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    Wyświetlanie 1-3 z 3
    Tytuł:
    Respiration and assimilation processes reflected in the carbon isotopic composition of atmospheric carbon dioxide
    Autorzy:
    Szaran, J.
    Niezgoda, H.
    Trembaczowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/146953.pdf
    Data publikacji:
    2002
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    atmosphere
    carbon dioxide
    carbon isotopes
    delta-C-13
    respiration
    Opis:
    This paper presents diurnal variations of concentration and carbon isotopic composition of atmospheric carbon dioxide caused by respiration and assimilation processes. Air samples were collected during early and late summer in 1998 in unpolluted area (village Guciow located near the Roztocze National Park, SE Poland) in three different environments: uncultivated field on a hill, a meadow in the Wieprz river valley and a forest. The effect is very strong during intensive vegetation growth on a sunny day and clear night. The largest diurnal variations in atmospheric CO2 concentration and its carbon isotopic composition in June above the meadow were about 480 ppm and 10‰, respectively.
    Źródło:
    Nukleonika; 2002, 47,suppl.1; 59-61
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Diurnal variations and vertical distribution of δ13C, and concentration of atmospheric and soil CO2 in a meadow site, SE Poland
    Autorzy:
    Szaran, J.
    Dudziak, A.
    Trembaczowski, A.
    Niezgoda, H.
    Hałas, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2058901.pdf
    Data publikacji:
    2005
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    SE Poland
    atmospheric CO2
    carbon dioxide concentration
    diurnal observations
    delta 13C
    soil CO2
    Opis:
    We provide the results of 24-hour observations made in a meadow site located in a small river valley in Central Europe. Samples of atmospheric air were taken from three horizons: near the soil (0.05 m), in the grass (0.5 m) and above the meadow (2 m) at two-hour intervals. At the same time, samples of soil air were collected from two horizons: -0.1 and -0.5 m. We have found a variation of δ13C above the ground from -6‰ during the day to -20‰ late at night accompanied by variations in CO2 concentration from 270 ppm during the day, to various levels late at night at different heights above the ground. The maximum concentration was 1430 ppm at the ground level. The correlation coefficient between δ 13C and reciprocal of concentration was the highest (R2 = 0.984) for the samples collected 2 m above the ground, the regression line clearly indicating CO2 mixing from the two sources: atmospheric and biogenic reservoirs. The intercept of the mixing line yields δC = -23.0‰ for the biogenic CO2. In contrast, the diurnal variations in the soil were relatively small, δ13C varied from -21.6 to -23.4‰, while CO2 concentration from 4300 to 8200 and from 24 700 to 34 500 ppm at depths of 0.1 m and 0.5 m respectively, which is less than 2-fold. Small diurnal variations are characteristic of dry soils, where δ13C is weakly correlated with CO2 concentration (in our case R2 was 0.30 and 0.54, respectively).
    Źródło:
    Geological Quarterly; 2005, 49, 2; 135--144
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Calcite cements and the stratigraphical significance of the marine [delta^13]C carbonate reference curve for the Upper Cretaceous Chalk of England
    Autorzy:
    Jeans, C.
    Hu, X.
    Mortimore, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/139078.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    cement kalcytowy
    chemostratygrafia
    izotopy
    korelacja
    kreda
    krzywa referencyjna
    ograniczenia
    calcite cement
    chemostratigraphy
    correlation
    Cretaceous
    [delta^13]C reference curve
    isotope events
    limitations
    Opis:
    The hypothesis of Jarvis et al. (2006) that a [delta^13]C (calcite) reference curve based upon bulk samples from the Upper Cretaceous Chalk of England can be used as a primary criterion for trans-continental correlation is reviewed in the light of new stable isotope data from the Upper Albian and Cenomanian chalks of eastern England and from the Cenomanian to Campanian chalks of southern England. Evidence demonstrates that in the coloured chalks of eastern England the cements invariably have positive [delta^13]C values (up to 3.5[per mil]) except where they have been affected by hardground development when the cements have negative [delta^13]C values down to -6.5[per mil]. in contrast, the White Chalk of southern England may have cements with [delta^13]C values as negative as -8[per mil]. Modelling indicates that the coloured chalks may preserve a truer record of the primary palaeo-oceanographic [delta^13]C signal than the white and grey chalks of southern England. it is suggested that (1) many of the 72 isotope events described from the [delta^13]C (calcite) reference curve and proposed for correlation may reflect the effects of variations in the type and extent of calcite cementation; and (2) until much more is known about the patterns of calcite cementation in the Upper Cretaceous Chalk the use of minor isotope events for trans-continental stratigraphic correlation can only be applied with the utmost caution.
    Źródło:
    Acta Geologica Polonica; 2012, 62, 2; 173-196
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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