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| Registros recuperados: 68 | |
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| Yool, A.; Popova, E. E.; Coward, A. C.. |
| One of the most characteristic features in ocean productivity is the North Atlantic spring bloom. Responding to seasonal increases in irradiance and stratification, surface phytopopulations rise significantly, a pattern that visibly tracks poleward into summer. While blooms also occur in the Arctic Ocean, they are constrained by the sea-ice and strong vertical stratification that characterize this region. However, Arctic sea-ice is currently declining, and forecasts suggest this may lead to completely ice-free summers by the mid-21st century. Such change may open the Arctic up to Atlantic-style spring blooms, and do so at the same time as Atlantic productivity is threatened by climate change-driven ocean stratification. Here we use low and high-resolution... |
| Tipo: Text |
Palavras-chave: Marine; Ocean; Biogeochemistry; Arctic; Atlantic; Future. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00332/44367/43972.pdf |
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| Foltz, G. R.; Brandt, P.; Richter, I.; Rodríguez-fonseca, B.; Hernandez, F.; Dengler, M.; Rodrigues, R. R.; Schmidt, J. O.; Yu, L.; Lefevre, N.; Da Cunha, L. Cotrim; Mcphaden, M. J.; Araujo, M.; Karstensen, J.; Hahn, J.; Martín-rey, M.; Patricola, C. M.; Poli, P.; Zuidema, P.; Hummels, R.; Perez, Rc; Hatje, V.; Lübbecke, J. F.; Polo, I.; Lumpkin, R.; Bourlès, Bernard; Asuquo, F. E.; Lehodey, P.; Conchon, A.; Chang, P.; Dandin, P.; Schmid, C.; Sutton, A.; Giordani, H.; Xue, Y.; Illig, S.; Losada, T.; Grodsky, S. A.; Gasparin, F.; Lee, T.; Mohino, E.; Nobre, P.; Wanninkhof, R.; Keenlyside, N.; Garcon, V.; Sánchez-gómez, E.; Nnamchi, H. C.; Drévillon, M.; Storto, A.; Remy, E.; Lazar, A.; Speich, S.; Goes, M.; Dorrington, T.; Johns, W. E.; Moum, J. N.; Robinson, C.; Perruche, Coralie; De Souza, R. B.; Gaye, A. T.; López-parages, J.; Monerie, P.-a.; Castellanos, P.; Benson, N. U.; Hounkonnou, M. N.; Duhá, J. Trotte; Laxenaire, R.; Reul, Nicolas. |
| The tropical Atlantic is home to multiple coupled climate variations covering a wide range of timescales and impacting societally relevant phenomena such as continental rainfall, Atlantic hurricane activity, oceanic biological productivity, and atmospheric circulation in the equatorial Pacific. The tropical Atlantic also connects the southern and northern branches of the Atlantic meridional overturning circulation and receives freshwater input from some of the world’s largest rivers. To address these diverse, unique, and interconnected research challenges, a rich network of ocean observations has developed, building on the backbone of the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). This network has evolved naturally over time... |
| Tipo: Text |
Palavras-chave: Tropical Atlantic Ocean; Observing system; Weather; Climate; Hurricanes; Biogeochemistry; Ecosystems; Coupled model bias. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00494/60612/64096.pdf |
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| Pagès, R.; Baklouti, M.; Barrier, Nicolas; Richon, C.; Dutay, J.-c.; Moutin, T.. |
| The Mediterranean Sea (MS) is a semi-enclosed sea characterized by a zonal west-east gradient of oligotrophy, where microbial growth is controlled by phosphate availability in most situations. External inputs of nutrients including Gibraltar inputs, river inputs and atmospheric deposition are therefore of major importance for the biogeochemistry of the MS. This has long been considered to be driven mainly by nutrient exchanges at Gibraltar. However, recent studies indicate that river inputs signi cantly a ect nutrients concentrations in the Mediterranean Sea, although their resulting impact on its biogeochemistry remains poorly understood. In this study, our aim was to make good this lack by addressing the large-scale and long-term impact of variations in... |
| Tipo: Text |
Palavras-chave: Mediterranean Sea; River inputs; Coupled physical-biogeochemical model; Flexible stoichiometry model; Biogeochemistry; Nutrient. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00599/71118/69420.pdf |
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| Hoppe, H. |
| Extracellular enzymes mediate the decomposition of polymeric organic compounds in natural waters. In many cases these enzymes comprise a component linked to the bacterial fraction of the aquatic community and react in close association with these cells. An annual survey of microbial activities in a brackish water fjord exhibited an excellent correlation between V sub(m) of proteases (ability to split the substrate analogue methylumbelliferyl-leucine) and V sub(m) as well as T sub(R) for leucine uptake by microorganisms. Hydrolysis rates (H sub(R)) for the decomposition of naturally occurring competitive substrate analogues of the model substrates (methylumbelliferyl-(MUF)-leucine, MUF- alpha -D-glucose, MUF-N-acetyl-glucosamine, MUF-phosphate) drastically... |
| Tipo: Text |
Palavras-chave: Biogeochemistry; Fjords; Bacteria; Brackishwater environment; Seasonal variations; Dissolved organic matter; Interspecific relationships; Hydrolysis; Enzymes. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/1984/acte-952.pdf |
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| Verdy, A.; Mazloff, M. R.. |
| A Biogeochemical Southern Ocean State Estimate (B-SOSE) is introduced that includes carbon and oxygen fields as well as nutrient cycles. The state estimate is constrained with observations while maintaining closed budgets and obeying dynamical and thermodynamic balances. Observations from profiling floats, shipboard data, underway measurements, and satellites are used for assimilation. The years 2008-2012 are chosen due to the relative abundance of oxygen observations from Argo floats during this time. The skill of the state estimate at fitting the data is assessed. The agreement is best for fields that are constrained with the most observations, such as surface pCO(2) in Drake Passage (44% of the variance captured) and oxygen profiles (over 60% of the... |
| Tipo: Text |
Palavras-chave: Southern Ocean; State estimation; Biogeochemistry. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00662/77394/78995.pdf |
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| Dulaquais, Gabriel; Boye, Marie; Middag, Rob; Owens, Stephanis; Puigcorbe, Viena; Buesseler, Ken; Masque, Pere; De Baar, Hein J. W.; Carton, Xavier. |
| Dissolved cobalt (DCo; <0.2 µm; 14 to 93 pM) and the apparent particulate cobalt (PCo; >0.2 µm; <1 to 15 pM) were determined in the upper water column (<1000 m) of the western Atlantic Ocean along the GEOTRACES-A02 section (64°N to 50°S). The lowest DCo concentrations, typical of a nutrient-type distribution were observed in surface waters of the subtropical domains. Strong linear relationships between DCo and phosphate (P) as well as meridional gradients of decreasing DCo from high latitudes were characterized and both linked to the Co biological requirement. External sources such as the Amazon and the atmospheric deposition were found to contribute significantly (>10%) to the DCo stock of the mixed layer in the equatorial and north... |
| Tipo: Text |
Palavras-chave: Cobalt; Biogeochemistry; Atlantic Ocean; Chemical Oceanography; GEOTRACES. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00241/35222/33732.pdf |
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| Smith, Shawn R.; Alory, Gaël; Andersson, Axel; Asher, William; Baker, Alex; Berry, David I.; Drushka, Kyla; Figurskey, Darin; Freeman, Eric; Holthus, Paul; Jickells, Tim; Kleta, Henry; Kent, Elizabeth C.; Kolodziejczyk, Nicolas; Kramp, Martin; Loh, Zoe; Poli, Paul; Schuster, Ute; Steventon, Emma; Swart, Sebastiaan; Tarasova, Oksana; Petit De La Villeon, Loic; Vinogradova-shiffer, Nadya. |
| The role ships play in atmospheric, oceanic, and biogeochemical observations is described with a focus on measurements made near the ocean surface. Ships include merchant and research vessels; cruise liners and ferries; fishing vessels; coast guard, military, and other government-operated ships; yachts; and a growing fleet of automated surface vessels. The present capabilities of ships to measure essential climate/ocean variables and the requirements from a broad community to address operational, commercial, and scientific needs are described. The authors provide a vision to expand observations needed from ships to understand and forecast the exchanges across the ocean–atmosphere interface. The vision addresses (1) recruiting vessels to improve both... |
| Tipo: Text |
Palavras-chave: Ships; Observations; Meteorology; Physical oceanography; Biogeochemistry; Data management; Climatology. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00509/62042/66191.pdf |
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| Morita, R; Jones, R. |
| The nitrifying bacteria were found to survive 24 weeks in the absence of ammonium without decreasing their number of cell size. Because H sub(2), CO, and CH sub(4) are present in the marine environment, these substrates were investigated as a possible source of the energy of maintenance for the nitrifying bacteria. super(14)CO and super(14)CH sub(4) were found to be oxidized by the nitrifiers. N-serve was found to inhibit the oxidation of CO. Using the nitrifiers' ability to oxide CO, a method for the determination of the nitrification rate was developed. The ability of nitrifiers to oxidize CO may play a significant role in the cycling of CO sub(2) in the marine environment. Whether CO and CH sub(4) oxidation play a role in the survival of nitrifiers in... |
| Tipo: Text |
Palavras-chave: Methane; Carbon dioxide; Survival; Bacteria; Nitrification; Nitrogen cycle; Oxidation; Carbon cycle; Biogeochemistry; Metabolism. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/1984/acte-975.pdf |
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| Peguero, Guille; Sardans, Jordi; Asensio, Dolores; Fernández-martínez, Marcos; Gargallo-garriga, Albert; Grau, Oriol; Llusià, Joan; Margalef, Olga; Márquez, Laura; Ogaya, Romà; Urbina, Ifigenia; Courtois, Elodie A.; Stahl, Clément; Van Langenhove, Leandro; Verryckt, Lore T.; Richter, Andreas; Janssens, Ivan A.; Peñuelas, Josep. |
| Soil fauna is a key control of the decomposition rate of leaf litter, yet its interactions with litter quality and the soil environment remain elusive. We conducted a litter decomposition experiment across different topographic levels within the landscape replicated in two rainforest sites providing natural gradients in soil fertility to test the hypothesis that low nutrient availability in litter and soil increases the strength of fauna control over litter decomposition. We crossed these data with a large dataset of 44 variables characterizing the biotic and abiotic microenvironment of each sampling point and found that microbe-driven carbon (C) and nitrogen (N) losses from leaf litter were 10.1 and 17.9% lower, respectively, in the nutrient-poorest site,... |
| Tipo: Text |
Palavras-chave: Biogeochemistry; Extracellular enzyme activity; Litter decomposition; Nutrients; Soil fauna. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00513/62424/69469.pdf |
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| Registros recuperados: 68 | |
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