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18 results on '"Cornec, E."'

1. Decoding drivers of carbon flux attenuation in the oceanic biological pump.

Author

Bressac, M, Laurenceau-Cornec, E, Kennedy, F, Santoro, Alyson, Paul, N, Briggs, N, Carvalho, F, and Boyd, P

Subjects
Animals, Carbon, Carbon Cycle, Carbon Sequestration, Ecosystem, Oceans and Seas, Seawater, Zooplankton, Temperature, Aquatic Organisms
Abstract

The biological pump supplies carbon to the oceans interior, driving long-term carbon sequestration and providing energy for deep-sea ecosystems1,2. Its efficiency is set by transformations of newly formed particles in the euphotic zone, followed by vertical flux attenuation via mesopelagic processes3. Depth attenuation of the particulate organic carbon (POC) flux is modulated by multiple processes involving zooplankton and/or microbes4,5. Nevertheless, it continues to be mainly parameterized using an empirically derived relationship, the Martin curve6. The derived power-law exponent is the standard metric used to compare flux attenuation patterns across oceanic provinces7,8. Here we present in situ experimental findings from C-RESPIRE9, a dual particle interceptor and incubator deployed at multiple mesopelagic depths, measuring microbially mediated POC flux attenuation. We find that across six contrasting oceanic regimes, representing a 30-fold range in POC flux, degradation by particle-attached microbes comprised 7-29 per cent of flux attenuation, implying a more influential role for zooplankton in flux attenuation. Microbial remineralization, normalized to POC flux, ranged by 20-fold across sites and depths, with the lowest rates at high POC fluxes. Vertical trends, of up to threefold changes, were linked to strong temperature gradients at low-latitude sites. In contrast, temperature played a lesser role at mid- and high-latitude sites, where vertical trends may be set jointly by particle biochemistry, fragmentation and microbial ecophysiology. This deconstruction of the Martin curve reveals the underpinning mechanisms that drive microbially mediated POC flux attenuation across oceanic provinces.

Published
2024

4. The effect of temperature on the release of silicon, iron and manganese into seawater from resuspended sediment particles

Author

Liao, W.-H., Planquette, H., Moriceau, B., Lambert, C., Desprez de Gesincourt, F., Laurenceau-Cornec, E., Sarthou, G., Gorgues, T., Liao, W.-H., Planquette, H., Moriceau, B., Lambert, C., Desprez de Gesincourt, F., Laurenceau-Cornec, E., Sarthou, G., and Gorgues, T.

Abstract

Sediments are considered to be refractory materials with limited influences on dissolved iron (dFe) pool in the ocean. However, recent field observations and laboratory experiments suggest that iron released from resuspended sediment particles and transported from continental margins is prone to fertilize large areas of the world ocean. Here we conducted a dissolution experiment to quantify the amount of dFe released from two types of resuspended sediments (silicate and calcite-rich) to open ocean surface seawater under two temperatures (5 and 15 °C). We followed pH, dissolved oxygen (dO2), phosphate, silicate, dissolved Fe and Mn concentrations (dFe and dMn), and bacterial abundance over 250 days. Extremely low and undetectable phosphate concentrations (<50 pmol kg−1) were measured throughout the duration of the experiment, causing limited bacteria growth and stable pH and dissolved O 2 concentrations under all conditions. Silicate and dFe concentrations increased through time and high temperature (15 °C) induced more iron dissolution from the two sediments than low temperature (5 °C). Temperature had no effect on the dissolution of Mn. Our results further show that Fe and Mn are not released concurrently from the sediment source and that their distribution can be very different. Scavenging of Fe likely caused a decrease of dFe observed during the experiment, which was probably linked to the formation of Mn oxides. We also observed elevated dissolved Fe isotope ratios after dissolution, around +0.16 to +0.27‰. Isotopically heavy Fe was released from sediments to the dissolved pool during the dissolution but no difference in Fe isotope ratios was observed between the two temperature conditions. The Fe isotope fractionation can likely be attributed to ligand complexation and scavenging of Fe. These two mechanisms can be important factors not only in controlling the amount of Fe released from sediments but also in fractionating Fe i

Published
2023

7. Resupply of mesopelagic dissolved iron controlled by particulate iron composition

Author

Bressac , M., Guieu , C., Ellwood, Michael, Tagliabue, Alessandro, Wagener, T., Laurenceau-Cornec, E. C., Whitby, H., Sarthou, G., Boyd, Phillip, Bressac , M., Guieu , C., Ellwood, Michael, Tagliabue, Alessandro, Wagener, T., Laurenceau-Cornec, E. C., Whitby, H., Sarthou, G., and Boyd, Phillip

Abstract

The dissolved iron supply controls half of the oceans' primary productivity. Resupply by the remineralization of sinking particles, and subsequent vertical mixing, largely sustains this productivity. However, our understanding of the drivers of dissolved iron resupply, and their influence on its vertical distribution across the oceans, is still limited due to sparse observations. There is a lack of empirical evidence as to what controls the subsurface iron remineralization due to difficulties in studying mesopelagic biogeochemistry. Here we present estimates of particulate transformations to dissolved iron, concurrent oxygen consumption and iron-binding ligand replenishment based on in situ mesopelagic experiments. Dissolved iron regeneration efficiencies (that is, replenishment over oxygen consumption) were 10- to 100-fold higher in low-dust subantarctic waters relative to higher-dust Mediterranean sites. Regeneration efficiencies are heavily influenced by particle composition. Their make-up dictates ligand release, controls scavenging, modulates ballasting and may lead to the differential remineralization of biogenic versus lithogenic iron. At high-dust sites, these processes together increase the iron remineralization length scale. Modelling reveals that in oceanic regions near deserts, enhanced lithogenic fluxes deepen the ferricline, which alter the vertical patterns of dissolved iron replenishment, and set its redistribution at the global scale. Such wide-ranging regeneration efficiencies drive different vertical patterns in dissolved iron replenishment across oceanic provinces.

Published
2019

8. Carbon export in the naturally iron-fertilized Kerguelen area of the Southern Ocean based on the 234Th approach

Author

Planchon, Frédéric, Ballas, D., Cavagna, A.-J., Bowie, A. R., Davies, D., Trull, T., Laurenceau-Cornec, E. C., Van Der Merwe, P., Dehairs, F., Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Analytical, Environmental and Geo- Chemistry, Vrije Universiteit Brussel (VUB), Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Institute for Marine and Antarctic Studies [Hobart] (IMAS), University of Tasmania [Hobart, Australia] (UTAS), CSIRO Marine and Atmosphere Research [Hobart], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), ANR-10-BLAN-0614,KEOPS 2,Kerguelen : Comparaison plateau Ocean2(2010), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institute for Marine and Antarctic Studies [Horbat] (IMAS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, ACL, lcsh:QE1-996.5, PHYTOPLANKTON BLOOM, lcsh:Life, ATLANTIC SECTOR, ANTARCTIC POLAR FRONT, PARTICLE EXPORT, DISSOLVED IRON, REGION, lcsh:Geology, NITROGEN UPTAKE, lcsh:QH501-531, PLATEAU, lcsh:QH540-549.5, lcsh:Ecology, SPRING BLOOM, PARTICULATE ORGANIC-CARBON, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

This study examined upper-ocean particulate organic carbon (POC) export using the 234Th approach as part of the second KErguelen Ocean and Plateau compared Study expedition (KEOPS2). Our aim was to characterize the spatial and the temporal variability of POC export during austral spring (October–November 2011) in the Fe-fertilized area of the Kerguelen Plateau region. POC export fluxes were estimated at high productivity sites over and downstream of the plateau and compared to a high-nutrient low-chlorophyll (HNLC) area upstream of the plateau in order to assess the impact of iron-induced productivity on the vertical export of carbon. Deficits in 234Th activities were observed at all stations in surface waters, indicating early scavenging by particles in austral spring. 234Th export was lowest at the reference station R-2 and highest in the recirculation region (E stations) where a pseudo-Lagrangian survey was conducted. In comparison 234Th export over the central plateau and north of the polar front (PF) was relatively limited throughout the survey. However, the 234Th results support that Fe fertilization increased particle export in all iron-fertilized waters. The impact was greatest in the recirculation feature (3–4 fold at 200 m depth, relative to the reference station), but more moderate over the central Kerguelen Plateau and in the northern plume of the Kerguelen bloom (~2-fold at 200 m depth). The C : Th ratio of large (>53 μm) potentially sinking particles collected via sequential filtration using in situ pumping (ISP) systems was used to convert the 234Th flux into a POC export flux. The C : Th ratios of sinking particles were highly variable (3.1 ± 0.1 to 10.5 ± 0.2 μmol dpm−1) with no clear site-related trend, despite the variety of ecosystem responses in the fertilized regions. C : Th ratios showed a decreasing trend between 100 and 200 m depth suggesting preferential carbon loss relative to 234Th possibly due to heterotrophic degradation and/or grazing activity. C : Th ratios of sinking particles sampled with drifting sediment traps in most cases showed very good agreement with ratios for particles collected via ISP deployments (>53 μm particles). Carbon export production varied between 3.5 ± 0.9 and 11.8 ± 1.3 mmol m−2 d−1 from the upper 100 m and between 1.8 ± 0.9 and 8.2 ± 0.9 mmol m−2 d−1 from the upper 200 m. The highest export production was found inside the PF meander with a range of 5.3 ± 1.0 to 11.8 ± 1.1 mmol m−2 d−1 over the 19-day survey period. The impact of Fe fertilization is highest inside the PF meander with 2.9–4.5-fold higher carbon flux at 200 m depth in comparison to the HNLC control station. The impact of Fe fertilization was significantly less over the central plateau (stations A3 and E-4W) and in the northern branch of the bloom (station F-L) with 1.6–2.0-fold higher carbon flux compared to the reference station R. Export efficiencies (ratio of export to primary production and ratio of export to new production) were particularly variable with relatively high values in the recirculation feature (6 to 27 %, respectively) and low values (1 to 5 %, respectively) over the central plateau (station A3) and north of the PF (station F-L), indicating spring biomass accumulation. Comparison with KEOPS1 results indicated that carbon export production is much lower during the onset of the bloom in austral spring than during the peak and declining phases in late summer.

Published
2015
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9. Carbon export in the naturally iron-fertilized Kerguelen area of the Southern Ocean based on the Th-234 approach

Author

Planchon, F., Ballas, Dionysios, Cavagna, A. -j., Bowie, A. R., Davies, D., Trull, Thomas, Laurenceau-cornec, E. C., Van Der Merwe, P., and Dehairs, F.

Abstract

This study examined upper-ocean particulate organic carbon (POC) export using the Th-234 approach as part of the second KErguelen Ocean and Plateau compared Study expedition (KEOPS2). Our aim was to characterize the spatial and the temporal variability of POC export during austral spring (October-November 2011) in the Fe-fertilized area of the Kerguelen Plateau region. POC export fluxes were estimated at high productivity sites over and downstream of the plateau and compared to a high-nutrient low-chlorophyll (HNLC) area upstream of the plateau in order to assess the impact of iron-induced productivity on the vertical export of carbon. Deficits in Th-234 activities were observed at all stations in surface waters, indicating early scavenging by particles in austral spring. Th-234 export was lowest at the reference station R-2 and highest in the recirculation region (E stations) where a pseudo-Lagrangian survey was conducted. In comparison Th-234 export over the central plateau and north of the polar front (PF) was relatively limited throughout the survey. However, the Th-234 results support that Fe fertilization increased particle export in all iron-fertilized waters. The impact was greatest in the recirculation feature (3-4 fold at 200 m depth, relative to the reference station), but more moderate over the central Kerguelen Plateau and in the northern plume of the Kerguelen bloom (similar to 2-fold at 200 m depth). The C : Th ratio of large (> 53 mu m) potentially sinking particles collected via sequential filtration using in situ pumping (ISP) systems was used to convert the Th-234 flux into a POC export flux. The C : Th ratios of sinking particles were highly variable (3.1 +/- 0.1 to 10.5 +/- 0.2 mu mol dpm(-1)) with no clear site-related trend, despite the variety of ecosystem responses in the fertilized regions. C : Th ratios showed a decreasing trend between 100 and 200 m depth suggesting preferential carbon loss relative to Th-234 possibly due to heterotrophic degradation and/or grazing activity. C : Th ratios of sinking particles sampled with drifting sediment traps in most cases showed very good agreement with ratios for particles collected via ISP deployments (> 53 mu m particles). Carbon export production varied between 3.5 +/- 0.9 and 11.8 +/- 1.3 mmol m(-2) d(-1) from the upper 100 m and between 1.8 +/- 0.9 and 8.2 +/- 0.9 mmol m(-2) d(-1) from the upper 200 m. The highest export production was found inside the PF meander with a range of 5.3 +/- 1.0 to 11.8 +/- 1.1 mmol m(-2) d(-1) over the 19-day survey period. The impact of Fe fertilization is highest inside the PF meander with 2.9-4.5-fold higher carbon flux at 200 m depth in comparison to the HNLC control station. The impact of Fe fertilization was significantly less over the central plateau (stations A3 and E-4W) and in the northern branch of the bloom (station F-L) with 1.6-2.0-fold higher carbon flux compared to the reference station R. Export efficiencies (ratio of export to primary production and ratio of export to new production) were particularly variable with relatively high values in the recirculation feature (6 to 27 %, respectively) and low values (1 to 5 %, respectively) over the central plateau (station A3) and north of the PF (station F-L), indicating spring biomass accumulation. Comparison with KEOPS1 results indicated that carbon export production is much lower during the onset of the bloom in austral spring than during the peak and declining phases in late summer.

Published
2015

10. Pseudohypobicarbonatemia in a patient with a kappa IgA monoclonal gammapathy [Pseudohypobicarbonatémie chez une patiente atteinte d'une gammapathie monoclonale à IgA kappa]

Author

Lazzouni, I., Cornec, E., Meskar, A., Lucas, D., Kerspern, H., Carré, J.-L., Institut de Recherche sur l'Enseignement des Sciences (IRES), and Université d'Orléans (UO)

Subjects
[SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014
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11. Kryoskopie

Author

Noyes, A. A., Falk, K. G., Washburn, Göbel, J. B., Hartung, C. B., Robertson, Ph. W., Beckmann, E., Maxim, M., Beckmann, E., Faust, O., Sackur, O., Hoenen, P. H. J., Bray, W. C., Leenhardt, C., Boutaric, A., Cornec, E., Urbain, G., Beckmann, E., Waentig, P., Hanslian, R., Deekhuyzen, M. C., Tezner, E., Roska, J., Giran, G., Scheuer, O., Kinoshita, Tosaka, Burian, R., Drucker, K., Guy, Bogdan, Poda, Lespieau, R., Blarez, Ch., Lematte, L., Rupp, E., Moulin, Baud, E., Gay, L., Adams, L. A., Jahn, G., Roth, W. A., Flügel, F., Bedford, T. G., Richards, Th. W., White, W. P., Olivari, Reidt, H. S., Mc Intosh, D., Kablukow, J. A., Moles, Atkins, W. R. G., Louguinine, Dupont, Protolongo, U., Mascarelli, Benati, Beckmann, E., Lockemann, Oddo, Jouniaux, Isbekow, W. A., Böseken, J., van der Eerden, J. A. L. M. C., and Hansen, C. C.

Published
1916
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13. Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean

Author

Trull, T. W., primary, Davies, D. M., additional, Dehairs, F., additional, Cavagna, A.-J., additional, Lasbleiz, M., additional, Laurenceau-Cornec, E. C., additional, d'Ovidio, F., additional, Planchon, F., additional, Leblanc, K., additional, Quéguiner, B., additional, and Blain, S., additional

Published
2015
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14. The relative importance of phytoplankton aggregates and zooplankton fecal pellets to carbon export: insights from free-drifting sediment trap deployments in naturally iron-fertilised waters near the Kerguelen Plateau

Author

Laurenceau-Cornec, E. C., primary, Trull, T. W., additional, Davies, D. M., additional, Bray, S. G., additional, Doran, J., additional, Planchon, F., additional, Carlotti, F., additional, Jouandet, M.-P., additional, Cavagna, A.-J., additional, Waite, A. M., additional, and Blain, S., additional

Published
2015
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15. Allgemeine Methoden

Author

Green, J., Zschacke, F. H., Gendre, J. L., Rinck, E., Cornec, E., Krombach, H., Lemarchands, M., Tranchat, C., and Harral, J. C.

Published
1933
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16. Carbon export in the naturally iron-fertilized Kerguelen area of the Southern Ocean based on the 234Th approach.

Author

Planchon, F., Ballas, D., Cavagna, A.-J., Bowie, A. R., Davies, D., Trull, T., Laurenceau-Cornec, E. C., Van Der Merwe, P., and Dehairs, F.

Subjects
CARBON & the environment, IRON fertilizers, BIOACCUMULATION, THORIUM isotopes
Abstract

This study examined upper-ocean particulate organic carbon (POC) export using 234Th approach as part of the second KErguelen Ocean and Plateau compared Study expedition (KEOPS2). Our aim was to characterize the spatial and the temporal variability of POC export during austral spring (October-November 2011) in the Fe-fertilized area of the Kerguelen Plateau region. POC export fluxes were estimated at high productivity sites over and downstream of the plateau and compared to a high-nutrient low-chlorophyll (HNLC) area upstream of the plateau in order to assess the impact of iron-induced productivity on the vertical export of carbon. Deficits in 234Th activities were observed at all stations in surface waters, indicating early scavenging by particles in austral spring. 234Th export was lowest at the reference station R-2 and highest in the recirculation region (E stations) where a pseudo-Lagrangian survey was conducted. In comparison 234Th export over the central plateau and north of the polar front (PF) was relatively limited throughout the survey. However, the 234Th results support that Fe fertilization increased particle export in all iron-fertilized waters. The impact was greatest in the recirculation feature (3-4 fold at 200m depth, relative to the reference station), but more moderate over the central Kerguelen Plateau and in the northern plume of the Kerguelen bloom (~2-fold at 200m depth). The C : Th ratio of large (>53 μm) potentially sinking particles collected via sequential filtration using in situ pumping (ISP) systems was used to convert the 234Th flux into a POC export flux. The C : Th ratios of sinking particles were highly variable (3.1±0.1 to 10.5±0.2 μmol dpm-1) with no clear site-related trend, despite the variety of ecosystem responses in the fertilized regions. C : Th ratios showed a decreasing trend between 100 and 200m depth suggesting preferential carbon loss relative to 234Th possibly due to heterotrophic degradation and/or grazing activity. C : Th ratios of sinking particles sampled with drifting sediment traps in most cases showed very good agreement with ratios for particles collected via ISP deployments (>53 μm particles). Carbon export production varied between 3.5±0.9 and 11.8±1.3 mmol m-2 d-1 from the upper 100m and between 1.8±0.9 and 8.2±0.9 mmol m-2 d-1 from the upper 200 m. The highest export production was found inside the PF meander with a range of 5.3±1.0 to 11.8±1.1 mmol m-2 d-1 over the 19-day survey period. The impact of Fe fertilization is highest inside the PF meander with 2.9-4.5-fold higher carbon flux at 200m depth in comparison to the HNLC control station. The impact of Fe fertilization was significantly less over the central plateau (stations A3 and E-4W) and in the northern branch of the bloom (station F-L) with 1.6-2.0- fold higher carbon flux compared to the reference station R. Export efficiencies (ratio of export to primary production and ratio of export to new production) were particularly variable with relatively high values in the recirculation feature (6 to 27 %, respectively) and low values (1 to 5 %, respectively) over the central plateau (station A3) and north of the PF (station F-L), indicating spring biomass accumulation. Comparison with KEOPS1 results indicated that carbon export production is much lower during the onset of the bloom in austral spring than during the peak and declining phases in late summer. [ABSTRACT FROM AUTHOR]

Published
2015
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18. [Pseudohypobicarbonatemia in a patient with a kappa IgA monoclonal gammapathy].

Author

Lazzouni I, Cornec E, Meskar A, Lucas D, Kerspern H, and Carré JL

Subjects
Aged, False Positive Reactions, Female, Humans, Paraproteinemias immunology, Bicarbonates blood, Blood Chemical Analysis, Immunoglobulin A, Paraproteinemias blood, Water-Electrolyte Imbalance blood
Abstract

Paraprotein interferences assays are known but rather unusual in clinical chemistry.we here report a paraprotein interference with a bicarbonate assay in a IgA kappa-type myeloma patient. Serum bicarbonate level was assessed by the enzymatic method of a multiparametric chemistry analyzer (Advia 1800, Siemens) as well as a specific electrode assay on a blood gas analyzer (GEM 4000, IL). Paraprotein interference with the enzymatic assay was evidenced by an abnomally low bicarbonate level measured by the enzymatic method in contrast with usual levels obtained by using the gas analyzer and with the clinical status of the patient. Therefore, gammapathy has to be taken into consideration when interpreting biological data.

Published
2014
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