摘要:

The question whether a series of whole rock samples can be attributed to an isochrone for radiogeochronological dating or for determining the initial isotopic ratio of the daughter element of igneous rocks can be valued by means of the correlation between the concentrations1c and2c of mother and daughter element. The slope of the correlation line in a lg1c to lg2c diagram is given by

ISSN:0021-1915    

DOI:10.1080/10256018608623616

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0021-1915    

DOI:10.1080/10256018608623617

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An efficient potential for radiation research has been developed at the Central Institute of Isotope and Radiation Research in Leipzig since 1969. 2Iany problems in the field of basic and applied research of radiation chemistry and biology have been studied. Ten gamma plants and two electron accelerators have been designed and established for scientific, industrial and agricultural application.

ISSN:0021-1915    

DOI:10.1080/10256018608623618

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Because of its half-life of 105 a32Si has a great potential for dating ground water in the range of 100–500 years. The utilization of3H and14C in this dating range is impossible. The results of32Si-measurements in precipitation, which are necessary for estimation of the32Si initial activity of groundwater, are discussed in this paper.

ISSN:0021-1915    

DOI:10.1080/10256018608623619

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The stable nitrogen isotope15N is being increasingly used in life sciences. Problems of following the course of nitrogen in digestion/absorption studies of nutrients, their intermediary metabolism and dynamic behaviour can be readily dealt with using nitrogen-15. The object of this paper is to discuss some aspects of the isotope analysis of15N, useful tracer techniques, and theoretical considerations. It is shown that nitrogen balance is a valuable concept for expressing the relationship between the overall nitrogen intake of the body and its nitrogen losses. However, a mere summary of total exchange gives little information of any particular metabolic processes within the body unless these are reflected in the total nitrogen exchange. Feeding trace doses of15N labelled substances like proteins and amino acids the kinetics of digestion and absorption is indicated by a measurable change of the15N abundance in serum and urinary nitrogen compounds, i.e. by a significant delay in nitrogen absorption in patients with gastrointestinal diseases.

ISSN:0021-1915    

DOI:10.1080/10256018608623620

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A method is described for approximate evaluation of thermodynamic oxygen isotope fractionations between different paragenetic silicates or between silicate and water, respectively. The evaluation uses a newly introduced18O index. It can be calculated for any silicate by means of isotopic increments of the different oxygen bonds within the silicate. Multiplying the18O index of any silicate by the expression in βQuartz(T) gives an adequate expression of the corresponding silicate and opens the possibility to calculate approximately isotope fractionations in dependence on the temperature.

ISSN:0021-1915    

DOI:10.1080/10256018608623621

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An einem Profil, das stratigraphisch das Obere Proterozoikum bis zum Unterkarbon einschlieβt, wurden von tonigen und Corg-reichen Lithotypen die C-Isotopenverteilung, der Mineralbestand und die Haupt- und Spurenelemente erfaβt. Elementverteilungen erlauben Aussagen zur erdgeschichtlichen Entwicklung. Die13C-Häufigkeit proterozoischer Proben unterscheidet sich signifikant von der phanerozoischer Schiefer. Eine detaillierte geochemisch-isctopengeochemische Untersuchung der lithostratigraphisch begründeten Grenze Proterozoikum–Kambrium (Goldisthaler Serie) ergab inner-halb weniger Profilmeter einen Sprung in der C-Isotopenverteilung. Vergleichsuntersuchungen an stratigraphisch gesicherten Tonschiefern im Ostteil der DDR wiesen ebenfalls signifikante Unterschiede in der C-Isotopenverteilung zwischen Kambrium und Oberen Proterozoikum auf.

ISSN:0021-1915    

DOI:10.1080/10256018608623622

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Due to the long term increase of atmospheric CO2its13C/12C ratio changes influenced by CO2emitted from combustion of fossil fuels particularly. The13C/12C records in tree rings make a contribution to the knowledge about the development of the atmospheric CO213C data from two trees of different locations in the GDR are presented and discussed in connection with the isotope data reported in the literature.

ISSN:0021-1915    

DOI:10.1080/10256018608623623

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The paper gives a first complete view about the isotope hydrological situation in the Schirmacher Oasis and surroundings by means of studies of δ Deuterium and δ Oxygen 18 variations. The precipitation is assumed to be condensed in a distance of about 100 km and in a hight of the surface of the inland ice between 1.000 in and 1.500 m a.s.l. in the mean wind direction South East. The δD value studies of the shelf and inland ice have shown that both the basal zone of the inland ice and the ice shelf represent relics of an assumed thicker late pleistocene ice cap of Dronning Maud Land. The main part of the glacier ice is composed of recent local precipitation. The isotope liydrological studies are also a contribution to the characterisation of the high polar fresh-water lakes, ponds and pools under different limnological conditions.

ISSN:0021-1915    

DOI:10.1080/10256018608623624

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Equations are derived for the description of changes in the isotopic composition of initial substances and intermediate products appearing at consecutive reactions of 1st order. For illustration some examples are given. In particular at environmental transformations of substances these equations should be important as shown by way of example of a fertilizer experiment.

ISSN:0021-1915    

DOI:10.1080/10256018608623625

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor