The isotope composition of evaporating brines: Effect of the isotopic activity ratio in saline solutions

Z. Sofer, J. R. Gat

Research output: Contribution to journalArticlepeer-review

188 Scopus citations

Abstract

The ratio of the activity coefficients of deuterated and light water (Γ) is given in chloridic saline solutions as a function of the molality of the salt components by the expression: 1- 1 Γ × 103 -δγ = 6.1MCaCl2 + 5.1MMgCl2 + 2.4MKCl + 0.4MNaCl. Calculations based on the Craig-Gordon evaporation model show that in the case of evaporating brines, the salt effect on the activity coefficients of the isotopic water species results in deviation of the δ values from a constant slope "evaporation line", when plotted on the conventional δ-diagram, of deuterium concentration versus 18O activity. Conversion of concentration data to activities eliminates these deviations to a large extent, indicating them to be an artifact of the scales employed for measuring the isotope abundance. The origin of Dead Sea waters and other natural brines is discussed in the light of these findings.

Original languageEnglish
Pages (from-to)179-186
Number of pages8
JournalEarth and Planetary Science Letters
Volume26
Issue number2
DOIs
StatePublished - 1 Jan 1975
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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