Understanding the origin of salinization of the Plio-quaternary eastern coastal aquifer of Cap Bon (Tunisia) using geochemical and isotope investigations

Abstract

As in many other semi-arid regions, the Plioquaternary aquifer of the eastern coast of Cap Bon peninsula (NE Tunisia) shows a parallel increase in overexploitation and mineralization of groundwater resources and so the water quality is deteriorating. Different methods using geochemistry (ions Na ? , Cl -, Ca 2? , Mg 2? , Br -) and stable isotopes ( 18 O, 2 H) are compared with the hydrodynamic information for identifying the main processes involved in the increase of salinization. Along the coast, intrusion of seawater resulting from groundwater overexploitation is identified, but is not the only cause of qualitative degradation: the development of irrigation that induces soil leaching and transfer of fertilizers to groundwater over the whole aquifer extent is another major reason for the increase in salinization. A total of 48 groundwater wells were sampled to obtain additional information on the hydrochemical characteristics of the groundwater defined in previous studies.

Combining boron isotopes and carbamazepine to trace sewage in salinized groundwater: A case study in Cap Bon, Tunisia

“…It showed almost no enrichment in magnesium and depletion in sodium and potassium. Na and K depletion along with Ca and Sr enrichment are in agreement with the cation exchange process (detailed in the Supporting Information) which were previously described (Ben Hamouda et al, 2011;Cary et al, 2012 a,b;Kouzana et al, 2009;Lerouge et al, 2010;).…”

“…This is consistent with a meteoric recharge which was confirmed with stable isotopes (Ben Hamouda et al, 2011;Ben Moussa et al, 2009). It can also result from mixing with lowly mineralized groundwaters like in Piez 16 (2011) with a δ 11 B between 16‰ and 20‰ with very low B contents (3 µmol/L).…”

“…This facies is truncated by a carbonate sequence and aeolian oolitic deposits. The uppermost continental Pleistocene is represented by continental red deposits and a centimeterto meter-thick calcrete extending over large areas (Ben Hamouda et al, 2011;Chakroun et al, 2005;Elmejdoub and Jedoui, 2009). At Taffeloun, the calcrete outcrops and its thickness is 15m (in clear blue in Fig 1b).…”

Hydrogeochemistry and groundwater salinization in an ephemeral coastal flood plain: Cap Bon, Tunisia

“…Several studies focused mainly on understanding the flow and hydrological budget of the regional groundwater flow system (Rouatbi 1968, Ennabli 1980, Rekaya 1989, Khlaifi 1998, Paniconi et al 2001, Chattouti 2006, Kerrou 2008, Zghibi 2011. Some others have dealt with characterizing the qualitative degradation of the aquifer caused by seawater intrusion (Kouzana et al 2009, Ben Hammouda et al 2011). All the above-mentioned authors focused exclusively on regional groundwater flow; there is no previous work that has studied small-scale groundwater flow and contamination.…”

Uso Dos Isótopos Estáveis De O18 E H2 Aplicados Ao Estudo De Salinização De Aquíferos Livres

“…Os artigos consultados para elaboração deste trabalho, demostraram que o principal uso dos isótopos estáveis de O 18 e deutério foi para confecção de uma reta meteórica local (VSMOW), seguido, em ordem de abundância, na determinação da origem do cloreto, sólidos totais dissolvidos e origem da salinidade (Gráfico 1) (Kim et al, 2003;Moller et al, 2007;Montety et al, 2008;Bouchaou et al, 2008;Carol et al, 2009;Gattacceca et al, 2009;Rosenthal et al, 2009;Schiavo et al, 2009;Hamouda et al, 2011;Moussa et al, 2011;Monjerezi et al, 2011;Vinson et al, 2011;Wang et al, 2012;Matthew Currell et al, 2013;Pauwels et al, 2013;Rina et al, 2013;Stoecker et al, 2013;Carreira et al, 2014;Han et al, 2014;Madioune et al, 2014;Villanueva et al, 2014;Cary et al, 2015;Kumar et al, 2015;Zhang et al, 2015). A assinatura isotópica da água subterrânea é inerente a razão isotópica da recarga, seja ela por água da chuva ou iteração com outro sistema aquífero, com isso é possível sugerir a origem de um dado elemento químico ou parâmetro físico.…”