• Economic and Environmental Geology
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• v.45 no.2
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• pp.121-135
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• 2012

Soil dispersion and heavy metal leaching with two heavy metal-contaminated soils were studied to derive the optimal dispersion condition in the course of developing the remedial technology using magnetic separation. The dispersion solutions of pyrophosphate, hexametaphosphate, orthophosphate and sodium dodecylsulfate (SDS) at 1 - 200 mM and the pH of solutions was adjusted to be 9 - 12 with NaOH. The clay content of suspension as an indicator of dispersion rate and the heavy metal concentration of the solution were tested at the different pHs and concentrations of the dispersion solution during the experiment. The dispersion rate increased with increasing the pH and dispersion agent concentration of the solution. The dispersion efficiency of the agents showed as follows: pyrophosphate > hexametaphosphate > SDS > orthophosphate. Arsenic leaching was sharply increased at 50 mM of phosphates and 100 mM of SDS. The adsorption of $OH^-$, phosphates and dodecysulfate on the surface of Fe- and Mn-oxides and soil organic matter and the broken edge of clay mineral might decrease the surface charge and might increase the repulsion force among soil particles. The competition between arsenic and $OH^-$, phosphates and dodecylsulfate for the adsorption site of soil particles might induce the arsenic leaching. The dispersion and heavy metal leaching data indicate that pH 11 and 10 mM pyrophosphate is the optimum dispersion solution for maximizing dispersion and minimizing heavy metal leaching.

• Journal of Mushroom
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• v.7 no.1
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• pp.9-21
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• 2009

This study was executed in an attempt to investigate a artificial requisites of fruitbody occurrence. Environmental requirements on habitat for fruitbody occurrence of collected cultures resulted in leading to $13-16^{\circ}C$ and 75% relative humidity, and requiring silt loam of soil texture which had more nutritional substances than a dry field. Optimal temperature was $25^{\circ}C$, medium PDB, and pH 5.0 in cultural conditions. Mannose required of 5% in ASI 59002, 59003, 59004, but 3% in ASI 59001 was selected as optimum carbon source. The substrates stimulating sclerotium formation were cotton waste, or cotton waste + oak sawdust (mixture ratio of 8:2), which had 20% additive of wheat barn respectively. Sclerotium was formed well in the substrate adjusted chemical properties by applying 2% of calcium sulfate. Sclerotium formation was the most effective in the treatment of peat moss + oak sawdust (mixture ratio of 5:5) + 30% of wheat barn.

• Geophysics and Geophysical Exploration
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• v.7 no.2
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• pp.130-135
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• 2004

This paper describes the physical properties of the factors controlling the electrical resistivity of the subsurface. Resistivities of various types of soil and rock samples saturated with sodium chloride solutions having nine different concentrations were measured, and the measured resistivities of these samples were compared with calculated resistivities obtained using the conventional empirical formulas. From the results obtained, we observed that the resistivity of the soil and rock samples increases with increasing in pore-fluids resistivity regardless of the media type. However, between 20 and 200 ohm-m, which is the normal range of resistivity of groundwater, the resistivity of the pore-fluids have little or no effect on the resistivities of the samples used. Below 10 ohm-m, the resistivities of the samples are mainly controlled by the pore-fluids, whereas, in the normal range of resistivity of groundwater, the sample resistivities are controlled by their intrinsic matrix resistivity more than by the pore-fluids resistivity. Also, the measured resistivity of rock and soil samples having more than $20\%$ clay contents showed a good agreement with the calculated resistivity using the parallel resistance model whereas, the calculated resistivities of glass beads correlate with that obtained using Archie's formula. When the pore-fluid resistivity is high, the computation of the resistivity values of the samples using the Archie's formula could not be carried out. Through this study, we were able to confirm that the tests are only applicable to the parallel resistance model considering the intrinsic matrix resistivity within the normal resistivity range of groundwater in the subsurface.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.77-91
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• 2015

This study aims to suggest adequate soil management through the analysis of physicochemical properties of soil in the planting grounds of Incheon International Airport, which was constructed on a massive land reclamation site. Study areas were 5 sites at the international business complex, the passenger terminal, the airport support complex, the free trade zone, and the access road. Soil profile analysis showed that 9 plots out of the 27 plots were hardpan and heterospere within 80cm from the soil surface. The earth laid on the ground was categorized as gravel based soil(4 plots), dredged soil from the sea bottom and mixed reclamation materials(2 plots), clay with poor permeability(3 plots) and waste construction material(1 plot). Average soil hardness was $11.5kg/cm^2$ and soil textures were sandy soil, sandy loam and loamy sand. Average soil pH was 6.7 and average organic matter content was 0.7%. Electrical conductivity was 0.0dS/m and exchangeable cation concentrations were $Ca^{2+}$ 3.4cmol/kg, $Mg^{2+}$ 1.5cmol/kg, $K^+$ 0.3cmol/kg and $Na^+$ 1.0cmol/kg. Average cation exchange capacity was 11.0cmol/kg. Although average figures in Solum mostly meet the landscape design criteria, properties of each soil layer showed various values sometimes over the limit. Base saturations were $Ca^{2+}$ 29.9%, $Mg^{2+}$ 13.3% and $K^+$ 3.7% for lower soil, $Ca^{2+}$ 33.3%, $Mg^{2+}$ 17.0% and $K^+$ 2.7% for mid-soil and $Ca^{2+}$ 32.6%, $Mg^{2+}$ 12.2% and $K^+$ 1.9% for upper soil. Exchangeable sodium percentages were 16.4% for lower soil, 7.5% for mid-soil and 4.7% upper soil. Sodium adsorption rates were 0.8 for lower soil, 0.3 for mid-soil and 0.2 for upper soil. Factors affecting to the vegetation growth were heterogeneity and poorness of solum, disturbance of dredged soils, high soil hardness including hardpan in the subsurface soil layer and shallow effective soil depth, high soil acidity, imbalance of base contents, low organic matter content and low available phosphate levels in the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.131-155
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• 1983

Though it has been widely known the nitrogen effects are influenced by soils, varieties, and mineral nutrients in the rice culture, few analyses in relation to the factors increasing nitrogen effect have been studied in Korea. The effects of potassium and silica on the factors increasing nitrogen effects in paddy soils were investigated in accordance with soil improvement practices and nitrogen application methods for the cultivated varieties. The results obtained are as follows. 1. For 413 paddy fields, the yield from soils without nitrogen application ranged from 200 to 850kg/10a and that from nitrogen application did 350 to 1,051kg/10a. The yield increament by nitrogen application varied 50 to 650kg/10a depending on soils. 2. Soil chemical characteristics for high yield were different between with nitrogen and without nitrogen application. In the without nitrogen application, however, contents of organic matter, phosphorous, potassium and calcium of high yield soils were lower than those of low yield, while the available silica content was higher in the former. 3. The yield increased with nitrogen application up to 22.4kg/10a and thereafter it decreased. These phenomena were supposed to be not be decrease of nitrogen uptake but by lowered silica uptake. 4. Clay soil incorporation, deep plough, and inorganic constituents control such as Ca, Mg, and $Sio_2$ were effective as soil improvement praitices. It was appeared that increases of silica content and Ca/Mg ratio were important to increase nitrogen effects. 5. For the correlation between yield and yield components, it was high between yield and panicle in low nitrogen level and so was it between grain yield and ripening rate in high nitrogen. 6. In the urea and super granule urea application plot, recovery rate of nitrogen by plant and soil was high and yield was remarkable high. 7. Regardless of fertilizer types such as ammonium sulfate and urea, the residual nitrogen was about 4kg/10a in both plots of 5.8 and 11.6kg/10a. N applied. 8. The potassium application to soil enhanced the nitrogen efficiency. It was more effective in low potassium soil. 9. Optimum pH value for gel formation in the 4% sodium silicate solution was approximately 6.6. 10. It was suggested that silica could affect to rice plant growth as the inorganic and organic chemical components.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.33-47
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• 2003

Various applied-mineralogical characterization including measurements of surface area, size distribution, swelling index, and viscosity were done for some domestic bentonites in order to decipher the rheological properties and their controlling factors. The bentonites, which are Ca-type and relatively low-grade (rnontmorillonite contents: 30 ∼ 75 wt%), occur mostly as subhedral lamellas with the size range of 2 ∼ 4 $\mu\textrm{m}$. The size distribution of mineral fractions in bentonite suspension is dominant in the range of 10 ∼ 100 $\mu\textrm{m}$, and though rather complicated, exhibits roughly bimodal patterns. The feature is more conspicuous in the case of zeolitic bentonite. The bentonites have surface areas ranging 269 ∼ 735 $\m^2$/g, which are measured by EGME adsorption method. The EGME surface areas are nearly proportional to the rnontmorillonite contents, moisture contents, or total CEC. In the surface area measurements, zeolitic bentonites have slightly higher values than those zeolite- free types. The measured swelling index and viscosity of domestic bentonites are comparatively low in values. The swelling values of bentonites were measured to be 250∼500% at maximum by progressively mixing amounts of 2 ∼ 5 wt% Na$_2$CO$_3$, which varies depending on the contents of rnontmorillonite and other impurities, especially zeolite. Much amount of sodium carbonate is required for optimum swelling property of zeolitic bentonited which has usually strong Na- exchanged capacity. The bentonites, which are comparatively feldspar-rich and low in size and crystallinity, tend to be higher in viscosity values. Tn addition, the viscosity is largely higher in case of the bentonites with higher pH in suspension. However, the rheological properties of bentonites such as swelling index and viscosity do not show any obvious relationships with rnontmorillonite contents and mean particle size in suspension. In contrast, roughly speaking, the swelling index of bentonites is reversely proportional to the values of surface area which can be regarded as a collective physico-chemical parameter encompassing all the effects caused by mineral composition, surface charge, particle size, morphological farm, and etc. in bentonites. Thus, the rheological properties in bentonite suspension appear to be rather complicated characteristics which mainly depend on the flocculation of clay particles and the mode of particle association, i.e. quasicrystals, controlled by surface charge, morphology, size, and texture of rnon-tmorillonite, and which partly affected by the finer impurities such as zeolite.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.147-154
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• 1984

Two Fe-hydrous oxide A,B and one Al-hydroxide minerals were synthesized precipitating Fe $Cl_3$ and $AlCl_3$ with alkali solution(NaOH) at pH 6.0, 12.0 and 4.5 respectively, for precise understanding of physico-chemical and surface charge characteristics of soils in which these minerals are dominant. Identification of these final products, effect of free and amorphous materials on X-ray diffraction analysis, particle size distribution and surface change characterics of these minerals were performed. Fe-hydroxide A and B were identified as great deal of X-ray amorphous material and as goethite with large amount of X-ray amorphous material, respectively. Dehydration by oven at $105^{\circ}C$ of these minerals exhibited akaganeite peaks with low X-ray amorphous hump and pure goethite peaks for Fe-hydroxide A and B, respectively. Both minerals, however, turned into hematite upon firing at $550^{\circ}C$. On the other hand, Al-hydroxide identified as mixture of gibbsite and bayerite of around 7:3 ratio. Application of sodium dithionite and ammonium oxalate solutions for removal of free or amorphous Fe and Al from these minerals revealed that only peak intensities of Al-hydroxide system were enhanced upon Al-extraction by oxalate solution even though dithionite solution was much powerful to extract Fe from Fe-hydrous oxide systems. Original(wet) Fe-hydrous oxide A has the highest specific surface and surface charge development(negative and positive), and the greatest amount of less than $2{\mu}m$ sized particles. Specific surface and clay sized particles(less than $2{\mu}m$) of Fe-hydrous oxide A, however, were drastically reduced upon dehydration($P_2O_5$ and oven drying) compare to the rest minerals. The Z.P.C. of these synthetic minerals were 8.0-8.5, 7.5-8.0 and 5.5-6.0 for Fe-hydrous oxide A, B and Al-hydroxide, respectively.