• Journal of the Korean Geosynthetics Society
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• v.7 no.3
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• pp.17-24
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• 2008

This study is conducted to investigate the possibility of the utilization of the mixed soil formed by mixing stone sludge, bentonite, and residual soil as a soil sealant sustaining both stability and capacity in the barrier system. A series of tests were performed on the mixed soils to evaluate basic properties such as compaction, compressive strength, permeability and CBR of these materials. The results indicates that as the stone sludge content increases, the optimum moisture content increases a little, but the maximum dry density decreases. The compressive strength and CBR decrease, and the cohesion, internal friction angle and expansion ratio increase. When the bentonite content increases, the maximum dry density decreases, and the optimum moisture content, compressive strength and cohesion, internal friction angle, CBR and expansion ratio increase. Mixing ratio of the mixed soil contained with the stone dust more than 10% and the bentonite less than 10% satisfies the standard of the permeability coefficient as the soil sealant.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.82-85
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• 2009

This study was performed to investigate if elevated $CO_2$ affects the residue pattern of $^{14}C$ in the soil environment after $^{14}C$-carbaryl treatment $^{14}C$-carbaryl was applied on the rice plant-grown greenhouse soil exposed to atmospheric and elevated $CO_2$ conditions. $^{14}C$-radioactivity was measured in the rhizospheric soil and rice straw samples six months after $^{14}C$-carbaryl application. Significantly high radioactivity was observed in the soil exposed to atmospheric $CO_2$ as compared to that in the soil exposed to elevated C(h. Background level of radioactivity was observed in rice plant samples. These observations suggest the possibility that elevated $CO_2$ may affect residual radioactivity of $^{14}C$-carbaryl in the soil rather than that in the plant.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.461-470
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• 2001

The Shihung mine was restored in the early 90's after abandonment for 20 yews since 1973. Although disposed mine tailings were removed and the site was replaced by an incineration plant, still some residual mine tailings remain in the places including the old mine tailing ditposal area and the adjacent agricultural area. These residual mine tailings are prone to impose an adverse impact on the soil and groundwater and needs investigation for the potential contamination. Mine tailing samples were collected from the old tailing disposal area and the iii paddy. The porewater from the mine tailing were extracted and analysed to investigate chemical changes along the reaction path. Batch leaching tests were also carried out in the laboratory to find any supporting evidence found in the field analysis. Evidence of elemental leaching was confirmed both by the mine tailing and the porewater chemistry in them. The element concentrations of Cu, Cd, Pb, Zn in the porewater exceed the standard for drinking water of Korean government and US EPA. Leaching of heavy metals from the mine tailing seem to be responsible for the contamination. In batch leaching test. heavy metals were either continuous1y released or declined rapidly. Combining the information with porewater variation with depths and the geochemical meodeling results, most of elements are controlled by dissolution and/or precipitation processes, with some solubility controlling solid phases (Cu, Pb, Fe and Zn). Batch leaching test conducted at fixed pH 4 showed much higher releases for the heavy metals up to 400 times (Zn) and this area is becoming more vulnerable to soil and groundwater pollution as precipitation pH shifts to acidic condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.68-71
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• 2005

We conducted simple experiments to consider the influence of nonlinear groundwater flow on Trichloroethylene (TCE) as Dense Non-Aqueous Phase Liquid (DNAPL) migration in a rough walled single fracture. A glass replica of a granite sample containing a rough single fracture was made and experiments were conducted over a range of Re. Observations are compared to the results of TCE migration tests that were conducted in two parallel glass plates over the same range of Re. Results show nonlinear groundwater flow in a single fracture affect TCE migration path and residual saturation of TCE.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.429-432
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• 2005

Geophysical investigations, as a non-invasive method, were conducted at the former gas station site contaminated with fuel hydrocarbons. GPR (Ground Penetrating Radar) survey was performed to locate buried objects such as USTs (Underground Storage Tanks) and fuel pipes which might serve as a origin of the site contamination. Additional GPR investigation and a resistivity survey were conducted to map water table and to characterize shallow geologic structures of the site. The results of the study have shown that seven USTs including one unknown UST and buried fuel pipes are present, and that the groundwater elevation varies with topography from approximately 1.5 to 3m below the surface and the water table is located in the residual soils above the bedrock in the site. The results also show that the geophysical methods can be a very useful tool for the characterization of the contaminated site.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.275-280
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• 2001

Although important developments have taken place since ESOPT 1974 both with respect to the test method as well as the interpretation of the results, many uncertainties still remain in the Standard Penetration Test(SPT). The main pitfall of SPT is that it has not been standardized differing from its terminology and further, the possibility of standardization is very low in practice. Therefore, lack of knowledge on the equipment and method of SPT tends to cause some errors in interpretation of the results. It Is especially important to understand this tendency in domestic design, because most foundations are designed based on SPT results only. Many researchers have made an effort to minimize the uncertainties of SPf in Korea, it is not cleary defined what the most effective method of execution and interpretation of SPT Some uncertainties which many geotechnical engineers encounter in practice are introduced to discuss about improvement of test procedure and interpretation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.06a
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• pp.79-83
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• 1998

This study was conducted to delineate plume occurred in hazardous waste disposal site. At first, CPT (Cone Penetrometer Test) rig and HydroPunch were used to collect depth-discrete groundwater samples in concerned area. However, it was not capable of sampling the groundwater due to the cone refusal where the residual clay are layered at nominal depth through the aquifer. Alternatively, a number of temporary wells were installed after each of locations was penetrated using a modified steel cone functioned by CPT rig. The samples taken from those of wells were characterized by GCMS and GCFID, which revealed that sulfolane and thiolane were mainly presented. Subsequent analyses performed for the samples taken from permanent nest piezometers consistently demonstrated that possible plume boundary can be presented in the study area where contaminants were found as low as detection limit or levels of not-detectable.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.45-53
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• 2015

This study has obtained Soil Water Retention Curve (SWRC) of the unsaturated soil from the volumetric pressure plate extractor test and the triaxial compression tests was also conducted. By using the rainfall data measured in the site the seepage analysis of unsteady flow was performed with the program of SEEP/W in Geostudio 2007 and stability of the slope was analyzed with SLOPE/W program. Results of analyses show that shear strength of the unsaturated soil increases with the increase of matric suction. And it was also found that the net volumetric stress and the apparent cohesion increased with the matric suction. The seepage analysis of rainfall represents that the increasing rate of negative pore pressure at the zone of large negative pore pressure is appeared to be high even though lower rainfall intensity, but this tendency declines with ground depth. The stability analysis of slope was carried out for the actual plane of failure with the data representing the field condition. The factor of safety thus calculated was about unity (1.0) or just below, which means that the adopted method of analysis is in good agreement with the field condition.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.148-155
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• 2014

The transfer pattern of chlorpyrifos present in soil to cucumber plants were assessed and reported with plant growth, concentration dependency, and duration. Cucumber seedlings cultivated in a growth chamber for 30 days and a greenhouse for 120 days. Weight and length of cucumbers cultivated in the chamber increased with the increasing time, while the uptake of chlorpyrifos by cucumber increased a period from 0 to 15 days and decreased after 15 days. Uptake rates of chlorpyrifos into a cucumber plant were 1.0~1.3% to initial amounts treated with 20 and 40 mg/kg to soil. Most chlorpyrifos residues were detected in root, followed by stem and leaf. Results of the greenhouse test showed that chlorpyrifos amounts in cucumber fruits were present less than LOQ (0.02 mg/kg), and chlorpyrifos was mainly found in the root of the cucumber plant. Chlorpyrifos absorbed in a cucumber under greenhouse condition was smaller than that in chamber condition as 0.03~0.04%. Degradation patterns of chlorpyrifos in soils were similar during indoor and outdoor tests with half-lives of 25.8~73.0 days. These results may be useful for establishing the management strategy of residual pesticides in soil environment.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.14-21
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• 2015

To determine residual characteristics of azoxystrobin in ginseng under different cultivation conditions such as use of straw mat on cultivation soil and filling gap between ginseng stem and soil surface and also to elucidate its approximate behavior after spraying, 20% azoxystrobin suspension concentrate solution was sprayed 4 times onto 5-year-old ginseng with 10 days interval at a application rate of about 200 L/10 a and then residues in samples were analyzed. The residue level was lower in case of use of straw mat and filling the gap with soil than in case of no use of straw mat and no filling the gap, representing that use of straw mat and filling the gap with soil were contributed to decrease of pesticide residues in ginseng. A large portion of the test pesticide distributed onto ginseng leaf with a higher specific surface area. The amounts of azoxystrobin residues decreased in ginseng leaf, while increased on soil surface, as close to harvest. About 0.1% of azoxystrobin sprayed was distributed in ginseng root and 12.7-20.4% (mean 16.6%) of azoxystrobin could be decreased for dietary intake by removing of rhizome from ginseng root before intake.