Ocean Temperatures
    Marine Food Webs
    Ocean Currents


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:

Improved oxygen isotope temperature calibrations for cosmopolitan benthic foraminifera
Geochimica et Cosmochimica Acta (2014)
T. M. Marchitto, W. B. Curry, J. Lynch-Stieglitz, S. P. Bryan, K. M. Cobb, D. C. Lund

Despite decades of use as a paleoceanographic proxy, considerable uncertainty still surrounds the temperature dependence of benthic foraminiferal ??18O. Widely applied paleotemperature equations may mix non-equilibrium foraminifera with equilibrium synthetic calcite, resulting in temperature sensitivities that are too large. Warm-water foraminiferal calibrations may give temperature sensitivities that are too small for very cold waters. Here we combine new core top measurements from the Florida Straits and the Arctic Ocean with published data to derive new ??18O:temperature relationships for three groups of benthic foraminifera. We derive a quadratic equation for Cibicidoides and Planulina that agrees well with equilibrium synthetic calcite, and that should be applicable over all oceanographic temperatures. We find that Uvigerina is not at equilibrium and is isotopically heavier than Cibicidoides and Planulina by 0.47???, in contrast to the historically used 0.64???. Hoeglundina elegans is further enriched and appears to be slightly heavier than equilibrium aragonite. Finally we discuss the implications of the Florida Straits observations for the hypothesis that benthic foraminifera precipitate their shells from a pH-dependent mixture of bicarbonate and carbonate ions. ?? 2014 Elsevier Ltd.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Lack of equivalence in the elemental and stable isotope chemistry within the sagittal otolith pair of the summer flounder, Paralichthys dentatus
Antranik Kajajian, Jason J Schaffler, Cynthia M Jones

In fish that are not bilaterally symmetrical, the left and right sagittae are often not symmetrical, exhibiting divergent growth patterns and mass, and may have differences in chemical composition. We investigated this in the asymmetrical summer flounder Paralichthys dentatus, collected from different nursery habitats along the US east coast. Significant differences were detected in otolith mass, d13C, d18O, Li:Ca, Mg:Ca, and Sr:Ca, and overall chemical signatures. These results refute the hypothesis of left– right equivalence that is prevalent for bilaterally symmetrical fishes. We tested whether a specific side was better suited for classification. The best models differed between sagittae and resulted in different classification accuracies. The left otolith produced better classification accuracies. Simulated samples of randomized sets of left or right otoliths produced mean accuracies intermediate to classification and were often highly variable. We recommend that future otolith chemistry studies involving bilaterally asymmetrical species test the hypothesis of equivalence within the sagittae before randomly choosing an otolith for chemical analyses
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Paleoceanographic changes of surface and deep water based on oxygen and carbon isotope records during the last 130kyr identified in MD179 cores, off Joetsu, Japan Sea
Journal of Asian Earth Sciences (2014)
Saeko Ishihama, Takeshi Oi, Shiro Hasegawa, Ryo Matsumoto

We reconstructed the paleoenvironmental history of surface and deep water over the last 130. kyr from oxygen and carbon isotope ratios of planktonic and benthic foraminifera in two cores (MD179-3312 and MD179-3304) from the Joetsu Basin, eastern margin of the Japan Sea. Our data showed that paleoceanographic changes such as influx of surface currents and vertical circulation were associated with global glacial-interglacial sea level change. Surface water conditions were influenced by the influx of Tsushima Current, East China Sea coastal or off-shore waters through the Tsushima Strait during interglacial or interstadial stages, and strongly affected by freshwater input during the glacial maximum. During interglacial maximums such as Marine Isotope Stages 1 and 5e, development of well-oxygenated bottom water was indicated. A density-stratified ocean with weak ventilation was inferred from the isotopic records of benthic foraminifera during the Last Glacial Maximum. Local negative excursions in carbon isotopes during deglacial or interglacial periods may suggest the dissolution of gas hydrates or methane seep activities. ?? 2014 Elsevier Ltd.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

A continuous flow isotope ratio mass spectrometry method for high precision determination of dissolved gas ratios and isotopic
Limnology and Oceanography: Methods (2014)
Chawalit N Charoenpong, Laura A Bristow, Mark A Altabet

Dissolved gas ratios and isotopic compositions provide essential information about the biological and phys- ical mechanisms influencing N2 , O2 , and Ar in aquatic systems. Current methods available are either limited by overall cost, labor-intensive sample collection and analysis, or insufficient precision. Here, we present a new highly accurate and robust method for sample collection and subsequent simultaneous measurement of the dis- solved gas ratios (N2 /Ar and O2/Ar) and isotopic compositions (δ15 N2 and δ18 O2 ) in seawater. The relatively sim- ple sampling procedure using low cost materials enables collection of hundreds to more than a thousand dis- crete samples on a single research cruise. Samples can be preserved and stored at room temperature and main- tain their integrity for many months. Laboratory analysis employs an on-line extraction system coupled to a multi-collector isotope ratio mass spectrometer (IRMS). A continuous flow of He carrier gas completely degasses the sample, and passes through the preparation and purification system before entering the IRMS for analysis. The use of this continuous He carrier permits short analysis times (less than 8 min per sample) as compared with current high-precision methods. In addition to reference gases, calibration is achieved using air-equili- brated water standards of known temperature and salinity. Assessment of reference gas injections, air equili- brated standards, as well as samples collected in the field shows the accuracy and precision of this new method to be equal to or better than current standard techniques
Schlagworte: ocea

Extreme warming of tropical waters during the Paleocene-Eocene Thermal Maximum
Geology (2014)
T Aze, P N Pearson, a. J Dickson, M P S Badger, P R Bown, R D Pancost, S J Gibbs, B T Huber, M J Leng, a. L Coe, a. S Cohen, G L Foster

The Paleocene–Eocene Thermal Maximum (PETM), ca. 56 Ma, was a major global environmental perturbation attributed to a rapid rise in the concentration of greenhouse gases in the atmosphere. Geochemical records of tropical sea-surface temperatures (SSTs) from the PETM are rare and are typically affected by post-depositional diagenesis. To circumvent this issue, we have analyzed oxygen isotope ratios (δ18O) of single specimens of exceptionally well-preserved planktonic foraminifera from the PETM in Tanzania (∼19°S paleolatitude), which yield extremely low δ18O, down to <–5‰. After accounting for changes in seawater chemistry and pH, we estimate from the foraminifer δ18O that tropical SSTs rose by >3 °C during the PETM and may have exceeded 40 °C. Calcareous plankton are absent from a large part of the Tanzania PETM record; extreme environmental change may have temporarily caused foraminiferal exclusion.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Orbital-scale benthic foraminiferal oxygen isotope stratigraphy at the northern Bering Sea Slope Site U1343 (IODP Expedition 323) and its Pleistocene paleoceanographic significance
Deep-Sea Research Part II: Topical Studies in Oceanography (2014)
H. Asahi, S. Kender, M. Ikehara, T. Sakamoto, K. Takahashi, A. C. Ravelo, C. A. Alvarez Zarikian, B. K. Khim, M. J. Leng

A continuous composite oxygen isotope (??18O) stratigraphy from benthic foraminifera in the Bering Sea was reconstructed in order to provide insight into understanding sea-ice evolution in response to Northern Hemisphere Glaciation. Oxygen isotope records from multiple species of benthic foraminifera at Integrated Ocean Drilling Program (IODP) Expedition 323 Site U1343 (54??33.4'N, 176??49.0'E, water depth 1950 m) yield a highly refined orbital-scale age model spanning the last 1.2 Ma, and a refined age model between 1.2 and 2.4 Ma. An inter-species calibration was used to define species offsets and to successfully obtain a continuous composite benthic ??18O record, correlated with the global composite benthic ??18O stack curve LR04 to construct an orbital-scale age model. The consistency of the benthic ??18O stratigraphy with biostratigraphy and magnetostratigraphy confirms the reliability of both methods for constraining age. The time difference between cyclic changes in sedimentary physical properties and glacial-interglacial cycles since 0.8 Ma is notable, and suggests that physical properties alone cannot be used to construct an orbital-scale age model. Amplitude changes in physical properties and a significant drop in the linear sedimentation rate during glacials after 0.9 Ma indicate that the glacial sea-ice edge extended beyond the Bering Sea Slope (Site U1343) at this time. ?? 2014 Elsevier Ltd. All rights reserved.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Characterization and source identification of organic matter in view of land uses and heavy rainfall in the Lake Shihwa , Korea
Marine pollution bulletin (2014)
Yeonjung Lee, Jin Hur, Kyung-hoon Shin

The characteristics and sources of organic matter in water of the Lake Shihwa, which receives inputs from rural, urban, and industrial areas, were evaluated by examining the biodegradable organic carbon con- centration, fluorescence spectra, and carbon and nitrogen isotope ratios, especially during rainy season and dry season. The organic matter transported from rural areas was of refractory nature, while that of industrial origin decomposed rapidly. As compared to the dry season, the organic matter in the rainy sea- son was characterized by a reduced labile fraction. During the dry season, the autochthonous organic matter dominated in the lake, however, the contributions of allochthonous organic sources by industrial and rural areas significantly increased at rainy season. This investigation revealed that the transport of organic matter of anthropogenic origin to the Lake Shihwa was mainly influenced by heavy rainfall. Moreover, each anthropogenic source could differently influence the occurrence of organic matter in water of the Lake Shihwa
Schlagworte: carbon , nitrogen , ocea , poll , elem

Effect of a controlled sub-seabed release of CO2 on the biogeochemistry of shallow marine sediments, their pore waters, and the overlying water column
International Journal of Greenhouse Gas Control (2014)
Anna Lichtschlag, Rachael H. James, Henrik Stahl, Doug Connelly

The potential for leakage of CO2 from a storage reservoir into the overlying marine sediments and into the water column and the impacts on benthic ecosystems are major challenges associated with carbon capture and storage (CCS) in subseafloor reservoirs. We have conducted a field-scale controlled CO2 release experiment in shallow, unconsolidated marine sediments, and documented the changes to the chemical composition of the sediments, their pore waters and overlying water column before, during and up to 1 year after the 37-day long CO2 release. Increased levels of dissolved inorganic carbon (DIC) were detected in the pore waters close to the sediment-seawater interface in sediments sampled closest to the subsurface injection point within 5 weeks of the start of the CO2 release. Highest DIC concentrations (28.8 mmol L−1, compared to background levels of 2.4 mmol L−1) were observed 6 days after the injection had stopped. The high DIC pore waters have high total alkalinity, and low ı13CDIC values (−20‰, compared to a background value of −2‰), due to the dissolution of the injected CO2 (ı13C = −26.6‰). The high DIC pore waters have enhanced concentrations of metals (including Ca, Fe, Mn) and dissolved silicon, relative to non-DIC enriched pore waters, indicating that dissolution of injected CO2 promotes dissolution of carbonate and silicate minerals. However, in this experiment, the pore water metal concentrations did not exceed levels considered to be harmful to the environment. The spatial extent of the impact of the injected CO2 in the sediments and pore waters was restricted to an area within 25 m of the injection point, and no impact was observed in the overlying water column. Concentrations of all pore water constituents returned to background values within 18 days after the CO2 injection was stopped
Schlagworte: carbon , geol , ocea , clim , gashead

Stable isotope characterization of the Vermigliana catchment
Journal of Hydrology (2014)
Gabriele Chiogna, Emilio Santoni, Federica Camin, Agostino Tonon, Bruno Majone, Alberto Trenti, Alberto Bellin

Characterizing the hydrological behavior of streams in small Alpine catchments spanning a wide range of elevations is a difficult task, often hampered by the intrinsic variability of streamwater sources. Stable isotope ratios of oxygen and hydrogen have been sampled monthly in order to determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy. This study aims at separating contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. The isotopic signature of precipitation has been collected at two locations at different altitudes (1176. m a.s.l. and 2731. m a.s.l.), while stream water was sampled at 11 locations, 8 along the main course of the Vermigliana creek and 3 along the two tributaries of the Vermigliana creek: the Presanella and Presena creeks. Groundwater was sampled monthly in a single location, whilst the waters of two small lakes, Capanna Presena and Cantiere, both located in the proximity of the Presena glacier, were sampled during summer, when the sites were accessible. Isotope analysis evidenced that Presena and Presanella creeks are the main contributors to the Vermigliana creek. The contribution of the Presanella creek is 44% of the total flow at the confluence with the Vermigliana, while the contribution of the Presena creek rises to 75% of the total flow immediately after the confluence. The mean residence times computed for the Vermigliana and the tributaries vary between 7 and 5. months, respectively. This work allows us to investigate the main components in the hydrological cycle of the Vermigliana catchment and constitutes the basis for future modeling and climate change impact studies on this important Alpine catchment. The methodology can be exported to other sites with the aim to provide additional data, with respect to streamflow at the catchment outlet, to reduce epistemic uncertainty of hydrological models. ?? 2013 Elsevier B.V.
Schlagworte: hydrogen , oxygen , ocea , gashead

Source characterization of sedimentary organic matter using molecular and stable carbon isotopic composition of n-alkanes and fatty acids in sediment core from Lake Dianchi, China.
The Science of the total environment (2014)
Jidun Fang, Fengchang Wu, Yongqiang Xiong, Fasheng Li, Xiaoming Du, Da An, Lifang Wang

The distribution and compound-specific carbon isotope ratios of n-alkanes and fatty acids in a sediment core (63 cm) collected from Lake Dianchi were examined to investigate organic matter sources in the eutrophic lake. Fatty acids included free and bound fatty acids. The carbon isotope compositions of individual n-alkanes and fatty acids from Lake Dianchi sediments were determined using gas chromatography/isotope ratio mass spectrometry (GC-IRMS). The δ(13)C values of individual n-alkanes (C16-C31) varied between -24.1‰ and -35.6‰, suggesting a dominance of (13)C-depleted n-alkanes that originated from C3 plants and lacustrine algae. Fatty acids from the sediment extracts were analyzed for their abundances and carbon isotopic compositions. Molecular and isotopic evidence indicates that most of the short-chain fatty acids from Lake Dianchi sediment extracts are sourced from intense microbial recycling and resynthesis of organic matter. Long-chain free fatty acids are mainly derived from terrestrial sources. However, long-chain bound fatty acids are sourced from a combination of terrestrial organic matter, bacteria and algae, with the contribution from algal sources higher in the hypereutrophic stage.
Schlagworte: carbon , geol , ocea , gaschrom