• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.952-964
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• 2005

The diesel-degrading activities of biofilms sampled from petroleum-contaminated groundwaters in urban subway drainage systems were examined in liquid cultures, and the microbial populations of the biofilms were characterized by denaturing gel gradient electrophoresis (DGGE) and 16S rDNA sequence analysis. Biofilm samples derived from two sites (19 K and 20 K) at subway Station N and Station I could degrade around $80\%$ of applied diesel within 20 and 40 days, respectively, at $15^{\circ}C$, and these results were strongly correlated with the growth patterns of the biofilms. The closest phylogenetic neighbor of a dominant component in the 19 K biofilm was Thiothrix fructosivorans strain Q ($100\%$ similarity). Four dominant strains in the 20 K biofilm were closely related to Thiothrix fructosivorans strain Q ($100\%$ similarity), Thiothrix sp. CC-5 ($100\%$ similarity), Sphaerotilus sp. IF14 ($99\%$ similarity), and Cytophaga-Flexibacter-Bacterioides (CFB) group bacterium RW262 ($98\%$ similarity). Three dominant members in the Station I biofilms were very similar to uncultured Cytophagales clone CRE-PA82 ($91\%$ similarity), Pseudomonas sp. WDL5 ($97\%$ similarity), and uncultured CFB group bacterium LCK-64 ($94\%$ similarity). The microbial components of the biofilms differed depending on the sampling site. This is the first report on the isolation of clones highly similar to Thiothrix fructosivorans and Thiothrix sp. from biofilms in petroleum-polluted groundwaters, and the first evidence that these organisms may play major roles in petroleum degradation and/or biofilm-development.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권3호
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• pp.65-73
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• 2020

Exposure assessment methodology for outdoor air inhalation pathways (i.e., inhalation of volatile compounds and fugitive dust in outdoor air) was investigated. Default values of several parameters currently used in Korea (e.g., Q/C; inverse value of concentration per unit flux, and frs; soil fraction in PM10) may not be suitable and lack site-specificity, as they have been adopted from the risk assessment guidance of the United States or the Netherlands. Such limitation can be addressed to a certain degree by incorporating the volatilization factor (VF) and the particulate emission factor (PEF) with Box model. This approach was applied to an exposure assessment of a site contaminated with petroleum hydrocarbons in Korea. The result indicated that the suggested methodology led to more accurate site-specific exposure assessment for outdoor inhalation pathways. Further work to establish methodology to determine site-specific Q/C values in Korea needs to be done to secure the reliability of the exposure assessment for outdoor air inhalation pathways.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.225-230
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• 2007

A physical model experiment with GPR and 3-D resisitivity survey were conducted to investigate the geoelectrical response of hydrocarbon-impacted zone, so called smeared zone, on the geophysical data. The results from the experiment show that GPR signals were enhanced when LNAPL was present as a residual saturation in the water saturated system (${\varepsilon}_r$ = 21) due to less attenuation of the electromagnetic energy through the medium, compared to when the medium was saturated with only water (${\varepsilon}_r$ = 21). 3-D resistivity data obtained from the former gas station site demonstrate that the highly contaminated zones could be imaged with low resistivities attributed to the biodegradation of petroleum hydrocarbons at the aged, hydrocarbon-impacted sites. The study results also show that the geophysical methods, as a non-invasive sounding technique, can be a very useful tool for mapping hydrocarbon-contaminated zones.

• 한국농공학회논문집
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• 제49권1호
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• pp.67-76
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• 2007

Bioventing is commonly used for petroleum hydrocarbon (PHC) spills. This process provides better subsurface oxygenation, thus stimulating degradation by indigenous microorganisms. Therefore soil vapor monitoring points (VMPs) are extremely important in determining the potential effectiveness of bioventing and in long-term monitoring of bioventing progress. In this study in-situ soil gas monitoring well (GMW) was developed and presented the pilot test results which recover the contaminated site by bioventing method. The result of application was successful and it was expected that GMW developed could be applied to the evaluation procedure of bioventing effectiveness and long-term remediation potential.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권4호
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• pp.27-35
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• 2003

연구대상부지는 주로 선캄브리아기의 변성암의 일종인 편마암으로 형성되어 있으며, 토양은 하천에 축적된 비교적 투수성이 높은 매질로 구성된 충적토를 모재로 형성되었다. 지하수위는 지표로부터 평균 3.5m 깊이에서 나타나며. 하류 방향으로 갈수록 깊어지는 경향을 나타내었다. 대상부지의 수리전도도는 자갈이 혼재된 조립질 모래층은 5.0${\times}$$10^{-2}$∼1.85${\times}$$10^{-1}$ cm/sec, 세립질 모래층은 $1.5{\times}$$10^{-3}$ to 7.6${\times}$$10^{-3}$ cm/sec, 복토층은 $10^{-4}$ cm/sec 이하로 나타났다. 연구대상부지의 주오염물질은 Toluene, Ethylbenzene, xylene(이하 TEX)이며, 오염토양층은 1.5 m내외로 깊이별 토양중 TEX의 농도는 추정오염원으로부터 70m떨어진 곳의 질이 2.4∼4.8m에서 가장 높았다. 지하수중 TEX의 농도는 추정오염원의 주변지역에서 가장 높았으며, 조사대상부지의 중앙지역과 남서쪽지역에서도 높게 나타났으며, 이러한 지하수중 TEX의 농도분포는 토양중의 TEX의 농도분포와 상당히 일치하는 경향을 보이고 있다. 연구대상부지에 서식하고 있는 톨루엔 분해 호기성세균의 주종은 Pseudomonas fluorescence, Burkholderia cepacia, Acinetobactor lwoffi로 확인되었다. 지하수 분석결과 전자수용체인 용존산소, 질산염, 황산염 등이 배경지역에 비해 오염지역에서 상당히 낮게 나타났다. 한편, 연구대상부지에서의 계산된 전체 자연저감속도는 0.0017da $y^{-1}$이며, 1차 생분해속도는 0.0008 da $y^{-1}$로 계산되었다.

• 대한환경공학회지
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• 제37권1호
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• pp.69-72
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• 2015

토양을 유류로 오염시킬 때 토양조성 및 유류 주입량 등이 토양 TPH 분석결과에 미치는 영향을 연구하였다. 동일한 양의 경유를 조성이 다른 토양과 혼합한 후 토양 TPH를 분석한 결과 토양에 점토 및 유기물함량이 존재한다면 모래로 구성된 토양에 비해 토양 TPH 결과가 적게 얻어졌다. 점토함량이 높은 토양일수록 분석전처리 시 토양이 굳는 현상이 발생하면서 실제 값보다 적은 TPH 결과치를 나타내었다. 토양 내 유기물 함유량 변화에 따른 토양 TPH 측정실험에서 유기물 함량이 높아질수록 토양 TPH 측정농도는 증가되지만, 극히 높은 18% 유기물함량조건에서는 전처리 및 용매추출의 불확실성으로 인해 오히려 낮은 TPH 분석 결과를 보여주었다. 경유 주입량에 따른 토양 TPH 농도 변화 실험 결과 경유 주입량이 많아질수록 높은 TPH 분석결과를 나타내었다. 동일한 양의 경유와 휘발유를 주입하여 유종에 따른 토양 TPH 분석결과 휘발유는 오염 즉시 휘발하여 극히 낮은 TPH 농도를 보여주었다. 본 연구결과는 차후 인위적 유류오염 토양 제조과정에서 TPH 농도를 가늠하거나 부지 정밀조사 결과 유류 유출량 등을 예측하는데 기초자료로 활용할 수 있다.

• KSBB Journal
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• 제16권6호
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• pp.632-637
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• 2001

본 실험에서 사용된 균주는 유류에 오염된 지역의 토양시료로부터 직접 분리하였는데 본 실험에서는 백색 콜로니를 형성하는 W균주와 황색 콜로니를 형성하는 Y균주 그리고 두 균주의 복합균주인 WY 균주를 사용하였다. 단일 균주보다는 복합균주를 사용하였을 때 디젤유의 분해가 더 효과적이었으며 질소원의 첨가가 분해에 제한인자로 작용하였다. 비록 토양시스템의 분해효율은 액체상에서의 분해능에 비해 다소 떨어지지만, 통기의 조건 및 질소원의 첨가등으로 그 능력을 어느 정도 향상시킬 수 있었다. 한편 디젤유의 분해에는 생물학적인 측면 뿐 아니라 증발이나 휘발에 의해서도 상당량 감소하였는데 교반에 의해 또 오염토양의 제조공정중에 상당량이 휘발하는 것으로 보이며, 디젤의 용해도가 낮기 때문에 침출되는 양도 적을 것이라고 보여지고 이는 다른 논문에서도 보고된 바 있다(21, 22) 앞서 언급한 것처럼 본 실험에서는 통기와 질소원의 첨가를 통해 미생물에 의한 디젤유의 분해능을 향상시켰는데, 이 뿐만 아니라 더욱 효과적인 디젤유의 분해를 위해서는 복잡한 토양시스템에 관계된 여러 요소들을 최적화하여 분해능을 향상시키기 위한 실험이 수행되어야한다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1372-1377
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• 2009

For the remediation of the subsurface contaminated by nonaqueous phase liquids(NAPLs), it is important to characterize the NAPL zone properly. Conventional characterization methods provide data at discrete points. To overcome the weak points of conventional characterization methods, the partitioning tracer method has been developed and studied. The average saturation of NAPL($S_n$), which is the representative and continuous saturation value within contaminated site, can be calculated by comparing the transport of the partitioning tracers to that of the conservative tracer in the partitioning tracer method. In this study, the application of the partitioning tracer method in heterogeneous media was investigated. To represent the heterogeneous condition of subsurface, a two-dimensional soil box was divided into four layers and each layer contained different sized soils. Soils in the soil box were contaminated by the mixture of kerosene and diesel, and partitioning tracer tests were conducted before and after the contamination using methanol as conservative tracer and 4-methyl-2-pentanol, 2-ethyl-1-butanol, and hexanol as partitioning tracers. The response curves of partitioning tracers from contaminated soils were separated and retarded in comparison with those from non-contaminated soils. The contamination of soils by NAPLs, therefore, can be detected by partitioning tracer method considering these retardations of tracers. From our experiment condition, the average saturation of NAPLs calculated by partitioning tracer method using the methanol as conservative tracer and hexanol as partitioning tracer showed the highest accuracy, though all results were underestimated. Further studies, therefore, were needed for improving the accuracy using the partitioning tracer test in heterogeneous media.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권5호
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• pp.11-16
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• 2019

In this study, a reliable number of soil samples for TPH fractionation was investigated in order to perform risk assessment. TPH was fractionated into volatile petroleum hydrocarbons (VPH) with three subgroups and extractable petroleum hydrocarbons (EPH) with four subgroups. At the study site, concentrations of each fraction were determined at 18 sampling points, and the 95% upper confidence limit (UCL) value was used as an exposure concentration of each fraction. And then, 5 sampling points were randomly selected out of the 18 points, and an exposure concentration was calculated. This process was repeated 30 times, and the results were compared statistically. Exposure concentrations of EPH obtained from 18 points were 99.9, 339.1, 27.3, and 85.9 mg/kg for aliphatic $C_9-C_{18}$, $C_{19}-C_{36}$, $C_{37}-C_{40}$, and aromatic $C_{11}-C_{22}$, respectively. The corresponding exposure concentrations obtained from 5 points were 139.8, 462.8, 35.1 and 119.4 mg/kg, which were significantly higher than those from 18 points results (p <0.05). Our results suggest that limited number of samples for TPH fractionation may bias estimation of exposure concentration of TPH fractions. Also, it is recommended that more than 30 samples need to be analyzed for TPH fractionation in performing risk assessment.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권1호
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• pp.32-41
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• 2011

By using a newly developed Korean risk-based corrective action (K-RBCA) software (K-RBCA) and the RBCA Tool Kit, risk assessment was performed on a site that was contaminated with aromatic hydrocarbons and heavy metals. Eight chemicals including benzene, ethylbenzene, xylenes, naphthalene, benz(a) anthracene, benzo(b) fluoranthene, benzo(a) pyrene, and arsenic that exceeded the US EPA Soil Screening Level were chosen as the target pollutants. A conceptual site model was constructed based on the site-specific effective exposure pathways. According to the RBCA Tool Kit the carcinogenic risk of arsenic was larger than $10^{-6}$, which is the generally acceptable carcinogenic risk level. The K-RBCA estimated the same level of carcinogenic risk for arsenic. With the RBCA Tool Kit, the carcinogenic risk of benzo(a) pyrene was estimated to be about $1.3{\times}10^{-6}$. However, with the K-RBCA benzo(a) pyrene did not exhibit any risk. The inconsistency between the softwares was attributed to the different fundamental settings (i.e., medium division) between the two softwares. While the K-RBCA divides medium into surface soil, subsurface soil, and groundwater, the RBCA Tool Kit divides medium into only soil and groundwater. These differences lead to the different exposure pathways used by the two softwares. The K-RBCA considers the exposure pathways in surface soil and subsurface soil separately to estimate risk, however, the RBCA Tool Kit considers the surface soil and subsurface soil as one and uses the integrated exposure pathways to estimate risk. Thus the resulting risk is higher when the RBCA Tool Kit is used than when the K-RBCA is used. The results from this study show that there is no significant difference in the risks estimated by the two softwares, thus, it is reasonable to use the K-RBCA we developed in risk assessment of soil and groundwater. In addition, the present study demonstrates that the assessor should be familiar with the characteristics of a contaminated site and the assumptions used by a risk assessment software when carrying out risk assessment.