geochemistry" /> Yong-Kwon Koh" /> Yong-Kwon Koh, Chun-Soo Kim, Dae-Seok Bae and Dong-Ik Lee

" /> Yong-Kwon Koh, Chun-Soo Kim, Dae-Seok Bae and Dong-Ik Lee

. Econ. Environ. Geol. 2000;33:469-89. https://doi.org/">

Econ. Environ. Geol. 2000; 33(6): 469-489

Published online December 31, 2000

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Hydrochemistry and Environmental Isotope Studies of the Deep Groundwater in the Munkeong Area

Yong-Kwon Koh*, Chun-Soo Kim*, Dae-Seok Bae* and Dong-Ik Lee**

*Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, Korea

**Korea Agricultural & Rural Infrastructure Corporation, Taejon 302-122, Korea

Correspondence to :

Yong-Kwon Koh

nykkoh@kaeri.re.kr

Received: September 4, 2000; Accepted: December 1, 2000

Abstract

<p class="바탕글">The hydrogeochemical and isotopic on deep groundwater (below a 550 m depth from the ground surface) in the Munkyeong are, Kyeongbuk province were carried out. Two types of deep groundwater (CO2-rich groundwater and alkali groundwater) occur together in the Munkyeong area. CO2-rich groundwater (Ca-HCO3 type) is characterized by low pH (5.8~6.5) and high TDS (up to 2,682 mg/L), while alkali groundwater (Na-HCO3 type) shows a high pH (9.1~10.4) and relatively low TDS (72~116 mg/L). CO2-rich water may have evolved by CO2 added at depth during groundwater circulation. This process leads to the dissolution of surrounding rocks and Ca, Na, Mg, K and HCO3 concentrations are eniched. The low Pco2 (10-6.4 atm) of alkali groundwaters seems to result from the dissolution of silicate minerals without a supply of CO2. The δ18O and δD values and tritium data indicate that two types of deep groundwater were both derived from pre-thermonuclear meteoric water and have evolved through prolonged water-rock interaction. The carbon isotope data show that dissolved carbon in the CO2-rich water was possibly derived from deep-seated CO2 gas, although further studies are needed. The δ34S values of dissolved sulfate show that sulfate reduction occurred at great depths. The application of various chemical geothermometers on CO2-rich groundwater shows that the calculated deep reservoir temperature is about 130~175°C. Based on the geological setting, water chemistry and environmental isotope data, each of the two types of deep groundwater represent distinct hydrologic and hydrogeochemical evolution at depth and their movement is controlled by the local fracture system.

Keywords

geochemistry, isotope, groundwater, CO2-rich water, water-rock interaction

Article

Econ. Environ. Geol. 2000; 33(6): 469-489

Published online December 31, 2000

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Hydrochemistry and Environmental Isotope Studies of the Deep Groundwater in the Munkeong Area

Yong-Kwon Koh*, Chun-Soo Kim*, Dae-Seok Bae* and Dong-Ik Lee**

*Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, Korea

**Korea Agricultural & Rural Infrastructure Corporation, Taejon 302-122, Korea

Correspondence to:

Yong-Kwon Koh

nykkoh@kaeri.re.kr

Received: September 4, 2000; Accepted: December 1, 2000

Abstract

The hydrogeochemical and isotopic on deep groundwater (below a 550 m depth from the ground surface) in the Munkyeong are, Kyeongbuk province were carried out. Two types of deep groundwater (CO2-rich groundwater and alkali groundwater) occur together in the Munkyeong area. CO2-rich groundwater (Ca-HCO3 type) is characterized by low pH (5.8~6.5) and high TDS (up to 2,682 mg/L), while alkali groundwater (Na-HCO3 type) shows a high pH (9.1~10.4) and relatively low TDS (72~116 mg/L). CO2-rich water may have evolved by CO2 added at depth during groundwater circulation. This process leads to the dissolution of surrounding rocks and Ca, Na, Mg, K and HCO3 concentrations are eniched. The low Pco2 (10-6.4 atm) of alkali groundwaters seems to result from the dissolution of silicate minerals without a supply of CO2. The δ18O and δD values and tritium data indicate that two types of deep groundwater were both derived from pre-thermonuclear meteoric water and have evolved through prolonged water-rock interaction. The carbon isotope data show that dissolved carbon in the CO2-rich water was possibly derived from deep-seated CO2 gas, although further studies are needed. The δ34S values of dissolved sulfate show that sulfate reduction occurred at great depths. The application of various chemical geothermometers on CO2-rich groundwater shows that the calculated deep reservoir temperature is about 130~175°C. Based on the geological setting, water chemistry and environmental isotope data, each of the two types of deep groundwater represent distinct hydrologic and hydrogeochemical evolution at depth and their movement is controlled by the local fracture system.

Keywords

geochemistry, isotope, groundwater, CO2-rich water, water-rock interaction

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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