Coastal Aquifer Salinization in Semi-Arid Regions: The Case of Grombalia (Tunisia)

Abstract

Groundwater resources are facing increasing pressure especially in semi-arid regions where they often represent the main freshwater resource to sustain human needs. Several aquifers in the Mediterranean basin suffer from salinization and quality degradation. This study provides an assessment of Grombalia coastal aquifer (Tunisia) based on multidisciplinary approach that combines chemical and isotopic (δ2H, δ18O, 3H, 14C and δ13C) methods to characterize the relation between groundwater quality variation and aquifer recharge. The results indicate that total dissolved solids exceed 1000 mg/L in the most of samples excepting the recharge area. In addition to water–rock interaction, evaporation and nitrate pollution contributing to groundwater mineralization, the reverse cation exchange process constitute an important mechanism controlling groundwater mineralization with enhancing risk of saltwater intrusion. Environmental isotope tracers reveal that groundwater is evolving within an open system to close system. A significant component of recent water that is recharging Grombalia aquifer system is confirmed by applying correction models based on the δ13C values and 14C activities and tritium contents. However, this recharge, which is mainly associated to the return flow of irrigation water, contributes to the groundwater salinization, especially for the shallow aquifer.

Various Natural and Anthropogenic Factors Responsible for Water Quality Degradation: A Review

“…Climate change not only influences ecological, hydrological, and biological systems; it also affects life and economy [39]. The primary and foremost occurrence and vulnerability of surface water and groundwater are natural regional climate oscillations and weather changes [40]. However, this also includes past weather patterns in the context of fossil groundwater.…”

“…Therefore, these reactions will impact ion exchange and reduction processes whether the groundwater is shallow or deep. These variables influence how specific solutes or contaminants moving through the pores or space in the sediment matrix are degraded [40].…”

Special Issue “Focus on the Salinization Issue in the Mediterranean Area”

“…The main goal of this Special Issue of Water is to focus on different methodological approaches to improve the understanding of salinization mechanisms of both groundwater and soil water, which may derive from actual seawater intrusion, paleo-seawater intrusion, an increase in atmospheric temperatures that in turn drives evapoconcentration and agricultural return flows. From its first announcement, and after being thoroughly peer reviewed, six papers have been accepted for publication [10][11][12][13][14][15]. To gain an overview of the ideas collected by this Special Issue, a brief summary of each published paper is reported below.…”

“…The results highlight the existence of saline groundwater at the bottom of the aquifer in most of the study area, thus stressing that groundwater quality is not suitable for human consumption and irrigation. The spatial analyses of the horizontal distribution of compound-specific stable and radioactive isotopes combined with major dissolved ions in the Grombalia coastal aquifer (Tunisia) were pivotal to unravel the main geochemical processes driving aquifer salinization and groundwater residence times [11]. In the same line of research, major and compound-specific isotope analyses were combined with major ions to disentangle the ongoing salinization and factors influencing groundwater quality in the coastal archeological site of Cumae located in the volcanic district of the Phlegraean Fields (Southern Italy) [12].…”

Historical analysis of a karst aquifer: recharge, water extraction, and consumption dynamics on a tourist island (Cozumel, Mexico)

“…Coastal aquifers (CAs) are a valuable source of freshwater for the coastal environment well-being of over 60% of the global population that is concentrated around the shoreline (Zepeda et al, 2018) and 11% that lives on islands (Mendoza-Vizcaino et al, 2016). Aquifers near coastal areas are susceptible and sometimes unable to cope with the adverse effects of overextraction (Jaleel et al, 2020;Zepeda et al, 2018), sea water intrusion (Deng et al, 2017), pollution (Hernández-Terrones et al, 2011;Kammoun et al, 2021), and climate change effects, such as rainfall pattern modification and sea level rise (Cashman, 2014;GWP, 2014;Hall et al, 2013;Pulido-Velazquez et al, 2018). Because of their nearness to the sea, CAs and island aquifers (IAs) share similarities, although IAs are unique in that they are confined to a geographical area.…”