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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The stable carbon and oxygen isotopic compositions of the massive coralPorites lobata collected from the Gulf of Eilat, Red Sea, in May 1987 were measured along the vertical growth axis. The isotopic compositions show annual periodicity. The variations along the isotopic profile, compared with the X-radiography, indicate that the high-density bands are enriched in18O and deposited during the season of lowest water temperature (winter). In contrast, the low-density bands are depleted in18O and deposited during the warmest seawater temperatures (summer). The stable carbon and the oxygen isotopic ratios are negatively correlated with a shift in phase. During the season of higher water temperatures and light intensity values (summer), the skeleton is depleted in18O and enriched in13C and vice versa for the winter time. The shift between the carbon and the oxygen isotopic curves reflects the shift between the seasonal light intensities and seasonal temperature variations in the shallow water. The oxygen isotope ratio was used to detect the seasonal variations in seawater temperatures. The coral aragonitic skeleton is depleted in18O compared to apparent equilibrium with ambient seawater. The disequilibria range from (ca.) -3.10‰ to -3.50‰ with an average value of 3.40‰. The isotope fractionation behavior during skeleton precipitation is discussed in light of the environmental variables.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 85 (1996), S. 278-292 
    ISSN: 1437-3262
    Keywords: Silurian Gotland ; stable isotopes ; brachiopods ; carbonate facies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Silurian of Gotland, Sweden, consists of 440 m of carbonate deposits. Repeatedly, uniform sequences of micritic limestones and marls are interrupted by complex-structured reefs and by adjacent platform sediments. Generally, the alteration of facies is interpreted as the result of sea-level fluctuations caused by a gradual regression with superimposed minor transgressive pulses. The purpose of this study is a facies interpretation based on both field observations and stable isotope measurements of brachiopod shells. Approximately 700 samples from stratigraphically arranged localities in different facies areas have been investigated. The carbon and oxygen isotopes show principally parallel curves and a close relationship to the stratigraphic sequence. Lower values occur in periods dominated by deposition of marly sequences. Higher values are observed in periods dominated by reefs and extended carbonate platforms. The oxygen isotope ratios are interpreted to reflect paleosalinity changes due to varying freshwater input, rather than to paleotemperature. Carbon isotope ratios are believed to have been connected to global changes in the burial of organic carbon in black shales during periods of euxinic deep water conditions. Consequently, the facies succession on Gotland results from global paleoclimatic conditions. Changes in terrigenous input due to different rates of weathering and freshwater runoff, rather than sea-level fluctuations, control the carbonate formation of the Silurian on Gotland.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Infection 4 (1976), S. S215 
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The concentrations of cephacetrile and cephalothin were evaluated in serum and heart muscle tissue of 18 and 8 patients respectively after intravenous application of 100 mg/kg of each substance. The mean levels were 51 µg/ml in the serum and 1.4 µg/g in heart muscle tissue in the case of cephalothin 60 minutes after application. Cephacetrile reached levels of 73 µg/ml and 11,2 µg/g in serum and tissue respectively after the same time.
    Notes: Zusammenfassung Bei 18 bzw. 8 Patienten, die je 100 mg/kg Cephacetril bzw. Cephalothin i. v. erhalten hatten, wurde die Konzentration der Substanzen im Serum und im Herzmuskelgewebe bestimmt. Die entsprechenden Werte lagen für Cephalothin im Serum durchschnittlich bei 51 µg/ml und im Herzmuskelgewebe bei 1,4 µg/g jeweils 60 Minuten nach Applikation. Cephacetril erreichte im Serum 73 µg/ml und im Gewebe 11,2 µg/g ebenfalls nach durchschnittlich 60 Minuten.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Infection 5 (1977), S. 228-231 
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The pharmacokinetics of cefazolin were studied in 25 males and females after administration of 4 g infused over 60 minutes. The mean microbiologically active concentration of cefazolin in serum five minutes after discontinuing the infusion was 410 µg/ml, after 60 minutes 190 µg/ml and after 8 hours 8.5 µg/ml. After 8 hours 84% of the drug was eliminated in the urine of four of the volunteers. The mean serum half-life was 87.38 minutes in the one compartment model, and the volume of distribution 9.20 1. The area under the curve was 44626.15 µg · min · ml−1. The mean value for the clearance was 73.5 ml/min. The importance of high dosages of cefazolin in severe infections caused by cefazolin-sensitive organisms is discussed. Side-effects were not observed.
    Notes: Zusammenfassung An 25 freiwilligen Versuchspersonen beiderlei Geschlechts wurde das pharmakokinetische Verhalten von Cefazolin bei einer Dosierung von 4 g i.v. als Kurzinfusion über 60 Minuten untersucht. Die biologisch aktiven Serumkonzentrationen betrugen 5 Minuten nach Beendigung der Infusionen durchschnittlich 410 µg/ml, nach 60 Minuten 190 µg/ml und nach 8 Stunden durchschnittlich 8,5 µg/ml. Bei vier Versuchspersonen waren nach 8 Stunden rund 84% der Substanz im Harn eliminiert. Die durchschnittliche Serumhalbwertszeit beträgt nach dem Ein-Kompartimentmodell 87,38 Minuten. Das Gesamtverteilungsvolumen beträgt im Mittel 9,20 1. Die Fläche unter der Kurve beträgt 44626,15 µg · min · ml−1. Die Clearance beträgt rund 73,5 ml/min. Die Bedeutung der Hochdosistherapie mit 4 g Cefazolin i.v. für schwere durch cefazolinempfindliche Erreger verursachte Infektionen wird diskutiert. Nebenwirkungen wurden nicht beobachtet.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0016-7835
    Keywords: Key words Silurian Gotland ; stable isotopes ; brachiopods ; carbonate facies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Silurian of Gotland, Sweden, consists of 440 m of carbonate deposits. Repeatedly, uniform sequences of micritic limestones and marls are interrupted by complex-structured reefs and by adjacent platform sediments. Generally, the alteration of facies is interpreted as the result of sea-level fluctuations caused by a gradual regression with superimposed minor transgressive pulses. The purpose of this study is a facies interpretation based on both field observations and stable isotope measurements of brachiopod shells. Approximately 700 samples from stratigraphically arranged localities in different facies areas have been investigated. The carbon and oxygen isotopes show principally parallel curves and a close relationship to the stratigraphic sequence. Lower values occur in periods dominated by deposition of marly sequences. Higher values are observed in periods dominated by reefs and extended carbonate platforms. The oxygen isotope ratios are interpreted to reflect paleosalinity changes due to varying freshwater input, rather than to paleotemperature. Carbon isotope ratios are believed to have been connected to global changes in the burial of organic carbon in black shales during periods of euxinic deep water conditions. Consequently, the facies succession on Gotland results from global paleoclimatic conditions. Changes in terrigenous input due to different rates of weathering and freshwater runoff, rather than sea-level fluctuations, control the carbonate formation of the Silurian on Gotland.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 88 (2000), S. 725-732 
    ISSN: 1437-3262
    Keywords: Key words Corals ; Stable isotopes ; Australia ; Leeuwin Current ; Ningaloo Reef ; Cooling events
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  116-year record of coral skeletal δ18O is presented from a colony of Porites lutea from Ningaloo Reef, western Australia. Interannual variability of sea-surface temperatures (SST) inferred from skeletal δ18O is dominated by a 9.5-year period, and may constitute a characteristic signal of the Leeuwin Current. On long-terms coral skeletal δ18O indicates a near-continuous increase of SST at Ningaloo Reef over one century. The skeletal δ18O time series was checked for the presence of seasonal cooling events resulting from major volcanic eruptions. An ∼1  °C cooling is evident following the eruption of Pinatubo in 1991, which reproduces the results of previous investigations. However, only weak or no signals can be related to the eruptions of Krakatau (1883) and Agung (1963).
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 88 (2000), S. 742-751 
    ISSN: 1437-3262
    Keywords: Key words African monsoon ; Corals ; Holocene ; Northern Red Sea ; Stable isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract We present a study based on X-ray chronologies and the stable isotopic composition of fossil Porites spp. corals from the northern Gulf of Aqaba (Red Sea) covering the mid-Holocene period from 5750 to 4450 14C years BP (before present). The stable oxygen and carbon isotopic compositions of five specimens reveal regular annual periodicities. Compared with modern Porites spp. from the same environment, the average seasonal δ 18O amplitude of the fossil corals is higher (by ca. 0.35–0.60‰), whereas annual growth rates are lower (by ca. 3.5 to 2 mm/year). This suggests stronger seasonality of sea surface temperatures and increased variability of the oxygen isotopic composition of the sea water due to changes in the precipitation and evaporation regime during the mid-Holocene. Most likely, summer monsoon rains reached the northern end of the Red Sea at that time. Average annual coral growth rates are diminished probably due to an increased input and resuspension of terrestrial debris to the shallow marine environment during more humid conditions. Our results corroborate published reports of paleodata and model simulations suggesting a northward migration of the African monsoon giving rise to increased seasonalities during the mid-Holocene over northeastern Africa and Arabia.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 88 (2000), S. 733-741 
    ISSN: 1437-3262
    Keywords: Key words Coral ; δ18O ; Sclerochronology ; Little Ice Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The reconstruction of the climatic history during the past several hundred years requires a sufficient geographical coverage of combined climate proxy series. Especially in order to identify causal connections between the atmosphere and the ocean, inclusion of marine records into composite climate time series is of fundamental importance. We present two skeletal δ 18O chronologies of coral skeletons of Diploria labyrinthiformis from Bermuda fore-reef sites covering periods in the nineteenth and twentieth centuries and compare them with instrumental temperature data. Both time series are demonstrated to display sea-surface temperature (SST) variability on inter-annual to decadal time scales. On the basis of a specific modern δ 18O vs instrumental SST calibration we reconstruct a time series of SST anomalies between AD 1350 and 1630 covering periods during the Little Ice Age. The application of the coral δ 18O vs temperature relationship leads to estimates of past SST variability which are comparable to the magnitude of modern variations. Parallel to δ 18O chronologies we present time series of skeletal bulk density. Coral δ 18O and skeletal density reveal a strong similarity during Little Ice Age, confirming the reliability of both proxy climate indicators. The past coral records, presented in this study, share features with a previously published climate proxy record from Bermuda and a composite time series of reconstructed Northern Hemisphere summer temperatures. The coral proxy data presented here represent a valuable contribution to elucidate northern Atlantic subtropical climate variation during the past several centuries.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1157
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Detailed 14C AMS data and isotope based stratigraphies from high-resolution paleoceanographic records for the last 22 ka of cores from the upper continental slope off NE Brazil reveal sedimentation rates of up to 100 cm per 1000 yr. Variations in the sediment composition relate to changes in the input of terrigenous material. The sedimentation is controlled by sea level and by the climatic regime of the hinterland. Short-term changes in the tropical wind field may act as a climatic trigger. The zonality of the SE trades was probably increased and the monsoonal activity over Africa reduced during the Younger Dryas period.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 3 (1984), S. 87-90 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Growth rhythms in the reef coral Porites lobata are revealed by X-radiography and stable carbon and oxygen isotopic analysis. High density increments were deposited during warm temperatures in summer and low density increments during winter. The seasonal temperature variations are reflected in the oxygen isotope ratios. The coral carbonate shows a constant depletion in 18O of −2.7%0 relative to calcite in equilibrium with the ambient seawater. The mean annual growth rate of the specimen studied was 1.3±0.3 cm/year.
    Type of Medium: Electronic Resource
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