Consulta: subjectFacets:"Nitrogen isotopes"
Registros recuperados: 6
Data/hora: 06/06/2024 04:22:35

Surface nitrate utilization in the Bering sea since 180 kA BP: Insight from sedimentary nitrogen isotopes
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Riethdorf, Jan-rainer; Thibodeau, Benoit; Ikehara, Minoru; Nuernberg, Dirk; Max, Lars; Tiedemann, Ralf; Yokoyama, Yusuke.
We present high-resolution records of sedimentary nitrogen (delta N-15(bulk)) and carbon isotope ratios (delta C-13(bulk)) from piston core S0201-2-85KL located in the western Bering Sea. The records reflect changes in surface nitrate utilization and terrestrial organic matter contribution in submillennial resolution that span the last 180 kyr. The delta N-15(bulk) record is characterized by a minimum during the penultimate interglacial indicating low nitrate utilization (similar to 62-80%) despite the relatively high export production inferred from opal concentrations along with a significant reduction in the terrestrial organic matter fraction (m(terr)). This suggests that the consumption of the nitrate pool at our site was incomplete and even more...
Tipo: Text
Palavras-chave: Bering Sea; Quaternary; Nitrogen isotopes; Nitrate utilization.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00421/53261/83376.pdf

Carbon and Nitrogen Acquisition in Shallow and Deep Holobionts of the Scleractinian Coral S. pistillata
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Ezzat, Leila; Fine, Maoz; Maguer, Jean-francois; Grover, Renaud; Ferrier-pages, Christine.
Reef building corals can host different symbiont genotypes (clades), and form distinct holobionts in response to environmental changes. Studies on the functional significance of genetically different symbionts have focused on the thermal tolerance rather than on the nutritional significance. Here, we characterized the nitrogen and carbon assimilation rates, the allocation patterns of these nutrients within the symbiosis, and the trophic condition of two distinct holobionts of Stylophora pistillata: one associated with Symbiodinium Glade A in shallow reefs and the other one associated with Glade C in mesophotic reefs. The main findings are that: (1) Glade C-symbionts have a competitive advantage for the acquisition of carbon at low irradiance compared to...
Tipo: Text
Palavras-chave: Light acclimation; Carbon isotopes; Nitrogen isotopes; Clades; Nitrate; Ammonium; Scleractinian coral; Mesophotic coral.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00602/71414/69897.pdf

Distribution of the organic matter in the channel-levees systems of the Congo mud-rich deep-sea fan (West Africa). Implication for deep offshore petroleum source rocks and global carbon cycle
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Baudin, Francois; Disnar, Jean-robert; Martinez, Philippe; Dennielou, Bernard.
The quantity and the source of organic matter preserved in the Recent turbiditic channel-levees systems around 4000 m-depth off the Congo River were determined using bulk geochemical approaches (Rock-Eval, elemental and isotopic analyses) as well as molecular and optical analyses on selected samples. These mud-rich sediments contain high amount of organic matter (3% Corg on average), the origin of which is a mixture of terrestrial higher-plant debris and deeply oxidized phytoplanktonic material. Although the relative contribution of continental source versus marine source of the organic matter cannot be precisely quantified, the continental fraction appears significant (at least 70-80%) especially for such depths and distances from the coast. The organic...
Tipo: Text
Palavras-chave: South-East Atlantic; Turbidites; Carbon isotopes; Nitrogen isotopes; Biomarkers; Source rocks.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00006/11700/9285.pdf

Macroalgae delta N-15 values in well-mixed estuaries: Indicator of anthropogenic nitrogen input or macroalgae metabolism?
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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

Insights into nitrogen cycling in the western Gulf of California from the nitrogen isotopic composition of diatom-bound organic matter
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Kalansky, Julie F.; Robinson, Rebecca S.; Popp, Brian N.
The nitrogen isotopic composition of organic matter contained within diatom frustules of different sediment size fractions from the Guaymas Basin, Gulf of California, suggests that multiple nutrient cycling processes can be examined from a single sediment sample. The diatom-bound delta(15)N values from the greater and less than 63 mu m size fractions were analyzed from six intervals of core MD02-2517, each representing similar to 30-40 years. The diatom-bound delta(15)N values are compared to bulk sedimentary delta(15)N values, weight percent biogenic opal, and weight percent organic carbon. Bulk sedimentary delta(15)N values range from 10 parts per thousand to 12.5 parts per thousand and diatom-bound delta(15)N values of the &lt;63 mu m size fraction from...
Tipo: Text
Palavras-chave: Gulf of California; Diatoms; Export flux; Nitrogen cycling; Nitrogen isotopes.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00227/33836/32444.pdf

Tramas tróficas en sistemas frontales del Mar Argentino: estructura, dinámica y complejidad analizada mediante isótopos estables
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Gaitán, E.N.
Two of the most important frontal systems of the Argentine Sea (SW Atlantic Ocean) were compared to obtain evidences on the regulatory mechanisms of food web length, incorporating both spatial (areas within fronts) and temporal (presence or absence of frontal structure) variability. The stable isotopes of Carbon and Nitrogen were used to evaluate the origin and composition of the organic matter used by primary consumers, the structure of food webs, the trophic levels of several taxa and the benthic-pelagic coupling within each system. In the Río de la Plata estuarine front, different sources of organic matter would support the food webs occurring in the three areas of the system. The particulate organic material (POM) would be the main resource supporting...
Tipo: Theses and Dissertations
Palavras-chave: Food webs; Trophic relationships; Trophic levels; Saline fronts; Estuarine front; Carbon isotopes; Nitrogen isotopes; Plankton; Benthos; Brackishwater fish; Marine fish; Brackishwater environment; Marine environment.
Ano: 2012
URL: http://hdl.handle.net/1834/4523