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Ozeanographie

Die Ozeanographie umfasst viele verschiedene Disziplinen, die sich mit den physikalischen, chemischen und biologischen Prozessen beschäftigen, die sich in den Ozeanen der Erde abspielen. Die Stabilisotopenanalyse ist ein leistungsfähiges Mittel, um diese Prozesse nachzuverfolgen, sowohl in der Gegenwart als auch in der Vergangenheit. Die Paläoozeanographie nutzt stabile Sauerstoffisotopensignaturen von Materialien, die in Eiskernen oder Sedimenten konserviert wurden, um die Geschichte der Meeresoberflächen- oder Tiefseetemperaturen nachzuvollziehen. Die Stabilisotopenanalyse von Sauerstoff und Wasserstoff kann auch die Hydrologie von ozeanischen Gewässern enthüllen, indem die Bewegung und Zirkulation von Gewässern, evaporitische Prozesse und meteorologische Einflüsse auf lokaler, regionaler und globaler Ebene verfolgt werden.

Nährstoffkreislauf und Ökologie der Weltmeere sind ebenfalls von Interesse; stabile Kohlenstoff-, Stickstoff- und Schwefelisotope sind leistungsfähige Werkzeuge, die eingesetzt werden, um Algenaktivität, Struktur von Nahrungsketten in oberflächlichen oder benthischen Gemeinschaften und Nährstoffflüsse während der Jahreszeiten zu untersuchen. Besonders nützlich ist die Stabilisotopenanalyse, um ungewöhnliche Grenzen von tiefen, hydrothermalen Systemen zu erforschen, wo ungewöhnliche chemosynthetische Organismen die Basis der Gemeinschaften sind, die unter diesen extremen Bedingungen gedeihen.

Publikationen zum Thema Ozeanographie mit unseren Geräten

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83 Ergebnisse:

Age model, physical properties and paleoceanographic implications of the middle Pleistocene core sediments in the Choshi area, central Japan
Island Arc (2006)
Koji Kameo, Makoto Okada, Moamen El-Masry, Toshio Hisamitsu, Saneatsu Saito, Hiroomi Nakazato, Naohiko Ohkouchi, Minoru Ikehara, Hisato Yasuda, Hiroshi Kitazato, Asahiko Taira

A continuous, well-preserved core was obtained from the Choshi area, on the Pacific side of Japan, to investigate paleoceanographic and paleoclimatic changes around the northwestern Pacific region during the middle Pleistocene. Siliciclastic sequences in the core are divided into five formations - the Obama, Yokone, Kurahashi and Toyosato Formations in the Inubo Group and the Katori Formation, in ascending order. Examination of calcareous nannofossils and magnetic polarities detected four datums in the core sediments of the Inubo Group: the top of Reticulofenestra asanoi, the base of Helicosphaera inversa, the top of Pseudoemiliania lacunosa and the Brunhes-Matuyama boundary. Fourteen marine isotope stages (MIS24-MIS11) were identified in the δ18O and δ13C records based on detected datums and the graphic correlation with the standard stack oxygen isotope curve. Magnetic susceptibility and gamma-ray attenuation porosity evaluator density were also measured and low values characterize the glacial intervals. Biogenic sedimentation by primary production may be larger during the glacial periods because of invasions of nutrient-rich northern surface-waters related to the southward shift of the Kuroshio front in the Choshi area. © 2006 The Authors; Journal compilation © 2006 Blackwell Publishing Asia Pty Ltd.
Schlagworte: carbon , oxygen , ocea , mulitcarb

Inorganic carbon acquisition in red tide dinoflagellates
Plant, Cell and Environment (2006)
Bjorn Rost, Klaus-Uwe Richter, Ulf Riebesell, Per Juel Hansen

Carbon acquisition was investigated in three marine bloom- forming dinoflagellates – Prorocentrum minimum , Hetero- capsa triquetra and Ceratium lineatum . In vivo activities of extracellular and intracellular carbonic anhydrase (CA), photosynthetic O 2 evolution, CO 2 and HCO 3 – uptake rates were measured by membrane inlet mass spectrometry (MIMS) in cells acclimated to low pH (8.0) and high pH (8.5 or 9.1). A second approach used short-term 14 C- disequilibrium incubations to estimate the carbon source utilized by the cells. All three species showed negligible extracellular CA (eCA) activity in cells acclimated to low pH and only slightly higher activity when acclimated to high pH. Intracellular CA (iCA) activity was present in all three species, but it increased only in P. minimum with increasing pH. Half-saturation concentrations ( K 1/2 ) for photosynthetic O 2 evolution were low compared to ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) kinet- ics. Moreover, apparent affinities for inorganic carbon (Ci) increased with increasing pH in the acclimation, indicating the operation of an efficient CO 2 concentration mechanism (CCM) in these dinoflagellates. Rates of CO 2 uptake were comparably low and could not support the observed rates of photosynthesis. Consequently, rates of HCO 3 – uptake were high in the investigated species, contributing more than 80% of the photosynthetic carbon fixation. The affin- ity for HCO 3 – and maximum uptake rates increased under – higher pH. The strong preference for HCO 3 was also con- firmed by the 14 C-disequilibrium technique. Modes of car- bon acquisition were consistent with the 13 C-fractionation pattern observed and indicated a strong species-specific dif- ference in leakage. These results suggest that photosynthe- sis in marine dinoflagellates is not limited by Ci even at high pH, which may occur during red tides in coastal waters. Key-words

Long-chain alkenone unsaturation index as sea surface temperature proxy in southwest Bay of Bengal
Current Science (2006)
Nittala S Sarma, Sk G Pasha, M Sri Rama Krishna, P V Shirodkar, M G Yadava, K Mohan Rao

This study uses the carbon isotope values (δ13C) to determine how environmental deterioration is expressed in the δ13C values of vegetation and gazelles in the southern Levant. The ultimate goal is to use these modern data to predict the climatic impact of the Younger Dryas (YD). Climatic deterioration associated with the YD has been cited as the trigger for the transition to agriculture in the southern Levant. However, the evidence for the local severity of this climatic event is equivocal. There is disagreement over whether Mediterranean forest was succeeded by arid adapted steppic plant communities in what has been termed the Natufian ‘core area’. The modern data show a moderately negative regression slope between aridity and the δ13C values of both modern C3 plants and gazelle horn keratin within the Mediterranean phytogeographic belt. This pattern is expressed in both seasonal and annual datasets. The incorporation of a C4 plant component into gazelle diets is evident in the arid Mediterranean region, and is more pronounced in the dry season. The latter is apparent even despite interference caused by gazelle foraging on cultivated land. Based on the present day data, it is predicted that the succession of Mediterranean forest by open steppic vegetation would cause a positive shift of >2‰ in the δ13C values of C3 plants and gazelles. The argument is based on the response of C3 vegetation to growth under increasing water stress conditions and the current distribution of C3 and C4 vegetation in relation to rainfall. This study presents a new tool with the potential to assess the climatic severity of the YD and its effect on Natufian foraging strategies.
Schlagworte: carbon , ocea , clim , mulitcarb