강화 석모도 지역 온천수와 지하수의 수리지구화학 및 동위원소 연구 (Hydrogeochemical, Stable and Noble gas Isotopic Studies of Hot Spring Waters and Cold Groundwaters in the Seokmodo Hot Spring Area of the Ganghwa Province, South Korea)

서지정보

· 발행기관 : 대한자원환경지질학회
· 수록지 정보 : 자원환경지질 / 41권 / 1호 / 15 ~ 32페이지
· 저자명 : 김규한, 정찬호, 정윤정, 長尾敬介

초록

The hydrochemical and isotopic (stable isotopes and noble gas isotopes) analyses for hot spring waters, cold
groundwaters and surface water samples from the Seokmodo hot spring area of the Ganghwa province were carried
out to characterize the hydrogeochemical characteristics of thermal waters and to interpret the source of thermal
water and noble gases and the geochemical evolution of hot spring waters in the Seokmodo geothermal system.
The hot spring waters and groundwaters show a weakly acidic condition with the pH values ranging from 6.42 to
6.77 and 6.01 to 7.71, respectively. The outflow temperature of the Seokmodo hot spring waters ranges from
43.3oC to 68.6oC. Relatively high values of the electrical conductivities which fall between 60,200 and 84,300 μS/
cm indicate that the hot spring waters were mixed with seawater in the subsurface geothermal system. The chemical
compositions of the Seokmodo hot spring waters are characterized by Na-Ca-Cl water type. On the other hand,
cold groundwaters and surface waters can be grouped into three types such as the Na(Ca)-HCO3, Na(Ca)-SO4 and
Ca-HCO3 types. The δ18O and δD values of hot spring waters vary from -4.41 to -4.47‰ and -32.0 to -33.5‰,
respectively. Cold groundwaters range from -7.07 to -8.55‰ in δ18O and from -50.24 to -59.6‰ in δD. The oxygen
and hydrogen isotopic data indicate that the hot spring waters were originated from the local meteoric water
source. The enrichments of heavy isotopes (18O and 2H) in the Seokmodo hot spring waters imply that the thermal
water was derived from the diffusion zone between fresh and salt waters. The δ34S values ranging from 23.1 to
23.5‰ of dissolved sulfate are very close to the value of sea water sulfate of δ34S=20.2‰ in this area, indicating
the origin of sulfate in hot springs from sea water. The 3He/4He ratio of hot spring waters varies from 1.243x10-6 to
1.299×10-6cm3STP/g, which suggests that He gas in hot spring waters was partly originated from a mantle source.
Argon isotopic ratio (40Ar/36Ar=298×10-6cm3STP/g) in hot spring waters corresponds to the atmospheric value.

영어초록

The hydrochemical and isotopic (stable isotopes and noble gas isotopes) analyses for hot spring waters, cold
groundwaters and surface water samples from the Seokmodo hot spring area of the Ganghwa province were carried
out to characterize the hydrogeochemical characteristics of thermal waters and to interpret the source of thermal
water and noble gases and the geochemical evolution of hot spring waters in the Seokmodo geothermal system.
The hot spring waters and groundwaters show a weakly acidic condition with the pH values ranging from 6.42 to
6.77 and 6.01 to 7.71, respectively. The outflow temperature of the Seokmodo hot spring waters ranges from
43.3oC to 68.6oC. Relatively high values of the electrical conductivities which fall between 60,200 and 84,300 μS/
cm indicate that the hot spring waters were mixed with seawater in the subsurface geothermal system. The chemical
compositions of the Seokmodo hot spring waters are characterized by Na-Ca-Cl water type. On the other hand,
cold groundwaters and surface waters can be grouped into three types such as the Na(Ca)-HCO3, Na(Ca)-SO4 and
Ca-HCO3 types. The δ18O and δD values of hot spring waters vary from -4.41 to -4.47‰ and -32.0 to -33.5‰,
respectively. Cold groundwaters range from -7.07 to -8.55‰ in δ18O and from -50.24 to -59.6‰ in δD. The oxygen
and hydrogen isotopic data indicate that the hot spring waters were originated from the local meteoric water
source. The enrichments of heavy isotopes (18O and 2H) in the Seokmodo hot spring waters imply that the thermal
water was derived from the diffusion zone between fresh and salt waters. The δ34S values ranging from 23.1 to
23.5‰ of dissolved sulfate are very close to the value of sea water sulfate of δ34S=20.2‰ in this area, indicating
the origin of sulfate in hot springs from sea water. The 3He/4He ratio of hot spring waters varies from 1.243x10-6 to
1.299×10-6cm3STP/g, which suggests that He gas in hot spring waters was partly originated from a mantle source.
Argon isotopic ratio (40Ar/36Ar=298×10-6cm3STP/g) in hot spring waters corresponds to the atmospheric value.

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