Résumé
Insights into past marine carbon cycling and water mass properties can be obtained by means of geochemical proxies calibrated through controlled laboratory experiments with accurate seawater carbonate system (C-system) manipulations. Here, we explored the use of strontium/calcium ratio (Sr/Ca) of the calcite shells of benthic foraminifera as a potential seawater C-system proxy through a controlled growth experiment with two deep-sea species (Bulimina marginata and Cassidulina laevigata) and one intertidal species (Ammonia T6). To this aim, we used two experimental set-ups to decouple as much as possible the individual components of the carbonate system, i.e., changing pH at constant dissolved inorganic carbon (DIC) and changing DIC at constant pH. Four climatic chambers were used with different controlled concentrations of atmospheric pCO2 (180 ppm, 410 ppm, 1000 ppm, 1500 ppm). Our results demonstrated that pH did not influence the survival and growth of the three species. However, low DIC conditions (879 μmol kg−1) negatively affected B. marginata and C. laevigata through reduced growth, whereas no effect was observed for Ammonia T6. Our results also showed that Sr/Ca was positively correlated with total Alkalinity (TA), DIC and bicarbonate ion concentration ([HCO3−]) for Ammonia T6 and B. marginata; i.e., DIC and/or [HCO3−] were the main controlling factors. For these two species, the regression models were coherent with published data (existing so far only for Ammonia T6) and showed overall similar slopes but different intercepts, implying species-specific effects. Furthermore, the Sr/Ca - C-system relationship was not impacted by ontogenetic trends between chamber stages, which is a considerable advantage for paleo-applications. This applied particularly to Ammonia T6 that calcified many chambers compared to the two other species. However, no correlation with any of the C-system parameters was observed for Sr/Ca in C. laevigata. This might imply either a strong species-specific effect and/or a low tolerance to laboratory conditions leading to a physiological stress, thereby impacting the Sr incorporation into the calcite lattice of C. laevigata.
Auteurs, date et publication :
Auteurs M. Mojtahid , P. Depuydt , A. Mouret , S. Le Houedec , S. Fiorini , S. Chollet , F. Massol , F. Dohou , H. L. Filipsson , W. Boer , G. -J. Reichart , C. Barras
Publication : Chemical Geology
Date : 2023
Pages : 121396
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Co-deployment of a portfolio of carbon removal technologies is anticipated in order to remove several gigatons of carbon dioxide from the atmosphere and meet climate targets. However, co-application effects between carbon removal technologies have rarely been examined, despite multiple recent perspectives suggesting potential synergies between basalt enhanced weathering and biochar application. To study the co-application effects of basalt for enhanced weathering and biochar on carbon sequestration, along with related co-benefits and risks, we conducted a fully replicated factorial mesocosm experiment with wheat. Basalt applied alone (74 t ha−1) resulted in an estimated carbon sequestration potential of 1.13 t of equivalent CO2 ha−1 over the course of approximately 6 months. Co-application with biochar (12 t ha−1) did not significantly increase estimated carbon sequestration potential. Total alkalinity fluxes and isotopic evidence indicated nearly exactly additive effects of basalt and biochar co-applied, with no significant interaction effect. Biochar carbon sequestration, approximately 32 t of equivalent CO2 ha−1 in our experiment, was unaffected by basalt addition during our experiment. Co-benefits of basalt and biochar on plant biomass as well as nutrient uptake and availability similarly mostly showed additive tendencies when co-applied. Nonetheless, a few synergistic tendencies were observed when co-applied for plant potassium and magnesium uptake as well as soil calcium availability. Soil calcium availability increased by 126% compared to expected effects based on separate application. Finally, we did not observe a reduction in the increased uptake of potentially harmful trace elements released from basalt when co-applied with biochar. Overall, our results support the co-application of basalt for enhanced weathering and biochar, with additive effects on carbon sequestration and additive, if not synergistic, effects on associated co-benefits.
Auteurs, date et publication :
Auteurs Nicolas Honvault , Marie-Laure Tiouchichine , Joana Sauze , Clément Piel , Damien Landais , Sébastien Devidal , Emmanuel Gritti , Delphine Bosch , Alexandru Milcu
Publication : Applied Geochemistry
Date : 2024
Volume : 169
Pages : 106054
Catégorie(s)
#CNRS #Ecotron de Montpellier #Ecotron IleDeFrance #ENSRésumé
Biochar undergoes changes that start almost immediately after removal from the reactor and continue indefinitely after application to soil. Such changes affect the physical-chemical properties of the biochar including particle size distribution, elemental content, oxidation state, acidity, ion exchange capacities, aliphatic and aromatic contents, degree of aromatic condensation, surface and pore characteristics, loss of matter from the biomass body, and other properties. Known as aging or weathering, these changes can influence the interaction of particles with small molecules and ions, dissolved natural organic matter, metal oxides and ions, and cells. This chapter reviews advances in knowledge and understanding of aging processes and their impacts since a similar chapter in the previous edition of the book. It discusses experimental methods of aging and their merits and shortcomings; transport of biochar particles and colloids in the soil profile; short- and long-term alterations in the physical-chemical properties of biochars; redox behavior of biochars; the effects of aging on the sorption of organic compounds; and the effects of aging on the reactions and sorption of metals.
Auteurs, date et publication :
Auteurs Joseph J. Pignatello , Minori Uchimiya , Samuel Abiven
Date : 2025
Catégorie(s)
#CNRS #Ecotron de Montpellier #Ecotron IleDeFrance #ENSRésumé
According to theories on cave adaptation, cave organisms are expected to develop a lower metabolic rate compared to surface organisms as an adaptation to food scarcity in the subterranean environments. To test this hypothesis, we compared the oxygen consumption rates of the surface and subterranean populations of a surface-dwelling species, the newt Calotriton asper, occasionally found in caves. In this study, we designed a new experimental setup in which animals with free movement were monitored for several days in a respirometer. First, we measured the metabolic rates of individuals from the surface and subterranean populations, both maintained for eight years in captivity in a natural cave. We then tested individuals from these populations immediately after they were caught and one year later while being maintained in the cave. We found that the surface individuals that acclimated to the cave significantly reduced their oxygen consumption, whereas individuals from the subterranean population maintained in the cave under a light/dark cycle did not significantly modify their metabolic rates. Second, we compared these metabolic rates to those of an obligate subterranean salamander (Proteus anguinus), a surface aquatic Urodel (Ambystoma mexicanum), and a fish species (Gobio occitaniae) as references for surface organisms from different phyla. As predicted, we found differences between the subterranean and surface species, and the metabolic rates of surface and subterranean C. asper populations were between those of the obligate subterranean and surface species. These results suggest that the plasticity of the metabolism observed in surface C. asper was neither directly due to food availability in our experiments nor the light/dark conditions, but due to static temperatures. Moreover, we suggest that this adjustment of the metabolic level at a temperature close to the thermal optimum may further allow individual species to cope with the food limitations of the subterranean environment.
Auteurs, date et publication :
Auteurs Olivier Guillaume , Marine Deluen , Allan Raffard , Olivier Calvez , Audrey Trochet
Publication : Ecology and Evolution
Date : 2025
Volume : 10
Issue : 23
Pages : 12983-12989
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #PLANAQUARésumé
Emerging organic micropollutants (OMPs) are ubiquitous in waterbodies and not fully eliminated by wastewater treatment plants (WWTP). A proposed WWTP upgrade includes OMPs sorption by biochar rather than activated carbon (AC). Activated biochar (AB) and non-activated biochar (NAB) sorption performance towards 4 target OMPs (benzotriazole, sulfamethoxazole, carbamazepine, diclofenac) were evaluated in real-wastewater. Sorption processes are discussed in light of sorption mechanisms that depend both on OMP and on biochar physico-chemical properties. AB and AC have similar average sorption efficiency (45%), while NABs are much less efficient (<19%). OMPs sorption significantly correlates to SSA, inversely to H/C (indicating hydrophobic interaction with graphene-like structures) and to CEC or ash content (indicating H-bond or ternary surface complexation sorption mechanisms). This highlights the need to mix AB sources with different physico-chemical characteristics to sorb a large OMP spectrum within WWTPs. Production and use of ABs alleviate the negative environmental impact of ACs.
Auteurs, date et publication :
Auteurs Fabienne Favre , Ana Slijepcevic , Umberto Piantini , Urban Frey , Samuel Abiven , Hans-Peter Schmidt , Laurent Charlet
Publication : Bioresource Technology Reports
Date : 2025
Volume : 17
Pages : 100966
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
When assessing the carbon storage potential of a crop, it is useful to 1) quantify the inputs that return to the soil, such as roots, rhizodeposition and sometimes aboveground biomass, and 2) estimate the carbon gains or losses attributed to the priming effect. This allows to draw up a balance of inputs and outputs at the end of the growing season. While the quantity of carbon supplied by roots and aboveground biomass is relatively easy to measure, the quantity of rhizodeposition and the priming effect are not.To establish such a balance, 12 intercropping plant species from 3 plant families (brassicaceae, fabaceae and poaceae) were grown for two months in mesocosms (15 liters) under controlled conditions simulating a temperate summer climate in real time in an ecotron. Multi-pulse atmospheric labeling with 13CO2 99% was used to trace photosynthesized carbon and thus quantify aboveground and root biomass, rhizodeposition and variations in carbon stock due to the priming effect.The results show that rhizodeposition represents a significant carbon input (around a quarter of root biomass), positively correlated with root biomass. Root biomass is therefore one of the main traits to be considered for increasing inputs. At the same time, 10 out of 12 plants accelerated the mineralization of soil organic matter (positive priming effect), resulting in a cumulative carbon loss over the course of the plant's growth that can be of the same order of magnitude as the biomass input.This priming effect is highly heterogeneous and difficult to explain by plant traits, but seems quantitatively more important for brassicaceae. We propose that this variability is due both to the spatial heterogeneity inducing these processes, but also to the great variability of processes that can occur in the rhizosphere, processes that can simultaneously lead to an acceleration and/or deceleration of the decomposition of native soil organic matter.
Auteurs, date et publication :
Auteurs Baptiste Hulin , Simon Chollet , Folrent Massol , Samuel Abiven
Date : 2024
Pages : 5143
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Soil respiration influences regional carbon dynamics, yet our limited
understanding of drivers of soil respiration currently constrains robust
modeling of soil CO2 efflux. There is evidence that soil respiration
does not follow the standard Arrhenius relationship with soil
temperature at the daily scale, as used in many ecosystem models, but
demonstrates a hysteretic response. The understanding of this hysteretic
response is critical to soil carbon and greenhouse gas emission
modeling. Why soil respiration deviates from monotonic temperature
dependence may depend on lag effects and antecedent features of abiotic
and biotic drivers associated with above- and belowground process
linkages. We set up a 6 months long experiment to determine the biotic
and abiotic drivers of the hysteretic relationship between soil
respiration and soil temperature. The experiment took place at Ecotron
IleDeFrance (France) using replicated closed environmental facilities
allowing the simultaneous control of environmental conditions and
on-line measurement of ecosystem processes. We reproduced semi-arid
ecosystems using basalt soil mesocosms planted with two functional
groups of plants (shrubs and grasses) in monocultures and in a mixture.
We independently controlled above- and belowground temperatures and
rainfall intensity. The split-plot, repeated-measures design allowed for
diel aboveground and temperature cycle treatments to mimic natural
conditions or for diel cycle aboveground temperature and constant soil
temperature treatments to constrain vertical soil temperature gradients,
yet mimic natural aboveground conditions. Soil CO2 concentrations were
measured under mild and heavy precipitations conditions that represent
current and project conditions. We calculated the soil respiration every
30 minutes using the gradient method and conducted additional plant
photosynthesis measurements to better target the role of biotic factors.
Our data show that abiotic and biotic treatments affect the total soil
respiration but also diel patterns and the strength of the hysteretic
effect. This demonstrates the power of experimental approaches to
disentangle physical and biological drivers of soil respiration and
better predict future CO2 efflux from soils.
Auteurs, date et publication :
Auteurs Yann Dusza , Sabrina Juarez , Simon Chollet , Régis Ferrière , Amandine Hansart , Florent Massol , Mathieu Llavata , Jean-François Le Galliard , Enrique Pérez Sánchez-Cañete , Greg Barron-Gafford
Date : 2018
Volume : 20
Pages : 8461
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Simon P. K. Bowring , Matthew W. Jones , Philippe Ciais , Bertrand Guenet , Samuel Abiven
Publication : Nature Geoscience
Date : 2025
Volume : 15
Issue : 2
Pages : 135-142
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Johanne Lebrun Thauront , Christian Walter , Philippa Ascough , Pierre Barre , Samuel Abiven
Date : 2023
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Johanne Lebrun Thauront , Severin Luca Bellè , Marcus Schiedung , Amicie Delahaie , Marija Stojanova , François Baudin , Pierre Barré , Samuel Abiven
Date : 2024