물-암석반응에 따른 물에서의 Sr동위원소의 거동에 대한 예비실험결과

Preliminary Experimental Result for Clarifying Sr Isotope Behaviour of Water due to Water-Rock Interaction

  • 이승구 (한국지질자원연구원 국토지질연구본부) ;
  • 김정찬 (한국지질자원연구원 지구환경연구본부)
  • Lee, Seung-Gu (Geological Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Kim, Jeong-Chan (Earth and Environment Research Division, Korea Institute of Geoscience and Mineral Resources)
  • 투고 : 2010.02.09
  • 심사 : 2010.06.05
  • 발행 : 2010.06.28

초록

물-암석 반응에 따른 물속의 Sr의 농도와 $^{87}Sr/^{86}Sr$ 비의 변화를 조사하기위해 실온에서의 회분식 실험(batch experiment)을 수행하였다. 실험방법은 기원이 서로 다른 2종류 화강암(강화 석모도 흑운모 화강암과 포천 석류석 화강암), 증류수, 지표수를 사용하여 암석을 증류수 및 지표수와 1:1의 비율로 각각 반응시킨 후의 물속의 양이온 및 음이온의 농도변화 및 물속의 $^{87}Sr/^{86}Sr$ 비를 측정하였다. 그리고 암석과 지표수의 경우, 혼합비의 차이에 의한 비교를 위해 암석과 지표수의 비율을 1:10으로 하여 반응시킨 후의 물속의 양이온과 양이온의 농도변화 및 $^{87}Sr/^{86}Sr$ 비를 측정하였다. 연구결과에 의하면, 물속의 용존성분의 함량은 초기 3-4개월간은 증가하였지만, 1년간 방치하여 놓은 시료에서는 함량이 현저하게 줄어들었다. 반면에 물속의 $^{87}Sr/^{86}Sr$ 비는 시간의 경과와 더불어 암석의 $^{87}Sr/^{86}Sr$ 비로 이동해가면서 비교적 안정되는 경향을 보여주었다. 이는 물-암석반응에 의한 물속의 $^{87}Sr/^{86}Sr$ 비는 거의 거의 평형에 도달한 이후에는 Sr 함량이나 기타 용존이온들보다 쉽게 안정됨을 지시해주는 것으로 볼 수 있다. 이 연구결과는 서로 다른 대수층에 분포하는 지하수의 연계성 혹은 혼합비를 계산하는데 있어서 $^{87}Sr/^{86}Sr$ 비가 유용하게 활용되어 질 수 있음을 지시해준다.

A batch experiment was carried out to investigate a variation of Sr concentration and $^{87}Sr/^{86}Sr$ ratio in the solution by water-rock interaction. The experiments were conducted at room temperature using two kinds of granites (biotite granite and garnet-bearing granite), de-ionized water. surface water. Water/rock ratio was 1:1. For comparison, we also performed another experiment under water/rock condition of 10:1. Then, the concentration of the cations and anions in the solutions showed severe variation during water/rock interaction. However, after sometime, the $^{87}Sr/^{86}Sr$ ratio of the solution moved to the $^{87}Sr/^{86}Sr$ ratio of the rocks and showed relatively constant value. This suggests that the $^{87}Sr/^{86}Sr$ ratio between water and rock becomes to be stable faster than the elemental equilibration of the element in the solution, and is not affected by interaction condition. Therefore, $^{87}Sr/^{86}Sr$ ratio of the groundwater may be useful in calculating the mixing ratio between different aquifer.

키워드

참고문헌

  1. Bullen, T.D., Krabbenhoft, D.P. and Kendall, C. (1996) Kinetic and mineralogic controls on the evolution of groundwater chemistry and 87Sr/86Sr in a sandy silicate aquifer, northern Wisconsin, USA. Geochim. Cosmochim. Acta, v.60, p.1807-1822. https://doi.org/10.1016/0016-7037(96)00052-X
  2. Edmunds, W.M., Kay, R.L.F., Miles, D.L. and Cook, J.M. (1987) The evolution of saline and thermal groundwaters in the Carmenellis granite. Mineralogical Magagine, v.48, p.407-424.
  3. Frost, C.D., Pearson, B.N., Ogle, K.M., Heffern, E.L. and Lyman, R.M. (2002) Sr isotopic tracing of aquifer interactions in an area of accelerating coal-bead methane production. Geology, v.30, p.923-926. https://doi.org/10.1130/0091-7613(2002)030<0923:SITOAI>2.0.CO;2
  4. Gosselin, D.C., Harvey, F.E., Frost, C., Stotler, R. and Macfarlane, P.A. (2004) Strontium isotope geochemistry of groundwater in the central part of the Dakota (Great Plains) aquifer, USA. Appl. Geochem., v.19, p.359-377. https://doi.org/10.1016/S0883-2927(03)00132-X
  5. Johnson, T.M. and DePaolo, D.J. (1994) Interpretation of isotopic data in groundwater-rock systems: model development and application to Sr isotope data from Yucca Mountain. Water Res. Res., v.30, p.1571-1587. https://doi.org/10.1029/94WR00157
  6. Klaus, J.S., Hansen, B.T. and Baupeng, S. (2007) $^{87}Sr$/86Sr ratio: a natural tracer to monitor groundwater flow paths during artificial recharge in the Bangkok area, Thailand. Hydrogeol. J., v.15, p.745-758. https://doi.org/10.1007/s10040-007-0175-z
  7. Lee, S.G., Kim, T-K., Lee, J-S., Lee, T., Cho, B.W. and Koh, H. (2008) Geochemical implication of $^{87}Sr/^{86}Sr$ ratio of high-temperature deep groundwater in a fractured granite aquifer, Geochemical J., v.42, p.429-441. https://doi.org/10.2343/geochemj.42.429
  8. Lee, S.G., Nakamura, T., Kim, T-K., Ohta, T., Kim, H.C. and Lee, T. (2009) Geochemical Significance of 14C Age from the Dongrae Hot Spring Water. Korea Soc. Econ. Environ. Geol., v.42, p.541-548.
  9. McNutt, R.H. (2000). Strontium Isotopes. In: Cook, P.G. and Herczeg, A.L. (Eds.), Environmental Tracers in Subsurface Hydrology. Kluwer Academic, Norwell, MA 02061, p.233-260.
  10. McNutt, R. H., Frape, S.K., Fritz, P., Jones, M.G. and MacDonald, I.M. (1990) The $^{87}Sr/^{86}Sr$ values of Canadian Shield brines and fracture minerals with applications to groundwater mixing, fracture history, and geochronology. Geochim. Cosmochim. Acta, v.54, p.205-215. https://doi.org/10.1016/0016-7037(90)90208-3
  11. Peterman, Z.E. and Stuckless, J.S. (1992) Application of strontium and other radiogenic tracer isotopes to paleohydrogic studies. In: Paleohydrogeological Methods and Their Applications. Proc. NEA Workshop, p. 59-84.
  12. Seimbille, F., Zuddas, P. and Michard, G. (1998) Granite-hydrothermal interaction: A simultaneous estimation of the mineral dissolution rate based on the isotopic doping technique. Earth and Planetary Science Letters, v.157, p.183-191. https://doi.org/10.1016/S0012-821X(98)00026-0
  13. Steiger, R.H. and Jager, E. (1977) Subcommission on geochronology: convention on the use of decay constants in geo- and cosmo-chronology. Earth Planet. Sci. Lett., v.36, p.359-362. https://doi.org/10.1016/0012-821X(77)90060-7
  14. White, A.F., Blum, A.E., Bullen, T.D., Vivit, D.V., Schulz, M.C. and Fitzpatrick, J. (1999) The effect of temperature on experimental and natural chemical weathering rates of granitoid rocks. Geochim Cosmochim Acta, v.63, p.3277-3291. https://doi.org/10.1016/S0016-7037(99)00250-1
  15. Zuddas, P., Seimbille, F. and Michard, G. (1995) Granitefluid interaction at near-equilibrium conditions: Experimental and theoretical constraints from Sr contents and isotopic ratios. Chemical Geology, v.121, p.145-154. https://doi.org/10.1016/0009-2541(94)00159-6