• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.175-178
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• 2004

Little study has been published specifically addressing the dynamics of nitrate reducing bacteria (NBR) during the bioremediation of nitrate-contaminated aquifer. In our previous study we successfully quantified fumarate-enhanced microbial nitrate reduction rate in a nitrate-contaminated aquifer by using a series of single-well push-pull tests (PPTs). In this study we analyzed the suspended population during PPTs. To monitor changes in the microbial community, PCR amplification of 16S rDNA genes and denaturing gradient gel electrophoresis (DGGE) were used to study the dynamics of the bacterial community in detail. Before the stimulation of NBR, the dominant DGGE bands obtained by PCR were affiliated with V-Proteobacteria consisting of Acinetobacter spp. and Pseudomonas fluorescens. However, as NBR biostimulation proceeded, the dominant patterns of DGGE bands changed, and they were affiliated with Azoarcus denitrificans Td-3 and Flavobacterium xanthum. Azoarcus denitrificans Td-3 is known to completely reduce nitrate to nitrogen gas. The series of single-well push-pull tests in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification and provide important information about which microorganisms play a key role in bioremediation of a nitrate contaminated aquifer.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.467-470
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Aerobic bioremediation has been highly effective in the remediation of many fuel releases. However, Bioremediation of aromatic hydrocarbons in groundwater and sediments is ofen limited by the inability to provide sufficient oxygen to the contaminated zones due to the low water solubility of oxygen. Nitrate can also serve as an electron acceptor and results in anaerobic biodegradation of organic compounds via the processes of nitrate reduction and denitrification. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. And denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. These studies have shown that BTEX and MTBE can be degraded by the nitrate-amended microcosms under aerobic and anaerobic conditons. Biodegradation of the toluene and ethylbenzne compounds occurred very quickly under denitrifying conditions. MTBE, benzene and p-xylene were recalcitrant under denitrifying conditions in this study, But finally Biodegradaton was observed for all of the test compounds.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.368-371
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Aerobic bioremediation has been highly effective in the remediation of many fuel releases, but Many aromatic hydrocarbons degrade very slowly under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen and denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. This study show that biodegradation of BTEX and MTBE is enhanced by the nitrate-amended microcosms under aerobic/anaerobic conditons. Although aromatic hydrocarbons degrade very slowly under anaerobic conditions. Biodegradaton was observed for all of the test compounds.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.392-396
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• 2003

본 연구에서는 하수처리장 반송라인으로부터 얻은 혼합미생물을 사용하여 실험실에서 회분식 실험을 실행하였으며, 산소가 제한되는 유류 오염지역 내에서의 질산염 전자수용체를 이용한 탈질 박테리아의 질산염 이용 평가와 이에 따른, 현장 적용 타당성을 검토하는데 있다. 미생물은 톨루엔(toluene)을 탄소원으로 하고 질산염을 에너지원으로 이용하는 균주로 우점화한 혼합미생물(mixed culture)을 배양하여 실험에 사용하였다. 본 실험을 통해 유류에 의해 오염된 토양의 혐기성 지역에서의전자수용체로 질산염이 존재한다면, 토착미생물에 의한 분해가 느리지만, 발생될 수 있음을 추정할 수 있었다. 또한 질산염의 유무에 따른 BTEX와 MTBE의 혼합기질의 분해 특성 및 부산물을 살펴볼 수 있었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.77-82
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• 2004

Quantifying rates of microbial processes under subsurface conditions is difficult, and is most commonly approximated by laboratory studies using aquifer materials. In this study a single-well, 'push-pull' test method is adapted for the in situ determination of denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push-pull tests at an experimental well field of Korea University. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifyinc microorganisms. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate '||'&'||'gt; nitrite '||'&'||'gt; nitrous oxide. The series of push-pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibi1ity assessments for in situ denitrification in nitrate-contaminated aquifers.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.138-141
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• 2004

The environmental tracers tritium/helium-3 (3H/3He) and chlorofluorocarbons (CFCs) were investigated in ground water from Jeju Island, Korea, a basaltic volcanic island. The apparent 3H/3He and CFC-12 ages were in relatively good agreement in samples with low concentrations of terrigenic He. Ground water mixing was evaluated by comparing 3H and CFC-12 concentrations with mixing models, which distinguished old water with negligible 3H and CFC-12, young water with piston flow, and binary mixtures of the two end members. The ground water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seoguipo formation in coastal areas than in water from the basaltic aquifer. Comparison of major element concentrations in ground water with the CFC-12 age shows that nitrate contamination processes contribute more solutes in young water than are derived from water-rock interactions in non-contaminated old water. Chemical evolution of ground water resulting from silicate weathering in basaltic rocks reaches the zeolite-smectite phase boundary. The calcite saturation state of ground water increased with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water was consistent with the known history of chemical fertilizer use on Jeju Island, but the response of nitrate concentration in ground water to nitrogen inputs follows an approximate 10-year delay. Based on mass balance calculations, it was estimated that about 40% of the nitrogen applied by fertilizers reached the water table and contaminated ground water resources when the fertilizer use was at the highest level.

• 대한토목학회논문집
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• 제32권1B호
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• pp.79-84
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• 2012

질산성질소는 일반적인 지하수 오염물질로서, 본 연구에서는 영가철을 충진한 복극전해조를 이용하여 서로 다른 조건에서 질산성질소 제거실험을 수행하였다. 실험에 사용된 전해조에는 양쪽 끝에 위치한 주 전극 사이에 전도체로서 영가철이, 비전도체로서 규사가 혼합하여 충진되었다. 모의폐수(오염된 지하수를 모사하였으며 초기 질산성질소 농도 약 30 mg/L, 전기전도도 약 300 ${\mu}S/cm$)를 이용한 연속식 실험에서 인가전압 600 V, 유입유량 20 mL/min으로 최대 99% 이상의 질산성질소를 제거하였다. 최적 혼합비 및 최적 유입유량은 각각 1:1~2:1(규사:영가철), 30 mL/min으로 결정하였다. 질산성질소의 주입농도에 따라 유출수의 pH가 비례적으로 거동하였으며, 질산성질소 환원의 최종산물로서 약 60% 정도가 암모니아로 유출되었다. 실험이 끝난 후 영가철 표면에서의 산화철은 대부분 magnetite형태로 존재하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제14권6호
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• pp.73-77
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• 2009

연구대상지역내에는 지하수수질이 상이한 상 하부 대수층이 각각 발달되어 있었다. 하부 대수층내 지하수의 주 오염원인은 상부의 질산성질소로 오염된 천부지하수가 지하수공 내로 유입되었기 때문으로 사료된다. 폐기 또는 방치지하수공을 통한 질산성질소의 하부 대수층으로 오염 확산 억제를 위하여 예비팩커를 공 내부에 설치하고 패커 상, 하부의 질산성질소 함량을 측정하였다. 예비패커 설치후 상, 하부 구간의 질산성질소 함량은 예천군 신월리 경우, 상부는 10.3 mg/L 이었으나 하부는 5.0 mg/L로 상부에 비해 50% 낮은 함량을 나타내였다. 예천군 어신리는 상부는 11.3 mg/L 이었으나 하부는 8.8 mg/L로 상부에 비해 22% 낮은 함량을 보였다. 예천군 저우리는 상부는 11.0 mg/L이고 하부는 1.6 mg/L로 상부에 비해 85% 낮은 함량을 보였다. 안동시 회곡리는 상부는 14.6 mg/L 이었으나 하부는 8.0 mg/L로 상부에 비해 45% 낮은 함량을 나타내였다. 연구지역에서 예비패커를 적용한 결과 패커 하부의 질산성질소 함량은 상부에 비해 22~85% 낮게 나타내였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.152-152
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• 2021

The importance of groundwater has long been recognized, but the ground water potential to become contaminated as a result of human activities has only been recognized in recently. Before 1980 it was thought that soils served as filters, preventing harmful substances deposited at the surface from migrating into groundwater. Today it is known that soils have a finite capacity to protect groundwater. It can be contaminated from divers sources. Therefore, Assessment of aquifer vulnerability to pollution is essential for the protection and management of groundwater and land use planning. In this study, we used DRASTIC and AVI for groundwater vulnerability to contamination assessment. the different methods were applied to the southern coastal sedimentary basin of Benin and DRASTIC method was modified in two different steps. First, we modified DRASTIC by adding land use parameter to include the actual pollution sources (DRASTIC_LcLu) and second, classic DRASTIC weights was modified using Shannon's entropy (Entropy weight DRASTIC). The reliability of the applied approaches was verified using nitrate (NO3^-) concentration and by comparing the overall vulnerability maps to the previous researches in the study area and in the world. The results from validation showed that the addition of landcover/land use parameter to the classic DRASTIC helps to improve the method for better definition of the vulnerable areas in the basin and also, the weight modification using entropy improved better the method because Entropy weight DRASTIC_LcLu showed the highest correlation with nitrate concentration in the study basin. In summary the weight modification using entropy approach reduced the uncertainty of the human subjectivity in assigning weights and ratings in the standard DRASTIC.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.127-130
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• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethene(TCE)-contaminated aquifer, A series of single-well natural drift tests (SWNDT) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Transformation of ethylene, a surrogate of overall TCE transformation activity, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolune-oxidizing microorganisms stimulated may express a monooxygenase enzymes. Also in situ transformation of TCE was confirmed by dilution-adjusted data analysis developed in this study. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing monooxygenase enzymes and that these are responsible for observed toluene utilization and cometabolism of ethylene and TCE. The simple, low-cost field test method provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism of TCE, which has previously hindered application of this technology to groundwater remediation.