Japan Geoscience Union Meeting 2015

Presentation information


Symbol B (Biogeosciences) » B-CG Complex & General

[B-CG28] Interrelation between Life, Water, Mineral, and Atmosphere

Tue. May 26, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Fumito Shiraishi(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), Tsubasa Otake(Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University), Yohey Suzuki(Graduate School of Science, The University of Tokyo), Ken Takai(Extremobiosphere Research Center, Japan Agency for Marine-Earth Science & Technology), Yuichiro Ueno(Department of Earth and Planetary Sciences, Tokyo Institute of Technology), Takeshi Naganuma(Graduate School of Biosphere Science), Takeshi Kakegawa(Graduate School of Science, Tohoku University), Tadashi Yokoyama(Department of Earth and Space Science, Graduate School of Science, Osaka University), Kentaro Nakamura(Precambrian Ecosystem Laboratory (PEL), Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

6:15 PM - 7:30 PM

[BCG28-P04] Immobilization of hazardous anions in andosol and alluvial soil using magnesium oxide

*Mimiko NAKAMURA1, Shoko NOZAWA1, Tsutomu SATO2, Tsubasa OTAKE2 (1.Graduate school of engineering, Hokkaido university, 2.Faculty of engineering, Hokkaido university)

Keywords:Fluorine, Boron, Soil, Magnesium oxide, Immobilization

Soil contamination by hazardous anions is a significant problem in Japan. Magnesium oxide (MgO) has been used as an immobilization agent for hazardous anions such as fluoride and boron. However, it is difficult to optimize the immobilization process because the immobilization depends on the type of soil and the long-term elution behavior of hazardous substances is uncertain.
In this study, to investigate whether MgO can be applied to immobilize fluoride and boron in andosol and alluvial soil and to clarify the immobilization mechanism, the following experiments were conducted; 1) characterization of different types of soil (andosol, alluvial soil), 2) MgO hydration rate determination, 3) interactions between soils and MgO, 4) fluoride and boron sorption behavior onto MgO, 5) immobilization experiments using the soils under several pH and anion loading.
The possible mechanisms of immobilization of fluoride and boron in andosol and alluvial soil using MgO are as follows. Fluoride is immobilized via incorporation into the magnesium hydroxide (Mg(OH)2) structure during the MgO hydration reaction. On the other hand, boron is immobilized by coprecipitation with magnesium following the formation of a magnesium borate complex. To summarize, proposals for carrying out immobilization were made. To immobilize the anions, MgO should be added into the soils to establish the above mechanisms. One significant point is that MgO addition should take the pH buffering capacity of soils into account.