Hydrogeochemical characteristics and assessment of drinking water quality in Zeuss–Koutine aquifer, southeastern Tunisia

Abstract

Zeuss-Koutine aquifer, located in southeastern Tunisia, has been used intensively as a primary source to meet the growing needs of the various sectors. Detailed knowledge of the geochemical evolution of groundwater and water quality can enhance understanding of the hydrochemical system, promoting sustainable development and effective management of groundwater resources. To this end, a hydrochemical and statistical investigation was conducted. Groundwater samples have been collected from 13 wells from 1995 to 2005; to understand the sources of dissolved ions and assess the chemical quality of the groundwater. Results demonstrate that among the cations, only the mean concentrations of Na( + ) exceed guideline values set by the World Health Organization (WHO). Regarding the analyzed anions, the concentration of SO(2-)(4) and Cl( - ) are above the WHO allowable concentrations. Total dissolved solids in most groundwater samples are greater than 1,000 mg l(-1), the limit set by the WHO, indicating slightly saline or moderately saline water. In general, a significant increase in the degree of water mineralization was observed in the direction of southwest to northeast following the regional flow direction. Calculated saturation indices show that all water samples were oversaturated with respect to aragonite, calcite, and dolomite, and undersaturated with respect to anhydrite, gypsum, and halite. Based on hydrochemical facies, two types of water predominate in the study area. The first is Ca-Na-SO(4)-Cl in type and located in the southwest which corresponds to the recharge part of the aquifer. The second type is Na-Ca-Cl-SO(4) and located in the east, which corresponds to the discharge part.

Hydrochemical assessment of water quality for irrigation: a case study of the Medjerda River in Tunisia

“…A similar impact of the bedrock composition to the water quality has been also described by Gamvroula et al (2013). It is commonly known that the ionic composition of water is the result of several factors during water-rock interaction (Hamzaoui-Azaza et al 2011). The water samples undersaturated with dolomite indicate that dolomite may also dissolve in this system, adding Ca 2?…”

“…The chemical composition of water is controlled by many factors which include the precipitation composition, the underlying geological structure, the mineralogy of the watersheds and the geochemical processes involved, as well as the residence time and the reactions that take place within the system (Hamzaoui-Azaza et al 2011;TliliZrelli et al 2013). In fact, modifications of the geochemical characteristics of saline waters can be due to water-rock interaction involving base exchange reactions with clay minerals, adsorption onto clay minerals and carbonate dissolution-precipitation (Thilagavathi et al 2012;Gamvroula et al 2013).…”

“…Silicate dissolution can be a possible source of sodium in some water samples. Thus, water salinization would be due to ionic concentrations increase as a result of the interactions between water and geological formations (Hamzaoui-Azaza et al 2011). However, the hydrochemical facies are not only depending on the solution kinetics, rock-water interactions and geology but also by the possible anthropogenic contaminations (Alexakis 2011).…”

Acquisition de salinité et qualité des eaux d’une nappe profonde en Tunisie: approche statistique et géochimique

“…Par la suite, les axes de projection sont assimilés aux vecteurs propres de la matrice de corrélation (Yidana et al 2008). On cherche d'abord l'axe qui permet de voir les individus, c'est-à-dire pour lequel la variance des individus est maximale, puis une deuxième composante principale qui fournit la plus grande information possible, complémentaire à la première (Hamzaoui-Azaza et al 2010). Le processus se déroule jusqu'à l'obtention de la dernière composante principale.…”

The Source of Arsenic and Nitrate in Borrego Valley Groundwater Aquifer

“…Thus, the understanding of groundwater chemistry, occurrence and distribution of chemical constituents in groundwater are valuable for identifying the natural and human factors affecting water quality [6]. The controlled processes on chemical composition of groundwater include evaporation, dissolution/precipitation, weathering of silicates, oxidation-reduction, sorption and exchange reactions, transformation of organic matter, and mixing processes [7].…”