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Wyszukujesz frazę "isotope analysis" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Geochemical study of precipitates in the architectural surfaces from Bern, Switzerland
Autorzy:
Huber, Miłosz Andrzej
Hałas, Stanisław
Powiązania:
https://bibliotekanauki.pl/articles/763337.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
precipitates
sulfate
geochemistry
pollution
microscopy
isotope analysis
Opis:
This geochemical study aims to resolve genesis of precipitation spots on the walls on the Nydeggbrücke in Bern, Switzerland. The bridge is composed of Jurassic limestone and dolomites and coated on both sides with Miocene flysch sandstone. As a result of infiltration of aqueous solutions derived directly from the road embankment into the sandstone, sulfate encrustation on the walls of sandstone has been formed.The study of these precipitates using optical and electron microscopy clearly shows dominant sulfate phases are gypsum (calcium sulfate), mirabilite (sodium hydrated sulfate) and polyhalite (potassium, calcium and magnesium sulfate). Impurities of Ni, Cu, Zn and Pb was encountered by ICP-MS analysis. Identified polymetallic mineralization is associated with the infrastructure of the bridge and the accumulation of pollution from vehicular traffic. This is also confirmed by sulfur and oxygen stable isotope analyses of sulfates.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica; 2015, 70
0137-6861
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbon and oxygen isotope variability among foraminifera and ostracod carbonated shells
Autorzy:
Fourel, François
Martineau, François
Emoke Tóth, Emoke
Görög, Agnes
Escarguel, Gilles
Lécuyer, Christophe
Powiązania:
https://bibliotekanauki.pl/articles/763395.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
stable isotope
foraminifera
ostracod
heterogeneity
single shell analysis
Opis:
This study investigates the effect of biological and environmental inter-individual variability on the meaning of d18O and d13C values acquired on small carbonated shells. First we present data obtained with a MultiPrep automated carbonate system on small sample sizes of a homogeneous carbonate material: Carrara marble. This demonstrates the capacities of the analytical system to reliably run small amounts of carbonates even down to 10 mg. Then we present two data sets obtained on real fossil samples of various size (sensu number of individual organisms) calibrated against the NBS19 carbonate standard. Both datasets evidence a clear trend of between-biological sample standard deviation increase for both d18O and d13C measurements when the number of pooled specimens per sample decreases. According to the results obtained from a systematic study of a geologically homogeneous sample of coeval fossil Elphidium foraminifera, we estimate that there is 95% of chances to reach between-biological sample standard deviation values higher than 1.02‰ (d18O) and 1.45‰ d13C) based on single-cell measurements. Such values are one order of magnitude higher than the instrumental standard deviations associated with these stable isotope ratios. Conversely, a minimum of 35 (d18O) and 44 (d13C) pooled specimens of Elphidium appears necessary to reach a between-sample standard deviation £ 0.25‰ with a probability of 95%. Such biological intrinsic and irreducible variability between coeval individuals, and thus samples, clearly questions the interest for single-cell analyses, more precisely, for coastal marine species, such as Elphidium, subject to many environmental changes during their life-time. Indeed, strong variations in salinity or temperature, as well as biogenic fractionation, could influence the isotopic composition of an individual specimen. Results might be less problematic for an average community including several tests. This paper underlines uncertainties linked to specific environments in which selected organisms live, especially for paleoceanographic or paleoclimatic reconstruction purposes where secular oxygen and carbon isotope variations typically range from 0.5 to 1.5‰.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica; 2015, 70
0137-6861
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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