GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Document type
Keywords
Publisher
Language
Years
  • 1
    Online Resource
    Online Resource
    Environment-Climate-Human interactions in Southern Morocco during the past 2000 years; inferences from high-resolution marine records : Schlussbericht nach Nr. 3.2 BNBest-BMBF 98 : ECHo 2016-2019 : ECHo PMARS III 2015/100 (2019)
    [Bremen] : [Universität Bremen]
    Details Availability
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (21 Seiten, 8,86 MB) , Diagramme, Illustrationen
    URL: https://doi.org/10.2314/KXP:1767693389
    DOI: 10.2314/KXP:1767693389
    Language: German
    Note: Förderkennzeichen BMBF 01DH16030 , Verfasser dem Berichtsblatt entnommen , Laufzeit des Vorhabens: 01.12.2016 - 30.11.2019; Berichtszeitraum: 01.12.2016 - 30.11.2019 , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 2
    Electronic Resource
    Electronic Resource
    Experimentelle Untersuchungen zur Barytübersättigung einer Thermalsole (1997)
    Springer
    Grundwasser 2 (1997), S. 111-117 
    Details
    ISSN: 1432-1165
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Description / Table of Contents: Abstract On the basis of thermodynamical modelling it was proves that pressure and temperature variations may induce precipitation of barite, anhydrite/gypsum and celestite in geothermyl power plants. The precipitation dynamics of earth-alkaline sulfates has been investigated in a column experiment simulating in-situ conditions for pressure, temperature, and salinity (216 g/l). In this paper we describe the experimental setup for simulating pressures up to 250 bar and high temperatures in a sandstone core. Additional precipitation experiments confirmed the expected second-orer reaction for the precipitation of barite at a medium rate of 2.5 · 10 −4 l · mg −1 · h −1 . The experiments show that the solubility of barite (2.5 mg/l Ba and 450 mg/ISO 4 ) is higher than the model forecast. Precipitation of celestite and anhydrite/gypsum was not observed. During the column experiments with a sandstone core under in-situ conditions no precipitation of barite, anhydrite/gypsum and celestite took place.
    Notes: Kurzfassung Wie geochemisch-thermodynamische Modellierungen gezeigt haben, können während des Betriebs einer geothermischen Heizanlage durch Druck- und Temperaturveränderungen Baryt, Anhydrit/Gips oder Cölestin ausfallen. Das Fällungsverhalten der Erdalkalisulfate wurde unter In-situ-Bedingungen (Druck, Temperatur, Salinität 216 g/l) in einem Durchströmungsversuch bestimmt. Es wird eine Durchströmungsanlage vorgestellt, die Drucke bis zu 250 bar und hohe Temperaturen bei der Durchströmung eines Sandsteinkerns zuläßt. Ergänzende Fällungsexperimente bestätigen eine zu erwartende Reaktion zweiter Ordnung bei der Kristallisation von Baryt mit einer mittleren Geschwindigkeitskonstanten von 2,5 · 10 −4 l · mg −1 · h −1 . Die real lösliche Menge Baryt (2,5 mg/l Ba und 450 mg/ISO 4 ) ist höher als das thermodynamische Gleichgewicht vorhersagt. Cölestin und Anhydrit oder Gipsausfällungen konnten nicht nachgewiesen werden. Bei der Durchströmung des Sandsteinkerns unter In-situ-Bedingungen findet keine Ausfällung von Baryt, Anhydrit/Gips oder Cölestin statt. Obwohl Kristallisationskeime im Sandstein vorhanden sind, erfolgt keine Fällung aus den metastabilen Lösungen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s767-1997-8532-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    facet.materialart.
    Unknown
    The influence of basaltic islands on the oceanic REE distribution: A case study from the tropical South Pacific (2018)
    Frontiers
    In:  Frontiers in Marine Science, 5 . Art.No.50.
    Details
    Publication Date: 2021-03-19
    Description: The Rare Earth Elements (REEs) have been widely used to investigate marine biogeochemical processes as well as the sources and mixing of water masses. However, there are still important uncertainties about the global aqueous REE cycle with respect to the contributions of highly reactive basaltic minerals originating from volcanic islands and the role of Submarine Groundwater Discharge (SGD). Here we present dissolved REE concentrations obtained from waters at the island-ocean interface (including SGD, river, lagoon and coastal waters) from the island of Tahiti and from three detailed open ocean profiles on the Manihiki Plateau (including neodymium (Nd) isotope compositions), which are located in ocean currents downstream of Tahiti. Tahitian fresh waters have highly variable REE concentrations that likely result from variable water–rock interaction and removal by secondary minerals. In contrast to studies on other islands, the SGD samples do not exhibit elevated REE concentrations but have distinctive REE distributions and Y/Ho ratios. The basaltic Tahitian rocks impart a REE pattern to the waters characterized by a middle REE enrichment, with a peak at europium similar to groundwaters and coastal waters of other volcanic islands in the Pacific. However, the basaltic island REE characteristics (with the exception of elevated Y/Ho ratios) are lost during transport to the Manihiki Plateau within surface waters that also exhibit highly radiogenic Nd isotope signatures. Our new data demonstrate that REE concentrations are enriched in Tahitian coastal water, but without multidimensional sampling, basaltic island Nd flux estimates range over orders of magnitude from relatively small to globally significant. Antarctic Intermediate Water (AAIW) loses its characteristic Nd isotopic signature (-6 to-9) around the Manihiki Plateau as a consequence of mixing with South Equatorial Pacific Intermediate Water (SEqPIW), which shows more positive values (-1 to -2). However, an additional Nd input/exchange along the pathway of AAIW, eventually originating from the volcanic Society, Tuamotu and Tubuai Islands (including Tahiti), is indicated by an offset from the mixing array of AAIW and SEqPIW to more radiogenic Nd isotope compositions.
    Type: Article , PeerReviewed
    Format: text
    Format: image
    DOI: 10.3389/fmars.2018.00050
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1 (2012)
    Nature Publishing Group
    In:  Nature Communications, 3 (965).
    Details
    Publication Date: 2017-02-23
    Description: The early last glacial termination was characterized by intense North Atlantic cooling and weak overturning circulation. This interval between ~18,000 and 14,600 years ago, known as Heinrich Stadial 1, was accompanied by a disruption of global climate and has been suggested as a key factor for the termination. However, the response of interannual climate variability in the tropical Pacific (El Niño-Southern Oscillation) to Heinrich Stadial 1 is poorly understood. Here we use Sr/Ca in a fossil Tahiti coral to reconstruct tropical South Pacific sea surface temperature around 15,000 years ago at monthly resolution. Unlike today, interannual South Pacific sea surface temperature variability at typical El Niño-Southern Oscillation periods was pronounced at Tahiti. Our results indicate that the El Niño-Southern Oscillation was active during Heinrich Stadial 1, consistent with climate model simulations of enhanced El Niño-Southern Oscillation variability at that time. Furthermore, a greater El Niño-Southern Oscillation influence in the South Pacific during Heinrich Stadial 1 is suggested, resulting from a southward expansion or shift of El Niño-Southern Oscillation sea surface temperature anomalies.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1038/ncomms1973
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    facet.materialart.
    Unknown
    Mg/Ca ratios of single planktonic foraminifer shells and the potential to reconstruct the thermal seasonality of the water column (2011)
    AGU (American Geophysical Union)
    In:  Paleoceanography, 26 (3). PA3218.
    Details
    Publication Date: 2019-09-23
    Description: Mg/Ca ratios of surface and subsurface dwelling foraminifera provide valuable information about the past temperature of the water column. Planktonic foraminifera calcify over a period of weeks to months. Therefore, the range of Mg/Ca temperatures obtained from single specimens potentially records seasonal temperature changes. We present solution-derived Mg/Ca ratios for single specimens of the planktonic foraminifera species Globigerinoides ruber (pink), Globigerinoides ruber (white), and Globorotalia inflata from a sediment trap off northwest Africa (20°45.6′N, 18°41.9′W). Cleaning of single specimens was achieved using a flow-through system in order to prevent sample loss. Mg/Ca ratios of surface dwelling G. ruber (pink) show strong seasonality linked to sea surface temperature. Mg/Ca ratios of G. ruber (white) do not show such seasonality. Subsurface dwelling G. inflata flux is largest during the main upwelling season, but Mg/Ca ratios reflect annual temperatures at intermediate water depths. The sediment trap time series suggests that changes in the range of Mg/Ca ratios exhibited by single specimens of G. ruber (pink) and G. inflata from the sedimentary record should provide information on the past temperature range under which these species calcified. Statistical analysis suggests detectable changes in the Mg/Ca range are ≥0.80 mmol/mol (G. ruber (pink)) and ≥0.34 mmol/mol (G. inflata). For G. ruber (pink), such changes would indicate changes in the seasonal sea surface temperature range 〉4°C or a shift in the main calcification and reproductive period. For G. inflata, such changes would indicate 〉1.7°C changes in the thermocline temperature or a change in the depth habitat.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2010PA002091
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
    facet.materialart.
    Unknown
    Mid- to late Holocene changes in tropical Atlantic temperature seasonality and interannual to multidecadal variability documented in southern Caribbean corals (2012)
    Elsevier
    In:  Earth and Planetary Science Letters, 331-332 . pp. 187-200.
    Details
    Publication Date: 2019-05-10
    Description: Proxy reconstructions of tropical Atlantic sea surface temperature (SST) that extend beyond the period of instrumental observations have primarily focused on centennial to millennial variability rather than on seasonal to multidecadal variability. Here we present monthly-resolved records of Sr/Ca (a proxy of SST) from fossil annually-banded Diploria strigosa corals from Bonaire (southern Caribbean Sea). The individual corals provide time-windows of up to 68 years length, and the total number of 295 years of record allows for assessing the natural range of seasonal to multidecadal SST variability in the western tropical Atlantic during snapshots of the mid- to late Holocene. Comparable to modern climate, the coral Sr/Ca records reveal that mid- to late Holocene SST was characterised by clear seasonal cycles, persistent quasi-biennial and prominent interannual as well as inter- to multidecadal-scale variability. However, the magnitude of SST variations on these timescales has varied over the last 6.2 ka. The coral records show increased seasonality during the mid-Holocene consistent with climate model simulations indicating that southern Caribbean SST seasonality is induced by insolation changes on orbital timescales, whereas internal dynamics of the climate system play an important role on shorter timescales. Interannual SST variability is linked to ocean–atmosphere interactions of Atlantic and Pacific origin. Pronounced interannual variability in the western tropical Atlantic is indicated by a 2.35 ka coral, possibly related to a strengthening of the variability of the El Niño/Southern Oscillation throughout the Holocene. Prominent inter- to multidecadal SST variability is evident in the coral records and slightly more pronounced in the mid-Holocene. We finally argue that our coral data provide a target for studying Holocene climate variability on seasonal and interannual to multidecadal timescales, when using further numerical models and high-resolution proxy data.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2012.03.019
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
    facet.materialart.
    Unknown
    An inter-laboratory study of coral Sr/Ca and other element/Ca ratios (2010)
    In:  [Poster] In: 10th International Conference on Paleoceanography, ICP 10, 29.08.-03.09.2010, San Diego, LaJolla, California, USA .
    Details
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Poster
  • 8
    facet.materialart.
    Unknown
    Using a Flow Through device to reconstruct the thermal gradient in the water column based on G. inflata Mg/Ca (2010)
    Copernicus
    In:  [Poster] In: EGU General Assembly 2010, 02.05.-07.05.2010, Vienna, Austria . Geophysical Research Abstracts ; /EGU2010-12153 .
    Details
    Publication Date: 2012-07-06
    Description: We present Mg/Ca analyses performed via a Flow Through sequential dissolution device connected to an ICP-OES on the planktonic foraminifer Globorotalia inflata. The aim of the study is to explore the possibility to reconstruct the thermal gradient in the water column by separating non-crusted and crusted calcite phases in the tests of G. inflata using the difference between their Mg/Ca ratios as a measure of the thermal gradient. An important assumption is that the non-crusted part of the tests is calcified in shallow, warmer water than the crusted part. For analyses a range of different preparation steps were used to determine the ideal way of separating the phases. Foraminifer tests were (not) cleaned, (not) crushed, and (not) pulverized before online analysis with the FT device. To analyze samples with a FT device the foraminifer tests are placed on a filter with a mesh of 0.45 μm preventing clay minerals to wash through. A sequential dissolution protocol first rinses the samples with buffered Seralpur water before QD HNO3 is added in small steps to create a ramp of increasing acid strength. As acid is kept constant at each concentration for several minutes, dissolution of a specific calcite phase can take place. Initial results show that it is most effective to slightly crush the tests without applying standard cleaning procedures, but rather analyze them without cleaning. Samples were selected from the South Atlantic (core tops and specific downcore samples) and the Mediteterranean (plankton tows). All samples were chosen based on previous work on them to provide comparison with routinely analysed Mg/Ca ratios. The South Atlantic samples have been analyzed extensively as bulk samples separated in difference size fractions and crusted vs. non-crusted (Groeneveld and Chiessi). The Mediterranean samples were not only analyzed as bulk samples but also by Laser Ablation ICP-MS (von Raden et al.). Results show that bulk analyses are reliably reproduced by the FT method, especially for samples which are dominated by crusted calcite. Samples which were uncrusted often gave much higher Mg/Ca ratios than the bulk analyses. These higher Mg/Ca ratios mainly occur in the plankton tow samples and were also identified with Laser Ablation ICP-MS. A possible reason for this could be the presence of a high Mg amorphous calcite layer on the outside of foraminifer tests which have not completed their calcification yet as was recently also pointed out in several other studies. Identification of the crusted and uncrusted phases, and therewith a thermal gradient, seems to give the expected differences but a more rigorous statistical treatment is needed to pinpoint singular dissolution phases.
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Poster
  • 9
    facet.materialart.
    Unknown
    Links between Ikaite Morphology, Recrystallised Ikaite Petrography and Glendonite Pseudomorphs Determined from Polar and Deep-Sea Ikaite (2023)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Petrography of recrystallised ikaite from Ocean Drilling Program material has been presented previously from Nankai Trough and Congo (ex-Zaire) deep-sea fan. This paper expands on the Nankai Trough ikaite observations, drawing on evidence from Laptev Sea, South Georgia, Okhotsk Sea, and coastal lagoon Point Barrow. However, even though many ikaite and glendonite sites occur at high latitudes, it cannot be that ikaite forms exclusively in polar environments, as demonstrated by the occurrences in the low latitude low temperature deep sea sediments offshore Gulf of Guinea (Angola Congo) and mid-latitude deep-sea trenches offshore Japan. Recrystallised ikaite occurs as mm large, zoned calcite crystals in all samples, along with secondary phases of calcite. Our data set is unique in that the origin, storage, and recrystallisation process of natural formed ikaite is recorded in detail and confirms that glendonite petrographic characteristics are a consequence of the structure and chemistry of recrystallising ikaite and not the physical or geochemical environment. The transformation of man-made ikaite to calcite as recorded in laboratory studies, is a process very similar to the one we have observed for natural ikaite. Most significant is that there is variation in the order of the calcite types within a single sample, leading to the conclusion that the variation is a consequence of impurities and geochemical variability in the ikaite, not the external environment. Morphological observations reveal similarities in ikaite and glendonite, this and the similarity in internal textures in glendonite and recrystallised ikaite confirms that glendonite may be used as an indicator of past presence of ikaite.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
    facet.materialart.
    Unknown
    Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements (2013)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-03-22
    Description: The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twentyone laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp- 1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence level, equates to 1.5°C for SST estimates using Porites, so is approaching fitness for purpose. The comparable median within laboratory error is 〈0.5°C. This difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the JCp-1. There are many potential sources contributing to biases in comparative methods but traces of Sr in Ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty. Consensus values that fulfil the requirements to be certified values were also obtained for Mg/Ca in JCp-1 and for Sr/Ca and Mg/Ca ratios in the JCt-1 giant clam reference material. Reference values with variable fitness for purpose have also been obtained for Li/Ca, B/Ca, Ba/Ca, and U/Ca in both reference materials. In future, studies reporting coral element/Ca data should also report the average value obtained for a reference material such as the JCp-1.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...