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3 results on '"Oxygen concentrations"'

1. Fish debris in sediments from the last 25 kyr in the Humboldt Current reveal the role of productivity and oxygen on small pelagic fishes

Author

Abdelfettah Sifeddine, Arnaud Bertrand, David B. Field, Sandrine Caquineau, Luc Ortlieb, Tim R. Baumgartner, Dimitri Gutiérrez, Renato Salvatteci, Vicente Ferreira, Institute of Geosciences [Kiel], Christian-Albrechts-Universität zu Kiel (CAU), Instituto del Mar del Peru (IMARPE), College of Natural Sciences, Hawaii Pacific University, LMI 'PALEOTRACES', IRD-UFF- Univ. of Antofagasta Chile, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Variabilité à long terme du climat de l'océan (VALCO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Centro de Investigacion Cientıfica y Educacion Superior de Ensenada, Universidad Autónoma de Baja California (UABC), Laboratory for Aroma Analysis and Enology, Instituto Agroalimentario de Aragón (IA2-Unizar-CITA), Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza - Universidad de Zaragoza [Zaragoza], MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), IMARPE-IRD project PALEOTRACES, IMARPE-IRD project DISCOH, Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Instituto Agroalimentario de Aragón (IA2), and University of Zaragoza - Universidad de Zaragoza [Zaragoza]-Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA)

Subjects
0106 biological sciences, Oxygen minimum zone, 010504 meteorology & atmospheric sciences, Fisheries, Laminated sediments, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, 01 natural sciences, Anchovy, Ecosystem structure, Climate change, Environmental conditions, 14. Life underwater, Glacial period, ComputingMilieux_MISCELLANEOUS, Productivity, 0105 earth and related environmental sciences, Last Glacial Maximum, biology, Engraulidae, 010604 marine biology & hydrobiology, Sardine, Engraulis ringens, Oxygen concentrations, Geology, Pelagic zone, biology.organism_classification, Glacial geology, Oxygen, Fish, Oceanography, Sampling resolution, Productivity (ecology), purl.org/pe-repo/ocde/ford#1.05.11 [https], 13. Climate action, Forage fish, Pisces, Global temperatures, Environmental science, Upwelling
Abstract

International audience; Upwelling of cold, nutrient-rich water from the oxygen minimum zone (OMZ) off Peru sustains the world’shighest production of forage fish, mostly composed of anchovy (Engraulis ringens). However, the potentialimpacts of climate change on upwelling dynamics and thus fish productivity in the near future areuncertain. Here, we reconstruct past changes in fish populations during the last 25,000 years to unraveltheir response to changes in OMZ intensity and productivity. We quantified and identified fish scales andbones deposited in laminated sediments from Pisco (Peru) with an average sampling resolution of 20.4years (±7.1). The records span the Last Glacial Maximum to the recent Holocene and thus encompass avariety of combinations of productivity, oxygen, and global temperature. Our results reveal thatproductivity appears to be the main factor controlling small pelagic fish abundance, while sub-surfaceoxygenation affects mainly anchovy and likely sardine populations. Lower productivity and higher oxygenconcentrations during the glacial resulted in lower total fish productivity, whereas higher productivity anda stronger OMZ in some time intervals during the Holocene resulted in higher fish abundances. A varietyof different conditions between these two oceanographic end members indicate preferred environmentalconditions for a variety of small pelagic fishes. There is no evidence in our record for an out of phaserelationship between anchovy and sardine at the timescales examined in the present study. Anchovy havebeen the predominant small pelagic fish throughout the record, at least over centennial to millennialtimescales. Its abundance reached a maximum during the Current Warm Period, an era characterized byhigh productivity and intense OMZ conditions. Thus, industrial fisheries developed during a period ofexceptional productivity in relation to that of the last 25 kyr. The records reveal that dramatic decreasesin pelagic fish abundances have occurred in response to past large-scale climate changes than thoseobserved in the instrumental period, which suggests that future climate change may result in substantialchanges in ecosystem structure.

Published
2019
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2. Heat feedback to the fuel surface of a pool fire in an enclosure

Author

Jean-Pierre Garo, Sylvain Suard, L. Rigollet, A. Nasr, Hazem El-Rabii, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Institut Pprime (PPRIME), Université de Poitiers-ENSMA-Centre National de la Recherche Scientifique (CNRS), EDF R&D (EDF R&D), and EDF (EDF)

Subjects
Convection, Meteorology, Enclosure, Combustion, General Physics and Astronomy, 020101 civil engineering, 02 engineering and technology, Fuels, Flow rate, 01 natural sciences, Fires, 0201 civil engineering, law.invention, Combustion products, Mechanical ventilation, law, General Materials Science, Compartment fires, Safety, Risk, Reliability and Quality, [PHYS]Physics [physics], Heptane, Heat flux measurement, Oxygen concentrations, General Chemistry, Mechanics, Ventilation, 010406 physical chemistry, 0104 chemical sciences, Volumetric flow rate, Adiabatic flame temperature, Plume, Oxygen, Lakes, Mass loss rate, Flame temperatures, Heat flux, Heat Release Rate (HRR), Ventilation (architecture), Environmental science, Limiting oxygen concentration
Abstract

International audience; As a part of an effort to determine the energy balance at the pool fire surface in compartments, a series of fire experiments were conducted to study heat flux of the flame in a vitiated environment formed with air and combustion products gases. This paper presents experimental results of the burning behaviour of a heptane pool fire in a reduced scale compartment equipped with a mechanical ventilation network. Measurements of heat fluxes, fuel mass loss rate, oxygen concentration and temperature are performed for heptane fires of 0.26 and 0.3 m diameter pans at different ventilation flow rates. An original method to separate effects of the radiant heat flux of the flame and of the external heat feedback to the fuel surface is developed. This was achieved by using an additional heat flux measurement located under the pool fire. A correlation was also developed to determine the temperature rise on the plume centerline in the compartment as a function of the heat release rate. The results indicate a decrease in the fuel mass loss rate, flame temperature and heat fluxes to the fuel surface as the oxygen concentration measured near the fuel decreases by varying the air refresh rate of the compartment. The flame radiation fraction shows a similar behaviour, whereas the convective fraction of the flame heat flux increases when oxygen concentration decreases. Based on these experimental findings, it was discussed that any classification of the burning regime of a pool fire should consider both the effects of pan diameter and the burning response to vitiated air. © 2013 Elsevier Ltd. All rights reserved.

Published
2013
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3. Experimental and numerical study of the effects of the oxygen index on the radiation characteristics of laminar coflow diffusion flames

Author

Rodrigo Henríquez, Jean-Louis Consalvi, Fatiha Nmira, Fengshan Liu, Andrés Fuentes, Departamento de Industrias, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chile, EDF (EDF), Measurement Science and Standards [Ottawa], National Research Council of Canada (NRC), Institut universitaire des systèmes thermiques industriels (IUSTI), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Co-flow, Soot oxidation, General Chemical Engineering, Diffusion, Analytical chemistry, Soot model, Radiation effects, General Physics and Astronomy, 02 engineering and technology, medicine.disease_cause, Measured values, Heat radiation, 01 natural sciences, Oxygen, 010305 fluids & plasmas, Rate of increase, Smoke, Soot volume fraction, Vertical distributions, ethylene, 0202 electrical engineering, electronic engineering, information engineering, Oxidizer stream, diffusion coefficient, Radiation characteristics, Fuel flow rates, Two-equation, [PHYS]Physics [physics], Soot formations, Acetylene, Correlated-k models, Volumetric flow rate, Dust, laminar coflow diffusion flame, Smoke point, Nondimensional, Soot, stoichiometry, Fuel Technology, Volume fraction, flow rate, fire, chemical parameters, Semi-empirical, oxidation, 020209 energy, Energy Engineering and Power Technology, chemistry.chemical_element, Oxygen index, complex mixtures, Laminar diffusion flames, Experimental and numerical studies, 0103 physical sciences, medicine, Narrow bands, Coflow diffusion flames, temperature, Oxygen concentrations, prediction, General Chemistry, Radiative fluxes, Adiabatic flame temperature, Two-regime, radiation, Ethylene diffusion flames, Flame height, chemistry, 13. Climate action, Limiting oxygen concentration, Forecasting
Abstract

International audience; The oxygen concentration in the oxidizer stream (O-2 + N-2) of laminar coflow ethylene diffusion flames is varied from 17% to 35% in order to study its influence on the flame height, the soot formation/oxidation processes, the smoke point characteristics, and the vertical distributions of radiative flux at a distance of 6.85 cm from the flame axis. Measured values for all the investigated parameters are compared with the predictions provided by a numerical model based on a two-equation semiempirical acetylene-based soot model and on the statistical narrow-band correlated-k model to compute thermal radiation. Predictions are in overall reasonable agreement with the experiments for oxygen indices in the range 19-35%, whereas all the investigated parameters are significantly underestimated for an oxygen index of 17%. Measured flame heights based on CH* emission below, at, or slightly above the smoke point, as well as predicted stoichiometric flame heights, are found to be proportional to xi = (V) over dot(f)[D-infinity In(1 + 1/S)](-1) (T-infinity/T-ad)(0.67), where (V) over dot(f), D-infinity, S, and T-ad are the volumetric flow rate of ethylene, the diffusion coefficient at ambient temperature, the stoichiometric molecular air-to-fuel ratio, and the adiabatic flame temperature. Soot formation processes are found to increase with the oxygen index, leading to higher values of the maximum soot volume fraction and the peak integrated soot volume fraction. In addition, the latter is reached at a nondimensional height (normalized by xi of approximately 0.05, regardless of the oxygen index within the investigated range. Two regimes are evidenced: The first regime, occurring for oxygen indices lower than 25%, is dominated by soot oxidation and is characterized by an enhancement in both the maximum soot volume fraction and the fuel flow rate at the smoke point with the oxygen index. The second regime, occurring for oxygen indices higher than 25%, is dominated by soot formation; the rate of increase in the maximum soot volume fraction with the oxygen concentration is lower than in the first regime, whereas the fuel flow rate at the smoke point decreases. Finally, the peak of radiative flux increases with the oxygen index, but its rate of increase is also found to be considerably reduced for oxygen indices greater than 25%. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Published
2013
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