• Proceedings of the Korean Radioactive Waste Society Conference
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• 2011.05a
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• pp.357-358
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• 2011

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.622-625
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• 2005

본 연구의 목적은 동해 울릉분지 천부퇴적층의 공극수와 메탄의 특징 및 상호작용을 규명하는데 있다. 울릉분지에서 채취한 코어에서 공극수를 추출하여 분석한 결과, 공극수의 황산염 농도가 퇴적물의 심도가 증가할수록 감소하며, 감소하는 경향은 크게 세 가지 (직선성, concave down, upward kink)로 나뉨을 알 수 있었다. 이는 모든 코어에서 황산염 환원작용이 일어나고 있음을 지시한다 황산염 농도의 수직적 구배를 이용하여 SMI (sulfate-methane interface) 심도를 계산하면, 남부울릉분지가 북부울릉분지보다 낮은 값을 갖는다. 반면에 메탄 농도는 퇴적물의 심도가 증가할수록 전반적으로 증가하며, 공간적으로는 남부 울릉분지가 북부울릉보지보다 높다. 또한 남부울릉분지에서 메탄가스 농도는 SMI 심도 아래에서 급격히 증가한다 메탄가스의 탄소 안정동위원소$(\delta^{13}C)$ 분석 값들은 대부분 $-60\%_{\circ}$이하로서 이는 메탄가스가 열기원 보다는 박테리아기원임을 지시해준다 또한 남부 울릉분지에서 메탄의 탄소 안정동위원소 분석 값들은 메탄농도가 증가할수록 낮은 값을 보여 주는 데 이러한 결과들은 남부 울릉분지에서 무산소 메탄 산화작용이 일어나고 있음을 지시하고, 메탄의 상향 분산 (diffusion)량이 북부 울릉분지보다 많이 일어난다는 것을 의미한다. 공극수내 황산염 이온 농도 구배와 메탄가스 농도를 종합적으로 고려할 때, 울릉분지에서 가스하이드레이트의 부존가능성은 북부 울룽분지보다 남부 울릉분지가 높은 것으로 추정된다.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.421-433
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• 2023

The final disposal of spent nuclear fuel(SNF) from nuclear power plants takes place in a deep geological repository. The metal canister encasing the SNF is made of cast iron and copper, and is engineered to effectively isolate radioactive isotopes for a long period of time. The SNF is further shielded by a multi-barrier disposal system comprising both engineering and natural barriers. The deep disposal environment gradually changes to an anaerobic reducing environment. In this environment, sulfide is one of the most probable substances to induce corrosion of copper canister. Stress-corrosion cracking(SCC) triggered by sulfide can carry substantial implications for the integrity of the copper canister, potentially posing a significant threat to the long-term safety of the deep disposal repository. Sulfate can exist in various forms within the deep disposal environment or be introduced from the geosphere. Sulfate has the potential to be transformed into sulfide by sulfate-reducing bacteria(SRB), and this converted sulfide can contribute to the corrosion of the copper canister. Bentonite, which is considered as a potential material for buffering and backfilling, contains oxidized sulfate minerals such as gypsum(CaSO4). If there is sufficient space for microorganisms to thrive in the deep disposal environment and if electron donors such as organic carbon are adequately supplied, sulfate can be converted to sulfide through microbial activity. However, the majority of the sulfides generated in the deep disposal system or introduced from the geosphere will be intercepted by the buffer, with only a small amount reaching the metal canister. Pyrite, one of the potential sulfide minerals present in the deep disposal environment, can generate sulfates during the dissolution process, thereby contributing to the corrosion of the copper canister. However, the quantity of oxidation byproducts from pyrite is anticipated to be minimal due to its extremely low solubility. Moreover, the migration of these oxidized byproducts to the metal canister will be restricted by the low hydraulic conductivity of saturated bentonite. We have comprehensively analyzed and summarized key research cases related to the presence of sulfates, reduction processes, and the formation and behavior characteristics of sulfides and pyrite in the deep disposal environment. Our objective was to gain an understanding of the impact of sulfates and sulfides on the long-term safety of high-level radioactive waste disposal repository.

• Economic and Environmental Geology
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• v.29 no.1
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• pp.65-75
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• 1996

Sulfate reduction and the precipitation of metal sulfides may have great potential to improve water quality of mine effluents in wetland treatment systems. Laboratory experiments using sulfate reducing bacteria (SRB) and limestone to treat effluents from the abandoned Dalsung tungsten-copper mine show that encouraging results, that have been attributed to sulfate reduction. Fe, Al, Cd, Cu and Zn are reduced to below detection limits with $99{\sim}100%$ metal removal rates, Mn is reduced by at least 90% to below 8.0 mg/l, and the pH is raised from 5.12 to 7.60 after 53 days of experiments. In the staged design, laboratory experiments are initiated to determine what would be reasonable substrate materials for remediation of the mine effluents. A substrate mixture containing 70% oak compost and 30% mushroom compost maintains $0.03{\sim}0.04mM$ of lactate, which provides good condition for the SRB granule. A downflow SRB wetland system is proposed as follows : 1) The lower part of the treatment system consists with a 25 cm thick layer of high quality (above 95% of $CaCO_3$) of limestone; 2) The geotextile (geonet) is recommended to be spread on the limestone bed to prevent clogging the limestones with the substrates; 3) The mixture of substrates with 70% oak and 30% spent mushroom composts, and SRB granules overlain on top of the geonet with 25 cm height. The sizes of the passive treatment systems are calculated according to metal loading and permeability criteria : 1) $220m^3$ ($15{\times}15{\times}1m$) for -1 level effluents; 2) $28m^3$ ($5.3{\times}5.3{\times}1m$) for -2 level; and 3) $2700m^3$ ($52{\times}52{\times}1m$) for the -3 level. The -3 level system needs to be broken down into 5 to 15 cells.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.575-585
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• 2007

Microbial control of the geochemical behavior of heavy metals (Cd, Cu, Pb, and Zn) and As in contaminated subsurface soil and sediment was investigated through activation of indigenous bacteria with lactate under anaerobic condition for 25 days. The results indicated that dissolved Cd, Pb and Zn were microbially removed from solutions, which was likely due to the formation of metal sulfides after reduction of sulfate by indigenous sulfate-reducing bacteria. Soils from the Dukeum mine containing a large amount of sulfate resulted in complete removal of dissolved As after 25 days by microbial activities, while there were gradual increases in dissolved As concentration in soils from the Hwabuk mine and sediments from the Dongducheon industrial area which showed low $SO_4{^2-}$ concentrations. Addition of appropriate carbon sources and sulfate to contaminated geological media may lead to activation of indigenous bacteria and thus in situ stabilization of the heavy metals; however, potential of As release into solution after the amendment should be preferentially investigated.

• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.9-18
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• 2003

Sampling of waters from each stage of treatment system (Successive Alkalinity Producing System; SAPS), tailings seepage, and spring near the Hanchang coal mine of Kangwon Province were carried out seasonally and analyzed to evaluate the source and possible path of groundwater contamination by acid mine drainage (AM). Sulfur isotope compositions were measured to identify the origin of groundwater contaminations and the sulfate reduction processes in the SAPS. Low pH and high metal concentration of spring water indicates possibility of the groundwater contamination by AMD. Removal efficiency of acidity of the SAPS was 18.17 g/$\textrm{m}^2$/day on an average and the metal removal efficiency was almost 100%, which was higher than those of other treatment systems. However, no appreciable decrease of sulfur content and almost similar sulfur isotope compositions of water from each stage of the treatment system may suggest incomplete or very poor sulfate reduction by sulfate reducing bacteria. Chemical and sulfur isotope compositions showed that spring water was contaminated by seepage from mine tailings. And seepage of stonewall, a part of treatment system was affected by both tailings seepage and mine adit drainage. In this study site, the treatment system was constructed for the only AMD from mine adit not for tailings seepages, which resulted in the groundwater contamination from tailing seepages. Similar situation is expected in other abandoned coal mine areas.

• Economic and Environmental Geology
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• v.53 no.3
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• pp.235-244
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• 2020

Copper (Cu), one of the main contaminants in the mine drainage from the closed mine area, needs to be removed before exposed to environment because of its toxicity even in the low concentration. In this study, passive treatment based field pilot experiments using limestone and compost media were conducted during 9 months for enhancing Cu removal efficiency of the mine water treatment facility of S mine located in Goseong, Gyeongsangnam-do in South Korea. The pH increase and Cu removal efficiency showed high value at Successive Alkalinity Producing System ( SAPS) > Reducing and Alkalinity Producing System (RAPS) > limestone reactor in a sequence. The compost media using in SAPS and RAPS contributed to raise pH by organic material decomposition with generating alkalinity, thus, Cu removal efficiency increased. Also, experimental results showed that Cu removal efficiency was proportional to pH increase, meaning that pH increase is the main mechanism for Cu removal. Moreover, Sulfate Reduction Bacteria (SRB) was identified to be most activated in SAPS. It is inferred that the sulfate reduction reaction also contributed to Cu removal. This study has the site significance in that the experiments were conducted at the place where the mine water generates. In the future, the results will be useful to select the more effective reactive media used in the treatment facility, which is most appropriate to remediate mine water from the S mine.

• Economic and Environmental Geology
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• v.43 no.1
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• pp.13-20
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• 2010

Acid mine drainage (AMD) from abandoned mine sites typically has low pH and contains high level of various heavy metals, aggravating ground- and surface water qualities and neighboring environments. This study investigated removal of heavy metals in a biological treatment system, mainly focusing on the removal by adsorption on a substrate material. Bench-scale batch experiments were performed with a mushroom compost to evaluate the adsorption characteristics of heavy metals leached out from a mine tailing sample and the role of SRB in the overall removal process. In addition, adsorption experiments were perform using an artificial AMD sample containing $Cd^{2+}$, $Cu^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ to assess adsorption capacity of the mushroom compost. The results indicated Mn leached out from mine tailing was not subject to microbial stabilization or adsorption onto mushroom compost while microbially mediated stabilization played an important role in the removal of Zn. Fe leaching significantly increased in the presence of microbes as compared to autoclaved samples, and this was attributed to dissolution of Fe minerals in the mine tailing in a response to the depletion of $Fe^{3+}$ by iron reduction bacteria. Measurement of oxidation reduction potential (ORP) and pH indicated the reactive mixture maintained reducing condition and moderate pH during the reaction. The results of the adsorption experiments involving artificial AMD sample indicated adsorption removal efficiency was greater than 90% at pH 6 condition, but it decreased at pH 3 condition.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.565-573
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• 2000

Sewer pipe in Korea is generally constructed with concrete pipes. Moreover, the sewer system is susceptible to the corrosion problem due to the regulation employing anaerobic treatment processes, such as domestic sewage treatment facilities, nightsoil septic tanks and so on. The objective of this study is investigated to experimental test of $H_2S$ production rate affecting corrosion of sewer pipe in Korea. In this study, tube-type and sealed-type reactor were used to examine the reactions in the microorganism suspended growth and biofilm. Furthermore. concentration changes were investigated with COD and sulfate reduction in each reactor. Sulfide production rate was $50.4mg-H_2S/g-VSS{\cdot}d$ in the sealed-type reactor and in the tube-type biofilm reactor was $2.8{\sim}18.8g-H_2S/m^2{\cdot}d$.

• Journal of Conservation Science
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• v.29 no.2
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• pp.187-196
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• 2013

This study is on the corrosion of iron objects caused by sulfides in undersea environment. The corrosion state of objects in seawater and their damage state after underwater and left in highly humid air were studied. The samples of this study were four iron objects which had been taken out from undersea mud layer located in Taean Mado, Chungcheongnamdo. SEM-EDS and XRD analyse on the objects to check whether they have sulfides or not. The result of analysis suggested that the major component of corrosion product generated in undersea deposit soil is sulfur(S) and iron sulfide(FeS) is formed as sulfide. However, there was no clear corrosion on the surface of objects which was exposed to sea water because of the impact of concretion which covered the surface. In order to check the damage status of iron objects after they had been taken out of sea water, exposure tests in high humidity environment and dehumidified environment were done on the corrosion products. The result of the test suggested that the oxidization of iron sulfide corrosion product makes iron sulfate ($FeSO_4$) and sulfuric acid ($H_2SO_4$) and they can cause secondary corrosion of iron objects. Therefore, it is believed that the iron sulfide corrosion product of iron objects taken out from underwater environment should be removed by all means and the keeping environment of the iron objects should also maintain dehumidified state.