Japan Geoscience Union Meeting 2014

Presentation information

Oral

Symbol U (Union) » Union

[U-05_30PM2] Interrelation between Life, Water, Mineral, and Atmosphere

Wed. Apr 30, 2014 4:15 PM - 5:45 PM 419 (4F)

Convener:*Tsubasa Otake(Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University), Yohey Suzuki(Graduate School of Science, The University of Tokyo), Fumito Shiraishi(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), 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)), Chair:Yohey Suzuki(Graduate School of Science, The University of Tokyo), Takeshi Naganuma(Graduate School of Biosphere Science)

5:15 PM - 5:30 PM

[U05-P13_PG] Soil micromorphology and the effect of biotic activity

3-min talk in an oral session

*Shigeyuki SUZUKI1, Tsutomu HATTORI2, Reiko HATTORI2, Kaori MIMURA3, Munehide ISHIGURO4 (1.Okayama University, 2.Atic Laboratory, 3.Kanematsu-NNK Corporation, 4.Hokkaido University)

Keywords:soil, microaggregate, silica-nano particle, bacteria

Soil is formed on a boundary between geosphere and biosphere in relation with hydrosphere and atmosphere. The major component is quite very fine-grained particles which are not still unknown in detail. A great variety of microbes are associated in soil (e.g., Hattori, 1987). Hattori (2006) suggests that there is a possibility some bacteria produce very fine-grained mineral particles, silica-nano particle as a part of soil material. Micromophology is observed under petrological microscope. The technique for preparation to make thin section from unconsolidated soil is followed by method in FitzPatrick (1993). Soil fragments are examined by scanning electron microscope. Samples are collected from recent cultivated soil (Okayama University Farm), fluvial soil (Sendai City), rice field soil (150 to 2000 years old fluvial soil from Okayama University), paleosol (about 3000 years old organic rich fluvial soil from Dhaka City, Bangladesh).The formation of microaggregates: The structure of soil macroaggregate (1〜2mm) which is composed of microaggregates (0.05〜0.3mm) and sand grains of mineral and rock fragments is observed in the recent cultivated soil from Okayama University Farm. Similar microaggregates (0.1〜0.5mm), structure with heterogeneous granular domains is observed in rice field soil from Okayama University. A paleosol from Dhaka, which is not considered to have artificial effects, also consists of microaggregate. The aggregates do not have distinctive boundary but are distinguished by different compositions (content of organic materials, deposited ferri-hydrite and .manganese dioxide, particles of mineral and rock fragment). Root pipes and cracks are associated in the soil. The compound structure is interpreted to be formed under effects of microorganisms, root and physical process as demonstrated by previous soil research (e.g., FitzPatrick, 1993). The formation of silica-nano particle: Under scanning electron microscope, surface of mineral grain has structures caused by weathering, for example embayment, fracture and etch pit. Crystallized nano-sized minerals are formed on weathered surface of a mineral. A bacterial cell surrounded by radiate fibrous mineral is found. The feature indicates a possibility that some bacteria promote to form minerals. And also there is a possibility that a part of inorganic soil materials might be formed relation with organism.FitzPatrick, E.A. (1993) Soil Microscopy and Micromorphology, WileyHattori, T. (1987) Microbial life in the soil, IwanamiHattori, T. (2006) Soil Microorganisms, 60(2), 105-107