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  • 1
    Keywords: Forschungsbericht ; Carbon dioxide capture and utilization
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (172 Seiten, 12,47 MB) , Illustrationen, Diagramme
    Series Statement: Forschungsbericht / Forschungsgemeinschaft Kalk und Mörtel Nr. 2018, 1
    Language: German , English
    Note: Literaturverzeichnis: Seite 121-125 , Förderkennzeichen AiF-Nr. 18560 N , Ausdruck der Online-Ressource. - Erzeugt aus: http://www.fg-kalk-moertel.de/forschungsberichte.html , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
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  • 2
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: Online-Ressource (8 p. = 854 KB) , graphs, map
    Language: German
    Note: Contract BMBF 03G0147B. - Joint project no. 01017724 , Differences between the printed and electronic version of the document are possible , Also available as printed version , Systemvoraussetzungen: Acrobat reader.
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  • 3
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: Online-Ressource (PDF-Datei: 64 S., 4.243 KB) , Ill., graph. Darst., Kt.
    Language: German
    Note: Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden , Förderkennzeichen BMBF 03F0617 A-C. - Verbund-Nr. 01075925 , Systemvoraussetzungen: Acrobat reader. , Berichte teilw. engl., teilw. dt.
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  • 4
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Description / Table of Contents: Abstract. The chemical composition of lithogenic components in Pliocene sediments from the eastern Mediterranean displays periodic variations that are related to earth's orbital parameters owing to changes in insolation of the northern hemisphere. This can be explained by two different paleoclimatic/palaeoceanographic scenarios. During oligotrophic periods, similar to those persisting in the modern Mediterranean, sedimentation is rather uniform, and sediments receive high proportions of eolian material from the surrounding deserts. During more humid intervals sedimentation is dominated by fluviatile material that has been introduced by the Nile and northern borderland rivers. Higher nutrient loads associated with enhanced riverine input and a change in water circulation led to eutrophication, water column anoxia, and sapropel deposition in the eastern Mediterranean. Our investigations confirm earlier works claiming that in large parts of the northern Sahara palaeoclimatic conditions changed frequently from arid to more humid. Our results suggest that these changes in the Pliocene match with the approximately 22-ka insolation cyclicity.
    Notes: Zusammenfassung Der Chemismus lithogener Komponenten pliozäner Sedimente des östlichen Mittelmeers weist periodische Änderungen auf, die mit den Orbitalparametern der Erde und dadurch hervorgerufenen Variationen der Sonneneinstrahlung im Bereich der Nordhemisphäre einhergehen. Dadurch entstehen zwei gegensätzliche paläoklimatische bzw. paläozeanographische Szenarien. In Zeiten mit geringen Niederschlägen und oligotrophen Bedingungen im Mittelmeer, wie sie auch heute vorherrschen, ist die Sedimentation sehr stark von äolischen Staubeinträgen angrenzender Wüstengebiete gekennzeichnet. Demgegenüber dominiert in feuchten Klimaperioden die Sedimentation von fluviatilem Material, das durch den Nil und Flüsse der nördlich an das Mittelmeer grenzenden Gebiete eingetragen wird. Die durch Zirkulationsänderungen sowie den Nährstoffeintrag der Flüsse induzierten eutrophen Bedingungen führten schließlich zur Ausbildung von Wassersäulen-Anoxia und der Ablagerung von Sapropelen im östlichen Mittelmeer. Unsere Untersuchungen unterstützen frühere Forschungsergebnisse, wonach in weiten Teilen der nördlichen Sahara ein häufigerer Wechsel zwischen ariden und humideren Klimabedingungen stattfand. Nach unseren Ergebnissen folgte dieser rhythmische Wechsel im Pliozän dem Insolationszyklus von ca. 22 ka.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 286 (1977), S. 361-366 
    ISSN: 1618-2650
    Keywords: Best. von Schwefel in Geolog. Material, Biolog. Material ; Coulometrische Titration ; Verbrennung im O2-Strom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A simple and rapid procedure for the determination of sulphur in geological and biological samples by combustion in an oxygen current followed by coulometric titration of the sulphur dioxide produced is described. Samples analysed include rocks, soils, sediments, ores, minerals and plants. 8-Hydroxyquinoline is used to remove interfering halogens from the combustion products. 100 mg of sample are mixed with 500 mg of V2O5 (oxidant) and 500 mg of Fe (flux) and ignited for 4–15 min in a resistance-type furnace at 1400° C. The method is applicable to sulphur contents in samples of 10 ppm to X0 wt.-% S with standard deviations ranging from 0.001–0.2% S. For testing accuracy 21 standard reference samples were analysed. Results obtained compare favourably with recent publications.
    Notes: Zusammenfassung Es wird eine einfache und schnelle Methode der Schwefelbestimmung in geologischen und biologischen Proben durch Verbrennung im Sauerstoffstrom und anschließende coulometrische Titration des freigesetzten SO2 beschrieben. Es wurden Gesteine, Böden, Sedimente, Erze, Minerale und Pflanzen analysiert. 100 mg der Probe werden mit 500 mg V2O5 (Oxidationsmittel) und 500 mg Fe (Fluß-mittel) in 4–15 min in einem Widerstandsofen bei 1400° C verbrannt. Zur Entfernung von Halogenwasserstoffen aus dem Reaktionsgas wird eine 8-Hydroxychinolin-Falle verwendet. Die Methode ist auf Proben mit Schwefelgehalten von 10 ppm bis X0 Gew.-% anwendbar. Die Standardabweichung liegt im Bereich von 0.001–0.2% S. Es wurden 21 Standardproben analysiert, um die Genauigkeit des Verfahrens zu überprüfen. Die Ergebnisse zeigen eine befriedigende Übereinstimmung mit neueren Literaturdaten.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2022-09-23
    Description: Trace metals (Mn, Fe, Mo, U, Cr, V) were studied in pore waters of an intertidal flat located in the German Wadden Sea. The study system is an example of a permeable tidal flat system where pore water exchange is affected by tidal driven pressure gradients besides diffusion. Permanently installed in situ samplers were used to extract pore waters down to 5 m depth throughout one year. The samplers were either located close to the tidal flat margin or in central parts of the tidal flat. Despite dynamic sedimentological and hydrological conditions, the general trends with depth in deep tidal flat pore waters are remarkably similar to those observed in deep sea environments. Rates of trace metal cycling must be comparably large in order to maintain the observed pore water profiles. Trace metals further show similar general trends with depth close to the margin and in central parts of the tidal flat. Seasonal sampling revealed that V and Cr vary concurrent with seasonal changes in dissolved organic carbon (DOC) concentration. This effect is most notable close to the tidal flat margin where sulphate, DOC, and nutrients vary with season down to some metres depth. Seasonal variations of Mn, Fe, Mo, and U are by contrast limited to the upper decimetres of the sediment. Their seasonal patterns depend on organic matter supply, redox stratification, and particulate matter deposited on sediment surfaces. Pore water sampling within one tidal cycle provides evidence for pore water advection in margin sediments. During low tide pore water flow towards the creekbank is generated by a hydraulic gradient suggesting that deep pore waters may be seeping out of creekbank sediments. Owing to the enrichment of specific elements like Mn in pore water compared to sea water, seeping pore waters may have an impact on the chemistry of the open water column. Mass balance calculations reveal that the impact of deep pore waters on the Mn budget in the open water column is below 4%. Mn deep pore water discharge of the whole Wadden Sea is estimated to be about 9% of the total dissolved riverine Mn input into the Southern North Sea.
    Type: Article , PeerReviewed
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  • 7
    Publication Date: 2021-02-08
    Description: The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 22 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017.
    Type: Article , PeerReviewed
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  • 8
    Publication Date: 2021-05-25
    Description: Recent rapid retreat of glacial front lines and the loss of land ice along the Antarctic margins may play an important role in exporting suspended particulate matter (SPM) potentially rich in bioavailable (defined as ascorbate leachable) iron (FeA) to coastal areas of the Southern Ocean. Sediment ablation is an additional source of iron for this high-nutrient low-chlorophyll region. In Potter Cove, King George Island, meltwater streams discharge up to 18 000 mg l-1 (average 283 mg l-1) of slightly weathered, finely ground bedrock particles into coastal waters during the summer. Approximately 15% of this SPM is exported within a low-salinity surface plume into Bransfield Strait. Based on our data, an estimated 12 mg m-2 yr-1 of FeA is exported from the South Shetland Island land surface (ice-free and subglacial areas) to the surrounding coastal waters. Extrapolated to an area of 2.5x104 km2, this FeA input is comparable to the contribution from icebergs and c. 240-fold higher than aeolian input via dust. An observed rise in local sediment accumulation rates suggests that glacial erosion has been increasing over recent decades and that (sub-)glacially derived SPM is becoming more important as a source of iron to the Southern Ocean.
    Type: Article , PeerReviewed
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  • 9
    Publication Date: 2017-07-14
    Description: Redox-sensitive trace metals (Mn, Fe, U, Mo, Re), nutrients and terminal metabolic products (NO3-, NH4+, PO43-, total alkalinity) were investigated for the first time in pore waters of Antarctic coastal sediments. The results of this study reveal a high spatial variability in redox conditions in surface sediments from Potter Cove, King George Island, western Antarctic Peninsula. Particularly in the shallower areas of the bay the significant correlation between sulphate depletion and total alkalinity, the inorganic product of terminal metabolism, indicates sulphate reduction to be the major pathway of organic matter mineralisation. In contrast, dissimilatory metal oxide reduction seems to be prevailing in the newly ice-free areas and the deeper troughs, where concentrations of dissolved iron of up to 700 μM were found. We suggest a combination of several factors to be responsible for the domination of metal oxide reduction over sulphate reduction in these areas. These include the increased accumulation of fine-grained material with high amounts of reducible metal oxides, a reduced availability of metabolisable organic matter and an enhanced physical and biological disturbance by bottom water currents, ice scouring and burrowing organisms. Based on modelled iron fluxes we calculate the contribution of the Antarctic shelf to the pool of potentially bioavailable iron (Feb) to be 6.9 × 103 to 790 × 103 t yr-1. Consequently, these shelf sediments would provide an Feb flux of 0.35-39.5 mg m-2 yr-1 (median: 3.8 mg m-2 yr-1) to the Southern Ocean. This contribution is in the same order of magnitude as the flux provided by icebergs and significantly higher than the input by aeolian dust. For this reason suboxic shelf sediments form a key source of iron for the high nutrient-low chlorophyll (HNLC) areas of the Southern Ocean. This source may become even more important in the future due to rising temperatures at the WAP accompanied by enhanced glacier retreat and the accumulation of melt water derived iron-rich material on the shelf.
    Type: Article , PeerReviewed
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  • 10
    Publication Date: 2023-06-29
    Description: Dissolved silicon isotope compositions (δ30Si) have been analysed for the first time in groundwaters of beach sediments, which represent a subterranean estuary with fresh groundwater discharge from a freshwater reservoir and mixing with recirculated seawater. The fresh groundwater reservoir has high and variable dissolved silica concentrations between 136 and 736 μM, but homogeneous δ30Si of +1.0 ± 0.15‰. By contrast, the seawater is strongly depleted in dissolved silica with concentrations of 3 μM, and consequently characterised by high δ30Si of +3.0‰. The beach groundwaters are variably enriched in dissolved silica compared to seawater (23–192 μM), and concentrations increase with depth at all sampling sites. The corresponding δ30Si values are highly variable (+0.3‰ to +2.2‰) and decrease with depth at each site. All groundwater δ30Si values are lower than seawater and most values are lower than dissolved δ30Si of freshwater discharge indicating a significant amount of lithogenic silica dissolution in beach sediments. In contrast to open North Sea sediments, diatom dissolution or formation of authigenic silica in beach sediments is very low (ca. 5 μmol Si g−1). Silica discharge from the beach to the coastal ocean is estimated as approximately 210 mol Si yr−1 per meter shoreline. Considering the extent of coastline this is, at least for the study area, a significant amount of the total Si budget and amounts to ca. 1% of river and 3.5% of backbarrier tidal flat area Si input.
    Type: Article , PeerReviewed
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