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RESEARCH ARTICLE
Contents Vol 6(5)

Gypsum saturation degrees and precipitation potentials from Dead Sea–seawater mixtures

Itay J. Reznik A B C , Jiwchar Ganor A , Assaf Gal A and Ittai Gavrieli B
+ Author Affiliations
- Author Affiliations

A Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, PO Box 653, 84105 Beer-Sheva, Israel.

B Geological Survey of Israel, 30 Malkhe Israel, 95501 Jerusalem, Israel.

C Corresponding author. Email: itayrez@bgu.ac.il

Environmental Chemistry 6(5) 416-423 https://doi.org/10.1071/EN09038
Submitted: 3 April 2009  Accepted: 10 August 2009   Published: 22 October 2009

Environmental context. Since the 1960s the Dead Sea water level has dropped by nearly 30 m and over the last decade the rate of decline accelerated to over 1 m per year. Conveying seawater to the Dead Sea to stabilise or even raise its water level is currently being considered but may result in ‘whitening’ of the surface water through the formation of minute gypsum crystals that will remain suspended in the water column for a prolonged period of time. This paper is a first step in attaining the relevant physical and chemical parameters required to assess the potential for such whitening of the Dead Sea.

Abstract. Introduction of seawater to the Dead Sea (DS) to stabilise its level raises paramount environmental questions. A major concern is that massive nucleation and growth of minute gypsum crystals will occur as a result of mixing between the SO42–-rich Red Sea (RS) water and Ca2+-rich DS brine. If the gypsum will not settle quickly to the bottom it may influence the general appearance of the DS by ‘whitening’ the surface water. Experimental observations and theoretical calculations of degrees of saturation with respect to gypsum (DSG) and gypsum precipitation potentials (PPT) were found to agree well, over the large range but overall high ionic strength of DS–RS mixtures. The dependency of both DSG and PPT on temperature was examined as well. Based on our thermodynamic insights, slow discharge of seawater to the DS will result in a relatively saline upper water column which will lead to enhanced gypsum precipitation.


Acknowledgements

This research was supported by the Israeli Ministry of National Infrastructure (grants #ES-38–2005 and #ES-28–2006 to J.G. and I.G.) and by the Israel Science Foundation (grant #902/05 to I.G.). I. Reznik is grateful to the Rieger Foundation – JNF Program for Environmental Studies and to the Water Authority of Israel for their generous support. The authors are grateful to G. Antler and Y. Tubul for their technical assistance.


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