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Datasets with PANGAEA technical keyword @ORFOISatWS1

Mostrando recursos 1 - 20 de 921

  1. A review of Si particle fluxes in the modern ocean

    Ragueneau, Olivier; Tréguer, Paul; Leynaert, Aude; Anderson, Robert F; Brzezinski, Mark A; DeMaster, David J; Dugdale, Richard; Dymond, Jack R; Fischer, Gerhard; Francois, Roger; Heinze, Christoph; Maier-Reimer, Ernst; Martin-Jézéquel, Véronique; Nelson, David M; Quéguiner, Bernard
    Due to the major role played by diatoms in the biological pump of CO2, and to the presence of silica-rich sediments in areas that play a major role in air-sea CO2 exchange (e.g. the Southern Ocean and the Equatorial Pacific), opal has a strong potential as a proxy for paleoproductivity reconstructions. However, because of spatial variations in the biogenic silica preservation, and in the degree of coupling between the marine Si and C biogeochemical cycles, paleoreconstructions are not straitghtforward. A better calibration of this proxy in the modern ocean is required, which needs a good understanding of the mechanisms that...

  2. Benthic foraminifera in South Atlantic Ocean surface sediments

    Schumacher, Stefanie
    Benthic foraminiferal assemblages were analyzed on forty-eight surfacesediment samples which were taken with a multiple corer from the southern South Atlantic Ocean and the northern Angola-Basin. The short cores were split into 1-cm-thick slices down to 15 cm sediment depth. Live (with Rose Bengal stained) and dead faunas were counted separately. The data were used to calculate numerical faunal characteristics like standing stocks, benthic foraminifera accumulation rates, diversity, average living depth, and habitat depth. Additionally the live and dead faunas were grouped into a number of principal faunal endmembers by Q-mode principal component analysis. Faunal composition, numerical faunal characteristics, and...

  3. Surface Ocean CO2 Atlas (SOCAT) V1.4

    Pfeil, Benjamin; Olsen, Are; Bakker, Dorothee C E; Hankin, Steven; Koyuk, Heather; Kozyr, Alexander; Malczyk, Jeremy; Manke, Ansley; Metzl, Nicolas; Sabine, Christopher L; Akl, John; Alin, Simone R; Bellerby, Richard G J; Borges, Alberto Vieira; Boutin, Jacqueline; Brown, Peter J; Cai, Wei-Jun; Chavez, Francisco P; Chen, Arthur; Cosca, Catherine E; Fassbender, Andrea J; Feely, Richard A; González-Dávila, Melchor; Goyet, Catherine; Hardman-Mountford, Nicolas; Heinze, Christoph; Hood, E Maria; Hoppema, Mario; Hunt, Christopher W; Hydes, David; Ishii, Masao; Johannessen, Truls; Jones, Steve D; Key, Robert M; Körtzinger, Arne; Landschützer, Peter; Lauvset, Siv K; Lefèvre, Nathalie; Lenton, Andrew; Lourantou, Anna; Merlivat, Liliane; Midorikawa, Takashi; Mintrop, Ludger J; Miyazaki, Chihiro; Murata, Akihiko; Nakadate, Akira; Nakano, Yoshiyuki; Nakaoka, Shin-Ichiro; Nojiri, Yukihiro; Omar, Abdirahman M; Padín, Xose Antonio; Park, Geun-Ha; Paterson, Kristina; Pérez, Fiz F; Pierrot, Denis; Poisson, Alain; Ríos, Aida F; Santana-Casiano, Juana Magdalena; Salisbury, Joe; Sarma, Vedula V S S; Schlitzer, Reiner; Schneider, Bernd; Schuster, Ute; Sieger, Rainer; Skjelvan, Ingunn; Steinhoff, Tobias; Suzuki, Toru; Takahashi, Taro; Tedesco, Kathy; Telszewski, Maciej; Thomas, Helmuth; Tilbrook, Bronte; Tjiputra, Jerry; Vandemark, Doug; Veness, Tony; Wanninkhof, Rik; Watson, Andrew J; Weiss, Ray F; Wong, Chi Shing; Yoshikawa-Inoue, Hisayuki
    A well-documented, publicly available, global data set of surface ocean carbon dioxide (CO2) parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT) project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC). Many additional CO2 data, not yet made public via the Carbon Dioxide Information Analysis Center (CDIAC), were retrieved from data originators, public websites and other data centres. All data were put...

  4. Estimation of sea surface temperature from sediment core PS1768-8

    Zielinski, Ulrich; Gersonde, Rainer; Sieger, Rainer; Fütterer, Dieter K
    The quantitative diatom analysis of 218 surface sediment samples recovered in the Atlantic and western Indian sector of the Southern Ocean is used to define a base of reference data for paleotemperature estimations from diatom assemblages using the Imbrie and Kipp transfer function method. The criteria which justify the exclusion of samples and species out of the raw data set in order to define a reference database are outlined and discussed. Sensitivity tests with eight data sets were achieved evaluating the effects of overall dominance of single species, different methods of species abundance ranking, and no-analog conditions (e.g., Eucampia Antarctica)...

  5. Radionuclides of bulk and terrigenous surface sediments in the Southern Ocean

    Walter, Hans-Jürgen; Hegner, Ernst; Diekmann, Bernhard; Kuhn, Gerhard; Rutgers van der Loeff, Michiel M
    Sr and Nd isotopic compositions of Late Quaternary surface sediment and sediment cores from the south Atlantic and southeast Pacific sectors of the Southern Ocean are used to constrain the provenance and transport mechanisms of their terrigenous component. We report isotopic and mineralogical data for core samples from three localities, the Mid-Atlantic Ridge at 41°S and the northern and southern Scotia Sea. In addition, data for surface sediment samples from the south Atlantic and southeast Pacific sectors of the Southern Ocean are presented. The variations of Sr and Nd isotopic compositions of the bulk sediment samples in all cores were...

  6. Radionuclides of sediment cores and a sediment trap in the Weddell Sea

    Walter, Hans-Jürgen; Rutgers van der Loeff, Michiel M; Hoeltzen, H; Bathmann, Ulrich
    The scavenging of 230Th and 231Pa was investigated in the central Weddell Sea by combining results from a sediment trap and three sediment cores. Scavenging of both radionuclides is closely coupled with the annual cycle of particle fluxes. For 230Th the mean radionuclide flux measured in the trap is only 40% of its expected flux from production in the water column. This value is in excellent agreement with the long-term record in the sediment cores (33-43%). Similar results were obtained for 231Pa, although burial fluxes are generally higher. The data suggest that during the last 130 ka the Weddell Sea...

  7. Flux data in the Southern Ocean

    Wefer, Gerold; Fischer, Gerhard
    Since 1983 time-series traps have been deployed in the Atlantic sector of the Southern Ocean to measure the flux of organic carbon, biogenic silica and carbonate. The organic carbon flux data are used to calculate primary production rates and organic carbon fluxes at 100 m water depth. From these calculations, annual primary production rates range from about 170 g C m**-2 in the coastal area (Bransfield Strait) to almost zero in the Permanent Sea-Ice Zone. High rates (of about 80 g C m**-2 year**-1 ) were calculated for the Polar Front Zone and rather low values (about 20 g C...

  8. Global compilation of benthic data sets I

    Seiter, Katherina; Hensen, Christian; Schröter, Jürgen; Zabel, Matthias
    Approaches to quantify the organic carbon accumulation on a global scale generally do not consider the small-scale variability of sedimentary and oceanographic boundary conditions along continental margins. In this study, we present a new approach to regionalize the total organic carbon (TOC) content in surface sediments (<5 cm sediment depth). It is based on a compilation of more than 5500 single measurements from various sources. Global TOC distribution was determined by the application of a combined qualitative and quantitative-geostatistical method. Overall, 33 benthic TOC-based provinces were defined and used to process the global distribution pattern of the TOC content in...

  9. Sedimentology of surface samples from the Weddell Sea, Antarctica

    Diekmann, Bernhard; Kuhn, Gerhard
    Mineralogical and granulometric properties of glacial-marine surface sediments of the Weddell Sea and adjoining areas were studied in order to decipher spatial variations of provenance and transport paths of terrigenous detritus from Antarctic sources. The silt fraction shows marked spatial differences in quartz contents. In the sand fractions heavy-mineral assemblages display low mineralogical maturity and are dominated by garnet, green hornblende, and various types of clinopyroxene. Cluster analysis yields distinct heavy-mineral assemblages, which can be attributed to specific source rocks of the Antarctic hinterland. The configuration of modern mineralogical provinces in the near-shore regions reflects the geological variety of the...

  10. Stable isotope record of foraminifera from the Southern Ocean

    Lynch-Stieglitz, Jean; Fairbanks, Richard G; Charles, Christopher D
    Sediment cores from the southern continental margin of Australia are near the formation region of Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water and record the changes in these water masses from the last glacial maximum through the present. Carbon and oxygen isotopes were measured on the benthic foraminiferal species Planulina wuellerstrorfi for both the Recent and last glacial maximum sections of the cores and were then used to reconstruct temperature and carbon isotopic water column profiles. The glacial oxygen isotope profile indicates a vertical temperature structure for this region similar to that in today's Subantarctic Zone. Although intermediate water...

  11. Physical, chemical and biological oceanography during Polarstern cruise ANT-X/6

    Smetacek, Victor; de Baar, Hein J W; Bathmann, Ulrich; Lochte, Karin; Rutgers van der Loeff, Michiel M
    The R.V. Polarstern cruise ANT X/6, part of the international Southern Ocean JGOFS programme, investigated phytoplankton spring bloom development and its biogeochemical effects in different water masses of the Atlantic sector of the Southern Ocean: the Polar Frontal region (PFr), the southern Antarctic Circumpolar Current zone (sACC), its boundary with the Weddell Gyre (AWB) and the marginal ice zone (MIZ). The relative roles of physical stability, iron limitation and grazing pressure in enhancing or constraining phytoplankton biomass accumulation were examined. Three sections were carried out between the PFr and the ice edge along the 6°W meridian from early October to...

  12. Radiolarian-based bransfer function for the estimation of sea surface temperatures in the Southern Ocean (Atlantic Sector)

    Abelmann, Andrea; Brathauer, Uta; Gersonde, Rainer; Sieger, Rainer; Zielinski, Ulrich
    A new radiolarian-based transfer function for sea surface temperature (SST) estimations has been developed from 23 taxa and taxa groups in 53 surface sediment samples recovered between 35° and 72°S in the Atlantic sector of the Southern Ocean. For the selection of taxa and taxa groups ecological information from water column studies was considered. The transfer function allows the estimation of austral summer SST (December-March) ranging between -1 and 18°C with a standard error of estimate of 1.2°C. SST estimates from selected late Pleistocene squences were sucessfully compared with independend paleotemperature estimates derived from a diatom transfer function. This shows...

  13. Ge/Si record of marine biogenic opal

    Shemesh, Aldo; Mortlock, Richard A; Froelich, Philip N
    We have determined germanium/silicon ratios in purified diatoms and radiolarians from siliceous sediments in Holocene core tops, one late Pleistocene piston core, and four high-latitude Southern Ocean Deep Sea Drilling Project (DSDP) sites ranging in age from Holocene to Oligocene. High-latitude Holocene diatoms in the 10- to 38-µm size fraction ([Ge/Si]opal = 0.693 +/- 0.039 * 10**-6) faithfully record the present oceanic ratio ([Ge/Si]seawater = 0.699 +/- 0.004 * 10**-6). This confirms that diatoms from siliceous oozes are monitors of seawater Ge/Si and may record past changes in rates of delivery of weathering products to the sea from continental and...

  14. Organic chemistry of Neogene sediments from ODP Leg 113

    Macko, Stephen A; Pereira, Christopher PG
    Stable carbon and nitrogen isotopic compositions as well as organic carbon and total nitrogen contents of cored material are reported for the Weddell Sea, Ocean Drilling Program (ODP) Sites 689 and 690 (Maud Rise), Site 693 (continental margin), and Site 694 (abyssal plain). Results from both high resolution sampling (up to six samples per section) and low resolution (one sample per section) are documented. In general, these results indicate large changes in the types and amounts of carbon and nitrogen preserved in the sediments of the Weddell Sea region during the past 25 m.y., with an especially important and dramatic...

  15. Geochemical investigation of ODP Leg 113 sites

    Egeberg, Per Kristian; Abdullah, Mohamed I
    Dissolved organic carbon (DOC) was determined in pore water extracted from pelagic and hemipelagic sediments recovered during Leg 113. DOC concentration varied between 1.82 and 13.6 mg C/L which is one to two orders of magnitude less than previously reported for hemipelagic sediments. It is argued that this difference is related to differences in the intensity of degradation of organic matter. As a first approximation it is found that in reducing sediments, the level of DOC is proportional to the intensity of sulfate reduction. It is suggested that DOC is formed by different mechanisms in oxic and reducing environments.

  16. Calcium carbonate global LGM Burial rate data

    Catubig, Nina R; Archer, David E; Francois, Roger; deMenocal, Peter B; Howard, William R; Yu, Ein-Fen
    Global databases of calcium carbonate concentrations and mass accumulation rates in Holocene and last glacial maximum sediments were used to estimate the deep-sea sedimentary calcium carbonate burial rate during these two time intervals. Sparse calcite mass accumulation rate data were extrapolated across regions of varying calcium carbonate concentration using a gridded map of calcium carbonate concentrations and the assumption that accumulation of noncarbonate material is uncorrelated with calcite concentration within some geographical region. Mean noncarbonate accumulation rates were estimated within each of nine regions, determined by the distribution and nature of the accumulation rate data. For core-top sediments the regions...

  17. Clay mineralogy of South Atlantic surface sediments

    Petschick, Rainer; Kuhn, Gerhard; Gingele, Franz
    Surface samples, mostly from abyssal sediments of the South Atlantic, from parts of the equatorial Atlantic, and of the Antarctic Ocean, were investigated for clay content and clay mineral composition. Maps of relative clay mineral content were compiled, which improve previous maps by showing more details, especially at high latitudes. Large-scale relations regarding the origin and transport paths of detrital clay are revealed. High smectite concentrations are observed in abyssal regions, primarily derived from southernmost South America and from minor sources in Southwest Africa. Near submarine volcanoes of the Antarctic Ocean (South Sandwich, Bouvet Island) smectite contents exhibit distinct maxima,...

  18. Physical oceanography of two transects in the southern South Atlantic

    Mackensen, Andreas; Hubberten, Hans-Wolfgang; Scheele, Norbert; Schlitzer, Reiner
    On a section between 72°S and 42°S and a transect between 60°E and 10°E through the Weddell Sea and the southernmost eastern Atlantic Ocean, the water column was sampled on 72 stations, and the stable carbon isotopic composition of total dissolved inorganic carbon (delta13C(SumCO2)) as well as the stable oxygen isotopic composition of seawater (delta18O) was determined. These data were compared with potential temperature, salinity, dissolved oxygen and phosphate data from the same stations. The observed delta13C(SumCO2)/PO4[3-] relationship in the deep Weddell Sea strongly differs from the global Redfield-driven deep water relationship. We attribute this to enhanced thermodynamic fractionation at...

  19. Primary data sets of the hydrographic atlas of the Southern Ocean

    Olbers, Dirk; Gouretski, Viktor V; Seiß, Guntram; Schröter, Jens
    The general knowledge of the hydrographic structure of the Southern Ocean is still rather incomplete since observations particularly in the ice covered regions are cumbersome to be carried out. But we know from the available information that thermohaline processes have large amplitudes and cover a wide range of scales in this part of the world ocean. The modification of water masses around Antarctica have indeed a worldwide impact, these processes ultimately determine the cold state of the present climate in the world ocean. We have converted efforts of the German and Russian polar research institutions to collect and validate the presently...

  20. Size distribution of Holocene planktic foraminifer assemblages

    Schmidt, Daniela N; Renaud, Sabrina; Bollmann, Jörg; Schiebel, Ralf; Thierstein, Hans R
    The size of any organism is influenced by the surrounding ecological conditions. In this study, we investigate the effects of such factors on the size spectra of planktic foraminiferal assemblages from Holocene surface sediments. We analyzed assemblages from 69 Holocene samples, which cover the major physical and chemical gradients of the oceans. On a global scale, the range of sizes in assemblages triples from the poles to the tropics. This general temperature-related size increase is interrupted by smaller sizes at temperatures characteristic of the polar and subtropical fronts, at 2°C and 17°C, respectively, as well as in upwelling areas. On...

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