Chikyukagaku
Online ISSN : 2188-5923
Print ISSN : 0386-4073
ISSN-L : 0386-4073
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Volume 19, Issue 1-2
Displaying 1-13 of 13 articles from this issue
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Original Papers
  • Uranium contents and 234U/238U activity ratios of modern and fossil marine bivalve molluscan shells –Alpha recoil effect on 234Th and 238U-234U-230Th(Io) Disequilibrium in fossil shells
    Hiroshi MITSUDA, Kunihiko KIGOSHI
    1985 Volume 19 Issue 1-2 Pages 1-12
    Published: October 15, 1985
    Released on J-STAGE: November 26, 2016
    DOIhttps://doi.org/10.14934/chikyukagaku.19.1
    JOURNAL FREE ACCESS
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    In order to elucidate the observed difference between the radioactivity ratio (234U/238U)AR in the living modern shells and that in the fossil shells, the authors made radiochemical analysis on the nuclides 238U, 234U and 230Th in the inorganic rod (mainly aragonite) and the organic matrix (mainly conchiolin) of molluscan shells. The analysis of uranium in the organic matrix of the shells were done by the extraction of uranium in the organic matrix by the ammonium carbonate solution. The inorganic rod and the organic matrix of modern shells showed the radioactivities of 238U of 0.1-0.2 dpm/gr and 27 dpm/gr respectively. In regard to the fossil shells, the inorganic rod and the organic matrix showed 0.13-1.2 dpm/gr and 84-140 dpm/gr respectively. The (234U/238U)AR ratios on the inorganic rod are 10 to 20% higher than the ratios on the organic matrix. The modern shells showed no such correlation. The uranium in the organic matrix has about one hundred or more times higher concentration that in the inorganic rod. Although, as a whole, the uranium in the organic part is nearly the same amount in the inorganic part. Owing to the differences of 238U concentration, density and geometry of the organic and inorganic matters in a shell, more than half of alpha decay products of uranium can enter into the inorganic part. On the other hand, the reversal process, the implantation of α-decay products of uranium from inorganic part never be expected to give measurable effect owing to low concentration of uranium in the inorganic part. Many of the fossil shells had been preserved as the open system in regard with the uranium. Assumig the exchange of uranium through organic matrix, the enrichment of 234U in molluscan shells by α-recoil process during a long time of preservation was calculated.
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  • Concentration of chemical species in aerosol at Fuchu, Tokyo
    Junko OKUBO, Norio OGURA
    1985 Volume 19 Issue 1-2 Pages 13-20
    Published: October 15, 1985
    Released on J-STAGE: November 26, 2016
    DOIhttps://doi.org/10.14934/chikyukagaku.19.13
    JOURNAL FREE ACCESS
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    Atmospheric aerosol concentrations were measured before and after rainfall at Fuchu City, Tokyo from June to November 1983. Before rainfall, the mean concentrations of total aerosol, (NO3-N + NO2-N) and SO4-S were 193 μg•m-3, 262 ng at•m-3 and 8.7 μg•m-3, respectively. And after rainfall, they decreased to 74 μg•m-3, 117 ng at•m-3 and 4.1 μg•m-3, respectively. Before rainfall, aerosol concentration was higher when there was little wind, and it became nearly constant after rainfall. Therefore it is considered that decrease of aerosol depends on its concentration before rainfall. The amount of decrease of aerosol from atmosphere was not equivalent to the amount of chemical species precipitated by rainfall.
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  • Occurrences and behaviors of heavy metals in a polluted urban river systems I. Distribution of heavy metals in the sediments
    Kazuo FUKUSHIMA, Takashi KANETAKE, Youichi SUZUKI, Ken-ichiro MUKAI
    1985 Volume 19 Issue 1-2 Pages 21-30
    Published: October 15, 1985
    Released on J-STAGE: November 26, 2016
    DOIhttps://doi.org/10.14934/chikyukagaku.19.21
    JOURNAL FREE ACCESS
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    Sediment samples were collected from 44 locations of a typical polluted urban river, the Sumida (Shingashi) River, which runs through the Tokyo area and pours into the Tokyo Bay, Japan. Fine particles under 76 μm diameter were sieved and analyzed for concentrations of Cr, Ni, Cu, Zn, Cd, Pb, organic carbon and nitrogen. The analytical results showed that most of the samples from upstream to downstream of the river were heavily polluted with those metals probably originated from waste waters of urban activities in the drainage area. The characteristics in the metal compositions and their distributions were examined by calculating the concentration correlation matrices and the correlations between elements. It was found that the heavy metal composition except Ni was nearly uniform among the majority of the samples from mid- to downstream of the river. The reference sediment samples from 22 and 6 locations near the river mouths of Tama-gawa and Ara-kawa, respectively, which run adjacent to the Sumida River, were analyzed in the same way. It appeared that there are some specific heavy metal compositions, probably reflecting the degree and quality of pllution to each river.
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  • Influence of pesticide and fertilizer on the ground water in vegetable field zone
    Hiroshi TERAO, Masakatsu KAJIKAWA, Yuki MORISHITA, Kikuo KATO
    1985 Volume 19 Issue 1-2 Pages 31-38
    Published: October 15, 1985
    Released on J-STAGE: November 26, 2016
    DOIhttps://doi.org/10.14934/chikyukagaku.19.31
    JOURNAL FREE ACCESS
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    Influence of pesticide and fertilizer on the ground water was investigated in vegetable field zone at Kakamigahara Heights located in the central Japan. Though organic bromine compounds have rarely been found in ground water, in this study, 1,2-dibromoethane derived from pesticide was found. Water samples from 9 locations in vegetable field zone were collected 12 times during 16 months, and 1,2-dibromoethane was always observed at 7 locations. Its mean value at each location ranged from 0.15 μg/1 to 0.28 μg/1. Though the pesticide containing 1,2-dibromoethane was used in the limited period, 2 weeks in a year, observed annual variation of 1,2-dibromoethane was small. Br- ion derived from decomposition of 1,2-dibromoethane raised Br/Cl ratio in the ground water and then, including sorrounding area, the locations where 1,2-dibromoethane was detected higher ratio as compared with those not detected. Of major components in the ground water, Ca2+, Mg2+, NO3-, and SO42- ions showed high concentations affected by fertilizer, but those annual variations were small, similar to that of 1,2-dibromoethane.
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Review
Special Issues: Recent Progress in Geochemistry
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