Characterization and thermodynamic study of humic acid in deep groundwater at Horonobe, Hokkaido, Japan

Shingo Kimuro, Akira Kirishima, Seiya Nagao, Takumi Saito, Yuki Amano, Kazuya Miyakawa, Daisuke Akiyama, Nobuaki Sato

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


In this study, humic substances (humic acid and fulvic acid) were isolated from deep groundwater at −350 m depth of Horonobe, Hokkaido, Japan to compare the characteristic property and reaction mechanism with generic humic acid isolated from surface soils. The size distributions of Horonobe humic substances were analyzed by size exclusion chromatography, flow-field flow fractionation, and total organic carbon measurement with ultrafiltration. All of them indicated small molecular weight and particle size of Horonobe humic acid in comparison with generic humic acids. Additionally, the simple protonation behavior of Horonobe humic substances similar to benzoic acid and/or phenol was revealed by thermodynamic quantities obtained by potentiometry and calorimetry. Consequently, molecular size and the reaction mechanism of Horonobe humic substances are different from generic humic acids, due to the characteristic origin.

Original languageEnglish
Pages (from-to)503-515
Number of pages13
Journaljournal of nuclear science and technology
Issue number5
Publication statusPublished - 2018 May 4


  • Humic acid
  • characterization
  • saline groundwater
  • thermodynamic quantities

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering


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