GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
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Volume 19, Issue 5
Displaying 1-6 of 6 articles from this issue
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  • Anomalous Xenon Isotopes in Carbonaceous Chondrites
    K. K. Saebo, P. K. Kuroda
    1986 Volume 19 Issue 5 Pages 251-257
    Published: October 20, 1986
    Released on J-STAGE: September 26, 2008
    DOIhttps://doi.org/10.2343/geochemj.19.251
    JOURNAL FREE ACCESS
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    The origin of the isotopically anomalous xenon components reported to have been isolated from the carbonaceous chondrites Allende and Murchison can be attributed to the products of known nuclear processes, which also produce isotopic anomalies in a wide variety of substances including the light elements carbon, nitrogen, oxygen, and magnesium.
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  • Sulfur isotope study of the Yatani Au-Ag and Zn-Pb vein-type deposits in Japan
    Naotatsu Shikazono, Hidehiko Shimazaki
    1986 Volume 19 Issue 5 Pages 259-267
    Published: October 20, 1986
    Released on J-STAGE: September 26, 2008
    DOIhttps://doi.org/10.2343/geochemj.19.259
    JOURNAL FREE ACCESS
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    Sulfur isotopic compositions of sulfide minerals from the Yatani deposits which occur in the Green tuff region of Japan were determined separately for those from Zn-Pb and Au-Ag veins. δ34S values of Au-Ag veins are higher than those of Zn-Pb veins. The values for Zn-Pb veins and Au-Ag veins are ca. 0.5–4.5 ‰ and ca. 3–6 ‰, respectively. This difference in δ34S of Zn-Pb veins and Au-Ag veins is difficult to be explained by the equilibrium isotopic fractionation between aqueous reduced sulfur species and oxidized sulfur species at the site of ore deposition. The non-equilibrium rapid mixing of H2S rich fluid (deep fluid) with SO42- rich fluid (shallow fluid) is the most likely process for the cause of this difference. This fluid mixing can also explain the higher oxidation state of Au-Ag ore fluid and lower oxidation state of Zn-Pb ore fluid. Deposition of gold occurs by this mechanism but not by oxidation of H2S rich fluid.
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  • Diurnal and seasonal variations in isoprene emission from live oak
    Keiichi Ohta
    1986 Volume 19 Issue 5 Pages 269-274
    Published: October 20, 1986
    Released on J-STAGE: September 26, 2008
    DOIhttps://doi.org/10.2343/geochemj.19.269
    JOURNAL FREE ACCESS
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    The emission rate of isoprene from an oak tree (Quercus serrata) in the field was measured at almost hourly intervals during daytime. The emission showed an marked diurnal variation with a maximum around noontime. More than 80% of daily emission occurred between 10:00 and 14:00. The emission rate correlated with light intensity, and their relationship could be described by a simple hyperbolic function. The daily isoprene emission showed a seasonal variation with a maximum in September. This seasonal variation differed considerably from the one presumed from average monthly temperatures, indicating the need of a check of seasonal variations in the case of the estimation of annual emission rate from vegetation.
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  • Variations in N2/Ar and He/Ar ratios of gases from some volcanic areas in Northeastern Japan
    Yasuhiro Kiyosu
    1986 Volume 19 Issue 5 Pages 275-281
    Published: October 20, 1986
    Released on J-STAGE: September 26, 2008
    DOIhttps://doi.org/10.2343/geochemj.19.275
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    Fumarolic and geothermal well gases from several volcanic areas in Northeastern Japan have been examined for the N2/Ar and He/Ar ratios. The N2/Ar and He/Ar ratios of the gas samples are 40 to 2, 000 and 10-3 to 1, respectively, higher than those of the atmospheric air dissolved in groundwaters. The N2/Ar ratio becomes larger with increasing ratio of He to Ar. The data also show that nitrogen and helium in gases increase with increasing contribution of magmatic gas to the discharges and with decreasing contribution of groundwater. This suggests that the observed volcanic and geothermal gases may be mixtures of magmatic gas of uniform N2/Ar (≅4, 000) and He/Ar ratios (≅2) and local meteoric waters.
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  • The origin of plutonium in the atmosphere
    S. C. Lee, H. H. S. C. Rao, Y. Sakuragi, N. Bakhtiar, F. S. Jiang, P. ...
    1986 Volume 19 Issue 5 Pages 283-288
    Published: October 20, 1986
    Released on J-STAGE: September 26, 2008
    DOIhttps://doi.org/10.2343/geochemj.19.283
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    Radiochemical measurements of 239, 240Pu were carried out for a total of 288 individual rain and snow samples collected at Fayetteville (36°N, 94°W), Arkansas, during the period between February 1976 and October 1984. The results indicate that the plutonium inventory in the northern stratosphere has been decreasing during the past several years at a rate corresponding to about 1.2 years for the mean stratospheric residence time of plutonium. However, the fallout of plutonium may not be attributable solely to the atmospheric injections of nuclear debris from the weapons tests. It appears that the recent volcanic eruptions may have played an important role in altering the stratospheric inventory of plutonium.
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  • ERRATUM
    1986 Volume 19 Issue 5 Pages e3
    Published: 1986
    Released on J-STAGE: February 06, 2009
    DOIhttps://doi.org/10.2343/geochemj.19.e3
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