• 한국지하수토양환경학회지:지하수토양환경
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• 제20권5호
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• pp.26-33
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• 2015

Batch experiments were performed to investigate the feasibility of a surfactant-enhanced soil washing process for soils heavily contaminated with crude oil in Kuwait. TPH concentration of the contaminated soil was 223,754 mg/kg, sampled from the bottom of a vaporized oil extraction pond in the Burgan reservoir field. Commercialized eight nonionic surfactants (Tween and Tergitol series) were used to measure the aqueous solubility for the crude oil. Among them, two Tergitol surfactants were used to evaluate the TPH removal efficiency of the surfactant-enhanced soil washing for heavily contaminated Kuwait soil. The solubility of the crude oil in surfactant solution was in the order Tergitol 15-S-7 > Tergitol 15-S-9 > Tergitol 15-S-12 > Tween-80 > Tween-20 > Tween-60, which showed that the crude oil solubilities of the Tergitol series were higher than those of the Tween series. The TPH removal efficiencies of 2% and 5% Tergitol 15-S-9 solution were 59% and 65%, respectively. Because the residual TPH concentration in the washed soil was still higher than the clean-up level (10,000 mg/kg), the soil washing process was repeated five times. After the fifth washing, the residual TPH concentration in the soil went down to 7,680 mg/kg and its removal efficiency was 97%.

• 한국환경복원기술학회지
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• 제5권3호
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• pp.9-14
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• 2002

It is common that the soil layer is few meters below the earth surface and there are rock masses below the soil layer in the view of geological characteristics in Korea. The boundary between rock and soil is clearly divided. When dealing with the stability of rock masses, as in the case of rock slopes or dam foundations, the majority of the collapses is not within the soil layer, but within the soil-rock boundary. Therefore, it is important to identify the shear strength characteristics between soil-rock contacts. It has been common practice to assume that the strength of the soil or shale represents the minimum strength present. However, it has been suggested by Patton(1968) that such an assumption may not be valid and that lower shear strengths might be obtained along the soil-rock interface than for either material alone. Then, in this thesis, introduce rock and residual soil shear strength tests and the specimen preparation and testing procedures are described in detail and also the testing results are presented and discussed.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1999년도 정기총회 및 춘계 공동 학술발표회
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• pp.57-57
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• 1999

• 한국환경농학회지
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• 제39권1호
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• pp.44-49
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• 2020

BACKGROUND: Benzo(a)pyrene is a highly toxic substance which has been listed as a Group I carcinogen by the International Agency for Research on Cancer. There have been numerous studies by researchers worldwide on benzo(a)pyrene. Soxhlet, ultrasound-assisted, and liquid-liquid extractions have been widely used for the analysis of benzo(a)pyrene. However these extraction methods have significant drawbacks, such as long extraction time and large amount of solvent usage. To overcome these disadvantages, we aimed to establish a rapid residual analysis of benzo(a)pyrene content in agricultural products and soil samples. METHODS AND RESULTS: A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was used as the pretreatment procedure. For rapid residual analysis of benzo(a)pyrene, a modified QuEChERS method were used, and the best codition was demonstrated after various performing instrument analysis. The extraction efficiency of this method was also compared with Soxhlet extraction, the current benzo(a)pyrene extracting method. Although both methods showed high recovery rates, the rapid residual analysis method markedly reduced both the measurement time and solvent usage by approximately 97% and 96%, respectively. CONCLUSION: Based on these results, we suggest the rapid residual analysis method established through this study, faster and more efficient analysis of residual benzo(a)pyrene in major agricultural products such as rice, green and red chili peppers and also soil samples.

• Geomechanics and Engineering
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• 제23권6호
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• pp.513-521
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• 2020

In this paper, due to the need for cutting cement-soil group pile composite foundation under the 7-story masonry structure of Zhenghe District and the shield tunnel of Zhengzhou Metro Line 5, a field test was conducted to directly cut cement-soil single pile composite foundation with diameter Ф=500 mm. Research results showed that the load transfer mechanism of composite foundation was not changed before and after shield tunnel cut the pile, and pile body and the soil between piles was still responsible for overburden load. The construction disturbance of shield cutting pile is a complicated mechanical process. The load carried by the original pile body was affected by the disturbance effect of pile cutting construction. Also, the fraction of the load carried by the original pile body was transferred to the soil between the piles and therefore, the bearing capacity of composite foundation was not decreased. Only the fractions of the load carried by pile and the soil between piles were distributed. On-site monitoring results showed that the settlement of pressure-bearing plates produced during shield cutting stage accounted for about 7% of total settlement. After the completion of pile cutting, the settlements of bearing plates generated by shield machine during residual pile composite foundation stage and shield machine tail were far away from residual pile composite foundation stage which accounted for about 15% and 74% of total settlement, respectively. In order to reduce the impact of shield cutting pile construction on the settlement of upper composite foundation, it was recommended to take measures such as optimization of shield construction parameters, radial grouting reinforcement and "clay shock" grouting within the disturbance range of shield cutting pile construction. Before pile cutting, the pile-soil stress ratio n of composite foundation was 2.437. After the shield cut pile is completed, the soil around the lining structure is gradually consolidated and reshaped, and residual pile composite foundation reaches a new state of force balance. This was because the condensation of grouting layer could increase the resistance of remaining pile end and friction resistance of the side of the pile.

• 한국환경복원기술학회지
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• 제7권6호
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• pp.39-48
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• 2004

The purpose of this paper was to confirm the application of the equation of the soil-water characteristic curve on an unsaturated soil. To this ends, a series of suction test was conducted on the selected 4 kinds of soil which is located in Korea, using the modified pressure extractor apparatus. And it was carried out to analyze the experimental parameters which can describe the soil-water characteristics, were determined by using the data obtained from the experiment. From the results, it was found that the matric suction was varied according to the grain size distribution, amount of fine grain particle and void ratio. Also it was found that the residual volumetric water content was decreased with the void ratio, but the index related air entry value, the soil parameter related water content and the parameter with residual water content were increased with the void ratio. And the application of equation of the soil-water characteristic curve was confirmed for the various conditions and the various state by the comparison between the volumetric water content measured by the experiment and the predicted values.

• International Journal of Railway
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• 제4권1호
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• pp.1-4
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• 2011

In this study, the feasibility of using bioremediation to treat lubricant-contaminated soil around railroad turnouts was investigated. Lubricants used during the maintenance of railroad turnouts can drip onto the ground causing soil contamination. In the laboratory experiments, the residual TPH (Total Petroleum Hydrocarbons) concentration in soil gradually decreased after microorganisms degrading the lubricants were added. Generally, the soil around railroad turnouts is covered by a layer of ballasts. In the column experiments that were designed considering field sites, the removal efficiency of TPH was about 11% after 60 days of cultivation time. In the field experiments, microorganisms were added into the soil periodically, and finally the residual TPH concentrations were reduced to less than 1,700 mg/kg-soil on average. These results indicate that the lubricant in the contaminated soil around railroad turnouts could be efficiently removed through bioremediation method.

• 한국환경농학회지
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• 제40권4호
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• pp.260-269
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• 2021

BACKGROUND: Diquat dibromide is a fast-acting nonselective herbicide and plant growth regulator. In this study, in order to understand the possibility of unintentional pesticide contamination in the following crops, the phytotoxicity and transition of diquat dibromide residue in soil into the following crops such as pepper, radish, lettuce and corn have been assessed through phytotoxicity trial and residual evaluation in the unintentional contamination of the higher residual diquat dibromide. METHODS AND RESULTS: The pepper, radish, lettuce and corn were cultivated in the sandy soil and loam soil where the 35 mg/kg and 90 mg/kg diquat dibromide were applied, respectively. Mild growth inhibition symptoms were observed in radish, lettuce and corn crops at the 90 mg/kg- diquat dibromide treatment on the 30 day of cultivation. Diquat dibromide was analyzed using liquid chromatography QTRAP (LC-MS/MS). The recovery rates of diquat dibromide from soil and crop were determined within range from 89.1 to 116.4% with relative standard deviation less than 14.7%. Diquat dibromide residues in soil were found to be 23.90-30.22 and 69.59-82.57 mg/kg from the 35 mg/kg and 90 mg/kg of diquat dibromide-treated soil, respectively after 30 days of crop cultivation. This result implicates that diquat dibromide did not convert to metabolites and remained mostly in the soil, even though it was partially decomposed during crop cultivation. In addition, the diquat dibromide in pepper and radish that were grown for 47 days, and lettuce and corn that were cultivated for 30 days were detected to be 0.01 mg/kg or less in the sandy loam and loam soil where the 90 mg/kg diquat dibromide was applied. CONCLUSION(S): Diquat dibromide did not cause severe phytotoxicity in the following crops as well as it did not uptake and distribute to the following crops, even though it was considered to be residual in the soil.

• 분석과학
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• 제10권3호
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• pp.168-178
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• 1997

기체 크로마토그래피법을 이용하여 제초제인 ethalfluralin의 잔류분석을 위한 최적 측정 조건을 구하고, 토양에서의 잔류량과 반감기를 조사하였다. 토양시료를 methanol과 dichloromethane으로 추출하여 농축하였다. Toluene으로 다시 녹이고, cyanosilica gel 카트리지로 분리하여 전자포착형 검출기가 장착된 기체 크로마토그래프(GC-ECD)로 분석하였다. 0.1과 1.0ppm의 표준물을 첨가하였을 때, 92.8~101.2%의 회수율을 얻었으며, 검출한계는 0.004ppm이었다. Ethalfluraline의 반감기는 토양 (A)의 경우에는 실내에서 35일, 야외에서 7.2일이었으며, 토양 (B)의 경우에는 실내에서 45일, 야외에서 9.7일이었다.

• Geomechanics and Engineering
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• 제14권2호
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• pp.115-129
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• 2018

This paper presents a set of results of plate load tests that imposed incremental cyclic loading to a sandy soil bed containing multiple layers of granulated rubber-soil mixture (RSM) at large model scale. Loading and unloading cycles were applied with amplitudes incrementally increasing from 140 to 700 kPa in five steps. A thickness of the RSM layer of approximately 0.4 times the footing diameter was found to deliver the minimum total and residual settlements, irrespective of the level of applied cyclic load. Both the total and residual settlements decrease with increase in the number of RSM layers, regardless of the level of applied cyclic load, but the rate of reduction in both settlements reduces with increase in the number of RSM layers. When the thickness of the RSM layer is smaller, or larger, settlements increase and, at large thicknesses may even exceed those of untreated soil. Layers of the RSM reduced the vertical stress transferred through the foundation depth by distributing the load over a wider area. With the inclusion of RSM layers, the coefficient of elastic uniform compression decreases by a factor of around 3-4. A softer response was obtained when more RSM layers were included beneath the footing damping capacity improves appreciably when the sand bed incorporates RSM layers. Numerical modeling using "FLAC-3D" confirms that multiple RSM layers will improve the performance of a foundation under heavy loading.