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| Registros recuperados: 45 | |
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| Raimonet, Melanie; Guillou, Gael; Mornet, Francoise; Richard, Pierre. |
| Although nitrogen stable isotope ratio (delta N-15) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in delta N-15 variability. Simultaneous determinations of delta N-15 of dissolved inorganic nitrogen (DIN) along the land sea continuum, inter-species variability of delta N-15 and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae delta N-15 in monitoring nitrogen origin in mixed-use watersheds. In this study, delta N-15 of annual and perennial macroalgae (Ulva sp., Enterommpha sp., Fucus vesiculosus and Fucus serratus) are compared to delta N-15-DIN along the Charente Estuary, after... |
| Tipo: Text |
Palavras-chave: Nitrogen isotopes; Nitrate; Ammonium; Primary producers; Indicators; Land-sea continuum. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00134/24558/23645.pdf |
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| Collos, Y; Descolas Gros, C; Mornet, Francoise. |
| During parallel sampling of seawater samples in bottles and in free water (1000-2000 m(3) clay ponds), we have measured phytoplankton biomass, Ribulose biphosphate carboxylase (Rubisco), phosphoenol pyruvate carboxylase, and phosphoenol pyruvate carboxykinase activities and major nutrients (ammonium, nitrate, phosphate, silicate). This was done in two ecosystems: one with high grazing pressure due to the presence of oysters and another with low grazing pressure (no oysters). In the ecosystem subjected to high grazing pressure, anaplerotic carbon fixation by phytoplankton in free water was higher in the light period and could represent 25% of total carbon fixation. Incubating samples in bottles led to a major increase in Rubisco activity (80% in 3 h)... |
| Tipo: Text |
Palavras-chave: Grazing; Carboxylases; Carbon assimilation; Anaplerotic; Ammonium. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-6437.pdf |
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| Bouchet, Vincent; Debenay, Vincent; Sauriau, Pierre-guy; Radford Knoery, Joel; Soletchnik, Patrick. |
| Sediment cores were collected from April to August 2004 on tidal mudflats of the macrotidal Marennes-Oléron Bay (SW France), famous for the cultivation of Pacific oysters (Crassostrea gigas). The response of living (stained) benthic foraminifera to short-term biogeochemical disturbances in the sediment and overlying water, which may be involved in oyster summer mortality, was monitored. Short-term hypoxia occurred in early June, in conjunction with a sudden rise in temperature. In mid-June, the ammonia content of sediment porewater increased, leading to potentially maximal flux towards overlying waters. Foraminiferal assemblages, particularly in the topmost layer, were altered. Ammonia tepida was the most tolerant to temperature increase and hypoxic... |
| Tipo: Text |
Palavras-chave: Marennes Oléron bay; Aquaculture; Crassostrea gigas; Intertidal; Ammonium; Hypoxia; Organic matter; Living benthic foraminifera. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2586.pdf |
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| Jauzein, Cecile; Collos, Yves; Garces, E; Vila, M; Maso, M. |
| In batch cultures of four Mediterranean strains (from France, Italy, and Spain) of Alexandrium catenella (Whedon et Kof.) Balech growing on a daily light cycle, ammonium and urea uptake were estimated by the N-15 tracer technique. Ammonium uptake could be described by Michaelis-Menten kinetics along a substrate gradient of 0.1-10 mu gat N.L-1 for the four strains, while two different patterns were observed for urea uptake with Michaelis-Menten kinetics for one strain and linear kinetics for the others. In all cases, an increase in uptake rates with time was noted over the daylight period. This trend led to a net increase in the maximum uptake rate (V-max; for saturable kinetics) and in the initial slope alpha. For ammonium, V-max increased by a factor of... |
| Tipo: Text |
Palavras-chave: Urea; Uptake kinetics; Temporal variability; Ammonium release; Ammonium; Alexandrium catenella. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6416.pdf |
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| Bedier, Edouard; Knoery, Joel Radford; Fleury, Pierre-gildas; Quiniou, Francoise; Langlade, Aime; Cozic, Amandine; Delesmont, Edith; Delesmont, Régis; Caisey, Xavier; Lecureuil, Laetitia. |
| The phenomenon of summer mortalities of the Pacific cupped oyster Crassostrea gigas is observed in France since the beginning of the 90's. These mortalities are classically associated to younger stages and summer temperatures and occur during the reproduction period of the animal. The studies undertaken during the project Morest (2001-2005), showed that a number of biological and environmental risks, the interaction of them induces lethal stresses for animals in physiological weakness, exists in summer. Among these risks, that which is withstood by the oysters bred close to the sediment proved to be significant in intertidal areas. In Quiberon bay (southern Brittany, France), the breeding practices of sowing oysters in deep water is thus likely to expose... |
| Tipo: Text |
Palavras-chave: Huître; Crassostrea gigas; Mortalité; Sédiment; Composé réduit; Flux; Sulfure; Ammonium; Oyster; Crassostrea gigas; Mortality; Sediment; Reduced compound; Flux; Sulphide; Ammonia. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/00108/21956/19550.pdf |
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| Mensi, F.; Ksouri, J.; Seale, E. G.; Romdhane, M.S.. |
| L'exploitation des algues rouges appartenant au genre Gracilaria pour l'extraction de l'agar a considérablement augmenté au cours des dernières décennies. En Tunisie Gracilaria verrucosa (Hudson) Papenfuss 1950 (Rhodophyta), est candidate pour la culture dans la lagune de Bizerte (Nord de la Tunisie) où ne pousse que sur une courte période de l’année. Ainsi, le but de cette étude est de recueillir des informations de base sur sa croissance dans cette région. Les effets de la salinité des sources d’azote et du phosphore ainsi que leurs concentrations sur la croissance de cette algue ont été étudiés à l'échelle de laboratoire en utilisant la méthodologie de surface des réponses. Afin de déterminer les interactions entre les variables et les niveaux optimaux... |
| Tipo: Journal Contribution |
Palavras-chave: Algae; Ammonium; Red algae; Salinity; Growth; Nitrates. |
| Ano: 2011 |
URL: http://hdl.handle.net/1834/4734 |
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| Piva,Jonatas Thiago; Sartor,Laércio Ricardo; Sandini,Itacir Eloi; Moraes,Anibal de; Dieckow,Jeferson; Bayer,Cimélio; Rosa,Carla Machado da. |
| ABSTRACT Brazilian agriculture contributes significantly to nitrous oxide (N2O) and methane (CH4) emissions, so the understanding of such emissions at the field is crucial for mitigation strategies. This study quantified the impact of N application and sheep grazing on the N2O and CH4 emissions from a subtropical Ferralsol under an integrated crop-livestock (ICL) management system. In a long-term experiment in southern Brazil, gaseous fluxes were measured during a year-long cycle of ryegrass (Lolium multiflorum) plus oats (Avena sativa) winter pasture and a summer crop of common beans (Phaseolus vulgaris). Three rates of urea-nitrogen (0, 75, and 150 kg ha-1) were applied to the winter-pasture, which was subjected to two sheep grazing levels (continuously... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Nitrate; Ammonium; Water filled pore space; Sheep. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832019000100520 |
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| Fernandes,Adalton Mazetti; Andrade,Gabriel José Massoni de; Souza,Emerson de Freitas Cordova de; Rosolem,Ciro Antonio. |
| Nitrification can lead to substantial losses of the applied N through nitrate leaching and N2O emission. The regulation of nitrification may be a strategy to improve fertilizer N recovery and increase its agronomic efficiency. The objective of this study was to evaluate the inhibiting capacity of nitrification in soil by Brachiaria species. The greenhouse experiment was conducted using pots with 10 dm³ of a Red Latosol sample. The treatments consisted of the cultivation of three forage species (Brachiaria brizantha, B. ruziziensis and B. decumbens) and four n rates (0, 100, 200, and 300 mg/pot), and the control (without plants). In the absence of the forage plants, all N fertilization levels raised the N-NO3- soil levels, as a result of nitrification. The... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ammonium; Nitrate; Nitrogen. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832011000500024 |
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| Kölln,Oriel Tiago; Franco,Henrique Coutinho Junqueira; Ferreira,Danilo Alves; Vargas,Vitor Paulo; Castro,Saulo Augusto de Quassi; Cantarella,Heitor; Caldana,Camila; Trivelin,Paulo Cesar Ocheuze. |
| ABSTRACT Retaining the mineral N in the form of NH4+ in the soil for a lengthy period is desirable for reducing losses. Furthermore, there is evidence that sugarcane prefers NH4+-N in place of NO3−-N. This study aimed firstly, to evaluate the potential of root extracts of Bracchiaria humidicola andSaccharum spontaneum, in contrast with the DCD (Dicyandiamide) inhibitor, to increase absorption of N by plants fertilized with ammonium sulfate, and secondly, to quantify the emission of N2O fluxes with the use of this inhibitor. The experiment was developed in a glasshouse in an entirely randomized design where four treatments were applied: AS) ammonium sulfate (control); AS+DCD) ammonium sulfate associated with dicyandiamide; AS+BCH) ammonium sulfate... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ammonium; Nitrate; Dicyandiamide; Nitrification; Nitrous oxide. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162016000100034 |
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| Lira,Claudia R.S. de; Gomes,Edna M.; Chagas,Generoso M.; Pinheiro,Jairo. |
| The total protein and ammonia contents in the hemolymph of Bradybaena similaris (Fèrussac, 1821) during the starvation were determined from August, 1996 to March, 1998. The results revealed a significant variation in the total protein content throughout the period of starvation analized, there being a negative relation between the total protein content and the time of starvation. But the same result was not observed in the ammonia content. After 30 days of starvation there was a reduction of 2,8% of the content of ammonia in the hemolymph. A negative relation between the ammonia content and the time of starvation was observed, but this relation was not significative. It is probable that the degradation of the proteins don't lead to an increase of the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Bradybaena similaris; Ammonium; Nitrogenous products; Starvation; Total proteins. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-81752000000400003 |
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| Gaiad,Sérgio; Rakocevic,Miroslava; Reissmann,Carlos Bruno. |
| The influence of different N sources on the growth of maté (Ilex paragurariensis St.Hil.) seedlings grown in greenhouse was studied. All seedlings received a base fertilization of 10 mg N.kg-1 soil as NH4NO3, 60 mg P2O5.and 40 mg K2O.kg-1 soil as KH2PO4 15 days before treatments application. Treatments were as follow: Control, with no extra N added; Urea = 100 mg N.kg-1 soil as Urea; NO3- = 100 mg N.kg-1 soil as Ca(NO3)2; and NH4+ = 100 mg N.kg-1 soil as (NH4)2SO4. It was concluded that: 1) increasing N content in leaves alone was not able to promote gain in biomass production of maté seedlings; 2) seedlings receiving N-NH4 showed a higher accumulation of P and Mg on shoot biomass; and 3) an increase in leaf area, leaf number and net photosynthesis... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ammonium; Nitrate; Soil pH. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132006000600001 |
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| Registros recuperados: 45 | |
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