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Behavior of elements in river watar of Tamagawa-Omonogawa River System containing acidic thermal watar in Akita Prefecture: Roles of dam lakes along the River System
https://doi.org/10.20569/00003568
https://doi.org/10.20569/00003568de448954-a544-4f76-89fd-12b3b5ad0030
| 名前 / ファイル | ライセンス | アクション |
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内容要旨及び審査結果要旨 (245.3 kB)
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本文 (6.9 MB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||||
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| 公開日 | 2018-06-14 | |||||||
| タイトル | ||||||||
| タイトル | Behavior of elements in river watar of Tamagawa-Omonogawa River System containing acidic thermal watar in Akita Prefecture: Roles of dam lakes along the River System | |||||||
| 言語 | ||||||||
| 言語 | eng | |||||||
| 資源タイプ | ||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_db06 | |||||||
| 資源タイプ | doctoral thesis | |||||||
| ID登録 | ||||||||
| ID登録 | 10.20569/00003568 | |||||||
| ID登録タイプ | JaLC | |||||||
| アクセス権 | ||||||||
| アクセス権 | open access | |||||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||||
| 別タイトル | ||||||||
| その他のタイトル | 秋田県の酸性温泉水を含む玉川－雄物川水系の河川水中の元素の挙動：河川におけるダム湖の役割 | |||||||
| 作成者 |
PHAM, MINH QUYEN
× PHAM, MINH QUYEN
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| 内容記述（抄録） | ||||||||
| 内容記述タイプ | Other | |||||||
| 内容記述 | For understanding the element cycles under subaerial environment, knowledge of chemical forms and the variation of chemical forms of elements in river water is important. The aim of this study was to assess the relevance of dissolved (<4 nm), colloidal (4 nm-0.2 μm) and particulate (>0.2 μm) forms for the transportation and accumulation of elements in the river water of Tamagawa-Omonogawa River System in Akita Prefecture, Japan. This river system contains acidic thermal water due to the discharge of the Obuki Cl-SO4 type thermal water to Tamagawa River and Kawarage Cl-SO4 type thermal water to Omonogawa River at the upstream of both rivers. Obuki Hot Spring discharges 9000 L/min of acidic thermal water (pH 1.2) to Tamagawa River while Kawarage discharges 7300 L/min thermal water of pH 1.4 to Omonogawa River. The environmental impact of thermal water of Obuki Hot Spring is larger than that of thermal water of Kawarage Hot Spring. Tamagawa River runs through the area mainly composed of Quaternary and Neogene volcanic rocks and has four lakes and dam lakes along the river, while Omonogawa River runs through the area mainly composed of Neogene strata and Quaternary strata covering Neogene sedimentary rocks and has no dam lakes. The characteristics of major elements are similar in Tamagawa and Omonogawa Rivers. All of the major elements are present in the dissolved form in the river water. Inflow of acidic thermal water into Tamagawa and Omonogawa Rivers changes the pH of the river waters to acidic in upstream. Toward downstream, the river water of Tamagawa and Omonogawa River become more neutral due to the addition of neutral river water from tributaries. However, the change of pH value of river water of Tamagawa-Omonogawa River System would not give effect to the state of chemical forms of major elements. According to acidic river water at upstream of Tamagawa River, concentrations of dissolved metals are also high except Fe and As. Dissolved Fe and As easily change into colloidal and/or particulate forms in river water in upstream of Tamagawa River. As a result of the process, Fe-rich layered sediment is present in Tamagawa Dam Lake. A large influence of hydrothermal activity from Obuki Hot Spring was recorded in the sediment at Tamagawa Dam Lake, resulting in high Pb content within sediment layers at 5 to 8 cm from bottom of the dam. At the downstream site, the influence of acidic thermal water becomes small due to addition of neutral river water from tributary and supply of particulate material from the erosion of Neogene and Quaternary sedimentary rocks. The pH of river water of Tamagawa River changes from 4.6 at Tamagawa Dam Lake in upstream to 7.1 in downstream at Ogamari in Daisen City. The particulate forms of Al, Fe and trace metals in river water contribute to the increase of concentration of these elements in lower Tamagawa River in Omagari. Based on observation and analyses by SEM-EDX and XRD, the particulate materials are thought to be clay minerals such as chlorite and illite/montmorillonite. In Omonogawa River, sizable proportion of Al and Fe were found within the particulate form that is similar to Tamagawa River. The small proportions of Cu and As were observed as dissolved form and the proportion of these elements in colloidal form increases toward downstream, which is a different tendency with the distribution of these elements in Tamagawa River. The clay minerals derived from the sedimentary rocks along Omonogawa River could be the host of elements as particulate form and caused the increasing concentration of Al, Fe, Mn and trace metals in river water at downstream site. Concentrations of Al, Fe, Mn and trace metals in particulate form of river water of Omonogawa River are higher than those of Al, Fe, Mn and trace metals in particulate form of river water of Tamagawa River. The amounts of Al, Fe, Cu and As that are transported by river water of Tamagawa River in winter season decreased from upstream to downstream (118 to 18 ton/month, 8 to 6 ton/month, 49 to 26 kg/month and 37 to 23 kg/month, respectively). On the other hand, the amounts of Fe, Cu, and As that are transported by river water of Omonogawa River in winter season increase from upstream to downstream (15-148 ton/month, 22-225 kg/month and 112-308 kg/month, respectively) while the amount of Al in river water of Omonogawa River is constant (27 ton/month). The amounts of Al, Fe, Cu, and As in river water of Omonogawa River, however, are 18, 5, 13 and 2 times larger than those are transported by river water of Tamagawa River to the Sea of Japan, respectively. In other seasons, the amounts of elements transported by Omonogawa River are also several times larger than the amounts of elements transported by Tamagawa River. These differences accord with (1) the presence or absence of dam lakes along Omonogawa (no dam lake) and Tamagawa Rivers (4 dam lakes) and (2) difference in dominance of Quaternary and Miocene sedimentary rocks between Omonogawa and Tamagawa Rivers. The dam lake could play an important role as a sink for particulate materials and reducing the environmental impact. |
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| 著者版フラグ | ||||||||
| 出版タイプ | VoR | |||||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||||
| 書誌情報 | 発行日 2018-03-22 | |||||||
| 出版者 | ||||||||
| 出版者 | 秋田大学 | |||||||
| 学位名 | ||||||||
| 学位名 | 博士（工学） | |||||||
| 学位授与機関 | ||||||||
| 学位授与機関識別子Scheme | kakenhi | |||||||
| 学位授与機関識別子 | 11401 | |||||||
| 学位授与機関名 | 秋田大学 | |||||||
| 学位授与年月日 | ||||||||
| 学位授与年月日 | 2018-03-22 | |||||||
| 学位授与番号 | ||||||||
| 学位授与番号 | 甲第1259号 | |||||||
