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1. Variation of the isotopic composition of dissolved organic carbon during the runoff cycle in the Amazon River and the floodplains

Author

Gwenaël Abril, Marc F. Benedetti, Marcela A.P. Pérez, Patricia Moreira-Turcq, Steven Bouillon, Patrick Albéric, Laboratoire « Environnements et Pale ́oenvironnements oce ́aniques et continentaux » (EPOC), CNRS, universite ́ de Bordeaux, 1, avenue des Faculte ́s, 33405 Talence, France, 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), Departamento de Geoquímica, Universidade Federal Fluminense [Rio de Janeiro] (UFF), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -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), Division of Soil and Water Management Leuven, Department of Earth and Environmental Sciences [Leuven] (EES), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven)-Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), CNRS-INSU : EC2CO, ANR-08-BLAN-0221,CARBAMA,CARBon biogeochemistry and atmospheric exchanges in the AMAzon river system(2008), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), 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 Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-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), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), and 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)

Subjects
C-13C-12, 010504 meteorology & atmospheric sciences, Floodplain, [SDE.MCG]Environmental Sciences/Global Changes, Drainage basin, C4 plant raft, Runoff cycle, DOC, 01 natural sciences, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Dissolved organic carbon, Tributary, Water cycle, 13C/12C, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Amazon Basin, Hydrology, Total organic carbon, Global and Planetary Change, geography, geography.geographical_feature_category, 010401 analytical chemistry, 15. Life on land, C-4 plant raft, 0104 chemical sciences, Macrophyte, General Earth and Planetary Sciences, Environmental science, Spatial variability
Abstract

Given the relative scarcity of stable isotope data on dissolved organic carbon (DOC) in the Amazon Basin, we hypothesized that the variability in DOC sources may be underestimated in such major river basins. To explore the links between the mainstem and tributaries and the floodplain, particular efforts were made during five distinct cruises at different stages of the hydrograph between October 2008 and January 2011, to document the spatial and temporal variation of DOC concentrations and delta C-13-DOC in the central Amazon River system (Brazil). Based on more than 200 data, the spatial and temporal variability of delta C-13-DOC values was found to be larger than previously reported in the same area. Although a small range of variation was observed throughout the hydrological cycle in the upper reach of the studied section (-29.2 to -29.5 parts per thousand in the Rio Negro and -28.7 to -29.0 parts per thousand in the Rio Solimoes), a much larger one (-28.0 to -34.6 parts per thousand) was found in the lower reach of the river, as the proportion of open lakes increased downstream in the floodplains. The low variability in the upper reaches suggests constant and homogeneous DOC sources from upland soils and flooded forest, while lower delta C-13-DOC values recorded in the lower reach mainstem at high and falling waters can be attributed to a greater export of plankton-derived C-13-depleted DOC from flooded lakes. Noteworthy are the higher delta C-13-DOC values measured in the Rio Madeira and the associated flooded lakes (-26.5 to -28.8 parts per thousand, which may reflect the imprint from upland headwaters and a weaker density of flooded forest in the watershed. The higher delta C-13-DOC values observed in the lower reach during low waters are still not fully understood. Floating meadows principally consisting of C-4 macrophytes were found to increase delta C-13-DOC values by similar to 1.5 parts per thousand in their vicinity, but this impact was no longer noticeable at distances of similar to 10 m from the plant rafts. This rather modest C-13-enrichment suggests rapid decomposition and/or dilution of this wetland-derived DOC.

Published
2018
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2. Wood decomposition in Amazonian hydropower reservoirs: An additional source of greenhouse gases

Author

Naziano Filizola, Marcelo Parize, Gwenaël Abril, and Marcela A.P. Pérez

Subjects
Hydrology, business.industry, Amazonian, Biomass, Geology, Methane, Atmosphere, chemistry.chemical_compound, chemistry, Hydroelectricity, Greenhouse gas, Carbon dioxide, business, Hydropower, Earth-Surface Processes
Abstract

Amazonian hydroelectric reservoirs produce abundant carbon dioxide and methane from large quantities of flooded biomass that decompose anaerobically underwater. Emissions are extreme the first years after impounding and progressively decrease with time. To date, only water-to-air fluxes have been considered in these estimates. Here, we investigate in two Amazonian reservoirs (Balbina and Petit Saut) the fate of above water standing dead trees, by combining a qualitative analysis of wood state and density through time and a quantitative analysis of the biomass initially flooded. Dead wood was much more decomposed in the Balbina reservoir 23 years after flooding than in the Petit Saut reservoir 10 years after flooding. Termites apparently played a major role in wood decomposition, occurring mainly above water, and resulting in a complete conversion of this carbon biomass into CO 2 and CH 4 at a timescale much shorter than reservoir operation. The analysis of pre-impounding wood biomass reveals that above-water decomposition in Amazonian reservoirs is a large, previously unrecognized source of carbon emissions to the atmosphere, representing 26–45% of the total reservoir flux integrated over 100 years. Accounting for both below- and above-water fluxes, we could estimate that each km 2 of Amazonian forest converted to reservoir would emit over 140 Gg CO 2 -eq in 100 years. Hydropower plants in the Amazon should thus generate 0.25–0.4 MW h per km 2 flooded area to produce lower greenhouse gas emissions than gas power plants. They also have the disadvantage to emit most of their greenhouse gases the earliest years of operation.

Published
2013
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3. Seasonal variability in concentration, composition, age, and fluxes of particulate organic carbon exchanged between the floodplain and Amazon River

Author

Marcelo Amorim, Laurence Maurice, Marcelo Bernardes, Patrick Seyler, Christelle Lagane, Marcela A.P. Pérez, Patricia Moreira-Turcq, and Marie-Paule Bonnet

Subjects
Total organic carbon, Hydrology, chemistry.chemical_classification, Atmospheric Science, Global and Planetary Change, geography, geography.geographical_feature_category, Floodplain, δ13C, Particulates, Macrophyte, chemistry, Dissolved organic carbon, Phytoplankton, Environmental Chemistry, Environmental science, Organic matter, General Environmental Science
Abstract

[1] The composition, sources, and age of particulate organic matter were determined in an Amazonian river-floodplain system during rising, high, falling, and low water periods over 7 yr (1999–2006), and a mass balance for total organic carbon (dissolved and particulate) was estimated. The Curuai floodplain, composed of several temporally interconnected lakes, is permanently connected to the Amazon River via channels. Organic matter (OM) is imported to the floodplain from the Amazon River mainly during the rising water period and produced in the floodplain and exported to the river during high and falling water periods. No significant exchanges occurred during low water periods. The OM produced in the floodplain is characterized by low C/N ratios and by high chlorophyll a concentrations (Chl-a). The δ13C signature has a seasonal trend, with more negative δ13C values during the high water period than other periods. Δ14C results indicate that the bulk OM present in floodplain lakes is predominantly post-bomb (i.e., post-1950). Particulate organic carbon (POC) and dissolved organic carbon (DOC) fluxes exported by the Curuai floodplain represent 1.3% and 0.1%, respectively, of the POC and DOC annual fluxes in the mainstem Amazon River at Obidos but may reach up to 3.3% and 0.8% during falling water. Based on Δ14C, δ13C, Chl-a, and elemental analysis of the particulate organic matter, we demonstrate that floodplain lakes have intense phytoplankton and macrophyte primary production, which is partly exported to the main river channel. Floodplains are thus a significant source of modern and labile organic carbon to the river mainstem, where it can be rapidly degraded and recycled back to the atmosphere.

Published
2013
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4. The fate of C4 and C3 macrophyte carbon in central Amazon floodplain waters: Insights from a batch experiment

Author

Cédric Hubas, Luciana O. Vidal, P. Albéric, Gwenaël Abril, Marc F. Benedetti, Najet Thiney, Claire Passarelli, Tarik Meziane, Marcela A.P. Pérez, Patricia Moreira-Turcq, Jean-Michel Mortillaro, Luis Felipe Artigas, Direction régionale à Madagascar (Dgdrs-Dre), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Universidade Federal Fluminense [Rio de Janeiro] (UFF), 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)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Biogéosystèmes Continentaux - UMR7327, PSL Research University (PSL)-PSL Research University (PSL)-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), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Université de Lille-Université du Littoral Côte d'Opale-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), 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), Institut de recherche pour le développement (IRD [Burkina Faso]), Laboratório de Ecologia Aquática, Universidade Federal de Juiz de Fora (UFJF), CNPq (National Council for Scientific and Technological Development – Brazil, Universal Program grant number 477655/2010-6), it was conducted within an international cooperation agreement between the CNPq (Brazil) and the IRD (Institute for Research and Development – France), and under the auspices of the Environmental Research Observatory Hydrology and Geochemistry of the Amazon Basin (HYBAM), supported by the INSU and the IRD, ANR-08-BLAN-0221,CARBAMA,CARBon biogeochemistry and atmospheric exchanges in the AMAzon river system(2008), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Centre National de la Recherche Scientifique (CNRS), 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), 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)-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)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Muséum national d'Histoire naturelle (MNHN), 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), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Université du Littoral Côte d'Opale (ULCO), Institut de Physique du Globe de Paris (IPG Paris), Université du Littoral Côte d'Opale-Université de Lille-Centre National de la Recherche Scientifique (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), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, F40 - Écologie végétale, F60 - Physiologie et biochimie végétale, [SDV]Life Sciences [q-bio], Heterotroph, Aquatic Science, 01 natural sciences, fatty acids, Degradation, Total inorganic carbon, stables isotopes, Aquatic plant, Organic matter, Ecosystem, Central amazon, Fatty acids, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Central Amazon, degradation, chemistry.chemical_classification, Total organic carbon, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, Ecology, 010604 marine biology & hydrobiology, Floodplains, Mineralization (soil science), 15. Life on land, Macrophyte, macrophytes, Stables isotopes, Macrophytes, chemistry, floodplains, 13. Climate action, Environmental chemistry, M40 - Écologie aquatique, Environmental science
Abstract

The central Amazon floodplains are particularly productive ecosystems, where a large diversity of organic carbon sources are available for aquatic organisms. Despite the fact that C-4 macrophytes generally produce larger biomasses than C-3 macrophytes, food webs in the central Amazon floodplains appear dominantly based on a C-3 carbon source. In order to investigate the respective fate and degradation patterns of C-4 and C-3 aquatic plant-derived material in central Amazon floodplains, we developed a 23-days batch experiment. Fatty acid and carbon concentrations as well as stable isotope compositions were monitored over time in 60 L tanks. These tanks contained Amazon water, with different biomasses of C-3 and C-4 macrophyte, representative of in situ densities occurring in central Amazon floodplains. In the C-4 Paspalum repens treatments, organic (POC, DOC) and inorganic carbon (DIC) got rapidly enriched in C-13, whereas in the C-3 Salvinia auriculata treatments, POC and DOC showed little change in concentration and isotopic composition, and DIC got depleted in C-13. The contribution of P. repens to POC and DOC was estimated to reach up to 94.2 and 70.7%, respectively. In contrast, no differences were reported between the C-3 S. auriculata and control treatments, an observation attributed to the lower C-3 biomass encountered in the field, to a slower degradation rate of C-3 compared to C-4 compounds, and to similar isotopic compositions for river POC and DOC, and C-3 compounds. The C-13 enrichments of POC, DOC, and DIC from P. repens treatments were attributed to an enhanced bacterially-mediated hydrolysis and mineralization of C-4 material. Evolutions of bacterial abundance and branched fatty acid concentrations confirmed the role of heterotrophic microbial communities in the high P. repens decomposition rate. Our experiment highlights the predominant role of C-4 aquatic plants, as a large source of almost entirely biodegradable organic matter available for heterotrophic activity and CO2 outgassing to the atmosphere.

Published
2016
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5. Fatty acid and stable isotope (δ13C, δ15N) signatures of particulate organic matter in the lower Amazon River: Seasonal contrasts and connectivity between floodplain lakes and the mainstem

Author

Rodrigo Lima Sobrinho, Tarik Meziane, Gwenaël Abril, Marcela A.P. Pérez, Patricia Moreira-Turcq, and Jean-Michel Mortillaro

Subjects
P33 - Chimie et physique du sol, geography, geography.geographical_feature_category, Detritus, Floodplain, δ13C, Ecology, Stable isotope ratio, δ15N, Macrophyte, Geochemistry and Petrology, Aquatic plant, M40 - Écologie aquatique, Phytoplankton, Environmental science
Abstract

Fatty acid (FA) composition and stable isotope (δ 13 C, δ 15 N) signatures of four aquatic plants, plankton, sediment, soil and suspended particulate organic matter (SPOM) collected from open floodplain lakes (Varzea) and rivers of the central Brazilian Amazon basin were gathered during high and low water stages in 2009. SPOM from Varzea had a major contribution of autochthonous material from phytoplankton and C 3 aquatic plants. As shown from stable isotope composition of SPOM (δ 13 C −31.3 ± 3.2‰; δ 15 N 3.6 ± 1.5‰), the C 4 aquatic phanerogam (δ 13 C −13.1 ± 0.5‰; δ 15 N 4.1 ± 1.7‰) contribution appeared to be weak, although these plants were the most abundant macrophyte in the Varzea. During low water season, increasing concentration of 18:3ω3 was recorded in the SPOM of lakes. This FA, abundant mainly in the Varzea plants (up to 49% of total FAs), was due to the accumulation of their detritus in the ecosystem. This dry season, when connectivity with the river mainstem was restricted, was also characterized by a high concentration in the SPOM of the cyanobacteria marker 16:1ω7 (up to 21% of total FAs). The FA compositions of SPOM from the Amazon River also exhibited significant seasonal differences, in particular a higher concentration of 16:1ω7 and 18:3ω3 during the dry season. This suggests a seasonal contribution of autochthonous material produced in Varzea to the Amazon River SPOM.

Published
2011
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6. Mercury distribution and exchanges between the Amazon River and connected floodplain lakes

Author

Laurence Maurice, Poliana Dutra Maia, Daniel Cossa, David Amouroux, Isabelle Rheault, Marcela A.P. Pérez, Patricia Moreira-Turcq, and Emmanuel Tessier

Subjects
Environmental Engineering, Floodplain, Rain, chemistry.chemical_element, Fresh Water, Rivers, Dry season, Environmental Chemistry, Organic matter, Particle Size, Water pollution, Waste Management and Disposal, Suspended sediments, chemistry.chemical_classification, Hydrology, geography, geography.geographical_feature_category, Amazon River, Water, Sediment, Mercury, Particulates, Pollution, Mercury (element), Fluxes, chemistry, Environmental science, Floodplain lakes, Surface water, Water Pollutants, Chemical
Abstract

This work presents the distribution and the partition of mercury (Hg) in the Curuai floodplain lakes along the Amazon River. The maximum Total Filtered Hg (T-FHg) concentrations in the floodplain lakes (28 to 52 pmol L(-1)) coincide with the maximum T-FHg concentrations of the Amazon River and are measured during the flooding period. The lowest T-FHg values (3 to 5 pmol L(-1)) are observed during the flood peak of the mainstream, during the rainy season, when waters are diluted by the local rainfall. In this system, Hg is mainly transported in the particulate phase, confirmed by elevated values of the Hg partition coefficient (4.77K(d) (Hg)5.83 Lkg(-1)). The highest Total Particulate Hg (T-PHg) concentrations (47-478 pmol L(-1)) in the lakes are measured during the dry season when they are isolated from the mainstream. This enrichment is due to the elevated TSS content associated to the re-suspension of the bottom sediments by the wind action and the bioturbation in shallow water lakes. In the flooded system, the lakes show different geochemical characteristics that control the Hg distribution and partition. In the white water (WW) lakes, characterized by oxidative neutral waters and highest TSS contents (till 2041 mg L(-1)), the T-PHg is associated to the particulate organic matter mainly during the dry season, while the T-FHg and T-FMn concentrations are correlated. In the black water (BW) lakes that show reductive pH conditions and lowest TSS load (2 to 5 2 mg L(-1)), P-iron and T-PHg display a positive relationship whereas the redox conditions favor the desorption of Hg from the particulate to the filtered phase. The mercury mass budget estimated in this study confirms that the Curuai floodplain system acts as a particulate mercury trap, with a net storage of particulate Hg of 150 kg PHg year(-1).

Published
2009
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7. Source, transport and fluxes of Amazon River particulate organic carbon: Insights from river sediment depth-profiles

Author

Jérôme Gaillardet, Christian France-Lanord, Laurence Maurice, Marcela A.P. Pérez, Patricia Moreira-Turcq, Julien Bouchez, Robert G. Hilton, Valier Galy, Institut de Physique du Globe de Paris (IPGP), 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), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Woods Hole Oceanographic Institution (WHOI), Department of Geography (UNIVERSITé DE DURHAM), Durham University, Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Institut de Recherche pour le Développement (IRD [France-Nord]), Departamento de Geoquimica Universidade Federal Fluminense (DEPARTAMENTO DE GEOQUIMICA), Universidade Federal do Rio de Janeiro (UFRJ), 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), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Hydrology, geography, geography.geographical_feature_category, Amazon rainforest, Stable isotope ratio, Drainage basin, Biosphere, Sediment, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 15. Life on land, law.invention, Oceanography, 13. Climate action, Geochemistry and Petrology, law, Tributary, Environmental science, Suspended load, Radiocarbon dating, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS
Abstract

In order to reveal particulate organic carbon (POC) source and mode of transport in the largest river basin on Earth, we sampled the main sediment-laden tributaries of the Amazon system (Solimoes, Madeira and Amazon) during two sampling campaigns, following vertical depth-profiles. This sampling technique takes advantage of hydrodynamic sorting to access the full range of solid erosion products transported by the river. Using the Al/Si ratio of the river sediments as a proxy for grain size, we find a general increase in POC content with Al/Si, as sediments become finer. However, the sample set shows marked variability in the POC content for a given Al/Si ratio, with the Madeira River having lower POC content across the measured range in Al/Si. The POC content is not strongly related to the specific surface area (SSA) of the suspended load, and bed sediments have a much lower POC/SSA ratio. These data suggest that SSA exerts a significant, yet partial, control on POC transport in Amazon River suspended sediment. We suggest that the role of clay mineralogy, discrete POC particles and rock-derived POC warrant further attention in order to fully understand POC transport in large rivers. To examine the source of POC in the Amazon Basin in more detail, we use radiocarbon (C-14) content and the stable isotope composition (delta C-13) of POC. C-14 activity demonstrates that rock-derived POC is a significant component of river bed sediments and contributes to POC across the river depth-profiles of suspended sediments. We estimate that the flux of rock-derived POC may reach similar to 10% of the total POC export by the Amazon River. After correcting for rock-derived POC input, we find that POC from the terrestrial biosphere (biospheric POC) is mostly sourced from C3-plants. Higher biospheric POC delta C-13 values in the Madeira River (by similar to 0.5-1 parts per thousand) are best explained by a small (

Published
2014
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8. Tracing soil organic carbon in the lower Amazon River and its tributaries using GDGT distributions and bulk organic matter properties

Author

Gwenaël Abril, Claudia Zell, Jaap S. Sinninghe Damsté, Jung-Hyun Kim, Johan W.H. Weijers, Jean-Michel Mortillaro, Tarik Meziane, Marcela A.P. Pérez, and Patricia Moreira-Turcq

Subjects
P33 - Chimie et physique du sol, Glycérol, sédiment, Carbone, 010504 meteorology & atmospheric sciences, Aardwetenschappen, 010502 geochemistry & geophysics, 01 natural sciences, Matière organique du sol, Geochemistry and Petrology, Tributary, traçabilité, Organic matter, Matière organique, Water cycle, 0105 earth and related environmental sciences, Propriété physicochimique, chemistry.chemical_classification, Hydrology, geography, geography.geographical_feature_category, Amazon rainforest, Sediment, Soil carbon, Cycle hydrologique, 15. Life on land, Particulates, Transport dans le sol, chemistry, 13. Climate action, Soil water, U30 - Méthodes de recherche, Cycle du carbone, Geology
Abstract

In order to trace the transport of soil organic carbon (OC) in the lower Amazon basin, we investigated the distributions of crenarchaeol and branched glycerol dialkyl glycerol tetraethers (GDGTs) by analyzing riverbed sediments and river suspended particulate matter (SPM) collected in the Solimoes-Amazon River mainstem and its tributaries. The Branched and Isoprenoid Tetraether (BIT) index, a proxy for river-transported soil OC into the ocean, was determined from the distributions of these GDGTs. The GDGT-derived parameters were compared with other bulk geochemical data (i.e. C:N ratio and stable carbon isotopic composition). The GDGT-derived and bulk geochemical data indicate that riverine SPM and riverbed sediments in the lower Amazon River and its tributaries are a mixture of C3 plant-derived soil OC and aquatic-derived OC. The branched GDGTs in the SPM and riverbed sediments did not predominantly originate from the high Andes soils (>2500 m in altitude) as was suggested previously. However, further constraint on the soil source area of branched GDGTs was hampered due to the deficiency of soil data from the lower montane forest areas in the Andes. Our study also revealed seasonal and interannual variation in GDGT composition as well as soil OC discharge, which was closely related to the hydrological cycle. By way of a simple binary mixing model using the flux-weighted BIT values at Obidos, the last gauging station in the Amazon River, we estimated that 70–80% of the POC pool in the river was derived of soil OC. However, care should be taken to use the BIT index since it showed a non-conservative behaviour along the river continuum due to the aquatic production of crenarchaeol. Further investigation using a continuous sampling strategy following the full hydrological cycle is required to fully understand how soil-derived GDGT signals are transformed in large tropical river systems through their transport pathway to the ocean.

Published
2012

9. Dissolved organic matter dynamic in the Amazon basin: Sorption by mineral surfaces

Author

Thierry Allard, Marc F. Benedetti, Marcela A.P. Pérez, Patricia Moreira-Turcq, Hervé Gallard, Departamento de Geoquímica, Universidade Federal Fluminense [Rio de Janeiro] (UFF), Univ Fed Fluminense, Inst Quim, Dept Geoquim, BR-24020007 Niteroi, RJ, Brazil, HYBAM, GET, IRD, F-93143 Bondy, France, Laboratoire de Chimie et Microbiologie de l'Eau (LCME), Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC), 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), Institut de Physique du Globe de Paris (IPGP), 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), 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), and National Council for Scientific and Technological Development (CNPq) IRD (Institut de Recherche pour le Developpement) HYBAm (Hydrologie et Geochimie du Basin Amazonien) CAPES SWE-CNPq

Subjects
Goethite, 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Fractionation, DOC, 010502 geochemistry & geophysics, 01 natural sciences, Adsorption, Rivers, Geochemistry and Petrology, Dissolved organic carbon, Organic matter, 0105 earth and related environmental sciences, chemistry.chemical_classification, Total organic carbon, Reactivity, Geology, Sorption, 15. Life on land, 6. Clean water, chemistry, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental chemistry, visual_art, Soil water, visual_art.visual_art_medium, Sediment
Abstract

International audience; In aquatic systems, soprtion of organic matter (OM) on environmental surfaces or its preference to remain dissolved is highly important for determining its potential transport and/or susceptibility to degradation. In the Amazon and other major rivers of the world, transported OM is either adsorbed to fine minerals or remains dissolved. The fate of autochthonous OM in Amazon floodplains and allochthonous OM from the river can be addressed by characterizing the nature of OM interactions with the sediment material. This goal was pursued in this study using Rio Negro and Amazon River samples as well as those collected from floodplain lakes during phytoplanktonic blooms, small black rivers, soil solution issued from podzolic areas in the Rio Negro watershed and "terra firme" stream flowing into the floodplain. The amount of carbon surface loading expressed as the adsorbed organic carbon per unit of surface area of the substrate was obtained by batch experiments with mineral phases representative of soils, suspended matter found in the Amazon basin and extracted OM fractions (the hydrophobic, HPO and the transphilic, TPH fractions of OM). The bulk dissolved organic matter samples were characterized by carbon and nitrogen isotopic measurements as well as elementary composition, specific UV absorbance (SUVA), molecular weight (Mw) and FTIR spectroscopy. To our knowledge, these are the first C and N isotopic composition data reported for extracted OM fractions in the Amazon basin. The Rio Negro basin water samples had high [DOC] correlated with conductivity. The SUVA values ranged from 4.0 to 7.3 m(-1)l mg(-1)C and were within the range of measurements reported for the Amazon River. The delta C-13 values of all HPO fractions varied from -27.7 to -30.2%.. The delta C-13 values for the TPH fractions were systematically 1%. higher than their respective HPO fraction. An increasing trend between the weight average Mw of the DOC as function of the C/N ratio (the higher C/N the higher Mw) is reported. This trend is inferred to result from both mixing between 2 end-members and OM fractionation. Carbon surface loadings calculated for HPO and TPH fractions ranged between 23 to 309 mu gC m(-2) and 38 to 145 mu gC m(-2), respectively. Carbon surface loadings with goethite and the Rio Negro organic matter fractions cluster around the average value of 24.5 +/- 4 mu gC m(-2). With the help of the pH dependant dissociation measurements and NICA-Donnan model parameters, it was possible to estimate the amount of deprotonated sites on the OM interacting with the sediment material. The amount of carbon surface loading was correlated with the calculated residual negative charge of the OM fractions (i.e. HPO or TPH). These analyses showed that higher residual negative charges were associated with lower carbon surface loadings on the treated sediment. The decrease of the negative charge was suggested to reduce the net electrostatic repulsion between the OM fractions and the clay surfaces and promote ligand exchange reactions governing sorption to clays. The preferential uptake of the high molecular weight fraction demonstrates that the chemical nature of the organic matter remaining in solution differs from that of the adsorbed fraction.

Published
2011
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10. Prediction of depth-integrated fluxes of suspended sediment in the Amazon River: particle aggregation as a complicating factor

Author

Julien Bouchez, Christian France-Lanord, Jérôme Gaillardet, Maarten Lupker, Marcela A.P. Pérez, Laurence Maurice, François Métivier, Institut de Physique du Globe de Paris (IPGP), 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), 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 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), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Rouse number, 010504 meteorology & atmospheric sciences, Sorting (sediment), 0207 environmental engineering, 550 - Earth sciences, 02 engineering and technology, 01 natural sciences, sedimentary, Acoustic Doppler current profiler, Settling, Tributary, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 020701 environmental engineering, sedimentary fluxes, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Water Science and Technology, Hydrology, geography, Suspended solids, geography.geographical_feature_category, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph], aggregated, fungi, Amazon River, Sediment, suspended particulate matter, fluxes, Environmental science, Sediment transport
Abstract

Large rivers have been previously shown to be vertically heterogeneous in terms of suspended particulate matter (SPM) concentration, as a result of sorting of suspended solids. Therefore, the spatial distribution of suspended sediments within the river section has to be known to assess the riverine sedimentary flux. Numerous studies have focused on the vertical distribution of SPM in a river channel from a theoretical or experimental perspective, but only a few were conducted so far on very large rivers. Moreover, a technique for the prediction of depth-integrated suspended sediment fluxes in very large rivers based on sediment transport dynamics has not yet been proposed. We sampled river water along depth following several vertical profiles, at four locations on the Amazon River and its main tributaries and at two distinct water stages. Depending on the vertical profile, a one-to fivefold increase in SPM concentration is observed from river channel surface to bottom, which has a significant impact on the 'depth-averaged' SPM concentration. For each cross section, a so-called Rouse profile quantitatively accounts for the trend of SPM concentration increase with depth, and a representative Rouse number can be measured for each cross section. However, the prediction of this Rouse number would require the knowledge of the settling velocity of particles, which is dependent on the state of aggregation affecting particles within the river. We demonstrate that in the Amazon River, particle aggregation significantly influences the Rouse number and renders its determination impossible from grain-size distribution data obtained in the lab. However, in each cross section, the Rouse profile obtained from the fit of the data can serve as a basis to model, at first order, the SPM concentration at any position in the river cross section. This approach, combined with acoustic Doppler current profiler (ADCP) water velocity transects, allows us to accurately estimate the depth-integrated instantaneous sediment flux. Copyright (C) 2010 John Wiley & Sons, Ltd.

Published
2011
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11. Evaluation du niveau de stress thermique par mesure de la température corporelle et du niveau d'hyperventilation chez le poulet de chair dans des conditions de production au Venezuela

Author

Denis Bastianelli, Vasco De Basilio, Shlomo Yahav, Yrina Colina, Michel Picard, Marcela A.P. Pérez, and Yngrid Oliveros

Subjects
Every other day, Poulet de chair, Feed consumption, Ecology, General Medicine, Biology, Heat stress, Food conversion, Animal science, Hyperventilation, medicine, L50 - Physiologie et biochimie animales, medicine.symptom, Weight gain
Abstract

Les mesures répétées sur des volailles en élevage sont difficiles à mettre en oeuvre à cause de la difficulté d’identification et de récupération des animaux. Une technique de suivi par isolement de petits groupes d’animaux dans des cercles situés au sein même de l’élevage est proposée. Cette méthode a été utilisée dans un poulailler de production au Venezuela pour déterminer la variation de la température corporelle (TC) et du niveau d’hyperventilation (NH), en fonction de la localisation dans le bâtiment et du sexe des animaux. Trois cercles grillagés ont été aménagés et divisés en deux, avec dans chaque demi-cercle 20 poulets mâles ou femelles. A partir du 29e jour d’âge, la température ambiante (TA) et l’humidité relative (HR) ont été enregistrées en continu, et la TC (côlon terminal) et le NH ont été mesurés chaque heure, de 9 h 00 à 19 h 00, un jour sur deux pendant deux semaines. Les mesures de la TC et du NH ont varié au cours de la journée, sans être rigoureusement parallèles aux paramètres climatiques TA et HR. Il y a eu des différences significatives entre les cercles pour tous les paramètres mesurés. L’effet du sexe n’a pas été significatif sur la TC (p = 0,06), mais il l’a été sur le NH (p = 0,01) et l’interaction avec la localisation du cercle (p < 0,001 pour la TC et p < 0,01 pour le NH). Le sexe a eu un effet significatif sur la consommation alimentaire (p < 0,01) et le gain de poids (p = 0,02) mais pas sur l’indice de consommation (p = 0,64). Les mesures climatiques ont également été différentes entre cercles et entre sexes, avec notamment une HR plus élevée près des mâles (p < 0,001). Sur l’ensemble des données, la TC et le NH ont augmenté respectivement de 0,139 °C et 12,1 inspirations/min par degré d’augmentation de la TA. Il est conclu que les conditions climatiques présentent une hétérogénéité au sein du bâtiment, avec des conséquences sur le confort des poulets, et que les mesures sur animaux (TC et NH) doivent compléter les données climatiques pour décrire l’état de stress thermique. La technique expérimentale proposée permet d’observer des animaux de manière répétée dans les conditions réelles d’un poulailler de production

Published
2006

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