Chikyukagaku
Online ISSN : 2188-5923
Print ISSN : 0386-4073
ISSN-L : 0386-4073
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Volume 35, Issue 4
Displaying 1-5 of 5 articles from this issue
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Memorials
Original Paper
  • Trace amount of dissolved selenium species in the Japan Sea
    Hiroshi HATTORI, Yuzuru NAKAGUCHI, Yuichiro KONDO, Masaki TAKADA, Keiz ...
    2001 Volume 35 Issue 4 Pages 151-158
    Published: December 20, 2001
    Released on J-STAGE: January 07, 2017
    DOIhttps://doi.org/10.14934/chikyukagaku.35.151
    JOURNAL FREE ACCESS
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    The vertical profiles of dissolved selenium species; selenite (Se (IV)), selenate (Se (VI)), and organic selenide, at 4 stations in the Japan Sea were determined with a high performance liquid chromatography (HLPC)-2,3-dimaninonaphtalene (DAN) fluorometric method. In the surface water, Se (IV) concentration was 0.075±0.021 nM, and it was a little higher than the subsurface water. Se (VI) concentration was also higher in the surface. The significant variations of dissolved oxygen profiles were observed at 600〜2,500 m (the Japan Sea Deep Water: JSDW). Se (IV) increased with depth in JSDW, and Se (VI) maximum was observed at a depth of 800 m at CM 10, CM 18 and CM 12 and 1,250 m at CM 20. Organic selenide existed in the surface water, the JSDW and Japan Sea Bottom Water (JSBW) with concentrations of 0.2〜0.5 nM. The production rate of selenium was estimated from the ventilation time of JSDW and JSBW using apparent oxygen utilization (A.O.U.). Se (IV) supplied from surface to subsurface was 5.16 pM yr-1, and organic selenide regenerated from particle matter was 12.9 pM yr-1. The fluxes of Se (IV) and organic selenide into JSDW were 0.65 and 2.83 pM yr-1, and those into JSBW were 0.98 and 0.05 pM yr-1, respectively. The rate constant for the oxidation of Se (IV) to Se (VI) in JSBW was estimated to be 1.7×1O^-3yr-1. Tne mean life of Se (IV) in JSBW was estimated to be 178 years.
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  • Sources apportioning of dioxin pollution recorded in Tokyo Bay sediment core based on congener composition
    Shigeki MASUNAGA, Yuan YAO, Hideshige TAKADA, Takeo SAKURAI, Junko NAK ...
    2001 Volume 35 Issue 4 Pages 159-168
    Published: December 20, 2001
    Released on J-STAGE: January 07, 2017
    DOIhttps://doi.org/10.14934/chikyukagaku.35.159
    JOURNAL FREE ACCESS
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    On the basis of the congener-specific analysis of dioxins in a dated sediment core, surface sediment, and soil samples, the sources and mass balance of dioxins in Tokyo Bay basin, Japan, were estimated. The dioxins in the sediment core showed that their deposition in the bay increased rapidly during the 1960s, peaked in the early 1970s and then decreased gradually. Principal component analysis of the congener-specific data showed that three major sources existed: combustion, pentachlorophenol (PCP), and chloronitrophen (CNP). PCP and CNP are paddy field herbicides used extensively in Japan in the past. The time trends of source contributions were estimated by multiple regression analysis using the source congener profiles. The results revealed that dioxin emission from PCP and CNP herbicides was high in the 1960s and the early 1970s, respectively. The total contribution in terms of TEQ from the two herbicides was at their maximum of 70% in the 1970s and decreased thereafter. Their contribution, however, was as high as 50% in recent sediment, indicating that dioxins sprayed as herbicide impurity were still remaining in terrestrial soil and river sediment of the basin and running off gradually.
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  • Temporal changes in the composition and concentration of neutral lipids in aerosol and rain samples simultaneously collected in suburban Tokyo
    Nobuyuki TANAKA, Kimitaka KAWAMURA
    2001 Volume 35 Issue 4 Pages 169-182
    Published: December 20, 2001
    Released on J-STAGE: January 07, 2017
    DOIhttps://doi.org/10.14934/chikyukagaku.35.169
    JOURNAL FREE ACCESS
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    To better understand the wet scavenging processes of organic aerosols from the atmosphere, aerosol and rain samples were simultaneously collected in suburban Tokyo and analyzed for neutral lipid components using a capillary gas chromatography (GC) and GC/mass spectrometry. n-Alkanes, unresolved complex mixture of hydrocarbons (UCM), polycyclic aromatic hydrocarbons (PAHs), n-alcohols and sterols were determined in both aerosol and rainwater samples. Concentrations of n-alkanes, UCM and PAHs that originate from terrestrial higher plants or anthropogenic sources, were found to decrease with time during precipitation in both rain and aerosols. In contrast, concentrations of n-alcohols (<C20) and cholesterol that are characteristic to marine organisms generally increased during precipitation events. This study demonstrates that composition and concentrations of organic compounds in rain and aerosol samples during wet precipitation can be controlled not only by the scavenging process but also by a likely inflow of air mass of marine origin.
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Abstract of doctoral thesis
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