composition is also characterised by (i) higher percentages of amorphous OM, (ii) lower percentages of mucilage and fungal hyphae, and (iii) lower cellulosic sugar contents and C/N ratio. In addition, at this time (around 5,000 yrs BP), pollen analysis revealed a change in vegetation with especially the disappearance of Pinus. Taken together, these results indicate that a rapid shift of the ecosystem functioning occurred ca. 5,000 years ago from a minerotrophic fen to an ombrotrophic Sphagnum-dominated peatland.

Published
2015

50. Combination of branched GDGTs and testate amoebae for the reconstruction of past climate change in a French peatland

Author

Huguet, Arnaud, Jassey, Vincent E. J., Laggoun-Défarge, Fatima, Derenne, Sylvie, Gilbert, Daniel, Delarue, Frédéric, Payne, Richard, Buttler, Alexandre, Mitchell, Edward A. D., Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), 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), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Manchester Metropolitan University (MMU), Wetlands Research Group, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Biogéochimie et écologie des milieux continentaux ( Bioemco ), École normale supérieure - Paris ( ENS Paris ) -Institut National de la Recherche Agronomique ( INRA ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -AgroParisTech-Université Paris-Est Créteil Val-de-Marne - Paris 12 ( UPEC UP12 ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Manchester Metropolitan University ( MMU ), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-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), 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), Laboratoire Chrono-environnement (UMR 6249) (LCE), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (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), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Swiss Federal Institute for Forest, Snow and Avalanche Research WSL

Subjects
[ SDE.MCG ] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; Peatlands are important archives for the reconstruction of past environmental changes because of their high rates of peat accumulation due to the low rate of plant litter decomposition. Branched glycerol dialkyl glycerol tetraethers (GDGTs) are complex lipids of high molecular weight, recently discovered in soils and suggested to be produced by anaerobic bacteria. The relative distribution of branched GDGTs in soils correlates with environmental variables: the degree of methylation, expressed in the methylation index of branched tetraethers (MBT), depends on mean annual air temperature (MAAT) and to a lesser extent on soil pH, whereas the relative abundance of cyclopentyl rings of branched GDGTs, expressed in the cyclisation ratio of branched tetraethers (CBT), is related to soil pH. The MBT/CBT proxies are increasingly used for the reconstruction of past air temperatures, but have rarely been applied in peatlands. Testate amoebae are common and diverse unicellular eukaryotes in peatlands. They build shells that are preserved in peat. They are good indicators of changing environmental conditions in peatlands and are thus used in both ecological and paleoecological studies, especially for reconstructing surface moisture. The aim of this study was to examine the applicability of branched GDGTs and testate amoebae as indicators of environmental changes (temperature and moisture) in temperate peatlands. Within the PEATWARM project, both GDGTs and testate amoebae were studied at high resolution in a 4 m peat core collected in Frasne mire (French Jura Mountains) and covering the last 7,400 years BP. GDGT-inferred temperatures ranged between 8 and 12 °C until 250 cm depth and were higher than present measured mean annual air temperature (ca. 6 °C). Temperature estimates in the top part of the bog were most consistent with spring and summer mean air temperatures recorded in the peatland (ca. 11.5 °C), suggesting that branched GDGT-producing bacteria might be more active during the warmest months of the year. At 250 cm depth, reconstructed temperature showed a pronounced shift, likely reflecting both a change in climatic conditions but also in the composition of the peat. Indeed, drier conditions were indicated by testate amoebae at the bottom of the peat core, whereas wetter conditions occurred at the top. Interestingly, temperature variations inferred from MBT/CBT proxies were weakly linked with moisture variations inferred from testate amoebae until 150 cm depth (r = -0.41, p = 0.06). Therefore, the distribution of branched GDGTs might also depend on peat moisture level, in addition to air temperature and pH. Our data suggest that the joint use of MBT/CBT and testate amoebae is a promising approach to estimate past climate change, but that more research is required to calibrate and apply with confidence these proxies in peatlands.

Published
2013

Catalog

Books, media, physical & digital resources
See catalog results