전라남도 나주시 동강면 일대 황토(풍화잔류토)의 토양학적 및 광물학적 특성 연구

Abstract

Department of Physical Science Education, Sunchon National University, Suncheon 540-742, KoreaThe objectives of this study were to characterize the physicochemical properties and mineralogy of Hwangto(yellow residual soils) from the southwestern part of Korea and to understand the soil-forming processes of theresidual soils from their parent rocks. Both the yellowish residual soils as well as the unweathered and weatheredparent rocks were obtained from Jangdong-ri, Donggang-myun, Naju, Jeollanam-do, Korea. The soil samples wereexamined to analyze the said soil's physicochemical properties such as color, pH, and particle size distribution. Ascanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron micros-copy (TEM) and X-ray diffraction (XRD) analysis were performed in order to understand the mineralogy, chemicalcomposition, and morphology of the soils. Two thin sections of a parent rock were analyzed to study its mineralcomposition. A particle size analysis of the soils indicates that the residual soil consists of mainly silt and clay(approximately 95%) and that soil textures are silty clay or silt clay loam. The soil colors of the residual soil aredark brown (7.5YR 3/4) through yellowish red (5YR 4/6). The pH of the residual soil ranges from 4.3 to 5.1. Themajor minerals of the parent rocks were quartz, biotite, chlorite, and plagioclase. The mineralogy of the sand frac-tion of the residual soil was quartz, biotite, muscovite and sanidine. The mineralogy of the silt fraction of the resid-ual soil was quartz, biotite, muscovite, Na-feldspar, K-feldspar, and sanidine. The clay mineralogy of the soil wasgoethite, kaolinite, ilite, hydroxy-interlayed vermiculite(HIV), vermiculite, mica, K-feldspar and quartz. The mineralcomposition of the residual soil and the parent rock indicates that feldspar and mica in the parent rock weatheredinto illite, vermiculite and hydroxy-interlayed vermiculite(HIV), and finally changed into kaolinite and halloysite inthe yellowish residual soils.