• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.38-47
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• 2011

This study focused on health risk assessment via multi-routes of As exposure to establish a target cleanup level (TCL) in abandoned mines. Soil, ground water, and rice samples were collected near ten abandoned mines in November 2009. The As contaminations measured in all samples were used for determining the probabilistic health risk by Monte-Carlo simulation techniques. The human exposure to As compound was attributed to ground water ingestion. Cancer risk probability (R) via ground water and rice intake exceeded the acceptable risk range of $10^{-6}{\sim}10^{-4}$ in all selected mines. In particular, the MB mine showed the higher R value than other mines. The non-carcinogenic effects, estimated by comparing the average As exposure with corresponding reference dose were determined by hazard quotient (HQ) values, which were less than 1.0 via ground water and rice intake in SD, NS, and MB mines. This implied that the non-carcinogenic toxic effects, due to this exposure pathway had a greater possibility to occur than those in other mines. Besides, hazard index (HI) values, representing overall toxic effects by summed the HQ values were also greater than 1.0 in SD, NS, JA, and IA mines. This revealed that non-carcinogenic toxic effects were generally occurred. The As contaminants in all selected mines exceeded the TCL values for target cancer risk ($10^{-6}$) through ground water ingestion and rice intake. However, the As level in soil was greater than TCL value for target cancer risk via inadvertent soil ingestion pathway, except for KK mine. In TCL values for target hazard quotient (THQ), the As contaminants in soil did not exceed such TCL value. On the contrary, the As levels in ground water and polished rice in SD, NS, IA, and MB mines were also beyond the TCL values via ground water and rice intake. This study concluded that the health risks through ground water and rice intake were greater than those though soil inadvertent ingestion and dermal contact. In addition, it suggests that the abandoned mines to exceed the risk-based TCL values are carefully necessary to monitor for soil remediation.

• Journal of Life Science
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• v.23 no.10
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• pp.1273-1279
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• 2013

Aromatic hydrocarbons, such as phenol, have been detected frequently in wastewater, soil, and groundwater because of the extensive use of oil products. Bacterial strains (56 isolates) that degraded phenol were isolated from soil and industrial wastewater contaminated with hydrocarbons. GN13, which showed the best cell growth and phenol degradation, was selected for further analysis. The GN13 isolate was identified as Neisseria sp. based on the results of morphological, physiological, and biochemical taxonomic analyses and designated as Neisseria sp. GN13. The optimum temperature and pH for phenol removal of Neisseria sp. GN13 was $32^{\circ}C$ and 7.0, respectively. The highest cell growth occurred after cultivation for 30 hours in a jar fermentor using optimized medium containing 1,000 mg/l of phenol as the sole carbon source. Phenol was not detected after 27 hours of cultivation. Based on the analysis of catechol dioxygenase, it seemed that catechol was degraded through the meta- and ortho-cleavage pathway. Analysis of the biodegradation of phenol by Neisseria sp. GN13 in artificial wastewater containing phenol showed that the removal rate of phenol was 97% during incubation of 30 hours. The removal rate of total organic carbon (TOC) by Neisseria sp. GN13 and activated sludge was 83% and 78%, respectively. The COD removal rate by Neisseria sp. GN13 from petrochemical wastewater was about 1.3 times higher than that of a control containing only activated sludge.

• Journal of Korea Soil Environment Society
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• v.5 no.2
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• pp.33-43
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• 2000

Mining wastes left without any proper treatment are affecting barren or arable lands where are located near and far from source through various pathway Metals are the only hazardous constituents that cannot be destroyed or altered by chemical or thermal methods and must be converted into the most insoluble and harmless form as possible, which have slower leaching rates than the original species, to prevent their reentry into the environment. Three types of chemical additives used in this study to immobilize heavy metals showed high immobilized capacity (q) and the efficiency (k) in the order of CaO, $Na_2$S.$5H_2$O, and $CaCO_3$. In addition, bentonite was considered as a good additive to remedy AM(Acid Mine Drainage) from the results of the physicochemical characteristics and immobilizing capacity. The Freundlich coefficients (n and k) from adsorption isotherm for the heavy metals adsorbed on 50g Benlonite were calculated.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.69-74
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• 2006

Recently, spillways are need to control stable water level for supporting main dams because of floods by unusual change of weather such as Typhoon Rusa. This study has been focused on the amount of leakage through the rock mass distributed fractures and joints under the opened emergency spillway. It is very important to evaluate the amount of leakage as these affect stability of spillway by interaction between effective stress and pore pressure. The commercial program MAFIC has been used for analyzing groundwater flow in fractured rock mass. The results showed that the values of range, average and deviation of leakage were $2.85\sim\;3.79\times10^{-1}$, $3.32\times10^{-1}$ and $1.70\times10^{-2}\;m^3/day/m^2$ respectively. Secondary, we have estimated the effect of grouting after the transmissivity$(T_f)$ of joint 1 as main pathway of leakage known from above results was changed from $1.78\times10^{-7}$ to $1.59\times10^{-9}\;m^2/s$. The results showed that the values of range, average and deviation of leakage were $7.80\times10^{-4}\sim1.53\times10^{-3}$, $1.18\times10^{-3}$ and $1.32\times10^{-4}\;m^3/day/m^2$ respectively. As the result, the amount of leakage after grouting has been decreased by a ratio of 1 to 277.

• Explosives and Blasting
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• v.27 no.1
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• pp.21-31
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• 2009

An excavation damaged zone (EDZ) is created by fracturing, excavation or stress redistribution of tunnels. In this zone the mechanical and hydraulic properties of rock are changed, which makes additional cracks and serves as a dominant pathway of groundwater flow. In this study, an assessment on an EDZ size was practiced by the measurement of the deformation modulus at the KAERI underground research tunnel (KURT), and the information was applied to the modelling analysis using FLAC2D software. The EDZ at KURT fell into the range of 0.6~1.8m and the deformation moduli of the EDZ generally correspond to about 40% of intact rock mass. With a consideration of the EDZ in numerical analysis, tunnel displacements increased by about 65% and the maximum principal stress decreased to 58% from the case without EDZ. The plastic zone of the tunnel was enlarged to the crown and invert zones of the tunnel within the range of the length of rock bolts. About 2% of the total tunnel displacement with EDZ was suppressed by the KURT support system. It is anticipated that the investigation of an EDZ can be used as an important and fundamental research for validating the overall performance of a high level waste disposal system.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.487-493
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• 2006

Reductive dechlorination of chlorophenols by nickel coated iron was investigated to understand the feasibility of using Ni/Fe for the in situ remediation of contaminated groundwater. Zero Valent Iron(ZVI) was amended with Ni(II) ions to form bimetal(Ni/Fe). Dechlorination of five chlorophenol compounds and formation of intermediates were examined using Ni/Fe. Rate constant for each reaction pathway was quantified by the numerical integration of a series of differential rate equation. Experimental results showed that the sequence of hydrodechlorination rate constant was in the order of 2-CP>4-CP>2,4-DCP>2,4,6-TCP>2,6-DCP. The hydrodechlorination pathways for the conversion of each chlorophenol compound involves a full dechlorination to phenol via both concerted and stepwise mechanisms. Reaction pathways and corresponding kinetic rate constants were suggested based on the experiments and numerical simulations.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.285-293
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• 1994

The transport of radionuclides in a compacted bentonite is dominated by diffusion. Through-diffusion tests for iodide were performed to investigate the diffusion characteristics of anionic radionuclides in a domestic bentonite. The bentonite used was sampled from the southeastern area of Korea and the solution was synthetic groundwater spiked with a tracer of I -125(as Na$^{125}$ I). The dry densities of compacted bentonite were 1.2, 1.4, and 1.7 Mg/㎥. The apparent diffusion coefficients and the effective diffusion coefficients of the iodide decrease with increasing dry density. The values were from 3.80 to 7.12$\times$10$^{-11}$ $m^2$/s for the apparent diffusion coefficients and from 1.25 to 7.97$\times$10$^{-12}$ $m^2$/s for the effective diffusion coefficient, respectively. The experimental results also showed that the apparent diffusion coefficients depended on the pore structure of compacted bentonite and the effective diffusion coefficients were attributed to the pore structure and the effective porosity that represents the available pathway for the diffusional transport of iodide. The results obtained will be used as basic data for the safety assessment of a repository.

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.414-431
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• 2016

There are numerous closed and abandoned mines in Korea, from which diverse heavy metals (e.g., As, Cd, Cu, Pb, Zn) are released into the surrounding soil, groundwater, surface water, and crops, potentially resulting in detrimental effects on the health of nearby residents. Therefore, we performed human risk assessments of two abandoned metal mines, Yanggok (YG) and Samsanjeil (SJ). The exposure parameters used in this assessment were specific to residents near mines and the included exposure pathways were relevant to areas around metal mines. The computed total excess carcinogenic risks for both areas exceeded the acceptable carcinogenic risk ($1{\times}10^{-6}$), indicating that these areas are likely unsafe due to a carcinogenic hazard. In contrast, the non-carcinogenic risks of the two areas differed among the studied receptors. The hazard indices were higher than the unit risk (=1.0) for male and female adults in YG and male adults in SJ, suggesting that there are non-carcinogenic risks for these groups in the study areas. However, the hazard indices for children in YG and female adults and children in SJ were lower than the unit risk. Consumption of groundwater and crops grown in the area were identified as major exposure pathways for carcinogenic and non-carcinogenic hazards in both areas. Finally, the dominant metals contributing to carcinogenic and non-carcinogenic risks were As and As, Cu, and Pb, respectively. In addition, the carcinogenic and non-carcinogenic risks of YG were evaluated to be 10 and 4 times higher than those of SJ, respectively, resulted from the relatively higher exposure concentration of As in groundwater within SJ area. Because of lacking of several exposure parameters, some of average daily dose (ADD) could not be computed in this study. Furthermore, it is likely that the ADDs of crop-intake pathway included some errors because they were calculated using soil exposure concentrations and bioconcentration factor (BCF) rather than using crop exposure concentrations.

• Journal of Environmental Policy
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• v.4 no.1
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• pp.39-67
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• 2005

In order to properly define the terms such as soil, soil contamination, soil contamination site and remediation, which are the key terms under the Soil Environment Conservation Act(SECA) in Korea, we analyzed the legal definitions of the similar key words in legislations of the developed western countries. The selected countries were the United States of America, the United Kingdom, the Netherlands, Germany, and Denmark. The legal definitions of these keywords were very much diversified due to different levels of soil contamination, as well as different industrial, social, and legal backgrounds in each country. However, fair suggestions for definitions of the key terms in SECA were derived from the comparative analyses of these countries. First and foremost, SECA should provide a definition of 'soil' which includes a concept of the natural soil layer produced from soil mineralization processes. Groundwater and sublayer of the groundwater would. be excluded in the boundary of the soil with regards to the Groundwater Act of Korea. Definition of 'soil contamination' of SECA should include a concept of risk assessment(soil contaminants, pathway, and receptors), purpose of land use, and the acquired limitation levels of soil contaminants. Soil contamination activity either industrial or anthropogenic in SECA article2-1, could be substituted for a concept of soil risk assessment. Definition of 'soil contamination site' could derive from amalgamating the concepts of i) soil contamination in conjunction with contaminants, ii) risk assessment, iii) a concept of land use, and iv) knowing limitation of contamination site designation. Definition of 'remediation of contaminated site' should include the objective, intention, action, methodology and limit of the remediation. These suggested definitions would increase the efficacy of soil environment conservation policies, which includes the survey of the potentially contaminated area, remediation, and removal of the site.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.305-315
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• 2020

For geological disposal of radioactive wastes, a method was proposed to evaluate the radionuclide transport in the biosphere by calculating the elapsed time of nuclide migration. The radionuclides were supposed to be introduced from a natural barrier and reached a large surface water body following a groundwater flow in a shallow subsurface. The biosphere was defined as a shallow subsurface environment that included aquifers on a host rock. Using the proposed method, a calculation algorithm was established, and a computer code that implemented the algorithm was developed. The developed code was verified by comparing the simulation results of the simple cases with the results of the analytical solution and a public program, which has been widely used to evaluate the radiation dose using the radionuclide transport near the surface. A case study was constructed using the previous research for radionuclide transport from the hypothetical geological disposal repository. In the case study, the code calculated the mass discharge rate of radionuclide to a stream in the biosphere. Because the previous research only demonstrated the transport of radionuclides from the hypothetical repository to the host rock, the developed code in the present study could help identify the total transport of radionuclide along the complete pathway.