Modeling the hydrogeochemical evolution of brine in saline systems: Case study of the Sabkha of Oum El Khialate in South East Tunisia

Abstract

We studied the effects of evaporation and groundwater flow on the formation of salt minerals in the sabkha of Oum El Khialate in South East Tunisia, which contains large amounts of sulfate sodium mineral deposits. Due to the fact that there are no important surface water bodies present in this sabkha, transport of solutes is dominated by advection rather than mixing in lakes. For our study we used both analytical conservative and numerical reactive transport models. Results showed that salinity varies with distance and may reach very high levels near a watershed where the groundwater flux is zero. As a consequence, reactive transport simulations results showed that more minerals precipitate and water activity decreases values near this watershed. Model results also showed that a sequence of precipitating minerals could be deduced after 140000 years. From the boundary of the sabkha towards the watershed the mineral sequence was dolomite, gypsum, magnesite, bloedite, halite and mirabilite. It was found that the amounts as well as the mineral precipitation distribution strongly depend on salinity and rates of inflowing water.

Genesis and pore evolution of dolomite reservoir in the Majiagou Formation, Ordos Basin, China

“…Three different diagenetic stages in variable diagenetic settings (Figure 10) successively modified the reservoir pores: Diagenesis on the seafloor in the contemporaneous–penecontemporaneous stage: The Ma 5 6 sub-member was deposited in a restricted evaporatic environment under hot–arid climate conditions. Due to the gradual evaporation, the seawater salinity increased, and gypsification affected the seafloor deposits and gypsum was continuously precipitated(Nasri et al, 2015). The precipitation of CaSO 4 increased the Mg/Ca ratio of the seawater, which was conducive to large-scale, penecontemporaneous dolomitization and dolomite cementation, which developed the lithological framework of the Ma 5 6 reservoirs.…”

Geochemistry and mineralogy of the sebkha Oum El Khialate evaporites mixtures, southeastern Tunisia

“…The brine underwent evaporation of 30, 60, and 100%. After each (Tagorti et al, 2014), and map of the dry residue within the sebkha (Nasri et al, 2015a) evaporation phase, the recuperated salt underwent XRD, XRF, and FTIR analyses. The mineralogical composition of the precipitated salt was also determined by XRD.…”

“…The economic interest of sebkha Oum El Khialate is twofold (2). The different mineral species already cited in previous works (Perthuisot, 1976;Tagorti et al, 2014Tagorti et al, , 2016Nasri et al, 2015aNasri et al, , 2015b are of great economic interest in the international salt markets due to an increasing ratio demand/supply and prices.…”

Experimentation of an evaporation-crystallization process of solar salt from Merouane Chott (South-East Algeria)

“…The motivation of our study is the saline systems in Southern Tunisia such us El Jerid Chott, sabkhas El Melah-Zarzis and Oum El Khialate [7]. Geological, hydrogeological and geochemical research showed that these regions contain very significant natural brine reserves.…”

“…1. Photography of two Brine pans Table 1 The hourly monitoring of brine and air temperatures, humidity, and wind speed and meteorological observation er curves for the two tests to the lowest values of 2 to 1 mm is due to the evaporation rate which regresses as it approaches the final crystallization of the salt [7]. According to the study, the average evaporation flux from the traditional system [4] is about 0.02 kg/m 2 -hr while that of the enhanced system is about 1.68 kg/m 2 -hr, corresponding to a brine temperature increment from 30 to 50 °C.…”