Geochemical Characterization of Deep Groundwater in KURT Using Geochemical Modeling

by Ji-Hun Ryu, Ph.D., Korea Atomic Energy Research Institute, 1045, Daedukdaero, Yuseong-Gu, Daejeon, 305-353, Korea., jryu@kaeri.re.kr,
Yong-Kwon Koh, Ph.D., Korea Atomic Energy Research Institute, 1045, Daedukdaero, Yuseong-Gu, Daejeon, 305-353, Korea., nykkoh@kaeri.re.kr,
Sang-Won Park, (corresponding author), Professor; Dept. of Energy and Environmental Science, Keimyung Univ., 2800, Dalgubeoldaero, Dalseo-Gu, Daegu, 704-701, Korea., swpark@kmu.ac.kr,
Geon-Young Kim, Ph.D., Korea Atomic Energy Research Institute, 1045, Daedukdaero, Yuseong-Gu, Daejeon, 305-353, Korea., kimgy@kaeri.re.kr,
Jong-Won Choi, Ph.D., Korea Atomic Energy Research Institute, 1045, Daedukdaero, Yuseong-Gu, Daejeon, 305-353, Korea., njwchoi@kaeri.re.kr,


Serial Information: Issue 3, Pg. 351-359


Document Type: Journal Paper

Abstract: A total of 11 boreholes were drilled at depths of 20–500 m to investigate the geochemical characteristics of groundwater at the KAERI Underground Research Tunnel (KURT) site. The groundwater chemistry up to a depth of 500 m at the KURT site was divided into Ca- HCO3 and Na- Ca- HCO3 types in the groundwater system. Ca- HCO3 and Na- Ca- HCO3 types showed that the geochemistry of the groundwater was influenced by weathering, dissolution, or precipitation of minerals in the system. The Na- Ca- HCO3 type of groundwater resulted from water-rock interaction such as weathering of plagioclase and dissolution of carbonate minerals. The Na/ Cl ratios increased at depths in the groundwater, implying that the weathering reaction of plagioclase occurred in the system, which released Na ions into the groundwater. Also, Ca/ Cl ratios showed a similar pattern in the groundwater, indicating a weathering reaction of carbonate minerals such as calcite that adds Ca2+ to the groundwater. The scattered distribution of Cl- and tritium values indicated that a mixing process occurred in the groundwater system, which new water recharged into the system and mixed with old groundwater formation in the deeper part of groundwater system. The results from geochemical modeling showed reasonable fits in major ion profiles from observed values at groundwater sampling points. The model indicated that the simulated major processes, including major parameters used in the modeling, reflected the actual groundwater condition well. This study showed that the geochemical characteristics of the groundwater were controlled by various factors including the weathering of minerals such as plagioclase and K-feldspar, dissolution or precipitation of calcite, a mixing process, and, possibly, ion exchange.

Subject Headings: Groundwater | Hydrologic models | Weathering | Minerals | Site investigation | Carbonation | Simulation models | Precipitation |

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