• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.331-337
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• 2000

When microorganism is injected into porous medium such as soils, biomass retained in the pore. Bacteria within these microcolonies produced large amounts of exopolysaccharides and formed a plugging biofilm. Soil pore size and shape are varied from the initial condition as a result of biofilm formation, which make hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. Also, pore sand of before and after biofilm formation compared with scanning electron microscopy. Hydraulic conductivity of Sand and Poorly Graded Sand was decreased approximately 1/10∼1/100 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition.

• Geomechanics and Engineering
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• v.15 no.6
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• pp.1135-1141
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• 2018

Volume changes of soils induced by inorganic acids cause severe foundation and superstructure failures in industrial buildings. This study aimed to assess the potential of fly ash to control volume changes in soils under acidic environment. Two soils such as black cotton soil predominant with montmorillonite and kaolin clay predominant with kaolinite were used for the present investigation. Both soils exhibited an increase in swelling subjected to phosphoric acid contamination. Ion exchange reactions and mineralogical transformations lead to an increase in swelling and a decrease in compressibility in black cotton soil, whereas phosphate adsorption and mineral dissolution lead to an increase in swelling and compressibility in case of kaolin clay. Different percentages of Class F fly ash obtained from Ramagundam national thermal power station were used for soil treatment. Fly ash treatment leads to significant reduction in swelling and compressibility, which is attributed to the formation of aluminum phosphate cements in the presence of phosphoric acid.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.1
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• pp.125-129
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• 1994

A field survey was carried out in Korea to assess the mineral composition of rice straw since it is a cheap and available cattle feedstuff. Forage and soil samples were collected in 4 localities in the Kyongbuk province. Soil analysis were also carried out in order to establish the relationships between soil composition and mineral content in the rice straw. Based on NRC tables, the rice straw samples provided adequate amounts of Mg, Ca, K, S, Mo, Mn and Zn. Percentages of samples deficient in P, Na, Cu and Se were 83, 50, 67 and 83 respectively. Soil samples, whose mean pH was 5.8 and mean organic matter content was 3.99%, were comparatively acidic and had high organic matter content. They also had high amounts of extractable Fe and Mn. Correlation coefficients between mineral content in soil and rice straw were low, i.e., 0.42 for Me (p < 0.05), and 0.37 for Mo (p < 0.05). The low or nonexistent correlation between soil and forage composition indicates the difficulty of establishing appropriate methods of mineral availability to the plants.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.337-348
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• 2020

Tropical organic soils having more than 65% of organic matters are named "peat". This soil type is extremely soft, unconsolidated, and possesses low shear strength and stiffness. Different conventional and industrial binders (e.g., lime or Portland cement) are used widely for stabilisation of organic soils. However, due to many factors affecting the behaviour of these soils (e.g., high moisture content, fewer mineral particles, and acidic media), the efficiency of the conventional binders is low and/or cost-intensive. This research investigates the impact of different constituents of cement-sodium silicate grout system on the compressibility behaviour of organic soil, including settlement and void ratio. A microstructure analysis is also carried out on treated organic soil using Scanning Electron Micrographs (SEM), Energy Dispersive X-ray spectrometer (EDX), and X-ray Diffraction (XRD). The results indicate that the settlement and void ratio of treated organic soils decrease gradually with the increase of cement and kaolinite contents, as well as sodium silicate until an optimum value of 2.5% of the wet soil weight. The microstructure analysis also demonstrates that with the increase of cement, kaolinite and sodium silicate, the void ratio and porosity of treated soil particles decrease, leading to an increase in the soil density by the hydration, pozzolanic, and polymerisation processes. This research contributes an extra useful knowledge to the stabilisation of organic soils and upgrading such problematic soils closer to the non-problematic soils for geotechnical applications such as deep mixing.

• The Korean Journal of Soil Zoology
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• v.1 no.1
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• pp.37-47
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• 1996

This research was carried out to investigate soil mictoarthropods fauna in Namsan and Kwangreung which were considered to receive different degreeds of environmental pressures. In basic environmental data, Namsan where under rather accelerated acidification by air contamination and acidic rain showed low pH, tardy decomposition and turnover rate. Population density of soil microarthropods was high in Kwangreung 17,169.8/\ulcorner\ulcorner(coniferous forests), 17,892.6/$\textrm{m}^2$(deciduous forests) than in Namsan, 12,143.8/$\textrm{m}^2$ (coniferous forests), 14,216$\textrm{m}^2$(deciduous forests). Biomass of soil microarthropods was 2,020.219mg/$\textrm{m}^2$ at coniferous forests and 4,270.172mg/$\textrm{m}^2$ at deciduous forests in Namsan, and 3,287.326mg/$\textrm{m}^2$ at coniferous forests and 4326.1mg/$\textrm{m}^2$ at deciduous forests in Kwangreung. Population density constantly showed high in spring, and seasonal fluctuations were correlated with seasonal precipitation. As far as vertical distribution is concerned, population density was concentrated in litter layer as 70% while 30% are in soil layer and also decreased with increasing depth.

• Nuclear Engineering and Technology
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• v.11 no.2
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• pp.105-110
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• 1979

In order to evaluate the effect of gamma ray irradiation to the soils added with several organic matters on release sad fixation of $^{65}Zn$, a soil incubation test was carried out by use of an acidic and a calcareous soil. The results obtained were summarized as follows : DTPA extractable $^{65}Zn$ decreased gradually with elapsed time of incubation owing to fixation of $^{65}$Zn by the soils but after four weeks DTPA extractable $^{65}Zn$ was reached an equilibrium state. The most parts of $^{65}Zn$ activity in the equilibrium state was found in the solid phase. The extent of zinc fixation in acidic Keumgok and calcareous Jecheon soils represented as activity basis was 89 and 93.7 per cent of applied $^{65}Zn$ respectively. Increased tendency of DTPA extractable zinc was shown by irradiating gamma ray to both soils because of $^{65}Zn$ fixation could be decreased by irradiation. The extractability of fixed $^{65}Zn$ by DTPA solution was 38.9 per cent in acidic Keumgok soil and only 9.5 per cent in calcareous Jecheon soil. Release of fixed $^{65}Zn$ by irradiation of gamma ray is closely related to pH of both soils. Much more $^{65}Zn$ could be released under low pH condition. Effect of gamma ray irradiation to organic matter sources on release of $^{65}Zn$ could not be differentiated. But in the case of nonirradiated soils, however, glucose treated soils couldrelease much more the extractable zinc as compared to those of the straw or cellulose treatment.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.109-114
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• 2003

To investigate ecophysiological characteristics of plants species adapted to moor habitat, we selected 22 species plants and analyzed inorganic cations (K, Ca, Mg), heavy metals (Al, Fe, Mn) and total nitrogen and phosphorus quantitatively. Moojechi moor indicated typical acidic and oligotrophic conditions with pH of 5.0∼5.6 (pH 4.3∼5.1 in soil) and EC of 15∼30μ S/cm, and contained very low contents of soil divalent cation such as Ca and Mg but high contents of heavy metals (esp. Al). With respect to inorganic cation contents, investigated plants species showed remarkable interspecific difference. Plant species belonging to J. effusus var. decipiens, M. japonica, I. globosa, M. sacchariflorus, R. mucronulatum, R. yedoense var. poukhanense, H. micrantha, D. rotundifolia showed very low contents of inorganic cation below 400 μ M/g DW, but plant species of C. palustris var. spontanea, L. sessilifolia, P. mandarinorum, C. lineare, S. austriaca sub. glabra, V. mandshurica, A. decursiva showed high cation contents in leaves. Especially, S. austriaca sub. glabra (Compositae) and V. mandshurica (Violaceae) showed pattern accumulating Ca and Mg with plant growth, but I. ensata var. spontanea (Iridaceae) and S. officinalis (Rosaceae) showed decreasing tendency. Meanwhile, most plant species showed low contents of soluble metal ions in leaves in spite of high heavy metal contents on soil, and indicated remarkable interspecific differences in the total contents and composition of heavy metals accumulated. Despite low contents of N and P on soil, most plant species indicated relatively high contents of N and P in leaves at the early stage of growth, and showed slowly decreasing pattern according to growth. Consequently, it seems that plant species inhabited on Moojechi moor cope with acidic-oligotrophic conditions, accumulating inorganic cations and nitrogen at the early growing stage and reutilizing them in the course of growth, and developing heavy metal excluding mechanism.

• Applied Biological Chemistry
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• v.41 no.8
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• pp.595-599
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• 1998

An analytical method was developed to determine tricyclazole residues in rice grain, straw, and soil using high-performance liquid chromatography (HPLC) with ultraviolet absorption detection. Tricyclazole was extracted with methanol from moist rice grain, straw, and soil samples. n-Hexane washing was employed to remove nonpolar co-extractives during liquid-liquid partition. Tricyclazole was then extracted with dichloromethane from alkaline aqueous phase, while acidic interferences remained in the phase. Dichloromethane extract was further purified by silica gel column chromatography prior to HPLC determination. Reverse-phase HPLC using an octadecylsilyl column was successfully applied to separate and quantitate the tricyclazole residue in sample extracts monitored at ${\lambda}_{max}$ 225nm. Recoveries from fortified samples averaged $95.5{\pm}3.0%\;(n=6),\;87.5{\pm}20.%\;(n=6),\;and\;84.3{\pm}2.8%$ (n=12) for rice grain, straw, and soil, respectively. Detection limit of the method was 0.02 mg/kg for rice grain and soil samples while 0.05 mg/kg for rice straw samples. The proposed method was reproducible and sensitive enough to evaluate the safety of tricyclazole residues in rice grain, straw, and soil.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.265-273
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• 2011

Bacterial diversity based on the denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA gene sequences was determined for soil samples from two abandoned mine sites and the corresponding enrichment cultures using soil sample as key inoculum. Sequencing analysis of DGGE bands obtained from both the soil samples matched mostly with sequences of uncultured and newly described organisms, or organisms recently associated with the acid mine drainage environment. However, the enrichment of soil samples in ferrous sulfate and elemental sulfur media yielded sequences that were consistent with well-known iron- and sulfur-oxidizing acidophilic bacteria. Analysis of enrichment cultures of soil samples from Dalsung mine revealed abundant ${\gamma}$-$Proteobacteria$, whereas that of Gubong mine sample displayed acidophilic groups of ${\gamma}$-$Proteobacteria$, ${\alpha}$-$Proteobacteria$, $Actinobacteria$ and $Firmicutes$. Chemical elemental analysis of the mine samples indicated that the Dalsung site contained more iron and sulfate along with other toxic components as compared with those of the Gubong site. Biogeochemistry was believed to be the primary control on the acidophilic bacterial group in the enrichment samples.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.2 s.109
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• pp.60-70
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• 2005

This study was carried out to elucidate the vertical characteristics of soil properties at six planted sites of land reclaimed from the sea, in Gwangyang Bay, Jeollanam-do Province, Korea. Based on the types of planting site, the chemical properties of the vertical soil layers varied. The vertical variation was great in the planting sites $Z_1\;and\;Z_2$, but less varied in the mounded planting sites $Z_3,\;Z_5,\;and\;Z_6$. Major reasons for the vertical variation in soil chemical properties included differences in the accumulation of organic matter, soil disturbance by heavy construction equipment, and heterogeneity of soil properties between soil horizons. As soil depths increased, soil salts varied. The electrical conductivity (ECe) increased in the lower areas of planting sites $Z_1\;and\;Z_2$, and the disturbed, saline planting site $Z_3$, but decreased in the lower areas of $Z_3,\;Z_5,\;and\;Z_6$. These tendencies did not coincided with exchange cation concentrations $(Na^+,\;K^+,\;Mg^{++},\;Ca^{++})$. Both total carbon (T-C) and total nitrogen (T-N) accumulated more in the lower areas of planting sites than in the higher areas, and levels were higher closer to the surface than in the soil depths. It is supposed that these tendencies are related to the accumulation of fallen leaves or other organic matter at the soil surface, and the soil chemicals then slowly move downward from the surface. Impediments to tree growth included soil hardiness, high soil salinity and exchangeable cation concentration, low soil moisture content, acidic or alkaline soil, low organic matter, heterogeneity of soil texture and establishment of soil stratification.