• Journal of Environmental Health Sciences
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• v.37 no.5
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• pp.358-368
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• 2011

Objectives: In order to evaluate the association between occupational exposure to chloroethylene (TCE) and risk of non-Hodgkin lymphoma (NHL), we conducted a meta-analysis of retrospective cohort studies and casecontrol studies and attempted to summarize the evidence of the association from molecular-epidemiological studies and experiments with human cells. Methods: In the meta-analysis, we restricted the analysis to those studies with data for chlorinated solvents, degreasers, or TCE. Studies involving dry cleaners or launderers were excluded from the analysis because use of TCE as a dry cleaning fluid has been rare since the 1960s. The data were combined using a random-effects model to estimate the summary risks (OR and RR) and 95% confidence intervals (CIs). Molecular evidence of the effect of TCE on human immune system were also reviewed and summarized. Results: Occupational exposure to TCE was strongly associated with NHL among cohort studies (number of studies=13, summary RR=1.33, 95% CI=1.04-1.70) whereas the association was not statistically significant among case-control studies (number of studies=15, summary OR=1.10, 0.98-1.23). When exposure level was considered, it became statistically significant for the highest exposure level (number of studies=5, summary OR=1.70, 1.25-2.32). Molecular evidences showed that TCE exposure in human or cultured human cells may cause a significant decrease immune cell subsets and changes in hormone levels related to immune response. Conclusions: Our results from meta-analysis and additional molecular evidence suggest that occupational exposure to TCE may cause NHL. However, unmeasured potential confounding and unclear dose-response relationships warrant further study on the role of TCE exposure in NHL carcinogenesis.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.10a
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• pp.70-86
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• 2003

Despite its usability, TCE has been managed as a hazardous material due to the toxicity and many contamination cases were surveyed in some developed countries. U.S.EPA(Kram et al., 2001) suggested DNAPL characterization methods and approaches based on survey experiences at several sites. However, Korea has not the least assessment of contamination and trial of remediation, although there are a lot of doubtable areas where ground water would be contaminated with TCE. In this study, we try to assess the volume and extent of ground water contamination with TCE and delineate the contamination source zones in an industrial area. Ground water in this area flows through fractures and the contaminant TCE has the properties of high volatility, high density and low partitioning to soil material. Thus, we applied a variety of technical approaches to identify the contamination status; documentary, hydrogeochemical, hydrogeological and geological surveys. In addition, additional survey was performed based on the interim findings, which showed that ground water contamination was limited to the relatively small area with high concentrations to the deep place. The contamination source zone is estimated to be the asphalt test institute where a great deal of TCE has been used to analyze the amount of asphalt soluble in TCE since 1984. Based on the contamination characterization and a myriad of documents about ground water remediation, appropriate site remediation management options will be recommended later. This study is now under way and this paper was focused on describing the technical approaches used to achieve the goals of this study.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.72-75
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• 2005

본 연구에서는 야외규모 TCE (trichloroethylene) 질량전이역학을 평가하기 위해 TCE의 대수층 내 유입 및 용해상 거동을 고해상도 수치 모사를 실시하였다. 공간적으로 불균질한 대수층 $10{\times}10{\times}10m$ 도메인 내부의 유입된 TCE 분포를 모사하기 위해 본 연구를 통해 개발된 정성적 침투모델(percolation model)이 이용되었다. 이를 기초로 하여 연계되어진 (coupled) 지하수 유동 및 용해상 거동 장기 (long-term) 모사를 실시하였다. 지엽적으로 일어나는 질량전이는 기존 연구를 통하여 발표되어진 실험실규모 연구에 기초하였다. 지하수가 도메인을 지나 흘러나가는 경계면에서 측정되어진 용해상 (aqueous phase) TCE의 질량선속 (mass flux)을 통해 실질 야외규모 질량전이 상수가 계산되었다. 관찰된 바 야외규모 질량전이 상수는 실험실 연구를 통해 측정된 값에 비하여 휠씬 작은 값을 보였으며 이는 지하수 유속 및 TCE의 불균질한 분포에 기인한다. 야외규모 질량전이 상수는 평균 지하수 유속에 직접 비례하는 것으로 관찰되었고 이는 기존 실험실 연구를 통해 알려진 평균 지하수 유속의 0.7승이라는 결과와 대조되는 것이다. 또한 모사를 통해 관찰된 야외규모 질량전이 상수는 상대 TCE 질량의 고갈상수 승에 비례함을 보였다. 이러한 고갈상수는 TCE가 측방으로 퍼지는 현상이 강한 대수층, 즉 저투수성 층의 발달이 양호한 대수층, 에서는 1보다 작은 값을 갖고 그렇지 않은 대수층, 즉 저투수성 층의 발달이 미약한 대수층, 에서는 대체적으로 1보다 높은 값을 갖는 것으로 관측되었다. 이는 DNAPL의 측방 퍼짐이 강한 대수층에서는 용해로 인한 시간에 따른 오염원 부근에서의 농도 감소가 미약하기 때문인 것이며, 그와 반대로 DNAPL의 측방 퍼짐이 약한 대수층에서는 시간이 지남에 따라 용해에 의해 지속적으로 오염원 부근에서의 농도가 감소 또는 소멸함으로 인하여 측정되는 용해상 DNAPL의 질량 선속 역시 계속적으로 감소되는 것으로 밝혀졌다.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.31-37
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• 2008

Diffused Aeration System (DAS) is one of the remediation methods used for removing contaminants in groundwater and this method brings air bubbles in contact with contaminated water, afterwards transferring contaminants in liquid phase into air phase. In this study, three applicability tests using DAS were conducted in two highly contaminated sites. For these tests, diffused air bubbles are generated with a in-flow rate of 17.1, 44.8 and 76.5 (1/min), respectively. The concentrations of TCE in grounwater and air phase were measured during the tests. The measured results showed that TCE concentration hit the highest value after 6~8 min and afterwards decreased gradually. Also, it was observed that the TCE concentration in air phase changed depending on the rate of diffused aeration. In addition, $K_La$ values from liquid to air phase were calculated based on the test results and those of three tests (test 1, 2 3) were 0.444, 1.158 and 1.836(1/hr), respectively. From the comparison of $K_La$ values, the faster air in-flow rate is, the higher the efficiency of the DAS is.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.229-239
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• 2002

The objective of this study was to design an optimal electro-remediation system for TCE contaminated water using zero talent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the effects of electrode arrangement and the location of permeable iron barrier in the column on the TCE removal efficiency and iron corrosion process. In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive degradation of TCE was improved with simultaneous application of both ZVI and DC compared to that used ZVI only. The moot effective arrangement of electrode and ZVI for TCE removal from water was a column set with ZVI and cathode installed at the down gradient, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.58-61
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• 2002

An alternative to pump and treat groundwater remediation is the use of reactive barriers. Zero valent iron (ZVI) is particularly useful as a reductant of chlorinated hydrocarbons because of its low cost and lack of toxicity ZVI can drive the dechlorination of chlorinated organic compounds and the reduction of chromium from the Cr(Ⅵ) to the Cr(III) state. The contaminants in subsurface environment usually exist as the mixed compounds. Therefore, the objective of this research is to study the effect of the other compounds on TCE removal by ZVI. The removal mechanism of TCE by ZVI is separated the dechlorination and sorption. TCE removal by ZVI slightly increased in presence of naphthalene as the non-reduced compound. TCE removal by ZVI remarkable decreased in presence of carbon tetrachloride, nitrate, and chromate as the reduced compounds. This research suggests that the effect of the coexisted compounds on the removal chlorinated compounds by reactive barrier technology should be considered for practical application.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.158-161
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• 2004

Chlorinated aliphatic hydrocarbons (CAHs) especially perchlorethylene (PCE) and trichlooethylene (TCE) are common groundwater contaminants in Korea. PCE and TCE were often reductively dechiorinated in an aquifer. Several isolates dechlorinate PCE to TCE or cis-1,2 dichloroethylene (c-DCE) were obtained from contaminated and pristine sites in USA and Europe. However in Korea, no information on indigenous microorganism being involved in reductive dechlorination of PCE and TCE is available and different dechlorinating microorganisms might be reside in Korea, since geochemical, and hydrogeological conditions are different, compared to those in the other sites. So we evaluate that: 1) if reductive dechlorinating microorganisms are present in PCE-contaminated site in Korea, 2) if so, what kinds of microorganisms are present; 3) to what extent PCE is reductively dechlorinated. As a results in some PCE-contaminated aquifers in Korea other dechlorinating microorganisms but Dehalococcoides ethenogenes may be responsible for PCE dechlorination. More detailed molecular works are required to evaluate that different dechlorinating microorganisms would reside in Korea.

• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.33-41
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• 1996

This study was performed to examine the factors influencing on the degradation of TCE, Benzene and 2,4 DCP in aqueous solution using ultrasonic irradiation. The TCE,Benzene and 2,4 DCP, which are hazard compounds causing environmental pollution, were not decomposable pollutants by convientional treatment. The results shows that the generation of H$_{2}$O$_{2}$, H$^{+}$ and OH$^{-}$ radical was formed by the oxidation and reduction reaction of ultrasound, and then theses decomposed the refractory pollutants of TCE, Benzene & 2,4 DCP in aqueous solution. we conformed that the ultrasonic irradiation was excellent in removal efficiency of the refractory pollutants any other than Advanced Oxidation Processes(AOP), utilized the treatment of organic compounds in the industrial wastewater. Consequently, these results suggest that ultrasonic irradiation may be extremely useful for the treatment of wastewaters contaminated organic pollutants, which is difficult to treat economically by conventional process.

• Journal of Soil and Groundwater Environment
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• v.23 no.4
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• pp.42-47
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• 2018

E. coli TG1 pBS TOM Green was cultured to produce toluene-o-monooxygenase (TOM). A biosensor system was successfully constructed using purified TOM to effectively detect trichloroethene (TCE) and tetrachloroethene (PCE), which represent some of the major contaminants in groundwater and soil. In order to utilize TOM as a sensor, NADH, a biological oxidizer, was replaced with hydrogen peroxide which is a chemical oxidizing agent. A three-layered sandwich-type sensing tip was fabricated on the outside of the hydrophilic polyvinylidene fluoride membrane. TCE and PCE were applied to the sensor and the hydrogen ions were measured by a fiber optic fluorometer using fluoresceinamine. Calibration curves were obtained for TCE and PCE in the concentration range of 0.2-100 mg/l, and the detection limit of the system was $10{\mu}g/l$ for TCE and PCE.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.53-56
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• 2001

The degradation of tetrachloroethene (PCE) and trichloroethene (TCE) by vitamin B$_{12}$, an electron mediator was examined when zero valent metals (ZVMs) were used as built electron donors. Dechlorination of PCE and TCE by iron and zinc in the presence of vitamin B$_{12}$ showed that the zinc and vitamin B$_{12}$ combination greatly enhances the reaction rates for both PCE and TCE, but iron and vitamin B$_{12}$ result in an increase in reactivity only for PCE degradation, not for TCE degradation in comparing with meta]s only. This result indicates vitamin B$_{12}$(I) Is active towards both PCE and TCE degradation while vitamin B$_{12}$(II) is active towards both PCE. Calculated activation energies for the dechlorination of PCE in the presence of Vitamin B$_{12}$ showed that vitamin B$_{12}$ lowered the activation energy about 40-60 kJ/㏖ for the both metals.the both metals.