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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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| Sarazin, Gérard; Jezequel, Didier; Leboulanger, Christophe; Fouilland, Eric; Le Floc'H, Emilie; Bouvy, Marc; Gerard, Emmanuelle; Agogué, Hélène; Bernard, Cédric; Hugoni, Mylène; Grossi, Vincent; Trousselier, Marc; Ader, Magali. |
| Dziani Dzaha is a maar the age of which is close to 4000 years. While its water is thought to have originated from seawater it is now considered as an extreme environment due to its hypersaline and alkaline characteristics. Those extreme features have led to the simplification of the trophic network. Cyanobacteria account for up to 95% of the photosynthetic biomass. The main biogeochemical processes, i.e. photosynthesis, bacterial sulfate reduction and methanogenesis could explain the current water composition. As far as we know, this ecosystem could be unique on Earth, extending the nature and chemical limits of aquatic inland ecosystems |
| Tipo: Text |
Palavras-chave: Thalassohaline lake; Endorheic ecosystem; Cyanobacteria; Methane emission; Biogeochemistry; Mayotte. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00667/77948/80128.pdf |
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| German, C. R.; Thurnherr, A. M.; Knoery, Joel; Charlou, Jean-luc; Jean-baptiste, P.; Edmonds, H. N.. |
| High-temperature hydrothermal activity occurs in all ocean basins and along ridge crests of all spreading rates. While it has long been recognized that the fluxes associated with such venting are large, precise quantification of their impact on ocean biogeochemistry has proved elusive Here, we report a comprehensive study of heat, fluid and chemical fluxes from a single submarine hydrothermal field. To achieve this, we have exploited the integrating nature of the non-buoyant plume dispersing above the Rainbow hydrothermal field, a long-lived and tectonically hosted high-temperature vent site on the Mid-Atlantic Ridge. Our calculations yield heat and volume fluxes for high-temperature fluids exiting the seafloor of similar to 0.5 GW and 450 Ls(-1), together... |
| Tipo: Text |
Palavras-chave: Hydrothermal fluxes; Biogeochemistry; Rainbow vent-field. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00003/11423/8040.pdf |
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| Rondeau, B; Cossa, Daniel; Gagnon, P; Pham, T; Surette, C. |
| Surface water samples from the St. Lawrence River were collected in order to study the processes controlling minor and trace elements concentrations (Al, Fe, Mn, Cd, Co, Cu, Ni and Zn), and to construct mass balances allowing estimates of the relative importance of their natural and anthropogenic sources. The two major water inputs, the upper St. Lawrence River, which drains waters originating from the Lake Ontario, and the Ottawa River were collected fortnightly over 18 months. In addition, other tributaries were sampled during the spring floods. The output was monitored near Quebec City at the river mouth weekly between 1995 and 1999. Dissolved metal concentrations in the upper St. Lawrence River carbonated waters were lower than in the acidic waters of... |
| Tipo: Text |
Palavras-chave: St. Lawrence; Mass balance; River; Biogeochemistry; Trace element. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1357.pdf |
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| Santos,Isaac Rodrigues; Costa,Ronaldo Cataldo; Freitas,Ubiratan; Fillmann,Gilberto. |
| The hypothesis that effluents treated through activated sludge process cause changes in nutrient biogeochemistry of receiving water bodies was investigated in Vieira creek, southern Brazil. Dissolved oxygen, suspended matter, and pH did not vary among the sampling stations. Nutrient, biochemical oxygen demand, and conductivity values were significantly higher downstream from the Wastewater Treatment Plant (WWTP) effluents. Further downstream, nitrate concentrations were higher due to ammonium nitrification, organic matter remineralization and/or the occurrence of unidentified sources. Per capita nutrient emission factors were estimated to be 0.16 kg P.yr-1 and 4.14 kg N.yr-1. Under pristine conditions, low N:P ratios were observed, which were significantly... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Activated sludge; Nutrients; Contamination; Coastal zone; Biogeochemistry; Eutrophication. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000100019 |
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| Koliyavu, Timoci; Martias, Chloe; Singh, Awnesh; Mounier, Stéphane; Gérard, Philippe; Dupouy, Cecile. |
| Heavy rain events alter the biogeochemical outflows, affects water quality and ecosystem health within the coastal waters of small Pacific Islands. We characterized snapshots of the optical fingerprints of dissolved organic matter (DOM) sources together with the select nutrients, biogeochemical and physical variables for 10 stations in December 2017 in Laucala Bay, Fiji Islands. DOM absorption coefficients and fluorescence components were determined via spectrofluorometry and Parallel Factor Analysis identifying four components: Type M, two terrestrial (humic, fulvic) components, and a protein component linked to marine biological activity. Associations of DOM together with climate variables and the other tested variables were determined via principal... |
| Tipo: Text |
Palavras-chave: DOM absorption; Fluorescence; Biogeochemistry; PARAFAC; EEM spectra; Autochthonous; Allochthonous; Chlorophyll; CDOM; FDOM. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00682/79372/81889.pdf |
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| Conway, T. M.; John, S. G.; Lacan, F.. |
| Intercomparison of trace metal data is a key aspect of the International GEOTRACES program, allowing data from multiple laboratories and countries to be combined to produce high-resolution datasets for the oceans. The use of crossover stations by the GEOTRACES program provides the opportunity both for comparison of analytical techniques and assessment of temporal variability in the cycling of trace metals such as iron (Fe). Here, we present the first comparison of dissolved Fe stable isotope ratio (δ56Fe; relative to IRMM-014) profiles in the oceans, from re-occupations of three locations in the Atlantic Ocean; (1) the Bermuda Atlantic Time Series Station (31.75°N 64.17°W) during the U.S. GEOTRACES IC1 cruise (June 2008) and the U.S. GEOTRACES GA03 cruise... |
| Tipo: Text |
Palavras-chave: Trace metals; GEOTRACES; Biogeochemistry; Intercomparison. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00332/44330/43932.pdf |
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| Mensi, F.; Ksouri, J.; Hammami, W.; Romdhane, M.S.. |
| L'algue rouge, Gracilaria verrucosa, a été cultivée, durant le printemps 2009, en mode suspendu à différents emplacements et profondeurs représentant les différences biogéochimiques de la lagune de Bizerte au Nord de la Tunisie. La concentration et la distribution des nutriments (ammonium, phosphate) dans l'eau, ainsi que la salinité, la température, l’oxygène et la transparence de l’eau ont été déterminées. Les méthodes analytiques internationales standardisées ont été appliquées. Les effets du mode de culture, de l’emplacement et de la profondeur sur les rendements en poids, protéines, R-Phycoérythrine et sucres totaux de l’algue ont été étudiés. La croissance de Gracilaria a été similaire dans les différents sites mais plus lente dans les profondeurs... |
| Tipo: Journal Contribution |
Palavras-chave: Algal culture; Ammonium compounds; Biochemical composition; Biogeochemistry; Carbohydrates; Dissolved oxygen; Environmental conditions; Growth; Intensive culture; Lagoons; Off-bottom culture; Raw materials; Red algae; Biogeochemical cycle. |
| Ano: 2009 |
URL: http://hdl.handle.net/1834/4497 |
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| Michel, Pierre. |
| Arsenic levels of in the marine environment are high in comparison with other contaminants. Over the past twenty years, a large number of arsenic organic compounds have been identified in the water, sediments and living species. This document constitutes a synthesis of current knowledge on arsenic sources, and contamination levels, on its biogeochemical cycle as well as its toxic effects on human and marine fauna. This paper highlights in particular the effects of phosynthesis on arsenic speciation and its distribution throughout the marine environment. Problems of toxicity in the case of certain phyto- and zooplankton species are identified. Bioaccumulation in seaweeds, molluscs and fishes is documented as well, with special attention to the species... |
| Tipo: Text |
Palavras-chave: Ecotoxicology; Contamination; Biogeochemistry; Arsenic; Ecotoxicologie; Contamination; Biogéochimie; Arsenic. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/1993/rapport-1448.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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| GINOCCHIO,ROSANNA; BAKER,ALAN J.M.. |
| In Latin America, metallic ores are abundant and diverse. However, few metal-tolerant and metal hyperaccumulator plants have been reported in the region in comparison with other areas of the world. This may be largely explained by the scarcity of scientific studies of the native vegetation growing on natural mineralized or metal-contaminated areas and the unfrequent use of biogeochemical prospecting techniques by the local mining industry, rather than the proven absence of these plants. Latin America is, however, an area where metal-tolerant and hyperaccumulator plants (metallophytes) should be found, not only because of the wealth of ore deposits and associated metal polluted areas, but also due to its high and unique plant diversity. If plant formations... |
| Tipo: Journal article |
Palavras-chave: Hyperaccumulators; Metal-tolerant plants; Biodiversity; Metal ores; Biogeochemistry. |
| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2004000100014 |
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| Registros recuperados: 68 | |
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