• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.18-20
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• 1999

• Proceedings of the KSEEG Conference
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• 2000.04a
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• pp.92-92
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• 2000

• Proceedings of the KSEEG Conference
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• 2000.04a
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• pp.63-65
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• 2000

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.89-90
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• 2002

• Economic and Environmental Geology
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• v.55 no.6
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• pp.737-760
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• 2022

For the geological disposal of high-level radioactive wastes (HLW), an understanding of deep subsurface environment is essential through geological, hydrogeological, geochemical, and geotechnical investigations. Although South Korea plans the geological disposal of HLW, only a few studies have been conducted for characterizing the geochemistry of deep subsurface environment. To guide the hydrogeochemical research for selecting suitable repository sites, this study overviewed the status and trends in hydrogeochemical characterization of deep groundwater for the deep geological disposal of HLW in developed countries. As a result of examining the selection process of geological disposal sites in 8 countries including USA, Canada, Finland, Sweden, France, Japan, Germany, and Switzerland, the following geochemical parameters were needed for the geochemical characterization of deep subsurface environment: major and minor elements and isotopes (e.g., ³⁴S and ¹⁸O of SO₄^2-, ¹³C and ¹⁴C of DIC, ²H and ¹⁸O of water) of both groundwater and pore water (in aquitard), fracture-filling minerals, organic materials, colloids, and oxidation-reduction indicators (e.g., Eh, Fe²⁺/Fe³⁺, H₂S/SO₄^2-, NH₄⁺/NO₃^-). A suitable repository was selected based on the integrated interpretation of these geochemical data from deep subsurface. In South Korea, hydrochemical types and evolutionary patterns of deep groundwater were identified using artificial neural networks (e.g., Self-Organizing Map), and the impact of shallow groundwater mixing was evaluated based on multivariate statistics (e.g., M3 modeling). The relationship between fracture-filling minerals and groundwater chemistry also has been investigated through a reaction-path modeling. However, these previous studies in South Korea had been conducted without some important geochemical data including isotopes, oxidationreduction indicators and DOC, mainly due to the lack of available data. Therefore, a detailed geochemical investigation is required over the country to collect these hydrochemical data to select a geological disposal site based on scientific evidence.

• Journal of the Korean earth science society
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• v.23 no.6
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• pp.474-485
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• 2002

The object of this study is to investigate the contamination degree and the interpretation of sea water intrusion phenomena with hydrogeochemical and hydrogen-oxygen stable isotope of coastal aquifer in the Gogum area, Korea. The physical characteristics of groundwaters is the neutral pH condition and transitional Redox environments, and groundwater is affected by sea water & surface water. The chemical properties of groundwaters are showing an increase in contamination owing to the sea water intrusion, waste water from the surface and agricultural chemicals. In the case of chloride, 6 samples of the groundwater in the study area are in excess of the drinking water standard. The Piper diagram shows the contamination in GG-4 and 14 by sea water intrusion. GG-3, 7 and 13 dominate the Na-HCO$_{3}$ type water and regional (GG-14) is indicated to dominate the Na-Cl type water such as sea water. According to the Sl (saturation index), sea water is oversaturated with respect to calcite and dolomite, GG-3, 14 and 18 are approaching the saturation state. The hydrogen-oxygen stable isotope ratio of groundwaters originates in the meteoric water, and groundwaters of GG-1, 5 and 14 display high oxygen isotope value due to surface water trespass and sea water intrusion. The result of this study, GG-14 is contaminated by sea water intrusion, groundwaters expected GG-3, 7 and 13 is in progress to artificial pollution and sea water intrusion.

• Journal of Environmental Impact Assessment
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• v.25 no.3
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• pp.209-221
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• 2016

The section from water source to 2.6km upper stream of Hantan River is protected as the drinking water quality protection area according to guidelines of Ministry of Environment, because water source of the Gwanin water intake plant has been known the river. However, opinions were consistently brought up that the standard of water source protection zone must be changed with using underground water as water source because of contribution possibility of underground water as the water source of Gwanin water intake facility. In this regard, hydrogeologic investigation including resistivity survey and hydrogeochemical investigation were carried out to assess water source and infiltration of contaminant for the plant. Quaternary basaltic rocks (50m thick with four layers) covered most of the study area on the granite basement. As the result of the resistivity survey, it is revealed that permeable aquifer is distributed in the boundary of two layers: the basaltic layer with low resistivity; and the granite with high resistivity. Considering of outflow from Gwanin water intake facility, the area possessing underground water was estimated at least $5.7km^2$. The underground water recharged from Cheorwon plain was presumed to outflow along the surface of unconformity plane of basalt and granite. Based on field parameters and major dissolved constituents, groundwater and river water clearly distinguished and the spring water was similar to groundwater from the basaltic aquifer. Temporal variation of $SiO_2$, Mg, $NO_3$, and $SO_4$ concentrations indicated that spring water and nearby groundwater were originated from the basaltic aquifer and other groundwater from granitic aquifer. In conclusion, the spring of the Gwanin water intake plant was distinguished from river water in terms of hydrogeochemical characteristics and mainly contributed from the basaltic aquifer.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.611-626
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• 2023

Overseas examples of the characterization stage of site selection proposed by the International Atomic Energy Agency were reviewed to highlight the factors necessary for consideration in the deep disposal of high-level radioactive waste. Studies in Sweden, Finland, the USA, and Canada were considered. Site investigations in Sweden and Finland commonly covered the fields of geology, hydrogeology, and hydrogeochemistry using similar field investigation techniques. The USA considered survey groups and factors under pre- and post-lockdown guidelines, as well as those for desaturated and saturated surveys. involving geophysical, hydrological, hydrogeological, hydrogeochemical, mechanical/physical, and thermal-characterization investigations. Canada provided a list of investigative methods for both preliminary and detailed site assessments including geological, physical, boring, hydrological, laboratory testing, and chemical analysis studies. Results of this study should elucidate site-selection investigation factors and survey methods applicable to Korea.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.435-450
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• 2005

The purpose of the study is to analyze the hydrogeochemical characteristics by multivariate statistical method, to interpret the hydrogeochemical processes for the new variables calculated from principal components analysis (PCA), and to infer the groundwater flow and circulation mechanism by applying the geostatistical methods for each element and principal component. Chloride and nitrate are the most influencing components for groundwater quality, and the contents of $NO_3$ increased by the input of agricultural activities show the largest variation. The results of PCA, a multivariate statistical method, show that the first three principal components explain $73.9\%$ of the total variance. PC1 indicates the increase of dissolved ions, PC2 is related with the dissolution of carbonate minerals and nitrate contamination, and PC3 shows the effect of cation exchange process and silicate mineral dissolution. From the results of experimental semivariogram, the components of groundwater are divided into two groups: one group includes electrical conductivity (EC), Cl, Na, and $NO_3$, and the other includes $HCO_3,\;SiO_2,$ Ca, and Sr. The results for spatial distribution of groundwater components showed that EC, Cl, and Na increased with approaching the coastal line and nitrate has close relationship with the presence of agricultural land. These components are also correlated with the topographic features reflecting the groundwater recharge effect. The kriging analysis by using principal components shows that PC 1 has the different spatial distribution of Cl, Na, and EC, possibly due to the influence of pH, Ca, Sr, and $HCO_3$ for PC1. It was considered that the linear anomaly zone of PC2 in western area was caused by the dissolution of carbonate mineral. Consequently, the application of multivariate and geostatistical methods for groundwater in the study area is very useful for determining the quantitative analysis of water quality data and the characteristics of spatial distribution.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.1-12
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• 2010

The objective of this study was to examine the hydrogeochemical and microbiological characteristics for stable maintenance of coastal LPG storage cavern. Cavern seepage water and groundwater in the vicinity of the LPG storage cavern were sampled and analyzed (February, May, August and October 2007). Groundwater samples of propane cavern showed high pHs of 8.1~12.4 due to dissolution of cement grouting materials that had been applied during the well and cavern construction. The EC values showed distinctive seasonal variation. The negative ORP indicated reduced condition. The seepage and surrounding groundwater are classified as Na-Cl type, which represents seawater effects. All of aerobic bacteria, anaerobic bacteria, slime forming bacteria and sulfate reducing bacteria were less than 500 CFU/mL, which indicated that there was no abrupt increase of bacteria in the cavern. Therefore there exist no hydrochemical symptoms to indicate unstable conditions of the cavern operation. However, regular and continuous monitoring is essentially required.