Bulletin of the Society of Sea Water Science, Japan
Online ISSN : 2185-9213
Print ISSN : 0369-4550
ISSN-L : 0369-4550
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Volume 74, Issue 4
Displaying 1-11 of 11 articles from this issue
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The 71th Annual Meeting
Preface
Special Issue : “Introduction to corrosion science and monitoring”
Commentary
Original Paper
  • Basic Study on a Localized Corrosion Monitoring System for Piping in an Actual Plant Using the Electrodes of a Short Pipe with a Potential Noise Technique
    Akio NAKAMURA, Hiroyuki INOUE, Kiyomi NAKAJIMA, Koji MASAOKA
    2020 Volume 74 Issue 4 Pages 221-225
    Published: 2020
    Released on J-STAGE: October 01, 2021
    DOIhttps://doi.org/10.11457/swsj.74.4_221
    JOURNAL FREE ACCESS
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    A basic study addressing a localized corrosion monitoring system using the electrodes of a short pipe was carried out to determine whether such a system could be applied to the piping in salt manufacturing plants. A short pipe made of SUS304 stainless steel, the inner surface of which was embedded with platinum electrodes, 76 μm in diameter, to simulate the local anodes, was configured as an evaluation test electrode. An anodic current simulating the local current from localized corrosion during the initial stages was applied to the simulated local anode, and the resulting potential noise response was measured in a 10-mass％ NaCl solution. When an anodic current of a level corresponding to that of the initiation of pit-embryos, 2.6 to 20.5 μm in diameter, was applied to the simulated local anode, synchronized RD-type potential noise was observed. For every investigated waveform of the anodic current, the amplitude of the potential noise increased with applied current.
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Commentary
Original Paper
  • Development of Ion-Exchange Membrane using Electron-Beam-Induced Graft Polymerization
    －Influence of Antioxidants in Polyethylene Film－
    Takaaki SASAKI, Takeshi NAGATANI, Jun-ichi TAYANAGI
    2020 Volume 74 Issue 4 Pages 233-240
    Published: 2020
    Released on J-STAGE: October 01, 2021
    DOIhttps://doi.org/10.11457/swsj.74.4_233
    JOURNAL FREE ACCESS
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    The influence of the antioxidants in polyethylene films on electron-beam-induced graft polymerization was studied. Four kinds of polyethylene film, namely, ultra-high molecular weight polyethylene（UHMWPE）, high-density polyethylene（HDPE）, low-density polyethylene（LDPE）, and LDPE-containing HDPE, were adopted. The antioxidants in these polyethylene films were extracted to enable their identification and quantification. The UHMWPE was found to contain one antioxidant: Irgafos168. Meanwhile, the HDPE and LDPE contained three antioxidants: BHT, Irgafos168, and Irganox1076. The LDPE-containing HDPE contained four antioxidants: BHT, Irgafos168, Irganox1076, and SUMILIZER GP. A monomer solution for graft polymerization to which these antioxidants were added was used for graft polymerization. When phenolic antioxidants such as BHT, Irganox1076, and SUMILIZER GP were added to the monomer solution for graft polymerization, the degree of grafting decreased as the amount of antioxidant increased. The behavior of antioxidants in polyethylene film before and after the electron beam irradiation was studied. Furthermore, the radical-scavenging activities of antioxidant degradants in LDPE-containing HDPE, irradiated with an electron beam, were studied. The amounts of BHT, Irgafos168, Irganox1076, and SUMILIZER GP in LDPE-containing HDPE were found to decrease as the electron beam irradiation dose was increased. When the electron beam irradiation dose was more than 100 kGy, the concentrations of BHT and Irganox1076 decreased to less than 10 ％. For an electron beam irradiation dose of more than 60 kGy, the concentrations of Irgafos168 and SUMILIZER GP decreased to less than 1 ％. A monomer solution for graft polymerization containing the antioxidant degradants in LDPE-containing HDPE, irradiated with an electron beam, was used to graft polymerization. As a result, the radical-scavenging activity of the antioxidant degradants disappeared.
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  • Application of an Automatic Analyzer to Onboard Analysis of Nitrate Concentration in a Reductive Fluid
    Tomohiro TOKI, Jun-ichiro ISHIBASHI, Yuji ONISHI, Toshiro YAMANAKA, Ka ...
    2020 Volume 74 Issue 4 Pages 241-248
    Published: 2020
    Released on J-STAGE: October 01, 2021
    DOIhttps://doi.org/10.11457/swsj.74.4_241
    JOURNAL FREE ACCESS
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    Prior to performance of onboard chemical analysis of nitrate in interstitial waters during the CK16-01 cruise, we conducted some laboratory experiments to estimate precision and accuracy of the determination under interference from hydrogen sulfide. A protocol using a reduction reagent of vanadium chloride was selected for a colorimetric analysis using an automated discrete analyzer. Results of the laboratory experiments certify determination of nitrate concentration of fluid samples that include hydrogen sulfide less of than 1 mM with deviation of 16 ％ in the worst case. Onboard chemical analysis of interstitial waters extracted from drilled sediment cores were demonstrated at Noho site along Iheya Minor Ridge, with several hydrothermal fluids showing that different chemical compositions are distributed in several layers below the seafloor of active hydrothermal field. In the middle of active hydrothermal fields at Iheya North Knoll, it is confirmed that nitrate reduction occurs prior to sulfate reduction below the seafloor.
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  • Evaluation of Productivity on Long-term Culture of Sterile ULVA（Chlorophyta）
    Shin HIRAYAMA, Shuichi TASHIRO, Kohei INOUE, Kazuya URATA, Masafumi II ...
    2020 Volume 74 Issue 4 Pages 249-253
    Published: 2020
    Released on J-STAGE: October 01, 2021
    DOIhttps://doi.org/10.11457/swsj.74.4_249
    JOURNAL FREE ACCESS
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    The sterile Ulva, a green alga, has the potential to grow stably, and is expected to be a resource for feed or food containing various nutrients such as proteins and minerals. Two types of Ulva were isolated from Tokyo Bay and Imari Bay, and these growth rates ［g-dry/m2・d］ were evaluated using a model reactor at Imari. In these experiments, the growth rate of the sterile Ulva lactuca was found to be approximately 11.4 g-dry/m2・d. In addition, a growth rate of 8.1 g-dry/m2・d was also obtained for the Ulva lactuca, which had been repeatedly cultured, and it was found that the Ulva lactuca can be produced in subculture. Furthermore, it was revealed for the first time that Ulva pertusa from Imari Bay can also be continuously cultured for 37 days. From these results, it is believed that the sterile Ulva has the property of being easily cultivated, and there are also species that can be subcultured. Based on these data, we newly proposed a type of efficient sterile Ulva production system using enriched seawater.
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Lecture
Relay Essay (44)
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