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| Registros recuperados: 36 | |
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| Lefèvre, Nathalie; Mejia, Carlos; Khvorostyanov, Dmitry; Beaumont, Laurence; Koffi, Urbain. |
| The carbon system in the eastern tropical Atlantic remains poorly known. The variability and drivers of the carbon system are assessed using surface dissolved inorganic carbon (DIC), alkalinity (TA) and fugacity of CO2 (fCO2) measured in the 12° N–12° S, 12° W–12° E region from 2005 to 2019. A relationship linking DIC to temperature, salinity and year has been determined, with salinity being the strongest predictor. The seasonal variations of DIC, ranging from 80 to 120 mol kg−1, are more important than the year-to-year variability that is less than 50 mol kg−1 over the 2010–2019 period. DIC and TA concentrations are lower in the northern part of the basin where surface waters are fresher and warmer. Carbon supply dominates over biological carbon uptake... |
| Tipo: Text |
Palavras-chave: Carbon cycle; Tropical Atlantic; Dissolved inorganic carbon; Alkalinity. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00678/79046/81494.pdf |
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| Ronge, Thomas A.; Prange, M.; Mollenhauer, Gesine; Ellinghausen, Maret; Kuhn, G.; Tiedemann, R.. |
| It is widely assumed that the ventilation of the Southern Ocean played a crucial role in driving glacial‐interglacial atmospheric CO2‐levels. So far however, ventilation records from the Indian sector of the Southern Ocean, are widely missing. Here we present reconstructions of water residence times (depicted as ΔΔ14C and Δδ13C) for the last 32,000 years on sediment records from the Kerguelen Plateau and the Conrad Rise (~570‐2500 m water depth), along with simulated changes in ocean stratification from a transient climate model experiment. Our data indicate that Circumpolar Deep Waters in the Indian Ocean were part of the glacial carbon pool. At our sites, close to or bathed by upwelling deep‐waters, we find two pulses of decreasing ΔΔ14C and δ13C values... |
| Tipo: Text |
Palavras-chave: Radiocarbon; Ventilation; Southern Ocean; Younger Dryas; Carbon cycle; Indian Ocean. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00611/72351/71258.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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| Laruelle, Goulven G.; Lauerwald, Ronny; Pfeil, Benjamin; Regnier, Pierre. |
| Over the past decade, estimates of the atmospheric CO2 uptake by continental shelf seas were constrained within the 0.18-0.45 Pg C yr(-1) range. However, most of those estimates are based on extrapolations from limited data sets of local flux measurements (n<100). Here we propose to derive the CO2 air-sea exchange of the shelf seas by extracting 310(6) direct surface ocean CO2 measurements from the global database SOCAT (Surface Ocean CO2 Atlas), atmospheric CO2 values from GlobalVIEW and calculating gas transfer rates using readily available global temperature, salinity, and wind speed fields. We then aggregate our results using a global segmentation of the shelf in 45 units and 152 subunits to establish a consistent regionalized CO2 exchange budget at... |
| Tipo: Text |
Palavras-chave: CO2; Coastal ocean; Carbon cycle. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00293/40426/38969.pdf |
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| Keller, Kathrin M.; Joos, Fortunat; Raible, Christoph C.; Cocco, Valentina; Froelicher, Thomas L.; Dunne, John P.; Gehlen, Marion; Bopp, Laurent; Orr, James C.; Tjiputra, Jerry; Heinze, Christoph; Segschneider, Joachim; Roy, Tilla; Metzl, Nicolas. |
| Climate modes such as the North Atlantic Oscillation (NAO), representing internal variability of the climate system, influence the ocean carbon cycle and may mask trends in the sink of anthropogenic carbon. Here, utilising control runs of six fully coupled Earth System Models, the response of the ocean carbon cycle to the NAO is quantified. The dominating response, a seesaw pattern between the subtropical gyre and the subpolar Northern Atlantic, is instantaneous (<3 months) and dynamically consistent over all models and with observations for a range of physical and biogeochemical variables. All models show asymmetric responses to NAO+ and NAO− forcing, implying non-linearity in the connection between NAO and the ocean carbon cycle. However, model... |
| Tipo: Text |
Palavras-chave: North Atlantic Oscillation; Carbon cycle; Ocean biogeochemistry; Climate modeling; Ocean-atmosphere interaction. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00140/25166/23272.pdf |
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| Touratier, Franck; Goyet, C; Coatanoan, Christine; Andrie, C. |
| With a limited number of properties (salinity, temperature, total dissolved inorganic carbon, total alkalinity, and oxygen) from a recent cruise in the tropical Atlantic Ocean, We use the simple and recent approach TrOCA (Tracer combining Oxygen, inorganic Carbon, and total Alkalinity) to estimate the distribution of anthropogenic CO2 along three latitudinal sections. In order to assess the quality of the anthropogenic CO2 distribution, results from the method are compared to the CFC-11 measurements. We discuss the large-scale distribution of the main water masses of the tropical Atlantic Ocean in the light of the anthropogenic CO2 and the CFC-11 distributions. Keeping in mind that the anthropogenic CO2 emission began similar to 60 years earlier than that... |
| Tipo: Text |
Palavras-chave: Tropical belt; Atlantic Ocean; Water mass; Carbon cycle. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-886.pdf |
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| Jennerjahn, Tc; Ittekkot, V. |
| The nature of sedimentary organic matter from mangroves and the continental margin of eastern Brazil (8 degrees-24 degrees S) has been investigated in order to obtain information on sources and diagenetic processes. The organic matter content of mangrove sediments is three to four times higher than the maximum content of continental margin sediments. Downslope distribution of organic carbon, nitrogen, amino acids and hexosamines shows an enrichment in water depths between 800 m and 1000 m. The distribution of individual amino acids and hexosamines is highly variable in sedimentary organic matter from mangroves and the continental margin, and the observed compositional differences are mainly due to diagenetic alteration. Organic matter is highly reactive in... |
| Tipo: Text |
Palavras-chave: Organic carbon; Amino acids; Carbon cycle; Mangroves; Continental margin. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20403/18070.pdf |
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| Lourantou, Anna; Metzl, Nicolas. |
| The fate of the Southern Ocean atmospheric CO(2) sink is under question. Here we assess seasonal to decadal changes of surface fCO(2) within an extended sink area along the track between Kerguelen and Amsterdam islands in the subantarctic zone. Data from 17 oceanographic cruises were used, from 1991 to 2011 and two distinct regions were examined, separated by the Subantarctic Front (SAF). The region south of the SAF displays a strong summer phytoplankton bloom of up to -28 mmol C m(-2) d(-1) within a calm area, constrained by physics and topography. On an annual basis, this region is a 6-fold more important sink than that deduced from Takahashi climatology, highlighting the importance of key-areas separate examination before proceeding to spatial... |
| Tipo: Text |
Palavras-chave: Kerguelen; Air-sea CO2 fluxes; Carbon cycle; Frontal region; Island mass effect; Subantarctic zone. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00144/25557/23706.pdf |
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| Couldrey, Matthew P.; Oliver, Kevin I. C.; Yool, Andrew; Halloran, Paul R.; Achterberg, Eric P.. |
| The North Atlantic is an important basin for the global ocean's uptake of anthropogenic and natural carbon dioxide (CO2), but the mechanisms controlling this carbon flux are not fully understood. The air-sea flux of CO2, F, is the product of a gas transfer velocity, k, the air-sea CO2 concentration gradient, Delta pCO(2), and the temperature-and salinity-dependent solubility coefficient, alpha, k is difficult to constrain, representing the dominant uncertainty in F on short (instantaneous to interannual) timescales. Previous work shows that in the North Atlantic, Delta pCO(2) and k both contribute significantly to interannual F variability but that k is unimportant for multidecadal variability. On some timescale between interannual and multidecadal, gas... |
| Tipo: Text |
Palavras-chave: Carbon flux; Gas transfer velocity; Carbon cycle; Ocean model; Climate dynamics; Variability. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00383/49418/49868.pdf |
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| Mckinley, Galen A.; Fay, Amanda R.; Eddebbar, Yassir A.; Gloege, Lucas; Lovenduski, Nicole S.. |
| The ocean has absorbed the equivalent of 39% of industrial‐age fossil carbon emissions, significantly modulating the growth rate of atmospheric CO2 and its associated impacts on climate. Despite the importance of the ocean carbon sink to climate, our understanding of the causes of its interannual‐to‐decadal variability remains limited. This hinders our ability to attribute its past behavior and project its future. A key period of interest is the 1990s, when the ocean carbon sink did not grow as expected. Previous explanations of this behavior have focused on variability internal to the ocean or associated with coupled atmosphere/ocean modes. Here, we use an idealized upper ocean box model to illustrate that two external forcings are sufficient to explain... |
| Tipo: Text |
Palavras-chave: Carbon cycle; Ocean carbon sink; Forced; Internal. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00676/78775/80950.pdf |
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| Reichardt, W. |
| The predominantly anoxic, sulfide-rich sandy sediment of a shallow lagoon at Kiel Fjord was densely inhabited by the polychaete worm Nereis diversicolor (280 cm super(3) m super(-2) of biomass volume). Burrow walls which contrasted by their brown coloration of at least 1.5 mm thickness with the bulk of the reduced black sediment, made up for 6% of the total volume of the 10 cm cores investigated. Only the uppermost mm of the internal surface layer contained detectable O sub(2). As a result of the build up of internal redox gradients, CO sub(2) dark fixation was activated in the burrow walls (by a factor of approximately equals 2). Assays of ribulose-biphosphate carboxylase activities and viable counts of potentially chemoautotrophic bacteria in different... |
| Tipo: Text |
Palavras-chave: Nereis diversicolor; Polychaeta; Bacteria; Microorganisms; Carbon cycle; Tube dwellers; Carbon fixation; Burrows; Bioturbation; Sediments. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/1984/acte-990.pdf |
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| Registros recuperados: 36 | |
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