A study on the salinization of coastal water of Sidi Boughaba Lake (Ramsar site 1980) in Morocco using the characteristic reports

Abstract

The Lake Sidi Boughaba is a Ramsar site (1980) located on the Atlantic coast of north-west Morocco. It is oriented NNE - SSW and located in a secondary interdunal depression formed in a complex of the main wetlands of Morocco. The waters of this lake are deteriorating in quality, with increasing salinization. To identify the processes and chemical reactions that govern salinization, the main major elements as well as the pH, electrical conductivity and salinity were monitored during the winter and summer seasons of the years, 2016-2017 in 6 sites distributed throughout the year. The interpretation of the analysis data is carried out using the correlation of the major elements with the chlorides, the Piper diagram and the variation of the ionic ratios Na/Cl, SO4/Cl, Mg/Ca and the calculation of the saturation index. The saturation index is calculated by the software PHREEQC 2.8, used for modelling the state of saturation of minerals. The results of these analyzes revealed a variety of origins and processes of salinization of the waters. The hydro chemical study shows that the waters are brackish too salty; they are characterized by sodium chloride facies. This remarkable transition is mainly due to the intense evaporation that accentuates the mineralization. The values of the saturation index of the chemical minerals show the under saturation the anhydrite of the gypsum and the halite, on the other hand, the saturation or even supersaturation by the calcite and dolomite. The characteristic ratios of the chemical composition of waters show that salinity has two main origins: ion exchange between rock-water and marine influence by aerosols and sea spray.