Journal of Geography (Chigaku Zasshi)
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
Volume 131, Issue 6
Displaying 1-9 of 9 articles from this issue
Cover
  • 2022 Volume 131 Issue 6 Pages Cover06_01-Cover06_02
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS

     In the western half of the Ata caldera, located at the mouth of Kagoshima Bay, topographic landscapes related to volcanic activity after the Pleistocene epoch of the Quaternary, such as the crater lakes of Lake Ikeda and Unagi pond, can be observed. Hot springs and steaming fields, represented by Ibusuki hot spring, are also distributed in this area. The photo shows boiling water issuing at a sand beach in the Fushime hydrothermal area, which can be observed only at low tide. The adjacent cliff, comprising Ikeda pyroclastic sediments, was formed 6300 BP when Lake Ikeda erupted (Kawabe and Sakaguchi, 2005). Various studies have been done related to development of the Yamagawa geothermal plant in the Fushime area, where hydrothermal water at 330°C was recovered from a depth of 2000 m (e.g., Yoshimura and Ito, 1994). Primary hydrothermal water in this area was formed through a reaction with seawater at that temperature, and its water chemistry was changed during the ascending path by dilution with subareal fresh groundwater and subsequent mineral precipitation (e.g., Okada et al., 2000). Located near the hot spring are municipal public and sand steam baths, as well as an abandoned salt field, where hot spring water was used to make table salt through condensation. Behind the issuing hot spring can be seen Mount Kaimon volcano, which last erupted in 885 AD. This area is one of the best for experiencing the reality of active volcanoes and geothermal energy, and for undertaking research on geology and geochemistry.

    (Photograph & Explanation: Harue MASUDA)

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Special Issue: Present Situation of Hot Spring and Geothermal Energy Studies in Japan
Review Articles
  • Harue MASUDA
    2022 Volume 131 Issue 6 Pages 573-584
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS
    Supplementary material

     The history of hot spring studies and research in Japan is reviewed mainly from the viewpoint of Earth science. Studies on the geochemistry of hot spring waters started with geochemical analyses of hot spring water in the 1830s. The relationships between the issuing mechanisms of hot springs and volcanism, active faults, and earthquakes have been studied since around 1910. These studies reveal sources and recycling paths of waters and dissolved materials in the Earth's crust and the upper mantle in relation to plate tectonics and subsequent volcanism. Microbiological studies on living organisms, such as algae, bacteria, and archaea, living in hot springs, began in the late 1880s, and have contributed to documenting the origins and evolution of life. Combined with mineralogical studies, minor and trace element analyses of hot spring water have contributed to an understanding of the formation mechanisms of ore deposits. Studies on hot spring waters triggered an understanding of the essential role of water in the Earth and its evolution.

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  • Tomo SHIBATA, Ryo TAKAHASHI, Fujio AKITA
    2022 Volume 131 Issue 6 Pages 585-595
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS

     The relationships between eruptive activities and changes in groundwater level, temperature, and chemical composition of thermal water at Toyako Onsen are discussed in relation to the 1977-1978 and 2000 eruptions of Usu volcano, Hokkaido, Japan. The temperature and chemical composition of thermal water observed since the 1977-1978 eruption are found to have changed after the eruptions. The groundwater levels in the hot spring wells, observed before the 2000 eruption, are found to have changed approximately six months before the eruption. Changes of groundwater level, which reflect pore water pressure, are generally faster than those of the temperature and chemical composition of thermal water attributed to fluid flow. However, thermal water flow during the 2000 eruption of Usu volcano was probably triggered as fast as propagation. Because the thermal water at Toyako Onsen is affected by the eruptive activities of Usu volcano, understanding the relationship between volcanic activity of Usu volcano and changes in temperature, chemical composition and groundwater levels of the thermal water is useful for inferring volcanic eruption and activity of Usu volcano.

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  • Saki TSUTSUMI, Jun-ichiro ISHIBASHI
    2022 Volume 131 Issue 6 Pages 597-607
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS

     Geothermal fluid heated by a magma heat source is available as a geothermal resource when the fluid or vapor is obtained continuously from the subsurface and is introduced into power generation facilities. Exploration of geothermal resources using a combination of various techniques is an essential process to successful developing geothermal energy, which has become attractive as a renewable and sustainable resource. Geochemical exploration provides direct information on the properties and behaviors of geothermal fluid, based on chemical analysis of hot spring waters, fumaroles collected at geothermal areas, and high-temperature fluids obtained from the heads of drilled wells. Chemical properties of those fluids reflect histories of various chemical processes during fluid circulation within a subsurface geothermal system where groundwater evolves into a high temperature fluid. Compositions of major cations (Na, K, Ca, Mg) and SiO2 reflect the course of fluid-mineral interactions, and function as a geothermometer when compositions are controlled by chemical equilibria within the reservoir. Meanwhile, compositions of major anions (Cl, SO4, HCO3) and B reflect contribution from various sources, such as seawater, magmatic volatiles, and crustal fluid. Gas species (CO2, H2S, H2, N2, CH4, Ar, He) are also derived from various sources such as the atmosphere, organic matter decomposition, and a magma heat source. These species provide information on the history of fluid circulation, because they are unaffected by fluid-mineral interactions in spite of some exceptions. Hydrogen and oxygen isotopes of H2O mainly provide an index of the origin of a fluid, such as meteoric water, seawater, and magmatic volatile, as well as evidence for fluid-mineral interactions and boiling processes. Isotopic compositions of light elements such as carbon and sulfur of gas species are useful for discriminating contributions from magmatic volatiles and from microbiological activities. Recent technical advances in mass spectrometry have enabled the isotopic composition of several elements to be obtained. These newly proposed geochemical indices would provide information that is difficult to extract using conventional geochemical tools. Developments in new geochemical extrapolation techniques are expected in the light of the present situation where expansion in the use of geothermal resources is demanded.

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  • Mayumi YOSHIOKA, Youhei UCHIDA
    2022 Volume 131 Issue 6 Pages 609-623
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS

     Achieving carbon neutrality is a measure for mitigating climate change. As a result, development of zero net buildings and houses is accelerating in Japan. In this connection, ground source heat pump (GSHP) systems are being promoted as a potential energy saving cooling and heating technology. The aquifer thermal energy storage (ATES) system is an GSHP system that has been attracting attention for its low initial cost and high operation efficiency compared to other GSHP systems such as closed-loop systems. However, successful implementation strongly depends on the hydrogeological conditions of the host area. ATES systems require an adequate groundwater supply to meet the thermal demand of buildings. To increase ATES adoption in Japan, research to evaluate areas that are appropriate for ATES, including the hydrogeological environment, have been actively carried out in the last decade. Existing literature on the thermal use of groundwater in Japan and studies related to ATES from the 1970s to the present are reviewed and analyzed. Then, the latest findings on the ATES potential map and/or suitability evaluation for Osaka city and Yamagata basin are presented. Both findings imply that geological conditions might impact the suitability of implementing an ATES system. Finally, challenges surrounding development of a technique to assess the applicability and potential of ATES at different locations in Japan are discussed. The safe and effective installation and operation of an ATES system requires an understanding of prevailing hydrogeological conditions.

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  • Yoshikazu KIKAWADA
    2022 Volume 131 Issue 6 Pages 625-645
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS

     Acid river systems and the actual situation of river neutralization at the Kusatsu-Shirane volcano, Gunma Prefecture, and Ebino highlands of the Kirishima volcanoes, Miyazaki Prefecture, are reviewed. In the case of the acid river system at the Kusatsu-Shirane volcano, sources of acid water are volcanic acidic hot springs and acid mine drainage (AMD) from closed sulfur mines. Volcanic hot springs and AMD have different effects on the river environment. Arsenic is predominantly supplied from hot springs, and heavy metals such as lead are predominantly supplied from AMD. The river neutralization system at the Kusatsu-Shirane volcano targets water from Kusatsu hot springs, the region's largest source of acidic components, resulting in a significant water quality improvement in the downstream river. The system at the Kusatsu hot springs directly injects a neutralizer prepared from powdered limestone into the river. The neutralization products formed in river water are finally accumulated in a dam constructed to function as a sedimentation basin. Then, the dredged sediment from the dam is dumped at dedicated disposal sites. In the case of the Ebino Highlands (Iwoyama volcano), the Kirishima volcano complex, an eruption in 2018 caused river water pollution. Phreatic eruptions at the Iwoyama volcano triggered discharges of acidic hydrothermal fluids containing large amounts of arsenic and heavy metals from vents newly opened with the eruptive events, resulting in a deterioration of river water quality and significant damage to local agriculture. Because the discharge of acidic hydrothermal fluids from the vents continued even after eruptive activity ended, Miyazaki Prefecture decided to neutralize the river in the Ebino Highlands. After starting river neutralization, the water quality of downstream rivers improved significantly. Because the amount of treatment required for river neutralization at the Ebino Highlands is not very large, a passive treatment method was adopted to enable low-cost operation.

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  • Wipoo PRASITWUTTISAK, Katsunori YANAGAWA
    2022 Volume 131 Issue 6 Pages 647-663
    Published: December 25, 2022
    Released on J-STAGE: January 12, 2023
    JOURNAL FREE ACCESS

     Previous single-gene surveys using 16S rRNA gene-based methods have revealed the phylogenetic classification, distribution, and diversity of as-yet uncultivated microbial lineages in diverse environments. In particular, archaeal communities associated with high-temperature terrestrial hot springs and sediments are dominated by novel thermophilic and hyperthermophilic populations whose physiological characters and ecological roles are unknown. Recent advances in metagenomic approaches and computational processing of huge volumes of DNA sequence data have further unveiled the evolutionary importance of uncultivated hot spring archaeal lineages and previously undescribed roles in biogeochemical cycles of carbon, nitrogen, sulfur, and metals. In this review article, the uncultured thermophilic and hyperthermophilic archaeal lineages that have accelerated our understanding of the tree of life are illustrated.

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