• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.39-46
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• 2008

Due to the growth in industrialization, potential hazards in subsurface environments are becoming increasingly significant. The extraction of the contaminant from the soil and movement of the water are restricted due to the low permeability and adsorption characteristics of the reclaimed soils. There are a number of approaches to in-situ remediation that are used in contaminated sites for removing contaminants. These include soil flushing, dual phase extraction, and soil vapor extraction. Among these techniques, soil flushing was the focus of the investigation in this paper. Incorporated technique with PVDs has been used for dewatering from fine-grained soils for the purpose of ground improvement by means of prefabricated vertical drain systems. The laboratory model tests were performed by using the flushing tracer solutions for silty soils and recorded the tracer concentration changes with the elapsed time and flow rates. The modeling was intended to predict the effectiveness and time dependence of the remediation process. Modeling has been performed on the extraction, considering tracer concentration and laboratory model test characteristics. The computer model used herein are SEEP/W and CTRAN/W, this 2-D finite element program allows for modeling to determine hydraulic head and pore water pressure distribution, efficiency of remediation for the subsurface environment. It is concluded that the coefficient of permeability of contaminated soil is related with vertical velocity and extracted flow rate. The vertical velocity and extracted flow rate have an effect on dispersivity and finally are played an important role in-situ soil remediation.

• Economic and Environmental Geology
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• v.54 no.3
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• pp.399-408
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• 2021

Natural soil was artificially contaminated with heavy metals (Cd, Pb, and Zn), and the movement of earthworm was characterized in real time using the ViSSET system composed of vibration sensor and the other components. The manifestation mechanism of ecological toxicity of heavy metals was interpreted based on the accumulative frequency of earthworm movement obtained from the real-time monitoring as well as the conventional indices of earthworm behavior, such as the change in body weight before and after tests and biocumulative concentrations of each contaminant. The results showed the difference in the earthworm movement according to the species of heavy metal contaminants. In the case of Cd, the earthworm movement was decreased with increasing its concentration and then tended to be increased. The activity of earthworm was severely increased with increasing Pb concentration, but the movement of earthworm was gradually decreased with increasing Zn concentration. The body weight of earthworm was proved to be greatly decreased in the Zn-contaminated soil, but it was similarly decreased in Cd- and Pb-contaminated soils. The bioaccumulation factor (BAF) was higher in the sequence of Cd > Zn > Pb, and particularly the biocumulative concentration of Pb did not show a clear tendency according to the Pb concentrations in soil. It was speculated that Cd is accumulated as a metallothionein-bound form in the interior of earthworm for a long time. In particular, Cd has a bad influence on the earthworm through the critical effect at its higher concentrations. Pb was likely to reveal its ecotoxicity via skin irritation or injury of sensory organs rather than ingestion pathway. The ecotoxicity of Zn seemed to be manifested by damaging the cell membranes of digestive organs or inordinately activating metabolism. Based on the results of real-time monitoring of earthworm movement, the half maximal effective concentration (EC50) of Pb was estimated to be 751.2 mg/kg, and it was similar to previously-reported ones. The study confirmed that if the conventional indices of earthworm behavior are combined with the results of newly-proposed method, the mechanism of toxicity manifestation of heavy metal contaminants in soils is more clearly interpreted.

• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.45-53
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• 2009

A quick and simple detection method of explosive compounds in environmental matrix (soil and water) can provide a screening step which reduces the number of unnecessary samples and the cost of expensive laboratory analysis at a site investigation. A commercially available EXPRAY$^{(R)}$Explosives Field Detection Kit (EXPRAY) was used to determine the minimum detection concentration and to test the possibility of semi-quantitative analysis of 14 explosive compounds using standard solutions. The results showed that EXPRAY could detect 5 explosive compounds, TNT, RDX, HMX, Tetryl, and TNB, out of 14 US EPA designated explosives. The minimum detection limit of the nitramine explosives was 14 ng/$^2$ for HMX and RDX. EXPRAY was more sensitive to nitroaromatics than the nitramines and the minimum detection limits per unit area (mm$^2$) for Tetryl, TNB, and TNT, were 3 ng, 3 ng, and 0.3 ng, respectively. The semi-quantification of 5 explosive compounds in an order ofmagnitude could be achieved by the intensity of developed color only when EXPRAY was applied on the standard solutions under controlled laboratory conditions. With contaminated soil samples, however, only the presence and type of explosive compounds was identified. Therefore, EXPRAY is an economic and sensitive method that can be used in a screening step for the identification of explosives in the field samples.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.49-57
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• 1997

Naturally-occurring iron minerals, goethite and magnetite, were used to catalyze hydrogen peroxide and initiate Fenton-like oxidation of silica sand contaminated with diesel, kerosene in batch systems. Reaction conditions were investigated by varying H$_2$0$_2$concentration(0%, 1%, 15%), initial contaminant concentration(0.2, 0.5, 1.0g diesel and kerosene/kg soil), and iron minerals(1, 5wt% magnetite or goethite). Contaminant degradations in silica sand-iron mineral-$H_2O$$_2$ systems were identified by determining total petroleum hydrocarbon(TPH) concentration. In case of silica sand contaminated with diesel(1g contaminan/kg soil with 5wt% magnetite) addition of 0%, 1%, 15% of $H_2O$$_2$showed 0%, 25%, and 60% of TPH reduction in 8 days, respectively When the mineral contents were varied from 1 to 5wt%, removal of contaminants increased by 16% for magnetite and 13.1% for goethite. The results from system contaminated by kerosene were similar to those of the diesel. Reaction of magnetite system was more aggressive than that of goethite system due to dissolution of iron and presence of iron(II) and iron(III); however, dissolved iron precipitated on the surface of iron mineral and seemed to cause reducing electron transfer activity on the surface and quenching $H_2$$O_2$. The system used goethite has better treatment efficiency due to less $H_2$$O_2$ consumption. Results of this study showed possible application of catalyzed $H_2$$O_2$ system to petroleum contaminated site without addition of iron source since natural soils generally contain iron minerals such as magnetite and goethite.

• Journal of the Korean GEO-environmental Society
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• v.2 no.1
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• pp.103-114
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• 2001

Sorption studies were conducted to determine if slow sorption fraction is observed in recent1y deposited organic matter by studying wetland soils explicitly. Sorption characteristics of hydrophobic organic compounds (chlorobenzene and phenanthrene) in recently deposited freshwater marsh soils were determined using a batch sorption procedure. Relative indicators of organic matter age were assessed using several techniques including the ratio of elemental oxygen to carbon in the organic matter. Slow sorption characteristics for both surface marsh soil (top 0-2 cm, <5 years old) and deeper marsh soil (below 10-cm, >20 years old) were compared against relatively older PPI (Petro Processors, Inc. Superfund site) and BM (Bayou Manchac) soils to investigate whether soil age can cause differences in sorption of organic compounds in wetland soils. Increases in sorption non-linearity of slow sorption model parameters (increase in KF and decrease in N) explain the existence of slow sorption fraction. The results of slow sorption model indicates the presence of a sizable slow sorption fraction; 25.4 - 26.3% (chlorobenzene) and 1.4 - 1.9% (phenanthrene) of the sorbed mass in wetland soils and 40.0 - 55.93% (chlorobenzene) and 2.9 - 3.19% (phenanthrene) of the sorbed mass in PPI and BM soils, respectively. The slow sorption fraction increased in the order of surface < deeper < PPI < BM soil indicating that size of the slow sorption fraction increases with soil organic matter age.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.13-21
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• 2008

Partitioning tracer method is a useful tool to characterize large domains of the aquifers contaminated with light nonaqueous phase liquids (LNAPLs). Sorption of the partitioning tracers to the organic matter content of soil can potentially influence the efficacy of partitioning tracer method. LNAPL-water partitioning coefficients of tracers ($K_{nw}$), measured by static method, showed linear relationship. Sorption isotherm tests were conducted to evaluate the sorption capacity of the soils packed in the columns and the results were appropriately represented by Freundlich sorption isotherm. The sorption of tracers proportionally increased with the increase of the organic matter content of the soil. Laboratory experiments were conducted in four columns each packed with soils of different organic matter contents to determine the potential interference effects of sorption to soil organic matter content and correction factors for the errors in estimation of LNAPLs by partitioning tracer method. Though there were no contaminants added, breakthrough curves from columns packed with mixture of Jumunjin standard sand and organic matter showed separation of tracers. Columns were then contaminated to residual saturation with kerosene and breakthrough curves were obtained. The results show that sorption of tracers to soil organic matter leads to an increase in the retardation factor (R) and hence, to an overestimation of the saturation of LNAPLs. A relation between the percentage of organic matter content and the corresponding percentage error in the estimation of NAPLs has been developed.

• Journal of Environmental Impact Assessment
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• v.29 no.3
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• pp.157-181
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• 2020

Sediments from rivers, lakes and marine ports serve as end points for pollutants discharged into the water, and at the same time serve as sources of pollutants that are continuously released into the water. Until now, the contaminated sediments have been landfilled or dumped at sea. Landfilling, however, was expensive and dumping at sea was completely banned due to the London Convention. Therefore, this study applied contaminated sedimentation soil of 'Royal Palace Livestock Complex' as soil purification method. Soil remediation methods were applied to pretreatment, composting, soil washing, electrokinetics, and thermal desorption by selecting overseas application cases and domestically applicable application technologies. As a result of surveying the site for pollutant characteristics, Disolved Oxigen (DO), Suspended Solid (SS), Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) exceeded the discharged water quality standard, and especially SS, COD, TN, and TP exceeded the standard several tens to several hundred times. Soil showed high concentrations of copper and zinc, which promote the growth of pig feed, and cadmium exceeded 1 standard of Soil Environment Conservation Act. In the pretreatment technology, hydrocyclone was used for particle size separation, and the fine soil was separated by more than 80%. Composting was performed on organic and Total Petroleum Hydrocarbon (TPH) contaminated soils. TPH was treated within the standard of concern, and E. coli was analyzed to be high in organic matter, and the fertilizer specification was satisfied by applying the optimum composting conditions at 70℃, but the organic matter content was lower than the fertilizer specification. As a result of continuous washing test, Cd has 5 levels of residual material in fine soil. Cu and Zn were mostly composed of ion exchange properties (stage 1), carbonates (stage 2), and iron / manganese oxides (stage 3), which facilitate easy separation of contamination. As a result of applying acid dissolution and multi-stage washing step by step, hydrochloric acid, 1.0M, 1: 3, 200rpm, 60min was analyzed as the optimal washing factor. Most of the contaminated sediments were found to satisfy the Soil Environmental Conservation Act's standards. Therefore, as a result of the applicability test of this study, soil with high heavy metal contamination was used as aggregate by applying soil cleaning after pre-treatment. It was possible to verify that it was efficient to use organic and oil-contaminated soil as compost Maturity after exterminating contaminants and E. coli by applying composting.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.51-56
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• 2007

The toxicities of contaminated soils with 8 consecutive year applications of three levels (12.5, 25.0, and $50.0t\;dry\;matter\;ha^{-1}yr^{-1}$) of four organic sludge [municipal sewage sludge (MSS), industrial sewage sludge (ISS), alcohol fermentation processing sludge (AFPS) and leather processing sludge (LPS)] on earthworm (Eisenia fetida) were examined by using microcosm container in the laboratory. Results were compared with those of pig manure compost (PMC) treated soil. In tests with three treatment levels (12.5, 25.0, and 50.0 t per plot), ISS treated soil showed higher contents of Cu (18.9~26.2 fold), Cr (7.7~34.7 fold), and Ni (14.8~18.8 fold) at 8 years post treatment, than PMC treated soil. LPS treated soil showed higher contents of Cr (35.7~268.0 fold) and Ni (4.5~7.6 fold) than PMC treated soil. There were no great differences in heavy metal contents among MSS, AFPS, and PMC treated soils. In these contaminated soils, earthworm mortalities of MSS and AFPS treated soils at 8 weeks post-exposure were similar to those of PMC treated soil regardless of each treatment level. Toxic effect (26.7~96.7 mortality) on the ISS and LPS treated soils was significantly higher than one of PMC treated soil, with an exception of LPS soil treated with 25.0 t per plot. At 16 weeks post-exposure, earthworm mortalities of AFPS' 12.5 and 25.0 t treated soils were similar to those of PMC treated soil. Toxic effect (53.3~100 mortality) on the 12.5, 25.0, and 50.0 t treated soils of MSS, ISS and LPS, and AFPS' 50.0 t treated soils was significantly higher than those of PMC treated soil. The data suggested that the 12.5, 25.0, and 50.0 t of MSS, ISS and LPS, and AFPS' 50.0 t treated soils were evaluated to have toxicity on earthworm.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.78-84
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• 2013

This study was conducted in order to evaluate the removal process for long-term contamination sources including chlorinated hydrocarbons (TCE and PCE) and explosive compounds (TNT, RDX, and HMX) in underground water using a pulsed-UV system. Crystallized cells containing the contaminants were placed 10, 20, and 40 cm away from a lamp that emits pulsed-UV rays in order to examine how the removal efficiency is influenced by the distance between the source of the light and the compounds. Chlorinated hydrocarbons were completely removed in 30 minutes with a distance of 10 cm, while PCE was completely removed even with a distance of 20 cm. In the case of explosive compounds, removal efficiencies slightly varied depending on the compounds. The majority of the compounds were perfectly removed with a contact time of 10 minutes. In particular, for RDX, the results showed that complete removal was obtained within one minute, regardless of the distance from the UV source. The amount of light energy is in inverse proportion to the distance, and thus the energy reaching the compounds severely diminishes as the distance increases. Therefore, the removal efficiency decreased with increasing distance in the system.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.52-58
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• 2012

Capillary fringe divides the groundwater and the vadose zone controlling the diffusive mass transfer of contaminants and gases. The thickness of capillary fringe is of great importance for the rate of contaminant mass transfer across the capillary fringe. Application of surface active chemicals including surfactants and alcohol-based products into the subsurface environment changes the surface tension of the aqueous phase, which in turn, affects the thickness of the capillary fringe. In this study, a bench-scale model was used to assess the quantitative relationship between the surface tension and the thickness of the capillary fringe. An anionic surfactant (Sodium dodecylbenzene sulfonate, SDBS) and an aqueous solution of ethanol were used to control the surface tension of the groundwater. It was found that the thickness of the capillary fringe is directly proportional to the surface tension. The air entry pressures measured by the Tempe Pressure Cell at different surface tensions using SDBS (200 mg/L) and ethanol (20%, v/v) solutions were in good agreement with the thicknesses of the capillary fringe measured by the model. A simple method to correct the conventional Brooks-Corey model for estimating the air entry pressure was also presented.