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  • Digitale Medien  (2)
  • 1995-1999  (1)
  • 1985-1989  (1)
Materialart
  • Digitale Medien  (2)
Erscheinungszeitraum
Jahr
  • 1
    ISSN: 1420-9071
    Schlagwort(e): Bivalve ; shell ; microlamination ; depth profiling ; secondary ion mass spectrometry (SIMS) ; archival biomonitor ; water chemistry ; manganese
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Specimens of the freshwater unionid bivalveHyridella depressa were experimentally exposed to a synthetic river water containing an elevated Mn water concentration (20 mg l−1) for 2 or 6 days. SIMS depth profiles through the incremental nacre microlaminations or tablets (∼0.6 μm breadth) of the shells of these bivalves showed increases in the signal intensity of Ca-normalised Mn that corresponded to the period of exposure. These results support the proposition that bivalve shells can be used as retrospective monitors of water chemistry. They also indicate that 1) there is a lag phase between exposure to the elevated Mn water concentration and its expression in the shell, and 2) the period for Mn in the shell to reach equilibrium with the aquatic medium is greater that 2 to 6 days.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1588-2780
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Energietechnik
    Notizen: Abstract The methodology of the detection of (n, α) nuclear reactions by means of cellulose nitrate detectors is discussed with special reference to the reliability of the quantitative estimates. The discrimination of10B and6Li from the other isotopes is possible by using thin coloured detectors. The ratio of the number of tracks found at the level of a10B or5Li-enriched calibrating sample, and the number expected from theoretical calculation, i.e. the detection efficiency, P is generally below 1. P is fairly sensitive to the experimental conditions, and for precise quantitative measurements it must be determined separately for each different experiment. The gelatin, used for solidification of liquid samples is boron contaminated (almost 1 μmol natural B per g). It has been observed, especially with10B-enriched liquid samples, that part of the stable tracer under study is lost during sample preparation.6Li extra tracks appear at the rear face of “thick”, non-plastic-supported detectors. Boron diffuses in the cellulose-nitrate detectors with the diffusion coefficient of the order of 10−8 cm2·s−1. Therefore it requires rapid operations for microlocation of boron with high resolving power.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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