Retrieval and interpretation of precipitation rates generated from the composition of the Merouane Chott ephemeral lake

Merouane Chott ephemeral lake is an ideal natural system for studying mineral dissolution and precipitation rates because (1) it undergoes annual cycles of filling and complete evaporation, and (2) it has a simple, well-defined hydrology. The major element concentrations of Merouane Chott lake waters have been measured weekly from January to June 2003. These concentrations are used together with estimates of the chott lake volume to calculate the temporal evolution of the total mass of these major elements. Dividing the first derivative of these masses with respect to time by the chott surface area yields precipitation rate estimates for halite, calcite, gypsum, and K–Mg salts during the complete evaporation of the lake. These rates are compared with the saturation indexes of these minerals to deduce the degree to which they are consistent with laboratory measured rates available in the literature.