• Environmental Analysis Health and Toxicology
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• 제28권
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• pp.6.1-6.7
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• 2013

Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.100-107
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• 2000

In a recently developed strategy for in-situ treatment of polychlorinated biphenyls (PCB), bioaugmentation was used in conjunction with a surfactant, sorbitan trioleate, as a carbon source for the degrader bacteria, along with the monoterpene, carvone, and salicylic acid as inducing substrates. Two bacteria were used for soil inoculants, including Arthrobacter sp. st. B1B and Ralstonia eutrophus H850. This methodology achieved 60% degradation of PCBs in Aroclor 1242 after 18 weeks in soils receiving 34 repeated applications of the degrader bacteria. However, an obvious limitation was the requirement for soil mixing after every soil inoculation. In the research reported here, bioaugmentation and biostimulation treatment strategies were modified by using the earthworm, Pheretima hawayana, as a vector for dispersal and mixing of surface-applied PCB-degrading bacteria and soil chemical amendments. Changes in microbial biomass and microbial community structure due to earthworm effects were examined using DNA extraction and PCR-DGGE of 16S rDNA. Results showed that earthworms effectively promoted biodegradation of PCBs in bioaugmented soils to the same extent previously achieved using physical soil mixing, and had a lesser, but significant effect in promoting PCB biodegradation in biostimulated soils treated with carvone and salicylic acid. The effects of earthworms were speculated to involve many interacting factors including increased bacterial transport to lower soil depths, improved soil aeration, and enhanced microbial activity and diversity.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권3호
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• pp.1-7
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• 2003

지하 유류저장탱크에서 유류가 지속적으로 누출되는 경우에는 지하수 이동에 비해서 LNAPL의 이동을 무시할 수 없다. 본 연구에서는 지하수면 위에서 LNAPL의 이동을 고려한 수정된 용질이동 모델을 개발하였다 LNAPL 이동을 고려하지 않는 기존 모델과 비교한 결과 수두 구배, 누출되는 기름의 양, 분산지수에 따라 두 모델은 차이점을 보였다. 수두 구배가 낮을수록, 누출되는 유류의 양이 증가할수록 수정된 모델과 기존 모델 사이의 평균편차가 증가하였다. 분산지수가 변화함에 따라서 평균편차는 변하지 않았지만, 분산지수가 증가할수록 두 모델 사이의 편차는 공간적으로 보다 넓게 나타났다. 수직방향으로의 분산이 크게 나타날 경우에는 LNAPL의 이동을 고려한 모델과 이동을 고려하지 않은 모델과의 차이가 지하수 유동 방향뿐만 아니라 수직방향으로도 크게 나타났다. 결국 LNAPL의 이동을 무시할 수 없는 지하환경에서는 기존의 모델을 가지고 용질이동을 모사할 경우 실제보다 농도가 낮게 추정될 가능성이 높다. 이 연구의 결과로 LNAPL이 지하수면 위에서 얼마나 빨리 이동하는지 아는 것이 올바른 오염물의 농도 예측에 중요하다는 것을 파악하였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.122-126
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• 2002

Contaminant transport in porous media is characterized by solving an advection-dispersion equation(ADE). The ADE can cover equilibrium phenomena of interest, which include sorption, decay, and chemical reactions. Among these phenomena, sorption mechanism is described by several types of sorption isotherm. If we assume the sorption isotherm as linear, the solution of ADE can be easily procured. However, if we consider the sorption isotherm as non-linear isotherm like a Dual Reactive Domain Model (DRDM), the resulting differential equation becomes non-linear. In this case, the solution of ADE cannot be easily acquired by an analytic method. In this paper, we present the numerical analysis of ADE using a DRDM. The results reveal that even if sorption data may be fitted well using linear or non-linear isotherm, the characteristics of contaminant transport of the two cases are different from each other. To be concrete, the retardation of linear isotherm has stronger effect than that of the DRDM. As the non-linearity of sorption isotherm increases, the difference of retardation effects of the two cases becomes larger. For a pulse source, the maximum concentration of the linear model is higher than that of the DRDM, but the plume of the DRDM moves faster than that of the linear model. Behaviors of contaminant transport using the DRDM are consistent with common features of a linear model. For instance, biodegradation effect becomes larger as time goes by The faster the seepage velocity is, the faster the plume of contaminant moves. The plume of the contaminant is distributed evenly over overall domain in the event of high dispersion coefficient.

• 한국지하수토양환경학회지:지하수토양환경
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• 제12권1호
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• pp.44-52
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• 2007

본 연구에서는 위해성평가 과정의 중요한 부분으로서 수행되는 오염물질의 지중(subsurface) 거동 모델의 이용에 관한 전반적인 내용을 고찰하였다. 모델의 종류, 그리고 모델을 선택하고 이용하기 위하여 선행되어야 할 부지조사 및 개념적 모델 수립에 대해서 살펴보았다. 모델 선택의 기준을 정리하였고 대표적 모델과 각 모델의 모의 가능한 부지 조건들을 소개하였다. 모델의 보정, 검증, 민감도 분석 등 모델 이용에 필요한 일련의 과정과 각 과정에서 유의하거나 고려하여야 할 점을 살펴보았다. 본 연구에서 검토한 바에 의하면, 모델 선택의 주요 기준은 모델링의 목표와 수준, 그리고 모델이 오염부지의 주요 현상을 모의할 수 있는지 여부지만, 모델이 실제 시스템을 적절히 모의할 수 있는지는 이러한 기준으로 판단할 수 없으며 모델 입력변수 등 부지 자료의 가용성 및 질적 수준에 따라 결정된다. 한편, 추정된 입력변수에 대하여 높은 민감도를 보인다거나 선택한 모델의 보정 및 검증이 만족스럽지 않은 경우 자료 측정으로 대신하거나 다른 모델로 전환하는 등 전략 수정을 할 필요가 있다.

• 자원환경지질
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• 제56권5호
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• pp.501-514
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• 2023

산불은 연소 과정에서 다양한 오염물질을 배출하여 심각한 환경 문제를 초래할 수 있다. 최근 지구 온난화와 기후변화의 영향으로 전 세계적으로 산불의 규모와 빈도가 증가하여 환경에 미치는 영향 역시 급증할 것으로 예상된다. 한국은 산불 발생이 빈번한 동해안 지역에 원자력 발전소가 위치하고 있어, 중대 사고에 대비하여 산불 환경에서 방사성 핵종의 거동 특성에 대한 이해가 요구된다. 본 리뷰 논문에서는 산불이 지하수 토양 환경에 가져오는 변화와 오염 특성을 검토하고, 산불로 변화된 지하수 토양 환경에서의 방사성 핵종 거동을 고찰하였다. 특히, 변화된 지중환경의 여러 특성 중 방사성 핵종의 거동에 영향을 미칠 수 있는 요인들을 고려하였으며, 보다 구체적인 메커니즘 이해를 위해 산불이 초래하는 지하수 토양 환경 변화와 오염에 대한 연구의 필요성을 기술하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제6권4호
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• pp.13-23
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• 2001

본 연구는 중금속 오염지반의 정화를 목적으로, Electrokinetic(EK) 기법을 적용 할 때 지반 내에서 pH와 오염물 분포특성을 알아보았다. 시료 내에서의 EK 처리로 인한 납 제거 효과를 살펴본 결과 1V/cm의 전압경사 하에서 납은 음극으로 이동하여, 전극 간 시료의 80%정도 영역에서 제거율은 대략 75% 정도에 이르렀다. 그러나 이동된 납은 대부분이 음극영역에 침전되어 궁극적으로 음극수로 배출되어 제거되는 납의 양은 미미하였다. 이때, EK 정화처리는 시료의 대부분인 80% 정도에서 토양환경보전법 상의 규준치를 만족할 수 있으나, 음극쪽 20%지역은 별도의 향상기법을 적용하여 처리하는 기법이 필요하다.

• 상하수도학회지
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• 제22권2호
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• pp.251-257
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• 2008

Food compost, having a higher organic contents than soil, could be an alternative material to prevent the proliferation of heavy metals contamination in soil. In this study we used a convection-dispersion local equilibrium sorption model(CDE) and a two-site non-equilibrium sorption model to find the effects on the adsorption and transportation of Pb by mixing food compost with soil and we also tried to find the effect of velocity and concentration of the injected solution on the characteristics of Pb. We measured Pb concentrations in injection-liquid and in effluent, and then applied them to CXTFIT program. As a result of column experiments, some parameters(D, R, ${\beta}$, ${\omega}$) used in two-site non-equilibrium adsorption model were obtained. Characteristics of Pb adsorption and transport were analyzed using the parameters(D, R, ${\beta}$, ${\omega}$) obtained from the CXTFIT program, We could know that mixed soil with food compost showed a higher adsorption capacity from the retardation factor(R) calculated from the breakthrough curve(BTCs) of Pb. Rs of soil and mixed soil are 20.45, 37.45 respectively, indicating that the adsorption and the transportation characteristics could be accessed quantitatively by using of two-site non-equilibrium adsorption model.

• Geomechanics and Engineering
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• 제29권1호
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• pp.91-97
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• 2022

The cohesive non-swelling soil (CNS) cushion technology has been widely applied in the subgrade and slope improvement at expansive soil regions. However, the mechanism of the inhibition effect of the CNS layer on expansive soil (ES) has not been fully understood. We performed four outdoor model tests to further understand the inhibition effect, including different kinds of upper layer and thickness, under the unidirectional seepage condition. The swelling deformation, soil pressure, and electrical resistivity were constantly monitored during the saturation process. It is found that when a CNS layer covered the ES layer, the swelling deformation and electrical resistivity of the ES layer decreased significantly, especially the upper part. The inhibition effect of the CNS layer increases with the increase of CNS thickness. The distribution of vertical and lateral soil pressure also changed with the covering of a CNS layer. The electrical resistivity can be an effective index to describe the swelling deformation of ES layer and analyze the inhibition effect of the CNS layer. Overall, the CNS deadweight and the ion migration are the major factors that inhibit the swelling deformation of expansive soil.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 사면안정학술발표회
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• pp.13-22
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• 2003

Train speed and infiltration of rainfall causes railway embankment to be unstable and may result in failure. Therefore, the variation in the safety factor of railway embankment should be analyzed as the function of rainfall intensity, rainfall duration, and train speed and the study is accomplished using numerical analysis program. Based on unsaturated soil engineering, the variables in the shear strength function and permeability function are also defined and used for the numerical model for evaluation of railway embankments under rainfall. As a result of the study, in order to secure the safety of train under rainfall, the variation in the safety factor of railway embankment is predicted as the function of rainfall intensity, duration time and the train load as a function of train speed. It is possible to ensure the safety of train under rainfall. Thereafter, the feasibility of the rail-transport operation control with engineering basis was established.