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Mostrando recursos 1 - 20 de 8.833

  1. Stable oxygen isotope in opal and seawater

    Anders, Tania-Maria
    Sauerstoff-Isotopenuntersuchungen wurden an frischem Diatomeenopal aus der obersten Wassersäule, Diatomeen aus Kulturen, sowie an sedimentärem Diatomeenopal durchgeführt, um die Anwendbarkeit von d18O-Signalen aus marinen Diatomeen für paläozeanographische Fragestellungen zu untersuchen. Diatomeenopal ist, besonders aus Sedimentproben, schwierig anzureichern. Physikalische und chemische Verfahren müssen mehrfach angewendet werden, um Proben zu erhalten, die den für Sauerstoff-Isotopenmessungen erforderlichen Reinheitsgrad aufweisen. Die Ausgangskonzentration an Diatomeen im Probenmaterial wirkt sich hierbei erheblich auf den Erfolg der Reinigung aus. Verläßliche und reproduzierbare d18O-Werte können nur an sehr reinen Diatomeenproben bestimmt werden. Mittels mikroskopischer Untersuchungen (Durchlichtmikroskopie, Rasterelektronenrnikroskopie), Röntgendiffraktametrie und geochernischer Analysen am ICP-MS können z.T. Art und Menge von Verunreinigungen...

  2. Stable oxygen isotope in opal and seawater

    Anders, Tania-Maria
    Sauerstoff-Isotopenuntersuchungen wurden an frischem Diatomeenopal aus der obersten Wassersäule, Diatomeen aus Kulturen, sowie an sedimentärem Diatomeenopal durchgeführt, um die Anwendbarkeit von d18O-Signalen aus marinen Diatomeen für paläozeanographische Fragestellungen zu untersuchen. Diatomeenopal ist, besonders aus Sedimentproben, schwierig anzureichern. Physikalische und chemische Verfahren müssen mehrfach angewendet werden, um Proben zu erhalten, die den für Sauerstoff-Isotopenmessungen erforderlichen Reinheitsgrad aufweisen. Die Ausgangskonzentration an Diatomeen im Probenmaterial wirkt sich hierbei erheblich auf den Erfolg der Reinigung aus. Verläßliche und reproduzierbare d18O-Werte können nur an sehr reinen Diatomeenproben bestimmt werden. Mittels mikroskopischer Untersuchungen (Durchlichtmikroskopie, Rasterelektronenrnikroskopie), Röntgendiffraktametrie und geochernischer Analysen am ICP-MS können z.T. Art und Menge von Verunreinigungen...

  3. Pteropoda abundances in multinet samples

    Schiebel, Ralf
    The vertical flux and sedimentation rate of planktic foraminiferal tests are quantified and a global planktic foraminiferal CaCO3 budget is presented. Test and calcite flux rates are calculated according to the distribution of species obtained from multinet and sediment trap samples. Modern planktic foraminiferal population dynamics are discussed as a prerequisite for the quantification of the calcite budget, highlighting the importance of ecological, autecological (e.g., reproduction), and biogeochemical conditions that determine the presence or absence of species. To complete the open-marine, particulate CaCO3 inventory, the contribution of coccolithophores, pteropods, and calcareous dinophytes is discussed. Based on the studied regions, the...

  4. Pteropoda abundances in multinet samples

    Schiebel, Ralf
    The vertical flux and sedimentation rate of planktic foraminiferal tests are quantified and a global planktic foraminiferal CaCO3 budget is presented. Test and calcite flux rates are calculated according to the distribution of species obtained from multinet and sediment trap samples. Modern planktic foraminiferal population dynamics are discussed as a prerequisite for the quantification of the calcite budget, highlighting the importance of ecological, autecological (e.g., reproduction), and biogeochemical conditions that determine the presence or absence of species. To complete the open-marine, particulate CaCO3 inventory, the contribution of coccolithophores, pteropods, and calcareous dinophytes is discussed. Based on the studied regions, the...

  5. 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...

  6. 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...

  7. 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...

  8. Physical oceanography during POLARSTERN cruise ANT-XVII/4

    Kuhn, Gerhard; Usbeck, Regina

  9. Physical oceanography during POLARSTERN cruise ANT-XVII/4

    Kuhn, Gerhard; Usbeck, Regina

  10. Pigments of sediment cores of the Northwest European Continental Margin

    Pfannkuche, Olaf; Soltwedel, Thomas
    In the context of the European OMEX Programme this investigation focused on gradients in the biomass and activity of the small benthic size spectrum along a transect across the Goban Spur from the outer Celtic Sea into Porcupine Abyssal Plain. The effects of food pulses (seasonal, episodic) on this part of the benthic size spectrum were investigated. Sediments sampled during eight expeditions at different seasons covering a range from 200 m to 4800 m water depth were assayed with biochemical bulk measurements: determinations of chloroplastic pigment equivalents (CPE), the sum of chlorophyll a and its breakdown products, provide information concerning...

  11. Pigments of sediment cores of the Northwest European Continental Margin

    Pfannkuche, Olaf; Soltwedel, Thomas
    In the context of the European OMEX Programme this investigation focused on gradients in the biomass and activity of the small benthic size spectrum along a transect across the Goban Spur from the outer Celtic Sea into Porcupine Abyssal Plain. The effects of food pulses (seasonal, episodic) on this part of the benthic size spectrum were investigated. Sediments sampled during eight expeditions at different seasons covering a range from 200 m to 4800 m water depth were assayed with biochemical bulk measurements: determinations of chloroplastic pigment equivalents (CPE), the sum of chlorophyll a and its breakdown products, provide information concerning...

  12. Calcareous dinoflagellate cycst in the mid-Cenomanian Boreal realm

    Wendler, Jens E; Gräfe, Kai-Uwe; Willems, Helmut
    A transect from the bathyal to proximal shelf facies of the Boreal Realm was investigated to compare spatial and temporal distribution changes of calcareous dinoflagellate cysts (c-dinocysts) throughout the mid-Cenomanian in order to gain information on the ecology of these organisms. Pithonelloideae dominated the cyst assemblages to more than 95% on the shelf, a prevalence that can be observed throughout most of the Upper Cretaceous. The affinity of this group with the dinoflagellates, which is still controversially discussed, can be confirmed, based on evidence from morphological features and distribution patterns. The consistent prevalence of Pithonella sphaerica and P. ovalis in...

  13. Calcareous dinoflagellate cycst in the mid-Cenomanian Boreal realm

    Wendler, Jens E; Gräfe, Kai-Uwe; Willems, Helmut
    A transect from the bathyal to proximal shelf facies of the Boreal Realm was investigated to compare spatial and temporal distribution changes of calcareous dinoflagellate cysts (c-dinocysts) throughout the mid-Cenomanian in order to gain information on the ecology of these organisms. Pithonelloideae dominated the cyst assemblages to more than 95% on the shelf, a prevalence that can be observed throughout most of the Upper Cretaceous. The affinity of this group with the dinoflagellates, which is still controversially discussed, can be confirmed, based on evidence from morphological features and distribution patterns. The consistent prevalence of Pithonella sphaerica and P. ovalis in...

  14. 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...

  15. 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...

  16. 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...

  17. Global data compilation of benthic data sets II

    Seiter, Katherina; Hensen, Christian; Zabel, Matthias
    In this study we present a global distribution pattern and budget of the minimum flux of particulate organic carbon to the sea floor (J POC alpha). The estimations are based on regionally specific correlations between the diffusive oxygen flux across the sediment-water interface, the total organic carbon content in surface sediments, and the oxygen concentration in bottom waters. For this, we modified the principal equation of Cai and Reimers [1995] as a basic monod reaction rate, applied within 11 regions where in situ measurements of diffusive oxygen uptake exist. By application of the resulting transfer functions to other regions with...

  18. Global data compilation of benthic data sets II

    Seiter, Katherina; Hensen, Christian; Zabel, Matthias
    In this study we present a global distribution pattern and budget of the minimum flux of particulate organic carbon to the sea floor (J POC alpha). The estimations are based on regionally specific correlations between the diffusive oxygen flux across the sediment-water interface, the total organic carbon content in surface sediments, and the oxygen concentration in bottom waters. For this, we modified the principal equation of Cai and Reimers [1995] as a basic monod reaction rate, applied within 11 regions where in situ measurements of diffusive oxygen uptake exist. By application of the resulting transfer functions to other regions with...

  19. Planktic foraminiferal populations and test flux in the eastern North Atlantic Ocean

    Schiebel, Ralf; Hemleben, Christoph
    Planktic foraminiferal assemblages vary in response to seasonal fluctuations of hydrographic properties, between water masses, and after periodical changes and episodic events (e.g. reproduction, storms). Distinct annual variability of the planktic foraminiferal flux is also known from sediment trap data. In this paper we discuss the short-term impacts on interannual flux rates based on data from opening-closing net hauls obtained between the ocean surface and 500 m water depth. Data were recorded during April, May, June, and August at around 47°N, 20°W (BIOTRANS) in 1988, 1989, 1990, 1992, 1993, and during May 1989 and 1992 at 57°N, 20-22°W. Species assemblages...

  20. Planktic foraminiferal populations and test flux in the eastern North Atlantic Ocean

    Schiebel, Ralf; Hemleben, Christoph
    Planktic foraminiferal assemblages vary in response to seasonal fluctuations of hydrographic properties, between water masses, and after periodical changes and episodic events (e.g. reproduction, storms). Distinct annual variability of the planktic foraminiferal flux is also known from sediment trap data. In this paper we discuss the short-term impacts on interannual flux rates based on data from opening-closing net hauls obtained between the ocean surface and 500 m water depth. Data were recorded during April, May, June, and August at around 47°N, 20°W (BIOTRANS) in 1988, 1989, 1990, 1992, 1993, and during May 1989 and 1992 at 57°N, 20-22°W. Species assemblages...

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