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Rayleigh Fractionation of Stable Water Isotopes during Equilibrium Freezing
평형 냉동에 의한 물동위원소의 레일리분별
Econ. Environ. Geol. 2021 Feb;54(1):61-7
Published online February 28, 2021;  https://doi.org/10.9719/EEG.2021.54.1.61
Copyright © 2021 the Korean society of economic and environmental gelology.

Jeonghoon Lee*, Hyejung Jung, Yalalt Nyamgerel
이정훈* · 정혜정 · 니암게렐 얄랄트

Dept. of Science Education, Ewha Womans University, Seoul 03760, Korea
이화여자대학교 과학교육과
Received December 21, 2020; Revised January 25, 2021; Accepted January 26, 2021.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
Isotopic compositions of snow or ice have been used to reconstruct paleoclimate and to calculate contribution to streamwater using isotopic hydrograph separation as an end member. During freezing and melting of snow or ice, isotopic fractionation occurs between snow or ice and liquid water. Isotopic evolution during melting process has been studied by field, melting experiments and modeling works, but that during freezing has not been well studied. In this review, isotopic fractionation during equilibrium freezing is discussed using the linear relationship between two stable water isotopes (oxygen and hydrogen) and the Rayleigh fractionation. Snow, evaporated from nearby ocean and condensated, follows the Global Meteoric Water Line (slope of 8), but the melting and freezing of snow affect the linear relationship (slope of 19.5/3.1~6.3). The isotopic evolution of liquid water by freezing observed in the open system during Rayleigh fractionation is also seen in the closed system. The isotopic evolution of snow or ice in the open system where the snow or ice is continuously removed becomes more enriched than the residual liquid water by the fractionation factor. The isotopic evolution of snow or ice in the closed system eventually equals the original isotopic compositions of liquid water. It is expected the understanding of isotopic evolution of snow or ice by freezing to increase the accuracy of the paleoclimate studies and hydrograph separation.
Keywords : freezing, melting, stable water isotopes, Global Meteoric Water Line, Rayleigh equation

 

February 2021, 54 (1)