Korean Journal of Mineralogy and Petrology (광물과 암석)

The Petrological Society of Korea & The Mineralogical Society of Korea (한국암석학회 & 한국광물학회)
권호 표지
DOI QR코드

DOI QR Code

The Origin of Radioactive Elements Found in Groundwater Within the Chiaksan Gneiss Complex: Focusing on the Relationship with Minerals of the Surrounding Geology

치악산 편마암 복합체에 분포하는 지하수 내 함유된 방사성 원소의 기원: 주변 지질을 구성하는 광물과의 연관성을 중심으로

  • Kim, Hyeong-Gyu (Department of Geology and Research Institute of Natural Science (RINS), Gyeongsang National University (GNU)) ;
  • Lee, Sang-Woo (Department of Geology and Research Institute of Natural Science (RINS), Gyeongsang National University (GNU)) ;
  • Kim, Soon-Oh (Department of Geology and Research Institute of Natural Science (RINS), Gyeongsang National University (GNU)) ;
  • Jeong, Do-Hwan (Soil & Groundwater Research Division, Environmental Infrastructure Research Department, National Institute of Environmental Research (NIER)) ;
  • Kim, Moon-Su (Soil & Groundwater Research Division, Environmental Infrastructure Research Department, National Institute of Environmental Research (NIER)) ;
  • Kim, Hyun-Koo (Soil & Groundwater Research Division, Environmental Infrastructure Research Department, National Institute of Environmental Research (NIER)) ;
  • Jeong, Jong Ok (Center for Research Facilities (CRF), Gyeongsang National University(GNU))
  • 김형규 (경상국립대학교 자연과학대학 지질과학과 및 기초과학연구소) ;
  • 이상우 (경상국립대학교 자연과학대학 지질과학과 및 기초과학연구소) ;
  • 김순오 (경상국립대학교 자연과학대학 지질과학과 및 기초과학연구소) ;
  • 정도환 (국립환경과학원 환경기반연구부 토양지하수연구과) ;
  • 김문수 (국립환경과학원 환경기반연구부 토양지하수연구과) ;
  • 김현구 (국립환경과학원 환경기반연구부 토양지하수연구과) ;
  • 정종옥 (경상국립대학교 공동실험실습관)
  • Received : 2022.06.13
  • Accepted : 2022.06.17
  • Published : 2022.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

Petrological and mineralogical analyses were conducted to identify minerals containing radioactive elements (uranium) in the Chiaksan gneiss complex and to confirm their association with the surrounding groundwater. Fourteen minerals were identified through the microscopic and electron microscopy (SEMEDS) investigation. The principal minerals included plagioclase, biotite, quartz, alkali feldspar, chlorite, and calcite. Minor minerals were sphene, allanite, apatite, zircon, thorite, titanite, pyrite, and galena. A small amount of thorite was observed in the size of ~1 mm within macrocrystalline allanite. Allanite, which includes a large amount of rare earth elements, appeared in three distinctive patterns. The results of the EPMA analyses indicated that macrocrystalline allanite had higher elemental contents of TiO2~1.70 wt.%, Ce2O3~11.86 wt.%, FeO ~13.31 wt.%, MgO ~0.90 wt.% and ThO2 ~1.06 wt.% with the lowest average content of Al2O3 17.35 ± 2.15 wt.% (n = 7), CaO 12.13 ± 1.81 wt.% (n = 7). An allanite existing at the edge of the sphenes encompassing titanites had a higher element content of Al2O3 ~24.00 wt.%, Nd2O3 ~5.10 wt.%, Sm2O3~0.66 wt.%, Dy2O3~0.86 wt.% and Y2O3~1.38 wt.% with the lowest average content of TiO2 0.35 ± 0.21 wt.% (n = 11), Ce2O3 5.25 ± 1.03 wt.% (n = 11), FeO 9.84 ± 0.26 wt.% (n = 11), MgO 0.12 ± 0.05 wt.% (n = 11), and La2O3 1.49 ± 0.29 wt.% (n = 11). Allanites in a matrix of parental rocks exhibited intermediate values between the two elemental compositions mentioned above. None of the uranium-rich minerals were observed in the migmatitic gneiss within the study area. Consequently, the origin of uranium in the groundwater was not associated with the geology of the surrounding environment, but our investigation proved the existence of abundant allanites containing significant amounts of radioactive thorium and rare earth elements.

치악산 편마암복합체에서 방사성원소를 포함하고 있는 광물을 파악하고, 주변 지하수에 포함되어 있는 방사선원소(우라늄)와의 연관성을 확인하고자 암석학적 및 광물 화학 분석을 수행하였다. 현미경 및 전자현미경 분석 결과, 주 구성광물은 사장석, 흑운모, 석영, 알칼리장석, 녹니석 그리고 방해석이며, 부수광물은 스펜, 갈렴석, 인회석, 저어콘, 토라이트, 티탄철석, 황철석 그리고 방연석 등 총 14종을 확인하였다. 토라이트의 경우 거정의 갈렴석 내 ~1 mm의 크기로 소량 관찰된다. 희토류 원소를 많이 포함하고 있는 갈렴석은 각기 다른 3 가지 산출양상을 보인다. EPMA 분석 결과, 거정의 갈렴석에서는 TiO2~1.70 wt.%, Ce2O3~11.86 wt.%, FeO~13.31 wt.%, MgO~0.90 wt.% 그리고 ThO2~1.06 wt.% 원소들의 함량이 높게 나타나며, Al2O3 17.35 ± 2.15 wt.% (n = 7), CaO 12.13 ± 1.81 wt.% (n = 7) 평균 함량이 가장 낮은 값을 보인다. 티탄철석을 둘러싸고 있는 스펜 집합체의 가장자리에 존재하는 갈렴석은 Al2O3~24.00 wt.%, Nd2O3~5.10 wt.%, Sm2O3~0.66 wt.%, Dy2O3~0.86 wt.% 그리고 Y2O3~1.38 wt.% 원소들의 함량이 높게 나타나며, TiO2 0.35 ± 0.21 wt.% (n = 11), Ce2O3 5.25 ± 1.03 wt.% (n = 11), FeO 9.84 ± 0.26 wt.% (n = 11), MgO 0.12 ± 0.05 wt.% (n = 11) 그리고 La2O3 1.49 ± 0.29 wt.% (n = 11) 등과 같이 평균 함량이 가장 낮은 값을 보인다. 모암의 기질부에서 관찰되는 갈렴석의 화학성분은 앞서 설명한 갈렴석의 중간 정도의 값을 가진다. 연구대상인 치악산 편마암복합체 내 미그마타이트질 편마암에는 주목할 만큼의 우라늄 함량을 가지는 광물이 발견되지는 않았다. 따라서 지하수에서 나타나는 우라늄의 기원과 주변 지질과의 연관성을 명확하게 밝혀내지는 못했다. 하지만 방사성 원소인 토륨 원소 및 희토류 원소를 다량 포함하는 갈렴석이 풍부하게 존재하는 것이 이번 연구결과로 확인되었다.

Keywords

Acknowledgement

This work was supported by a grant from the National Institute of Environment Research (NIER), funded by the Korean Ministry of Environment (ME) (NIER-2021-01-01-002).

References

  1. Choo, C.O., 2002, Characteristics of uraniferous minerals in Daebo granite and significance of mineral species, Journal of Mineral Society of Korea, 15, 11-21.
  2. Han, J.-H., Park, K.-H., 1996, Abundances of Uranium and Radon in Groundwater of Taejeon Area, Economic and Environmental Geology, 29, 589-595.
  3. Hwang, J., 2013, Occurrence of U-minerals and source of U in Groundwater in Daebo granite, Daejeon area, The Journal of Engineering Geology, 23, 399-407. https://doi.org/10.9720/KSEG.2013.4.399
  4. Hwang, J., 2018, Geological Review on the Distribution and Source of Uraniferous Grounwater in South Korea, The Journal of Engineering Geology, 28, 593-603. https://doi.org/10.9720/KSEG.2018.4.593
  5. Hwang, J., and Moon, S.-H., 2021, Geochemistry of U and Th of Mesozoic granites in South Korea: implications of occurrences of different U-host minerals and dissolved U and Rn between Jurassic and Cretaceous granite aquifers, Geosciences Journal, 25, 183-195. https://doi.org/10.1007/s12303-020-0033-8
  6. IMA (International Mineralogical Association), 2019, The IMA List of Minerals - A Work in Progress - Updated: September 2019, 219.
  7. Jeong, C.H., Kim, M.S., Lee, Y.J., Han, J.S., Jang, H.G., Joe, B.U., 2011, Hydrochemistry and occurrence of natural radioactive materials within borehole groundwater in the Cheongwon area, The Journal of Engineering Geology, 21, 163-178. https://doi.org/10.9720/KSEG.2011.21.2.163
  8. Jeong, C.H., Yang, J.H., Lee, Y.J., Lee, Y.C., Choi, H.Y., Kim, M.S., Kim, H.K., Kim, T.S. and Jo, B.U., 2015, Occurrences of Uranium and Radon-222 from Groundwaters in Various Geological Environment in the Hoengseong Area, The Journal of Engineering Geology, 25, 557-576. https://doi.org/10.9720/KSEG.2015.4.557
  9. Jeong, C.H., Lee, Y.J., Lee, Y.C., Kim, M.S., Kim, H.K., Kim, T.S., Jo, B.U., Choi, H.Y., 2016, Hydrochemistry and Occurrences of Natural Radioactive Materials from Groundwater in Various Geological Environment, The Journal of Engineering Geology, 26, 531-549. https://doi.org/10.9720/KSEG.2016.4.531
  10. Kim, I.H., Kim, M.S., Hamm, S.-Y., Kim, H.K., Kim, D.S., Jo, S.J., Lee, H.M., Hwang, J.H., Jo, H.J., Park S.H. and Chung, H.M., 2018, Characteristics of Naturally Occurring Radioactive Materials in Groundwater from Aquifers Composed of Different Geological Settings in Ganghwa, Economic and Environmental Geology, 51, 27-38. https://doi.org/10.9719/EEG.2018.51.1.27
  11. Kim, S.W., Kho, H.J. and Kim, J.M., 2014, Geochronological study for the gneiss complex in the Wonju-Anheung-Pyeongchang area, central part of the Korean Peninsula, Journal of the Geological Society of Korea, 50, 327-342.
  12. Kim, S.W., 2020, Concentration of Radioactive Materials for the Phanerozoic Plutonic Rocks in Korea and Its Implication, Economic and Environmental Geology, 53, 565-583. https://doi.org/10.9719/EEG.2020.53.5.565
  13. Koh, H.J., Kim, S.W. and Lee, S.Y., 2011, Geological Report of The Anheungri Sheet (Scale : 1: 50,000), Korea Institute of Geoscience and Mineral Resources, 1-54.
  14. Lafuente, B., Downs, R.T., Yang, H. and Stone, N., 2015, The power of databases: the RRUFF project. In: Highlights in Mineralogical Crystallography, T Armbruster and R.M Danisi, eds. Berlin, Germany, W. De Gruyter, pp 1-30.
  15. Langmuir, D., 1978, Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits. Geochimica et Cosmichimica Acta, 42, 547-569. https://doi.org/10.1016/0016-7037(78)90001-7
  16. Murphy, W.M. and Shock, E.L., 1999, Environmental aqueous geochmistry of actinides. Uranium: mineralogy, Geochemistry and the Environment(eds. Burns, P., C. and Finch, R.), Reviews in Mineralogy and Geochemistry, 38, 221-253. https://doi.org/10.1515/9781501509193-010
  17. NIER (National Institute of Environmental Research), 1999, Study on the radionuclides concentration in groundwater (I), Report, 338.
  18. NIER (National Institute of Environmental Research), 2000, Study on the radionuclides concentration in groundwater (II), Report, 323.
  19. NIER (National Institute of Environmental Research), 2001, Study on the radionuclides concentration in groundwater (III), Report, 388.
  20. NIER (National Institute of Environmental Research), 2002, Study on the radionuclides concentration in groundwater (IV), Report, 357.
  21. NIER (National Institute of Environmental Research), 2006, Study on the radionuclide concentration in the groundwater, NIER Report, 200.
  22. NIER (National Institute of Environmental Research), 2008, An investigation of natural radionuclide levels in groundwater (I), Report, 293.
  23. NIER (National Institute of Environmental Research), 2009, An investigation of natural radionuclide levelsin groundwater (III), Report, 273.
  24. NIER (National Institute of Environmental Research), 2010, An investigation on natural radioactivity levels in groundwater('10), Report, 251.
  25. Yun, S.W., Lee, J. and Park Y., 2016, Occurrence of radionuclides in groundwater of Korea according to geologic condition, The Journal of Engineering Geology, 26, 71-78. https://doi.org/10.9720/KSEG.2016.1.71