Search

Your search keyword '"Escoffier, Nicolas"' showing total 144 results
Start Over Author "Escoffier, Nicolas"
144 results on '"Escoffier, Nicolas"'

4. Calcite precipitation: The forgotten piece of lakes' carbon cycle.

Author

Many, Gaël, Escoffier, Nicolas, Perolo, Pascal, Bärenbold, Fabian, Bouffard, Damien, and Perga, Marie-Elodie

Subjects
*CALCITE, *CARBON cycle, *LAKES, *CARBON emissions, *BEDROCK, *CARBON dioxide
Abstract

Lakes emit substantial amounts of carbon dioxide (CO2) into the atmosphere, but why they do remains debated. The long-standing vision of lakes as solely respirators of the organic matter leaking from the soils has been challenged by evidence that inorganic carbon produced by weathering of the catchment bedrock could also support lake CO2 emissions. How inorganic carbon inputs ultimately generate lake CO2 outgassing remains a blind spot. We develop and introduce a calcite module in a coupled one-dimensional physical-biogeochemical model that we use to simulate the carbon cycle of the large Lake Geneva over the past 40 years. We mechanistically demonstrate how the so-far neglected process of calcite precipitation boosts net CO2 emissions at the annual scale. Far from being anecdotal, we show that calcite precipitation could explain CO2 outgassing across various lakes globally, including some of the largest lakes in the world. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

5. Long‐range transport of littoral methane explains the metalimnetic methane peak in a large lake.

Author

Khatun, Santona, Berg, Jasmine S., Jézéquel, Didier, Moiron, Marthe, Escoffier, Nicolas, Schubert, Carsten J, Bouffard, Damien, and Perga, Marie‐Elodie

Subjects
MICROBIAL diversity, METHANE, LAKES, SEDIMENTS, HABITATS
Abstract

In large and stratified lakes, substantial methane stocks are often observed within the metalimnion. The origin of the methane (CH4) accumulated in the metalimnion during stratification, which can sustain significant emissions during convective mixing, is still widely debated. While commonly attributed to the transport of methane produced anaerobically ex situ, recent evidence suggests that oxic in situ methane production could also contribute to metalimnetic methane peaks. Here, we assessed the origin, that is, pelagic CH4 production or transport of sublittoral CH4 through the interflow, of metalimnetic methane in Lake Geneva, the largest lake in Western Europe. Microbial diversity data do not support the hypothesis of oxic methane production in the metalimnion. In contrast, both spatial and temporal surveys of methane show that maxima occur at depths and sites most affected by the Rhône River inflow. Methane δ13C values point to an anaerobic sublittoral methane source, within a biogeochemical hotspot close to the river delta region, and an efficient transport across several kilometers in a vertically well‐constrained metalimnion. Our current findings emphasize the indirect role of river interflows for the long‐range transport of CH4 produced in sediment biogeochemical hotspots, even for large lakes where sublittoral habitats represent a fairly limited fraction of the lake volume. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

8. Near-bed stratification controls bottom hypoxia in ice-covered alpine lakes

Author

Perga, Marie-Elodie, Minaudo, Camille, Doda, Tomy, Arthaud, Florent, Beria, Harsh, Chmiel, Hannah E., Escoffier, Nicolas, Lambert, Thibault, Napolleoni, Raphaelle, Obrador, Biel, Perolo, Pascal, Ruegg, Janine, Ulloa, Hugo, and Bouffard, Damien

Subjects
depletion, sediment, water, morphology, dissolved-oxygen, temperature, dynamics, shallow, climate, phenology
Abstract

In ice-covered lakes, near-bottom oxygen concentration decreases for most of the wintertime, sometimes down to the point that bottom waters become hypoxic. Studies insofar have reached divergent conclusions on whether climate change limits or reinforces the extent and duration of hypoxia under ice, raising the need for a comprehensive understanding of the drivers of the dissolved oxygen (DO) dynamics under lake ice. Using high-temporal resolution time series of DO concentration and temperature across 14 mountain lakes, we showed that the duration of bottom hypoxia under ice varies from 0 to 236 d within lakes and among years. The variability of hypoxia duration was primarily explained by changes in the decay rate of DO above the lake bottom rather than by differences in DO concentration at the ice onset or in the ice-cover duration. We observed that the DO decay rate was primarily linked to physical controls (i.e., deep-water warming) rather than biogeochemical drivers (i.e., proxies for lake or catchment productivity). Using a simple numerical model, we provided a proof-of-concept that the near-bed stratification can be the mechanism tying the DO decay rate to the sediment heat release under the ice. We ultimately showed that the DO decay rate and hypoxia duration are driven by the summer light climate, with faster oxygen decline found under the ice of clearer cryostratified alpine lakes. We derived a framework theorizing how the hypoxia duration might change under the ice of alpine lakes in a warmer climate., Limnology and Oceanography, 68 (6), ISSN:0024-3590, ISSN:1939-5590

Published
2023

9. Enhanced bioavailability of dissolved organic matter (DOM) in human-disturbed streams in Alpine fluvial networks

Author

Lambert, Thibault, Perolo, Pascal, Escoffier, Nicolas, and Perga, Marie-Elodie

Subjects
QE1-996.5, Ecology, Life, QH501-531, Earth-Surface Processes, Ecology, Evolution, Behavior and Systematics, Geology, QH540-549.5
Abstract

The influence of human activities on the role of inland waters in the global carbon (C) cycle is poorly constrained. In this study, we investigated the impact of human land use on the sources and biodegradation of dissolved organic matter (DOM) and its potential impact on bacterial respiration in 10 independent catchments of the Lake Geneva basin. Sites were selected along a gradient of human disturbance (agriculture and urbanization) and were visited twice during the winter high-flow period. Bacterial respiration and DOM bioavailability were measured in the laboratory through standardized dark bioassays, and the influence of human land uses on DOM sources, composition and reactivity was assessed from fluorescence spectroscopy. Bacterial respiration was higher in agro-urban streams but was related to a short-term bioreactive pool (0–6 d of incubation) of autochthonous origin, whose relative contribution to the total DOM pool increased with the degree of human disturbance. On the other hand, the degradation of a long-term (6–28 d) bioreactive pool related to terrestrial DOM was independent from the catchment land use and did not contribute substantially to aquatic bacterial respiration. From a greenhouse gas emission perspective, our results suggest that human activities may have a limited impact on the net C exchanges between inland waters and the atmosphere, as most CO2 fixed by aquatic producers in agro-urban streams is cycled back to the atmosphere after biomineralization. Although seasonal and longitudinal changes in DOM sources must be considered, the implications of our results likely apply more widely as a greater proportion of autochthonous-DOM signature is a common feature in human-impacted catchments. Yet, on a global scale, the influence of human activities remains to be determined given the large diversity of effects of agriculture and urbanization on freshwater DOM depending on the local environmental context.

Published
2022

18. Controls on oxygen depletion under lake ice 

Author

Perga, Marie-Elodie, primary, Minaudo, Camille, additional, Ulloa, Hugo, additional, Doda, Tomy, additional, Perolo, Pascal, additional, Escoffier, Nicolas, additional, Arthaud, Florent, additional, Obrador, Biel, additional, and Bouffard, Damien, additional

Published
2022
Full Text
View/download PDF

34. No evidence of a human influence on the mineralization of terrestrial dissolved organic matter (DOM) in Alpine fluvial networks.

Author

Lambert, Thibault, Perolo, Pascal, Escoffier, Nicolas, and Perga, Marie-Elodie

Subjects
DISSOLVED organic matter, MICROBIAL respiration, FLUORESCENCE spectroscopy, LAND degradation, WATERSHEDS, MINERALIZATION, FLUVIAL geomorphology
Abstract

The influence of human activities on the role of inland waters in the global carbon (C) cycle is poorly constrained. In this study, we investigated the impact of human land use on the degradation of terrestrial dissolved organic matter (DOM) and its potential impact on bacterial respiration in ten independent catchments of the Lake Geneva Basin. Sites were selected along a gradient of human disturbance (agriculture and urbanization), and we monitored bacterial respiration in parallel to DOM bioavailability. Fluorescence spectroscopy was used to determine the influence of human land uses on DOM sources and composition as well as the dynamic of degradation or production of the fluorophores identified in our study sites. Higher bacterial respiration measured in agro-urban streams related to a short-term bioreactive pool (0-6 days of incubation) from autochthonous origin, whose the size increased with human disturbance. On the other hand, the degradation of terrestrial DOM was not impacted by human activities and was not found to contribute substantially to aquatic bacterial respiration. Although human land uses controlled DOM sources, composition and bioavailability at the basin scale, our results showed that human activities in the Lake Geneva Basin had a limited impact on the net C exchanges between inland waters and the atmosphere related to DOM mineralization. Considering that greater proportion of autochthonous-DOM signature is a common feature in human-impacted catchments, the implications of our results likely apply more widely. Yet, on a global scale, the influence of human activities remains to be determine given the large diversity of effects of agriculture and urbanization on freshwater DOM depending on the local environmental context. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

37. Carbon fate in a large temperate human-impacted river system: focus on benthic dynamics

Author

Vilmin, Lauriane, Flipo, Nicolas, Escoffier, Nicolas, Rocher, Vincent, Groleau, Alexis, Geochemistry, Bio-, hydro-, and environmental geochemistry, Centre de Géosciences (GEOSCIENCES), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), 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), 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), SIAAP - Direction du Développement et de la Prospective, SIAAP, Université Pierre et Marie Curie - Paris 6 (UPMC)-École pratique des hautes études (EPHE), MINES ParisTech - École nationale supérieure des mines de Paris, 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 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), EGU, 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), 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), Université Pierre et Marie Curie - Paris 6 (UPMC)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), MINES ParisTech - École nationale supérieure des mines de Paris-PSL Research University (PSL), IPGP, Université Paris Diderot - Paris 7 (UPD7), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), and 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)

Subjects
sediment-water exchanges, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, human-impacted system, carbon, [SDE.MCG]Environmental Sciences/Global Changes, benthic and pelagic dynamics, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, river export and metabolism, hydrobiogeochemical modeling, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; Fluvial networks play an important role in regional and global carbon (C) budgets. The SeineRiver, from the Paris urban area to the entrance of its estuary (220 km), is studied here as an example ofa large human-impacted river system subject to temperate climatic conditions. We assess organic C (OC)budgets upstream and downstream from one of the world’s largest wastewater treatment plants and fordifferent hydrological conditions using a hydrobiogeochemical model. The fine representation of sedimentaccumulation on the river bed allows for the quantification of pelagic and benthic effects on OC export toward the estuary and on river metabolism (i.e., net CO2 production). OC export is significantly affected by benthic dynamics during the driest periods, when 25% of the inputs to the system is transformed or stored in the sediment layer. Benthic processes also substantially affect river metabolism under any hydrological condition. On average, benthic respiration accounts for one third of the total river respiration along the studied stretch (0.27 out of 0.86 g C m−2 d−1). Even though the importance of benthic processes was already acknowledged by the scientific community for headwater streams, these results stress the major influence of benthic dynamics, and thus of physical processes such as sedimentation and resuspension, on C cycling in downstream river systems. It opens the door to new developments in the quantification of C emissions by global models, whereby biogeochemical processing and benthic dynamics should be taken into account.

Published
2016
Full Text
View/download PDF

38. Biogéochimie de l’axe fluvial

Author

Groleau, Alexis, Varrault, Gilles, Garnier, Josette, Laverman, Anniet, Flipo, Nicolas, Mouchel, Jean-Marie, Vilmin, Lauriane, Grouz, Nejla, Escoffier, Nicolas, Raimonet, Mélanie, Billen, Gilles, de Fouquet, Chantal, Poulin, Michel, Rocher, Vincent, Ramarson, Antsiva, Blanchoin, Arnaud, Hilaire, Fanny, Carrière, Alexandra, Martinez, Anunciacion, Mercier, Benjamin, Fauchon, Nils, Viollier, Eric, Sebilo, Mathieu, Cazier, Thibaut, Vaury, Véronique, Perrin, Emilie, Mothet, Aurélie, Roose-Amsaleg, Céline, Nguyen, Thanh Phuong, Matar, Zeinab, Soares-Pereira, Caroline, Bonnot, Caroline, Parlanti, Edith, Derenne, Sylvie, Benedetti, Marc, Gelabert, Alexandre, Bressy, Adèle, Boudahmane, Lila, Guo, Yuzhe, Parot, Jérémie, Cordier, Marie-Ange, Cordier, Laure, Anquetil, Christelle, Tharaud, Mickaël, Saad, Mohamed, Anthony, Auge, Bensoussan, Nathaniel, François, Métivier, Benoit, Prevost, Francoise, Lucas, Goncalves, Alexandre, Fanny, Richard, Sébastien, Wurtzer, and Moulin, Laurent

Published
2015
Full Text
View/download PDF

40. Modélisation du fonctionnement hydro-écologique de la Seine: Impact des vases sur la qualité de l'eau

Author

Vilmin, Lauriane, Flipo, Nicolas, Poulin, Michel, Groleau, Alexis, Escoffier, Nicolas, 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), Laboratoire de géochimie des Eaux (LGE), Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris, and MINES ParisTech - École nationale supérieure des mines de Paris-PSL Research University (PSL)

Subjects
[SDE]Environmental Sciences, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2012

Catalog

Books, media, physical & digital resources
See catalog results