地球化学
Online ISSN : 2188-5923
Print ISSN : 0386-4073
ISSN-L : 0386-4073
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20 巻, 2 号
選択された号の論文の11件中1～11を表示しています
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報文
  • 岐阜県春日地方の熱変成堆積岩中に含まれる炭素物質の水素および炭素同位体比
    能登 征美, 吉田 尚弘, 水谷 義彦, 富田 俊弘
    1987 年 20 巻 2 号 p. 51-58
    発行日: 1987/03/15
    公開日: 2016/11/28
    DOIhttps://doi.org/10.14934/chikyukagaku.20.51
    ジャーナル フリー
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    Carbonaceous materials in Paleozoic shales from the Kasuga area, Gifu, Japan, which were subjected to contact metamorphism during the Jurassic, have been studied for the X-ray diffraction, elemental composition, and hydrogen and carbon isotopic compositions. Results on the X-ray diffraction and elemental analyses clearly indicate that the degree of graphitization of the carbonaceous materials decreases with distance from the contact. Within the metamorphic zone, δ13C values for the materials decerase with distance from the contact, from -18‰ to -31‰. The trend of δD values for the carbonaceous materials is similar to that of δ13C values. The δD values are rather constant at the level of -130‰ outside the metamorphic zone and increase up to -95‰ within the metamorphic zone. The results on the isotopic compositions suggest that some volatiles depleted in D and 13C have been removed from the carbonaceous materials during the contact metamorphism.
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  • 鬼首地域における地熱流体の起源
    清棲 保弘
    1987 年 20 巻 2 号 p. 59-68
    発行日: 1987/03/15
    公開日: 2016/11/28
    DOIhttps://doi.org/10.14934/chikyukagaku.20.59
    ジャーナル フリー
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    Chemical and isotopic compositions have been determined for steam and water samples from fumaroles, hot springs and wells in the Onikobe geothermal field. The thermal waters are grouped into acid sulfate type, acid sulfate-chloride type and NaCl type waters. The stable isotopic data indicate that the reservoir fluids extremely enriched in 18O are meteoric in origin and that the NaCl type hot spring waters are mixtures of these fluids and meteoric waters. The acid sulfate type waters are formed in shallow aquifer with oxidation of fumarolic hydrogen sulfide. The sulfate enriched in 34S from acid sulfate-chloride and NaCl type waters originate in the disproportionation of volcanic sulfur dioxide. δ13CCO2 value suggests that a carbon source for C02 in steam and waters at Onikobe is related to volcanic activity. The gas ratio such as CO2/N2, N2/Ar and He/Ar indicates that the Onikobe geothermal fluid is a mixture of volcanic gases and groundwaters and that these gases are dissolved in liquid reservoir fluids at near reservoir temperature.
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  • 海洋のスキャベンジング・モデル
    野崎 義行
    1987 年 20 巻 2 号 p. 69-77
    発行日: 1987/03/15
    公開日: 2016/11/28
    DOIhttps://doi.org/10.14934/chikyukagaku.20.69
    ジャーナル フリー
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    Although its concentration is very low (〜10 μg/l) in ambient deep waters, particulate matter controls the oceanic distribution of reactive metals such as Al, Fe, Mn, Th and Pb through processes called "scavenging." This phenomenon has been modeled by marine geochemists largely based on radioactive disequilibria of the U/Th decay series nuclides in the water column. Nozaki et al. (1987) have proposed a new model which includes two particle size classes (small and large) as an extension of the earlier one particle phase adsorption-desorption model of Nozaki et al. (1981). The new model assumes a reversible exchange of the two classes of particles to occur through aggregation and disaggregation processes. Using Pacific data for dissolved and particulate 230Th profiles, the rate constants have been estimated for the adsorption-desorption and aggregation-disaggregation processes. However, the estimates of Nozaki et al. (1987) are dependent upon unreliable surface 230Th concentration in particles and hence the calculated values for the rate constants are highly uncertain. In this paper, another approach is described that the rate constants can be estimated without using the surface particulate 230Th value in the presence of 234Th data. Recalculation based on this approach and published 234Th data suggests that suspended small particles form aggregates on the time scale of 10 months and that the large aggregates with sinking speed higher than 100 m/day disintegrate within one week.
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  • 人の食生態系における炭素・窒素同位体の分布
    南川 雅男, 柄沢 亨子, 蒲谷 裕子
    1987 年 20 巻 2 号 p. 79-88
    発行日: 1987/03/15
    公開日: 2016/11/28
    DOIhttps://doi.org/10.14934/chikyukagaku.20.79
    ジャーナル フリー
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    Carbon and nitrogen isotope ratios of human diets and hairs were studied for seven ethnic populations. The protein fraction of Japanese food purchased at Tokyo showed similar δ13C and δ15N with those of previously reported American foods. Based on representative isotope ratios of food classes, the carbon and nitrogen isotope ratios of human hairs were estimated for each populations. The estimation was illustrative of observed isotopic differences of hairs of examined populations except of Brazilian. A mixing model of plant and animal diets was developed to study the relation between the δ15N of hair and the animal protein dependence of each nation. The δ13C and δ15N of Japanese hairs, from foreign residents or from Edo era (ca.130 years BP), showed quite different values as compared with those of recent native Japanese. These suggest that the carbon and nitrogen isotope ratios of human tissues were characterized mainly by food preferences and the isotope ratios of foods, but not by ethnic factors.
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課題討論 (富山,1986)「環境における放射性および安定同位体の動態」
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