Salinisation of soils in semi‐arid endorheic zone: Case of Chott El Beida (Algeria)

Abstract

Chott El Beida, North of Algeria (Setif, 585 km2), is an endorheic zone located in a semi‐arid climate. It is among the first chotts listed under the Ramsar Convention on the Wetlands of International Importance. Numerous studies on wetlands in the Setif region have focused on hydrogeology, avifauna, and vegetation. However, only one study has been devoted to soil studies. This study focused on the pedological and geochemical aspects of salinity in this area. This study was conducted on a toposequence of 200 m comprising eight soil profiles. A set of 24 samples were collected from the top to a depth (0–200 cm) and were subjected to a series of physical and chemical analyses. The concentrations of the major elements were used to determine the chemical facies and calculate the saturation indices for each mineral and residual alkalinity using geochemical modelling with PHREEQC. This study shows that the salinity in Chott El Beida is very variable, varying from less saline to extremely saline, moving from the outside to the centre of the chott, with two types of saline profiles: the descending type towards the outside of the chott and the ascending type in the highly saline depression. Geochemical investigations demonstrated that the dominant facies is (Na‐Cl) which is in accordance with the neutral saline pathway. The phenomenon of salinisation in Chott El Beida is controlled mainly by the precipitation of minerals, namely, calcite, aragonite, dolomite, gypsum, and anhydrite, and the dissolution of evaporite minerals. The study of calcite residual alkalinity and generalised residual alkalinity showed that salinisation evolves in the neutral saline path without the risk of alkalinization.