Economic and Environmental Geology (자원환경지질)

The Korean Society of Economic and Environmental Geology (대한자원환경지질학회)
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Preliminary Experimental Result for Clarifying Sr Isotope Behaviour of Water due to Water-Rock Interaction

물-암석반응에 따른 물에서의 Sr동위원소의 거동에 대한 예비실험결과

  • 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)
  • 이승구 (한국지질자원연구원 국토지질연구본부) ;
  • 김정찬 (한국지질자원연구원 지구환경연구본부)
  • Received : 2010.02.09
  • Accepted : 2010.06.05
  • Published : 2010.06.28
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Abstract

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.

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.

Keywords

References

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