• Economic and Environmental Geology
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• v.48 no.2
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• pp.131-145
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• 2015

Thermodynamic prediction of weathering products from primary aquifer minerals around underground disposal sites was investigated. The distribution of solubility quotients for kaolinite-smectite reactions showed the trend of reaching at equilibrium with Ca-, Mg-, and Na-smectite for deep groundwaters in granitic aquifers. The values of $10^{-14.56}$, $10^{-15.73}$, and $10^{-7.76}$ were proposed as equilibrium constants between kaolinite and Ca-, Mg-, and Na-smectite end members, respectively. On stability diagrams, most of deep groundwaters were located at equilibrium boundaries between stability fields of kaolinite and smectites or on stability fields of smectites and illite. Shallow groundwaters in basic rock aquifer were plotted at the same stability areas of deep granitic groundwaters on stability diagrams. The results indicated that the primiary mineralogical composition may be important to predict weathering products in deep aquifers.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.78-85
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• 2005

This study, combining geophysical and environmental approaches, was undertaken to investigate the causes of secondary salinity in the Goondoola basin, in southwestern Queensland. Airborne radiometric, electromagnetic and ground electromagnetic datasets were acquired, along with data on soils and subsurface materials and groundwater. Relationships established between radiometric, elevation data, and measured material properties allowed us to generate predictive maps of surface materials and recharge potential. Greatest recharge to the groundwater is predicted to occur on the weathered bedrock rises surrounding the basin. Electromagnetic data (airborne, ground, and downhote), used in conjunction with soil and drillhole measurements, were used to quantify regolith salt store and to define the subsurface architecture. Conductivity measurements reflect soil salt distribution. However, deeper in the regolith, where the salt content is relatively constant, the AEM signal is influenced by changes in porosity or material type. This allowed the lateral distribution of bedrock weathering zones to be mapped. Salinisation in this area occurs because of local-andintermediate-scale processes, controlled strongly by regolith architecture. The present surface outbreak is the result of evaporative concentration above shallow saline groundwater, discharging at break of slope. The integration of surficial and subsurface datasets allowed the identification of similar landscape settings that are most at risk of developing salinity with groundwater rise. This information is now being used by local land managers to refine management choices that prevent excess recharge and further salt mobilisation.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.97-108
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• 2002

The use of land at the time of investigation of groundwater quality in the rapidly urbanized Bu-chon city is classified into 5 categories based on the change process of land use. The difference in groundwater quality according to the land use and its usage period is tested by non-parametric statistical procedures. The seven constituents of water quality with the highly frequent detection in the area for this study are used for the statistical test. The shallow groundwater quality within the areas of the same land use at the time of investigation varies significantly according to the period of land usage. The concentration of KMnO$_4$consumed and hardness is significantly higher in the old residential area (of more than 20 years old) than in the younger one (of less than 10 years old). The quality of the shallow groundwater is also significantly different among the three categories with the similar period of land usage (of more than 15 years old). The concentration of No$_3$-N, hardness and total solid is significantly higher in the residential area than in the agricultural one (namely, the area used as paddy fields 2 to 5 years ago). The median concentration of these constituents is 2.2 to 3.8 times higher in the residential area than in the agricultural one. The concentration of NO$_3$-N, KMnO$_4$, consumed and Cl is significantly higher in the industrial area than in the agricultural one. The median concentration of these constituents is 5.5 to 18 times higher in the industrial area than in the agricultural one. The concentration of KMnO$_4$consumed is significantly higher in the industrial area than in the residential area. The median concentration of these constituents is 12 times higher in the industrial area than in the residential one. The spatial distribution of shallow groundwater quality in the rapidly urbanized area is closely related to the period of land usage as well as the land use, which is presumed to be attributed to the difference in the concentration and leakage rate of the contaminants leaking from damaged sewer into shallow groundwater.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.123-126
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• 1998

We have conducted surface electrical resistivity surveys along with the electrical logging at Bookil-Myun, Chungwon-Goon, Choongchungbuk-Do to determine the depths of basement and water table, and for the purpose of preparing the basic input data for hydrogeologic model combined with GIS. A twenty lines of dipole-dipole array survey and a twenty-five stations of resistivity sounding were performed and ten holes were employed for electrical logging to cross check the surface data. A combined interpretation gave the quantitative information of the shallow geologic structure over the area and we constructed layers using the grid analysis of Arc/info. The constructed layers were turned out to be similar to the geologic structure confirmed from the drilling data and we concluded that the methodology adopted in this study would be applicable to hydrogeologic model setup as a tool of providing the basic input data.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.399-402
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• 2004

An aquifer thermal energy storage (ATES) model is simulated by FEFLOW according to the scenario of heat pump operation in two layered confining aquifer. The scenario is consisted of 4 steps: 90 days pumping (west well) and waste water injection (east well: 35 $^{\circ}C$), 90 day s stop, 90days pumping (east well) and waste water injection (west well: 5 $^{\circ}C$), and 95 days stop. The injection of the waste water is limited in the second layer and the first layer is aquitard. The temperature distribution at the surface shows low difference with reference temperature and opposit aspect with that of the second layer because the thermal transition through the first layer is very slow. Even though the simulated thermal transition in the aquifer system have a difference with real ATES system, optimal design and operate system can be developed with field tests and operational experience.

• Economic and Environmental Geology
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• v.31 no.3
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• pp.201-213
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• 1998

From the Jungwon and Munkyeong areas which are among the famous producers of the carbonate-type groundwaters in Korea, various kinds of natural waters (deep groundwater, shallow groundwater and surface water) were collected between 1996 and 1997 and were studied for hydrogeochemical and environmental isotope (${\delta}^{34}S_{so4}$, ${\delta}^{18}O$, ${\delta}D$)systematics. Two types of deep groundwaters (carbonate type and alkali type) occur together in the two areas, and each shows distinct hydrogeochemical and environmental isotope characteristics. The carbonate type waters show the hydrochemical feature of the 'calcium(-sodium)-bicarbonate(-sulfate) type', whereas the alkali type water of the 'sodium-bicarbonate type'. The former type waters are characterized by lower pH, higher Eh, and higher amounts of dissolved ions (especialJy, $Ca^{2+}$, $Na^{+}$, $Mg^{2+}$, $HCO_3{^-}$ and $SO_4{^{2-}}$). Two types of deep groundwaters are all saturated or supersaturated with respect to calcite. Two types of deep groundwaters were both derived from pre-thermonuclear (about more than 40 years old) meteoric waters (with lighter 0 and H isotope data than younger waters, i.e., shallow cold groundwaters and surface waters) which evolved through prolonged water-rock interaction. Based on the geologic setting, water chemistry, and environmental isotope data, however, each of these two different types of deep groundwaters represents distinct hydrologic and hydrogeochemical evolution at depths. The carbonate type groundwaters were formed through mixing with acidic waters that were derived from dissolution of pyrites in hydrothermal vein ores (for the Jungwon area water) or in anthracite coal beds (for the Munkyeong area water). If the deeply percolating meteoric waters did not meet pyrites during the circulation, only the alkali type groundwaters would form. This hydrologic and hydrogeochemical model may be successfully applied to the other carbonate type groundwaters in Korea.

• Journal of Soil and Groundwater Environment
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• v.12 no.4
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• pp.35-53
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• 2007

Geochemical and isotope studies on the groundwater system of the Youngcheon area were carried out. Most groundwaters belong to Ca-$HCO_3$ and Ca-$SO_4$ types and some groundwaters belong to Na-$HCO_3$ type. Geochemical characteristics of these groundwaters were mainly affected by their basement rocks around the boreholes. High $SO_4$ content of groundwater is the result of reaction with sulfate or sulfide minerals in the host rock. Ca was originated from the carbonate minerals in the sedimentary rock. After the groundwater was saturated with calcite, the Na-$HCO_3$ type groundwaters were evolved by the reaction with plagioclase for a relatively long residence time. This explanation was supported by low tritium contents of Na-$HCO_3$ type groundwaters. ${\delt}a^{18}O$ and ${\delta}D$ data indicate that the groundwaters are of meteoric water origin and there was no difference between the various types of waters. Grondwaters from the boreholes BH-1, BH-9 and BH-12 showed the geochemical and isotopic characteristics of deep groundwater. Most borehole groundwaters except them did not show the systematic geochemical variations with sampling depth indicating that the shallow and deep groundwaters were mixed with each other throughout the study area. The results of water quality analysis indicate that the study area is highly contaminated by the introduction of agricultural sewage.

• Economic and Environmental Geology
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• v.43 no.1
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• pp.43-52
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• 2010

The geochemical and nitrogen isotopic analyses for shallow groundwater of Ogcheon area were carried out to characterize the geochemical characteristics of the groundwater and to identify the source of nitrate. Groundwater shows a neutral pH to weakly alkalic condition with pH values ranging from 6.9 to 8.4. The average of EC, Eh and DO is $344.2\;{\mu}s/cm$, 195 mV, 4 mg/L, respectively. According to piper diagram, chemical composition of groundwater is dominantly characterized by Ca-$HCO_3$ type. On the other hand, groundwater type in the study area include Ca-Cl+$NO_3$ type that were highly influenced by agricultural activities. $NO_3$-N concentration of the collected samples(n=45) range from 12.4 to 34.2 mg/l. These data show that the $NO_3$-N concentration exceeds Korea Drinking Water Standard (10 mg/l). The $\delta^{15}N-NO_3$ values range from $2.7^{\circ}/_{\circ\circ}$ to $18.8^{\circ}/_{\circ\circ}$. The enrichments of heavy isotope in the groundwater indicate that major origin of nitrate pollution were associated with animal and human waste. Also the denitrification may have partly contributed as one of the sources of nitrogen.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.197-205
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• 2010

Recently abrupt climate changes have been occurred in global and regional scales and $CO_2$ reduction technologies became an important solution for global warming. As a method of the solution shallow underground thermal energy storage (UTES) has been applied as a reliable technology in most countries developing renewable energy. The geothermal energy system using thermal source of soil, rock, and ground water in aquifer or cavern located in shallow ground is designed based on the concept of thermal energy recovery and storage. UTES technology of Korea is in early stage and consistent researches are demanded to develop environmental friendly, economical and efficient UTES systems. Aquifers in Korea are suitable for various type of ground water source heat pump system. However due to poor understanding and regulations on various UTES high efficient geothermal systems have not been developed. Therefore simple closed U-tube type geothermal heat pump systems account for more than 90% of the total geothermal system installation in Korea. To prevent becoming wide-spread of inefficient systems, UTES systems considering to the hydrogeothemal properties of the ground should be developed and installed. Also international collaboration is necessary, and continuous UTES researches can improve the efficiency of shallow geothermal systems.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.587-598
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• 2023

To assess the distribution and temporal changes in radon concentration within a region in Yeonpung-myeon, Goesan-gun, known for elevated groundwater radon levels, we conducted a series of analyses, measuring radon concentration and DTW (Depth to water table) at 2-month intervals over 12 cycles. The investigation covered 10 groundwater wells and one stream within the designated area. The groundwater in the central part of the region exhibited high radon concentrations, ranging from 37.0 to 2,675.2 Bq/L. Conversely, the peripheral zones displayed comparatively lower radon concentrations, ranging from 10.6 to 37.9 Bq/L. This variation is attributed to the presence of granite porphyry that intruded into the Okcheon Formation, forming a fracture zone and contributing to elevated radon levels in the central part. In contrast, the peripheral locations, located within the Okcheon Formation and away from the granite porphyry intrusion, demonstrated lower radon concentrations. The observed significant fluctuation in radon concentration in the central area is associated with its low-lying topography. The pronounced seasonal changes in groundwater levels contribute to the migration of shallow, low-radon groundwater into areas with higher radon concentrations, explaining the observed variations in radon levels within the central part of the studied area.