TY - JOUR
T1 - Constraints on evaporation and dilution of terminal, hypersaline lakes under negative water balance
T2 - The Dead Sea, Israel
AU - Zilberman, Tami
AU - Gavrieli, Ittai
AU - Yechieli, Yoseph
AU - Gertman, Isaac
AU - Katz, Amitai
N1 - Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017/11/15
Y1 - 2017/11/15
N2 - The response of hypersaline terminal lakes to negative water balance was investigated by studying brines evaporating to extreme salinities in sinkholes along the western coast of the Dead Sea and during on-site evaporation experiments of the Dead Sea brine. Density and temperature were determined in the field and all samples were analyzed for their major and a few minor solutes. The activity of H2O (aH2O) in the brines was calculated, and the degree of evaporation (DE) was established using Sr2+as a conservative solute. The relations between density and water activity were obtained by polynomial regression, and the relation between the lake's volume and level was established using Hall's (1996) hypsographic model for the Dead Sea basin. Relating the results to the modern, long-term relative humidity (RH) over the basin shows that (a) The lowermost attainable level of a terminal lake undergoing evaporation with no inflow is dictated by the median RH; this level represents equilibrium between the brine's aH2O and RH; (b) Small, saline water bodies with high surface to volume ratios (A/V), such as the hypersaline brines in the sinkholes, are very sensitive to short term changes in RH; in these, the brines' aH2O closely follows the seasonal changes; (c) the level decline of the Dead Sea due to evaporation under present climatic conditions and assuming no inflow to the lake may continue down to 516–537 m below mean sea level (bmsl), corresponding to a water activity range of 0.46–0.39 in its brine, in equilibrium with the overlying relative air humidity; this suggests that the lake level cannot drop more than ∼100 m from its present level; and (d) The maximum RH values that existed over the precursor lake of the Dead Sea (Lake Lisan) during geologically reconstructed minima levels can be similarly calculated.
AB - The response of hypersaline terminal lakes to negative water balance was investigated by studying brines evaporating to extreme salinities in sinkholes along the western coast of the Dead Sea and during on-site evaporation experiments of the Dead Sea brine. Density and temperature were determined in the field and all samples were analyzed for their major and a few minor solutes. The activity of H2O (aH2O) in the brines was calculated, and the degree of evaporation (DE) was established using Sr2+as a conservative solute. The relations between density and water activity were obtained by polynomial regression, and the relation between the lake's volume and level was established using Hall's (1996) hypsographic model for the Dead Sea basin. Relating the results to the modern, long-term relative humidity (RH) over the basin shows that (a) The lowermost attainable level of a terminal lake undergoing evaporation with no inflow is dictated by the median RH; this level represents equilibrium between the brine's aH2O and RH; (b) Small, saline water bodies with high surface to volume ratios (A/V), such as the hypersaline brines in the sinkholes, are very sensitive to short term changes in RH; in these, the brines' aH2O closely follows the seasonal changes; (c) the level decline of the Dead Sea due to evaporation under present climatic conditions and assuming no inflow to the lake may continue down to 516–537 m below mean sea level (bmsl), corresponding to a water activity range of 0.46–0.39 in its brine, in equilibrium with the overlying relative air humidity; this suggests that the lake level cannot drop more than ∼100 m from its present level; and (d) The maximum RH values that existed over the precursor lake of the Dead Sea (Lake Lisan) during geologically reconstructed minima levels can be similarly calculated.
KW - Ca-chloride brine
KW - Condensation
KW - Dead Sea
KW - Evaporation
KW - Lake level
KW - Relative humidity
KW - Water activity
UR - http://www.scopus.com/inward/record.url?scp=85029355088&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2017.08.040
DO - 10.1016/j.gca.2017.08.040
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AN - SCOPUS:85029355088
SN - 0016-7037
VL - 217
SP - 384
EP - 398
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -