Identification of major sources controlling groundwater chemistry from a multilayered aquifer system

Abstract

The Maknassy basin is a typical example of an arid area in Central Tunisia. The geology of the area is mainly composed of Cretaceous calcareous formations. To identify the major process involved in controlling the groundwater chemistry, 53 groundwater samples for three different aquifer levels have been examined. The groundwater chemistry is dominated by SO 4 (Na þ Mg) and (Cl þ SO 4 ). The presence of (Ca þ Mg) and (Na þ K) with HCO 3 indicates the domination of dolomitic rock weathering as the major source of cations. The plots for Na to Cl indicate a fine correlation and reflects their release from halite dissolution during groundwater transition. An ion exchange process is also activated in study area which is indicated by a shift to the right in a plot for Ca þ Mg to SO 4 þ HCO 3 . The plot of Na À Cl to Ca þ Mg À (HCO 3 þ SO 4 ) confirms that Ca, Mg and Na concentrations in groundwater are derived from aquifer materials. Saturation indexes of groundwater samples indicate undersaturation for gypsum and anhydrite, and oversaturation for calcite, dolomite and aragonite confirming waterrock interactions by dissolution and dilution processes. In general, water chemistry is guided by weathering process, ion exchange and water -rock interaction during groundwater transition.

Groundwater Conditions and Hydrogeochemistry of the Sombreiro-Warri Deltaic Plain Deposit (Shallow Benin Formation) in the Vicinity of Agbarho, Nigeria

“…The Piper [28] and Stiff [29] diagrams have been widely used [20,[30][31][32][33][34][35][36] as a descriptive tool to interpret and classify groundwater on the basis of the major ion contents. The Piper diagram plotted for the area is shown in Fig.…”

Groundwater recharge sources in semiarid irrigated mountain fronts

“…The main advantage of using stable isotopes to analyse the mountain-front recharge is that the signature of local rainfall on the plain are likely to significantly vary from the signature of rainfall in the mountains due to rainout effects (Clark & Fritz, 1997;Kalbus, Reinstorf, & Schirmer, 2006;Lambs, 2004;Scanlon, Healy, & Cook, 2002). Similarly, for major ions, because changes in recharge rates and flow pathways can result in significant differences in the composition of the major ions, the latter could provide insights into mixing between different groundwater recharge sources (Chenini, Farhat, & Ben Mammou, 2010).…”

Complementary use of dating and hydrochemical tools to assess mixing processes involving centenarian groundwater in a geologically complex alpine karst aquifer

“…This could indicate that gypsum dissolution does not occur during all the groundwater transit time, contrary to dedolomitization. Thus, groundwater would dissolve gypsum within the EZ substratum, which would enhance the gain in Mg 2+ through dedolomitization, although it cannot be discarded that some of the Mg 2+ present in the groundwater comes from the dissolution of evaporite rocks (Hamill & Bell, 1986;Chenini, Farhat & Ben Mammou, 2010).…”