• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.520-523
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• 2003

강원도 지역의 대표적인 탄산용출수에 대한 수리지구화학적 연구를 통하여 심부 지열 저장지의 온도와 심부환경을 추정하였다. 탄산용출수는 공통적으로 약산성의 pH와 높은 이온함량으로 특징되지만, 화학적으로는 Na-HCO$_3$형, Ca-Na-HCO$_3$형, 그리고 Ca-HCO$_3$형으로 뚜렷이 구분된다. 심부에서 생성된 탄산용출수가 지표로 상승하는 도중에 수반된 지표수 혼합차이로 인해 이런 화학조성의 차이가 유발된 것으로 판단된다. Na-HCO$_3$형 탄산수는 화학 조성상 ‘mature water’의 특징을 보여주는 반면, 다른 두 유형의 탄산수들은 ‘immature water’에 해당하였다. Na-HCO$_3$ 형 탄산수에 대하여 실리카, Na-K 및 Na-K-Ca 지온계를 적용한 결과, 약 l15-157도의 심부저장지 온도가 산출되었으며, 이 결과는 다성분 평형계를 이용한 추정 온도 (약 140-160도)와도 잘 일치하였다. 반면, Ca-HCO$_3$ 형 탄산수들은 지표수와의 혼합 때문에 상대적으로 낮고 넓은 범위의 추정 온도 (약 60-130도)를 나타내었다. 따라서 연구지역 내 탄산용출수의 심부저장지 온도는 Na-HCO$_3$형에 대해서만 타당하게 적용될 수 있으며, 약 140-160도일 것으로 추정된다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.408-412
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• 2004

A total of 23 springs distributed in the southern and northern sides of Mt. Hala in Jeju Island were seasonally sampled and analyzed for their major ion chemistry and oxygen and hydrogen isotope compositions to investigate their hydrogeochemical and isotopic characteristics. Dissolved ion concentrations of the south-side springs slightly increase with decreasing altitude. This indicates that dissolved ion concentrations of groundwater recharged at higher altitudes increase by water-rock interaction during the downgradient migration of groundwater through highly permeable volcanic aquifer. Dissolved ion concentrations of the north-side springs also slightly increase with decreasing altitude, but dramatically increase at ～300 m.a.s.l. This may indicate a sudden input of contaminants to the north-side groundwater system around ～300 m.a.s.l. Springs located in areas above ～300 m.a.s.l. have very low concentrations of dissolved ions, showing little seasonal variations. Whereas springs located in areas below ～300 m.a.s.l. show a big seasonal variation in the concentration of dissolved ions. Seasonal variation of oxygen isotope compositions of springs is ～3$\textperthousand$ for high-altitude springs (～1700 m.a.s.l.) and is ～2$\textperthousand$ near shore, indicating an attenuation of the variation through mixing with other groundwater bodies during migration.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.139-142
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• 2001

서울시 대도시 지하수의 수리지구화학 및 오염 특성을 토지 이용 특성(청정지역, 주거지역, 농업지역, 교통혼잡지역, 공단지역)과 관련하여 고찰함으로써 대도시 지하수 수질의 효율적 관리에 활용하기 위한 3개년 모니터링 연구를 수행하고 있다. 본 논문에서는 현재까지의 연구 결과를 요약하여 소개한다. 총용존고체 함량(TDS)은 지하수 수질 특성 파악에 손쉽고 효과적으로 활용할 수 있는 파라미터임이 확인되며, 청정지역, 주거지역, 농업지역, 교통혼잡지역, 공단지역의 순으로 증가하는 경향이 뚜렷하다. 따라서, 서울 도시 지하수 수질은 일차적으로 부근의 도시화 특성과 밀접한 상관성을 가짐을 확인하였다. 한편, 청정지역의 수질 특성 자료를 제시하여 지하수 오염도 평가의 기준(배경 수질) 자료로 활용토록 하였다. 서울 동부 지역 암반 지하수의 수질 특성을 보면, 강북, 노원, 도봉 등 중랑천 상류 지역의 지하수가 동대문, 성동, 송파구 등 하류쪽의 지하수에 비해 낮은 TDS 함량을 갖는 경향이 있다. 서부 지역 지하수는 동부 지역에 비해 높은 TDS 값을 보이며, 공단부지 면적이 큰 영등포, 금천, 구로구 일대 및 종로, 중구 등 교통혼잡지역 등에서 매우 높은 TDS 함량을 나타내었다. 결국, 서울시 지하수의 TDS 함량은 수-암 반응보다는 인위적인 오염원에 의해 크게 지배되는 것으로 판단된다.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.93-104
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• 2004

This paper intended to assess the hydro-structure characteristics of volcanic rocks based on the hydrogeological data obtained from the underground storage cavern during construction. The variation of groundwater levels was periodically measured from the 28 surface monitoring holes(NX size) and the hydraulic pressures and injection rates were daily monitored from the water curtain holes(95 horizontal holes and 63 vertical holes). The hydraulic interference tests were performed in whole water curtain holes. The distribution patterns of hydraulic pressure are closely related to the dip angles of fracture intersected to the water curtain holes. Three domains can be grouped by the distribution of hydraulic pressures in the horizontal water curtain holes. The initial hydraulic pressures measured immediately after drilling of water crutain holes are high in ascending order of the cavern C-2, C-1, and C-3. The priliminary hydrochemical data also indicate that the portions of the deep groundwater composition is relatively great in the cavern C-3 area. Some of the horizontal water curtain holes in the cavern C-3 show a steady higher groundwater pressure with the composition of shallow groundwater indicating the outer boundary as constant hydraulic boundary. The water curtain holes in the cavern C-2 is characterized as low initial hydraulic pressure and less injection rates, suggesting poor hydraulic connectivity to a shallow groundwater system. The results of the study can help to understand a hydraulic compartment concept in a fracture hydro-geology and be utilized during the surface investigation for a groundwater system.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.1
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• pp.41-53
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• 1997

Geochemical data of soil and water samples were presented in order to assess the environmental impart for drinking water sites. Microscopic observation of rock samples and physical and chemical analysis of soil and water samples were undertaken. The geology of study areas are classified into three groups such as granitic rocks, meta-sedimentary rocks and sedimentary rocks. Enrichment of heavy metals derived from those rocks is not found in this study areas. Soils were analyzed for Cu, Pb, Zn, Cd and Cr using AAS extracted by HNO$_3$+HClO$_4$ and 0.1 N HCl. Heavy metal concentrations in soils are within the range of those in uncontaminated soils. In comparison of metal contents extracted by 0.1 N HCl and HNO$_3$+HC1O$_4$, less than 10% of the heavy metals are present in the exchangeable fraction. In particular, an pollution index has been proposed to assess the degree of soil contamination. Pollution index in soils are between 0.03 and 0.47 therefore, soils are not polluted with heavy metals. Deep groundwaters within granitic rocks have been evolved into Na$\^$＋/-HCO$_3$$\^$-/ type, whereas other deep groundwaters evolved into Ca$\^$2＋/-HCO$_3$$\^$-/ type. The predominance of Na$\^$＋/ over Ca$\^$2＋/ in deep groundwaters within granitic rocks is a result of dissolution of plagioclase, but for sedimentary and meta-sedimentary rocks, dissolution of calcite is a dominant factor for their hydrogeochemistry. The pH, conductivity and contents of the most dissolved ions in the water increase with depth. Shallow groundwaters, however, are highly susceptible to pollution owing to agricultural activities, considering the fact that high contents of nitrate, chloride and potassium, and high K/Na ratio are observed in some shallow groundwaters. In a thermodynamic approach, most natural water samples are plotted within the stability fields of kaolinite and smectite. Therefore, microcline and other feldspars will alter to form clay minerals, such as kaolinite and smectite. From the modelling for water-rock interactions based on mass balance equation, models accord well with behavior of the ions and results of thermodynamic studies are derived.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.699-707
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• 2021

Hwajinpo Lagoon, located on the eastern coast of Korea, is a unique environment where freshwater and saltwater are mixed. Systematic management of the lagoon is required because it is a biodiversity-rich and area of high conservation value. The existing environment of the lagoon was evaluated by identifying the distribution of the groundwater level and groundwater flow characteristics. In addition, hydrogeochemical fluctuations were analyzed to determine the effect of seawater intrusion into the aquifer. The results demonstrate that the freshwater-saltwater interface is distributed throughout the aquifer and rises when water of the lagoon evaporates due to prolonged periods of low rainfall and high temperature, thereby increasing the possibility of seawater inflow through groundwater. As for the ionic delta properties (difference between the measured and theoretical concentration of mixed waters), it was estimated that the cation-exchange and precipitation reactions occurred in the aquifer due to seawater intrusion. The ratio of seawater mixed at each point was calculated, using oxygen isotopes and chloride as tracers, resulting in an average of 0.3 and a maximum of 0.87. The overall seawater mixing ratio appears to be distributed according to the distance from the coast. However, some of the results were deviated from the theoretical expectations and reflected the characteristics of the nearby aquifers. Further research on seasonal changes and simulation of seawater intrusion mechanisms is required for specific analysis.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.435-450
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• 2022

In step-by-step site selection for geological disposal of high-level radioactive waste, parameters necessary for site selection will be acquired through deep drilling surveys from the basic survey stage. Unlike site investigations of rock mass structures such as tunnels and underground oil storage facilities, those related to the geological disposal of high-level radioactive waste are not only conducted in relatively deep depths, but also require a high level of quality control. In this report, based on the 750 m depth drilling experience conducted to acquire the parameters necessary for deep geological disposal, the methodology for deep drilling and the geology, geophysics, geochemistry, hydrogeology and rock mechanics obtained before, during, and after deep drilling are discussed. The procedures for multidisciplinary geoscientific investigations were briefly described. Regarding in-situ stress, one of the key evaluation parameter in the field of rock engineering, foreign and domestic cases related to the geological disposal of high-level radioactive waste were presented, and variations with depth were presented, and matters to be considered or agonized in acquiring evaluation parameters were mentioned.

• Korean Journal of Heritage: History & Science
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• v.45 no.1
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• pp.102-121
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• 2012

The purpose of this study is to verify homoteneity of soil and earthenwares and identify firing temperature of earthenwares excavated from Yeoncheon Hapsuri: two earthenwares of the New Stone Age(YCP-1, YCP-2); two of the Bronze Age(YCP-3, YCP-4); and four of the Three States Age(YCP-4~8). The comparative analysis of soil (YCRM) and the earthenwares displays that soil geochemical patterns were similar to YCP-1, YCP-3, YCP-5, YCP-6, YCP-7 and YCP-8. On the other hand, YCP-2 and YCP-4 did not show the similarity to the one of soil because they had been enriched with MgO by contained talc and chlorite. Based on the absorption rate, specific gravity, structural characteristics and XRD analysis, firing temperature has been estimated: for YCP-7 and YCP-8 was $870^{\circ}C$ or over; for YCP-2 and YCP-4 $800^{\circ}C$ or below; and for YCP-1, YCP-3, YCP-5 and YCP-6 between 800 and $870^{\circ}C$. Mineralogical analysis displays that the geochemical pattern of the soil is coincide with the one around Yeoncheon Hapsuri site, which also shows similarity to the one of earthenwares. Such result persuades that the excavated earthenwares were produced with the soils within the precinct of the archaeological sites.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.59-65
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• 1999

Both the groundwater changes due to different pumping rates and the geochemistry of thermal waters in the Suanbo area are considered in this study. The observation of groundwater level change since 1991 shows that the change is directly correlated with pumping rates of thermal waters and reveals the retardation of ca. 5 weeks after pumping. The hydrogeological aquifer in the area is under reducing condition. The thermal waters are of Na-HCO$_3$ type. and are alkaline (pH=8.5∼8.7) with low TDS values (274∼284 mg/l) and high concentrations of Na (68∼72 mg/l). F (6.4∼8.9 mg/l), and HCO$_3$(136∼146 mg/l). Oxygen and hydrogen isotope ratios of thermal water indicate a meteoric water origin. The activities of Rn-222 and Ra-226 in both thermal water and local groundwater were determined to delineate possible geochemical controls on the Rn-222 and Ra-226. The Rn-222 concentrations are several orders of magnitude greater than the Ra-226 concentrations. The concentrations of Rn-222 range from 190 to 7.490 pCi/1 with an average of 2,522 pCil/l. and those of Ra-226 average 0.32 pCi/1 with the range from 0.25 to 0.42 pCi/1. The concentrations of Rn-222 and Ra-226 are inversely correlated with EC and alkalinity. The pH it positively correlated with Ra-226. The correlation between Rn-222 and Ra-226 is poor. Thermal waters in the study area are produced from highly fractured phyllite. The thermal water qualify. CSAMT (controled-source audiofrequency magnetotelluric) prospecting, and petrological evidences, however, indicate that the heat is possibly transmitted through deep normal faults reaching a deep granite batholith, and the phyllite acts only as a groundwater pathway.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.293-304
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• 2017

This study was performed in order to hydrogeological analysis of aquifer, which is a necessary part for evaluating the efficiency of the combined well and open-closed loops geothermal (CWG) systems. CWG systems have been proposed for the effective utilization of geothermal energy by combining open loop geothermal systems and closed loop geothermal systems. Small aperture CWG systems and large aperture CWG systems were installed at a green house land with water curtain facilities in Chungju City. Aquifer tests include pumping tests and step-drawdown tests were conducted to analyse hydrogeological characteristics of aquifer in the study area. The transmissivity was estimated in the range of $13.49{\sim}58.99cm^2/sec$, and the storativity was estimated in the range of $1.13{\times}10^{-5}{\sim}5.20{\times}10^{-3}$. The geochemical analysis showed $Ca^{2+}$ ion and ${HCO_3}^-$ ion were dominant in groundwater. The Langelier Saturation Index and the Ryznar Stability Index showed low scaling potential of groundwater. In the analysis of vertical water temperature change, the geothermal gradient was estimated as $2.1^{\circ}C/100m$, which indicated the aquifer was enough for geothermal systems. In conclusion, groundwater is rich, can stably use geothermal heat, and it is less likely to cause deterioration of thermal energy efficiency by precipitation of carbonate minerals in study area. Therefore, the study area is suitable for installation of the combined geothermal system.