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| Registros recuperados: 225 | |
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| Van Langenhove, Leandro; Depaepe, Thomas; Vicca, Sara; Van Den Berge, Joke; Stahl, Clement; Courtois, Elodie; Weedon, James; Urbina, Ifigenia; Grau, Oriol; Asensio, Dolores; Peñuelas, Josep; Boeckx, Pascal; Richter, Andreas; Van Der Straeten, Dominique; Janssens, Ivan A.. |
| Background and aims Biological fixation of atmospheric nitrogen (N2) is the main pathway for introducing N into unmanaged ecosystems. While recent estimates suggest that free-living N fixation (FLNF) accounts for the majority of N fixed in mature tropical forests, the controls governing this process are not completely understood. The aim of this study was to quantify FLNF rates and determine its drivers in two tropical pristine forests of French Guiana. Methods We used the acetylene reduction assay to measure FLNF rates at two sites, in two seasons and along three topographical positions, and used regression analyses to identify which edaphic explanatory variables, including carbon (C), nitrogen (N), phosphorus (P) and molybdenum (Mo) content, pH, water... |
| Tipo: Text |
Palavras-chave: Free-living nitrogen fixation; Tropical forest; French Guiana; Nutrients; Phosphorus; Molybdenum. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59901/63083.pdf |
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| Chopin, T; Floc'H, J; Bodeau, B; Penot, M. |
| Phosphorated nutrition of the red alga Chondrus crispus Stackh. is studied is two morphologically very dissimilar forms of the thallus. Phosphorus measurements, which were monthly carried out at different parts of the alga, showed first that the distribution of this element is not homogeneous along the thallus, and second that seasonal variations occur. It is suggested that the classical polymorphism of the species can be taken into account as concerns its physiology. Besides, from absorption and exsorption experiments which were performed with super(32)P as a tracer, it is shown that the high concentration factor of phosphorus in the alga as compared to the environmental seawater (up to 17.9 x 10 super(4)) can be explained as an effect of metabolic process. |
| Tipo: Text |
Palavras-chave: Chondrus crispus; Algae; Distribution; Metabolism; Seasonal variations; Food absorption; Phosphorus; Plant nutrition. |
| Ano: 1983 |
URL: http://archimer.ifremer.fr/doc/1983/acte-1175.pdf |
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| Van Langenhove, Leandro; Janssens, Ivan A.; Verryckt, Lore; Brechet, Laetitia; Hartley, Iain P.; Stahl, Clement; Courtois, Elodie; Urbina, Ifigenia; Grau, Oriol; Sardans, Jordi; Peguero, Guille; Gargallo-garriga, Albert; Peñuelas, Josep; Vicca, Sara. |
| Theory states that tree growth in lowland tropical forests on old, weathered soils is limited by low phosphorous (P) availability. However, evidence for P limitation from nutrient manipulation experiments remains unclear, which raises the question whether trees are taking up added P. In French Guianese lowland rainforest, we measured changes in nitrogen (N) and P availability before and up to two months after N and P addition. We measured in soils with intact root systems and soils excluding roots and mycorrhizal fungi with root exclusion cylinders. When the root system was excluded, P addition increased P availability to a much greater extent and for a longer time than where the roots remained undisturbed. N dynamics were unaffected by root... |
| Tipo: Text |
Palavras-chave: Tropical forest; Phosphorus; Nitrogen; Fertilization; Root system; Plant root simulator probes. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00589/70161/68163.pdf |
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| Souchu, Philippe; Gasc, Anne; Collos, Y; Vaquer, A; Tournier, Henri; Bibent, B; Deslous-paoli, Jean-marc. |
| Physical and chemical characteristics (temperature, salinity, dissolved oxygen), nutrients [dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP) and silicate], dissolved organic nitrogen (DON) and phosphorus and particulate matter [particulate organic carbon (POC) and nitrogen (PON) and chlorophyll a] were measured at a station located in the deepest part of the Thau lagoon (8.5 m), France, during a 10 d period of bottom anoxia in summer 1994. The upper 8 cm of sediment were also analyzed for ammonium (NH(4)(+)) and SRP concentrations in the porewater. The study period was characterized by mean wind speed under 4 m s(-1) which induced an increase of surface temperature from 18 to 29 degrees C with the formation of a thermocline. The... |
| Tipo: Text |
Palavras-chave: Anoxia; Nitrogen; Phosphorus; Eutrophication; Thau lagoon; Mediterranean Sea. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00070/18142/15694.pdf |
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| Roque D'Orbcastel, Emmanuelle; Blancheton, Jean-paul; Boujard, Thierry; Aubin, Joel; Moutounet, Yves; Przybyla, Cyrille; Belaud, Alain. |
| European water legislation enforces increasingly restrictive measures with regards to reduction of water consumption and waste emission in order to minimise the potential environmental impact of the agro industry sector. Fish farms are particularly concerned, but legislation covering effluent discharge varies significantly from country to country. However, recommendations and directives from institutional, national or regional bodies suggest the enforcement of increasingly strict waste reduction measures and the development of waste treatment. Before treatment, it is necessary to evaluate waste production in terms of composition and quantity. The waste quantification methods used today for fish culture systems are either based on direct measurements of... |
| Tipo: Text |
Palavras-chave: Phosphorus; Nitrogen; Suspended solids; Trout farm; Waste. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6822.pdf |
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| Chapelle, Annie; Mesnage, Valérie; Mazouni, Nabila; Deslous-paoli, Jean-marc; Picot, Bernadette. |
| A simulation of nitrogen and phosphorus exchanges for the sediment-water interface is presented, The aim of the sttudy is to understand the dynamic behaviour of an eutrophie coastal lagoon (Thau, France), ln situ experiments were performed to estimate the different pools of nitrogen and phosphorus in the water column and in the sediment. The diffusive fluxes between them were also estimated. A numerical mode1, simulating nitrogen and phosphorus cycles, was developed and calibrated with data recorded .at two seasons (winter and summer). This study leads to the conclusion that is necessary to know the different pools of nitrogen and phosphorus in order to estimate which fraction is bioavailable and the rate of nutrient exchange between sediment and water. It... |
| Tipo: Text |
Palavras-chave: Modèle; Phosphore; Azote; Sédiment; Ecosystème conchylicole; Modelling; Phosphorus; Nitrogen; Sediment; Shellfish ecosystem. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/00039/15026/12360.pdf |
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| Andrieux, Francoise; Azandegbe, Afi; Caradec, Florian; Philippon, Xavier; Kerouel, Roger; Youenou, Agnes; Nicolas, Jean-louis. |
| This study aims to compare the impact of oyster cultures on diagenetic processes and the phosphorus cycle in the sediments of the Aber Benoît and the Rivière d’Auray, estuary of Brittany, France. Our results showed clear evidence of the seasonal impact of oyster cultures on sediment characteristics (grain size, organic matter parameters), and the phosphorus cycle, especially in the Aber Benoît. At this site, seasonal variations of sulfide and Fe concentrations in pore waters, as well as Fe-P concentrations in the solid-phase highlighted a shift from a system governed by iron reduction (Reference) to a system governed by sulphate reduction (Beneath Oyster). This could be partly explained by the increase in labile organic matter (ie, biodeposits) beneath... |
| Tipo: Text |
Palavras-chave: Sediment; Phosphorus; Sulfide; Dissolved Fe/P ratios; Labile organic matter; Oyster cultures. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00209/32003/30441.pdf |
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| Huang, Bing; Marchand, Justine; Thiriet-rupert, Stanislas; Carrier, Gregory; Saint-jean, Bruno; Lukomska, Ewa; Moreau, Brigitte; Morant-manceau, Annick; Bougaran, Gael; Mimouni, Virginie. |
| Nitrogen (N) and phosphorus (P) limitations induce neutral lipid accumulation and membrane lipid remodeling in the domesticated oleaginous microalga Tisochrysis lutea. This study compared growth, photosynthetic activity, biochemical and transcriptional responses of T. lutea throughout batch cultures under N or P limitation compared with non-limiting nutrient condition (NP). The results show that, under N limitation, the breakdown and re-use of cellular N-containing compounds contributed to carbohydrates and further triacylglycerol (TAG) accumulation, where the accumulation of docosahexaenoic acid (DHA) in neutral lipids might mainly be derived from the recycling of membrane polar lipids. Conversely, P limitation did not hinder the photosynthetic capacity;... |
| Tipo: Text |
Palavras-chave: Tisochrysis lutea; Phosphorus; Nitrogen; Lipid remodeling; Betaine lipid; Polyunsaturated fatty acid. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00492/60409/64776.pdf |
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| Deborde, J; Anschutz, P; Auby, Isabelle; Gle, C; Commarieu, M; Maurer, Daniele; Lecroart, P; Abril, G. |
| The hypothesis of nutrient-rich pore-waters seeping at low tide through sediments to channel waters, which drain tidal flats during ebb, was evaluated in the Arcachon lagoon. The back of the bay is affected by freshwater inputs and underground freshwater discharges. The upper part of tidal flat consists of permeable sandy sediments, which are covered by a muddy sediment layer on the lower part. Permeable sediments outcrop in the bed of channel web. Surface water chemistry and early diagenesis processes in sediment were estimated by collecting channel web waters and cores on a tidal flat and in channels at different seasons and time scales. Waters from tidal creeks are under-oxygenated, and enriched in reduced solutes. Muddy sediments showed evidences of... |
| Tipo: Text |
Palavras-chave: Arcachon Bay; Pore waters seeping; Nitrogen; Phosphorus; Organic matter mineralization; Tidal creek water; Tidal pump. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/2008/publication-3927.pdf |
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| Lemoine, Gérard. |
| Within the national molluscan monitoring network, a sedimentary study was carried out on five experimental sites located in southern Brittany (i.e., from Etel to Pen-Bé rivers). The study aimed to specify sediment integrating characteristics with regards to hydrobiological variables. Moreover, interactions between sediment and water column characteristics were specified. It appears that this approach is likely unappropriate to characterize interdical rearing area productivity. However, this approach can support the site evaluation on a long term basis to sustain shellfish culture management. This would require additional study to assess sediment reactivity to abnormal events like drastic salinity decrease. |
| Tipo: Text |
Palavras-chave: Sédiment; Ostréiculture; Estran; Phosphore; Eutrophisation; Sediment; Oyster culture; Intertidal area; Phosphorus; Eutrophication. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/00102/21344/18967.pdf |
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| Huang, Bing; Marchand, Justine; Blanckaert, Vincent; Lukomska, Ewa; Ulmann, Lionel; Wielgosz-collin, Gaëtane; Rabesaotra, Vony; Moreau, Brigitte; Bougaran, Gael; Mimouni, Virginie; Morant-manceau, Annick. |
| Nitrogen (N) and phosphorus (P) limitations induce triacylglycerol (TAG) accumulation and membrane lipid remodelling in the marine diatom Phaeodactylum tricornutum. However, a clear understanding of the metabolic reorientation is still lacking. Carbon partitioning is of great interest because this microalga produces various highly valuable molecules such as lipids and polyunsaturated fatty acids. This study compared growth, photosynthetic activity, biochemical and transcriptional responses of P. tricornutum throughout batch culture under N or P limitation. The integrated results show that the photosynthetic intensity was greatly reduced under N or P limitation. Under N limitation, the degradation and re-use of cellular N-containing compounds contributed to... |
| Tipo: Text |
Palavras-chave: Betaine lipid; Lipid remodelling; Microalga; Nitrogen; Phosphorus; Polyunsaturated fatty acid. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00491/60249/63861.pdf |
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| Ait Ballagh, Fatima Ezzahra; Rabouille, Christophe; Andrieux Loyer, Francoise; Soetaert, Karline; Elkalay, Khalid; Khalil, Karima. |
| Sediments play an important role in dissolved inorganic phosphorus (DIP) recycling, which needs to be precisely quantified in eutrophic estuaries. A coupled field data and diagenetic modelling approach was used to study P dynamics in two estuaries (Elorn and Aulne, Brittany, France). An existing model (OMEXDIA) was extended with phosphorus (P) benthic cycle by adding dissolved inorganic phosphorus (DIP) and particulate P fractions (organic P, Fe-bound P and Ca-bound P). The model was fitted to pore water oxygen, nitrate, ammonium, oxygen demand units (reduced substances that were produced by the anoxic mineralization; Fe2+, Mn2+ and H2S; ODU), DIP, sediment organic P and C, Fe-bound P and Ca-bound P data from four seasons (February, May, July and October... |
| Tipo: Text |
Palavras-chave: Phosphorus; Estuarine sediments; Eutrophication; Diagenetic modelling; Fe-bound P formation-release; Ca-bound P precipitation. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00598/71041/73089.pdf |
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| Huang, Bing; Mimouni, Virginie; Lukomska, Ewa; Morant-manceau, Annick; Bougaran, Gael. |
| The domesticated marine microalga Diacronema lutheri is of great interest for producing various highly valuable molecules like lipids, particularly long‐chain polyunsaturated fatty acids (LC‐PUFA). In this study, we investigated the impact of phosphorus (P) and nitrogen (N) starvation on growth, carbon fixation (photosynthetic activity) and partitioning, and membrane lipid remodeling in this alga during batch culture. Our results show that the photosynthetic machinery was similarly affected by P and N stress. Under N starvation, we observed a much lower photosynthetic rate and biomass productivity. The degradation and re‐use of cellular N‐containing compounds contributed to triacylglycerol (TAG) accumulation. On the other hand, P‐starved cells maintained... |
| Tipo: Text |
Palavras-chave: Carbon partitioning; Diacronema lutheri; Nitrogen; Phosphorus; Polyunsaturated fatty acid. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00619/73071/72204.pdf |
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| Guillaud, Jean-francois; Andrieux-loyer, Francoise; Menesguen, Alain. |
| As part of the French National Programme for Coastal Oceanography, this paper focuses on improvement of biogeochemical modelling in the: Bay of Seine (Eastern Channel), by introducing phosphorus in nutrient cycles. The Bay of Seine receives the Seine river, which exhibits very high nutrient concentrations, and this coastal zone constitutes a typical case of eutrophication in a river plume area. In terms of analyses, sequential extraction and analysis of sedimentary phosphorus were used in order, to measure various forms of particulate phosphorus in suspended matter and sediment (calcium-bound phosphate, Fe/Al-bound phosphate, exchangeable phosphate and organic phosphorus). In the modelling approach, the Bay is divided into 42 boxes and a two-layer,... |
| Tipo: Text |
Palavras-chave: Bay of Seine; Phytoplankton; Phosphorus; River plume; Biological two layer box model. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-462.pdf |
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| Labry, Claire; Youenou, Agnes; Delmas, Daniel; Michelon, Pascale. |
| The speciation of particulate phosphorus (TPP) into inorganic (PIP) and organic phosphorus (POP), has been scarcely investigated in suspended particulate matter (SPM), contrary to numerous sediment studies. This work evaluates the actual capacity of methods for TPP, POP and PIP determination in SPM to measure efficiently and specifically each pool. Methods were tested on a range of plankton-associated organic and inorganic P compounds, on microalgal cultures and estuarine samples. Then results are specifically discussed reviewing P speciation in phytoplankton. For TPP analysis, the method of Solorzano and Sharp (1980) is recommended compared with that of Aspila et al. (1976), originally dedicated to sediment, as there is one step less, the protocol is more... |
| Tipo: Text |
Palavras-chave: Phosphorus; Speciation; Waters; Phytoplankton; HTC; CWO. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00149/26046/26385.pdf |
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| Registros recuperados: 225 | |
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