著者

淵田 茂司

出版者

日本地球化学会

雑誌

地球化学 (ISSN:03864073)

巻号頁・発行日

vol.49, no.4, pp.247-259, 2015-09-25 (Released:2015-12-25)

参考文献数

87

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Amino acids, necessary to form life body, are present in greater abundances in natural seafloor hydrothermal fluids over 200℃ than in ambient seawater, although these are unstable and decomposed rapidly under simulated hydrothermal conditions. Serine and aspartic acid, which are thermally labile amino acids, are detected in the high temperature fluids. Inorganic matters such as metal ions and minerals could protect these labile amino acids in the fluids. Most of the dissolved amino acids are combined form and L form, suggesting that these are derived from organisms around hydrothermal vents. In addition, low levels of non-protein amino acids content indicate that amino acids are fresh and not experienced thermal alteration for long time. Amino acids are important as common sources of carbon and nitrogen for heterotrophic marine microbes. The release of biogenic amino acids along circulation paths of hydrothermal fluids could be effective for the development of hydrothermal vent fauna. In this paper, I review the origins and characteristics of dissolved amino acids in the natural hydrothermal fluids and implicates importance of the biogeochemical cycle of nitrogen and carbon around hydrothermal venting in detail.

著者

淵田 茂司 田嶋 翔太 所 千晴

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.138, no.11, pp.160-169, 2022-11-30 (Released:2022-11-25)

参考文献数

24

被引用文献数

1

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This study examined effective removal methods for high amounts of manganese (Mn) and zinc (Zn) in acid mine drainage (AMD) by addition of different neutralizing agents (NaOH and NaClO) and synthesized birnessite (δ-MnO2) using two-type AMD samples which Mn and Zn concentrations were 778 and 410 mg L−1 for A mine and 18.0 and 5.51 mg L−1 for B mines, respectively. The precipitation mechanism of these metal ions was investigated by geochemical modeling (PHREEQC) and X-ray absorption near edge structure (XANES) analysis. Mn concentrations were below the effluent standard (10 mg L−1) at pH 9–10 with the NaOH neutralization, whereas it was accomplished at lower pH (6–7) condition with the NaClO addition; it could act as an oxidizing agent, resulting that most of Mn precipitated as δ-MnO2. Zn concentrations decreased below the effluent standard (2 mg L−1) at pH 8–9 using both neutralizing agents. XANES analysis results indicated Zn was removed by the surface complexation formation on manganite and δ-MnO2 surface. More effective removal of Mn and Zn from AMD was found around pH 6 when a sufficient amount of δ-MnO2 was added to both AMD before the NaOH neutralization; a geochemical model coupling charge distribution multisite ion complexation revealed the triple-corner-sharing on δ-MnO2 was the most reasonable mechanism. Our result suggests that the presence of sufficient δ-MnO2 was the most effective for high Mn and Zn contents AMD treatment; however, ferrous ion (Fe2+) can inhibit the adsorption reaction and decompose δ-MnO2. Thus, pre-precipitation of Fe2+ is required to enhance the effect of δ-MnO2 on Mn and Zn removals from AMD.

著者

髙谷 雄太郎 淵田 茂司 濱井 昂弥 堀内 健吾 正木 悠聖 所 千晴

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.138, no.2, pp.19-27, 2022-02-28 (Released:2022-02-26)

参考文献数

42

被引用文献数

3

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In decades, various studies on passive treatment methods of acid mine drainage (AMD) have been actively conducted in order to reduce the cost of AMD treatment. Open limestone channel is one of the most common methods and has already been implemented mainly in overseas. On the other hand, it is difficult to secure large channels in Japan due to its topography, we need to consider the use of alkaline materials with higher acid neutralization potential which enables successful treatment with narrower space. In this study, therefore, PAdeCS, a cement-derived environmental remediation agent, was used to remove the harmful metal elements by neutralization treatment. Then, we developed a simulation model assuming a combined system of open limestone channel and alkaline material (PAdeCS) channel and predicted the behavior of harmful metal elements within the combined channel. The simulation results showed that PAdeCS has extremely high acid neutralization potential, that high temperature is advantageous for neutralization treatment of harmful metal elements, and that the channel design needs to be changed depending on the initial drainage composition. Finally, a new flowchart for selecting the appropriate passive treatment method was proposed, which consists of three steps of the preferential removal of Fe, neutralization by limestone, and additional treatments.

著者

淵田 茂司 門倉 正和 所 千晴

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.137, no.12, pp.116-122, 2021-12-25 (Released:2021-12-25)

参考文献数

15

被引用文献数

2

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Acid mine drainage (AMD) generation is a serious problem from the environmental and economic perspectives, because it contains a large amount of heavy metals and because there are high costs associated with maintaining the facilities, purchasing neutralizing agents, and disposing sludges; which are required for the treatment process. In this study, changes in AMD quantity and quality for the next decades were predicted by a three series tank model in three stages, by combining the first order kinetic calculation of sulfide minerals' dissolution for two metal mines (X and Y) in Japan. Results from the AMD quality model represented the decrease of heavy metal concentrations below the effluent standard values in 30–140 years, by considering dilution and/or additional dissolution by heavy rain and snow melting, although these predicted values diverged by our previous model. However, the low correlation coefficient values (0.23–0.63) observed between the measured values of heavy metal concentration and the values calculated by our new model, mean that other chemical reactions, such as sulfate and/or carbonate mineral dissolution could greatly affect the AMD quality. In fact, there was no correlation between the metal potential calculated by our model and the real distribution of sulfide minerals at X mine. Our results therefore indicate that specific geochemical reaction and geological information should be included in the AMD quality prediction model, to estimate more accurately the fluctuation of each heavy metal concentration during different seasons.

著者

土岐 知弘 大竹 翼 石橋 純一郎 松井 洋平 川口 慎介 加藤 大和 淵田 茂司 宮原 玲奈 堤 映日 中村 峻介 川喜田 竜平 宇座 大貴 上原 力 新城 竜一 野崎 達生 熊谷 英憲 前田 玲奈

出版者

一般社団法人日本地球化学会

雑誌

日本地球化学会年会要旨集

巻号頁・発行日

vol.64, 2017

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<p>2016年11月16日~12月15日にかけて、SIP「海のジパング計画」の一環として沖縄トラフの伊是名海穴HAKUREIサイトにおいて、地球深部探査船「ちきゅう」を用いて海底熱水域を掘削した。掘削は、HAKUREIサイトの北部マウンドの頂上から、東側に約500 mの測線上において5本、またリファレンスサイトとしてマウンドから北西500 mほど離れた地点において1本を掘削した。採取したコアから、船上でヘッドスペースガス測定用および間隙水抽出用の試料を採取した。試料から抽出した間隙水について、船上でpH、アルカリ度、栄養塩および硫化水素濃度を、陸上で主成分および微量元素濃度、並びにホウ素同位体比を測定した。また、ガス測定用の試料については、船上で炭化水素および水素濃度を、陸上においてメタンの炭素同位体比を測定した。</p>

著者

淵田 茂司 水野 友貴 益田 晴恵 土岐 知弘

出版者

一般社団法人日本地球化学会

雑誌

日本地球化学会年会要旨集 2013年度日本地球化学会第60回年会講演要旨集

巻号頁・発行日

pp.27, 2013 (Released:2013-08-31)

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アミノ酸およびその高分子体は海洋における有機炭素の主要なリザーバーとして,生物地球化学サイクルの中で重要な役割を果たしている。本研究では,南部マリアナトラフ付近から採取した熱水中に含まれるアミノ酸量を測定し,熱水循環に伴うアミノ酸の挙動について考察した。200℃以上の高温の熱水からは,10 μM以上の加水分解性アミノ酸が検出されたが,50℃以下の低温の熱水および海水では1 μM以下で,アミノ酸の濃度は一貫して低かった。一般的に,アミノ酸等の有機分子は温度の上昇に伴不安定となるが,今回,高温の熱水ほどアミノ酸の濃度は高くなった。生物由来のアミノ酸を含む岩石や堆積物と高温の熱水が反応することで,アミノ酸の溶出が促進されているのであろう。