Temperature and evaporation dynamics of saline solutions

Abstract

An analytic procedure is presented to investigate the response of temperature in and evaporation from saline solutions whose activity coefficients are subject to dynamic changes. The temperature change ( γ) with respect to changes in the activity coefficient is found to be a strong function of the saturation vapor pressure at the temperature of the saline solution and the transfer coefficients for water vapor and sensible heat. Results show that γ increases appreciably as the activity coefficient ( β) departs further from unity. As the activity coefficient approaches unity, γ becomes quite small particularly when both the saline solution temperature and the transfer coefficients decrease. For a given change in the activity coefficient, the largest temperature response is experienced during the summer months. The procedure developed in this paper is applied to the current chemical composition of the Dead Sea to examine the sensitivities of its temperature and evaporation rate due to the alteration of its activity coefficient during the past 40 years. Results show that currently evaporation from the Dead Sea ( β≈0.67) is about 175 mm year −1 less than the values prior to 1960 ( β≈0.75).