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

Itay J. Reznik; Jiwchar Ganor; Assaf Gal; Ittai Gavrieli

doi:10.1071/EN09038

RESEARCH ARTICLE

Previous Next 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 SO4^2–-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.

References

[1] Gavrieli I., Lensky N. G., Dvorkin Y., Lyakhovsky V., Gertman I., A multi-component chemistry-based model for the Dead Sea: modifications to the ID Princeton Oceanographic Model, Report GSI 24/2006 2006 (Geological Survey of Israel: Jerusalem).

[2] Kircher A., Subterranean World (Mundus Subterraneus) 1664, vol. 1.

[3] Herzl T., Altneuland (Old New Land) 1902 (Seemann Nachf: Leipzig). [In German]

[4] A. Katz , A. Starinsky , N. Taitel-Goldman , M. Beyth , Solubilities of gypsum and halite in the Dead Sea and in its mixtures with seawater. Limnol. Oceanogr. 1981 , 26, 709.
        | CAS |

[5] B. S. Krumgalz , F. J. Millero , Physico-chemical study of the Dead Sea waters. III. On gypsum saturation in Dead Sea waters and their mixtures with Mediterranean Sea water. Mar. Chem. 1983 , 13, 127.
        | Crossref | GoogleScholarGoogle Scholar | CAS |

[6] B. S. Krumgalz , F. J. Millero , Physico-chemical study of the Dead Sea waters. I. activity coefficients of major ions in Dead Sea water. Mar. Chem. 1982 , 11, 209.
        | Crossref | GoogleScholarGoogle Scholar | CAS |

[7] Levy Y., Kushnir Y., Laboratory measurements of nucleation processes and the growth of gypsum in the Mediterranean–Dead Sea mixed brine 1981 (Geological Survey of Israel: Jerusalem).

[8] Levy Y., The influence of the admixture rate of partly evaporated Mediterranean water to the Dead Sea on the properties of gypsum that is formed in the brine. Mediterranean–Dead Sea projects, summary of research and surveys Mediterranean Dead Sea Co. 1984, vol. 5, pp. 279–282 (Geological Survey of Israel: Jerusalem). [In Hebrew]

[9] Levy Y., Calculations of chemical composition of mixed layers of Mediterranean Sea and Dead Sea water, Report MGG/1/82 1982 (Geological Survey of Israel: Jerusalem).

[10] Ben Yaakov S., Katz A., Field experiments in mixing Mediterranean water with Dead Sea water. Preliminary report for the period July–Oct. 1982 Report submitted to the Mediterranean–Dead Sea Co. 1982 (Geological Survey of Israel: Jerusalem). [In Hebrew]

[11] Mediterranean–Dead Sea Co., Mediterranean–Dead Sea projects. Vol. 5, Summary of Research and Surveys 1984 (Geological Survey of Israel: Jerusalem). [Reports in Hebrew and English]

[12] R. Bloch , H. Z. Littman , B. Elazari-Volcani , Occasional Whiteness of the Dead Sea. Nature 1944 , 154, 402.
        | Crossref | GoogleScholarGoogle Scholar | CAS |

[13] Pitzer K. S., Theory, ion interaction approach, in Activity coefficients in Electrolyte Solutions 1979, vol. 1, pp. 157–208 (CRC Press: Boca Raton, FL, USA).

[14] J. Christoffersen , M. R. Christoffersen , G. M. Van Rosmalen , W. G. J. Marchee , The affinity of crystal growth and dissolution in aqueous solution with special reference to calcium sulphate dihydrate. J. Cryst. Growth 1979 , 47, 607.
        | Crossref | GoogleScholarGoogle Scholar | CAS |

[15] G. M. Marion , J. S. Kargel , D. C. Catling , Modelling ferrous-ferric iron chemistry with application to martian surface geochemistry. Geochim. Cosmochim. Acta 2008 , 72, 242.
        | Crossref | GoogleScholarGoogle Scholar | CAS |

[16] Gavrieli I., Halite Deposition from the Dead Sea: 1960–1993, in The Dead Sea – the Lake and its Setting 1997 (Oxford University Press: New York).

[17] Parkhurst D. L., Appelo C. A. J., PHREEQC 2.15. A computer program for speciation, batch-reaction, one-dimentional transport and inverse geochemical calculation, Water- Resources Investigation Report 99–4259 1999 (US Geological Survey).

[18] I. J. Reznik , I. Gavrieli , J. Ganor , Kinetics of gypsum nucleation and crystal growth from Dead Sea brine. Geochim. Cosmochim. Acta 2009 , 73, 6218.
        | Crossref | GoogleScholarGoogle Scholar | CAS |

[19] I. Gertman , A. Hecht , The Dead Sea hydrography from 1992 to 2000. J. Mar. Syst. 2002 , 35, 169.
        | Crossref | GoogleScholarGoogle Scholar |

[20] I. Gavrieli , A. Bein , A. Oren , The expected impact of the ‘Peace Conduit’ project (the Red Sea–Dead Sea pipeline) on the Dead Sea. Mitig. Adapt. Strategies Glob. Change 2005 , 10, 3.
        | Crossref | GoogleScholarGoogle Scholar |

[21] A. Oren , I. Gavrieli , J. Gavrieli , M. Kohen , J. Lati , M. Aharoni , Biological effects of dilution of Dead Sea brine with seawater: implications for the planning of the Red Sea–Dead Sea ‘Peace Conduit’. J. Mar. Syst. 2004 , 46, 121.
        | Crossref | GoogleScholarGoogle Scholar |

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

Acknowledgements

Subscriber Login