APPROCHE HYDROGEOCHIMIQUE A L’ETUDE DE LA FLUORATION DES EAUX DE LA NAPPE DU COMPLEXE TERMINAL DE LA BASSE VALLEE DE L’OUED M’YA (OUARGLA) Hydrogeochemical approach to study the water fluoridation of the Terminal Complex aquifer in the low algeria

Le présent travail porte sur la présence et l’origine géochimique du fluor dans les eaux de la nappe du Complexe Terminal (CT) de Ouargla. Les résultats obtenus montrent qu’il existe avec des teneurs variables allant de 0,9 à 1,42 mg.l-1. Le calcul de l’indice de saturation des eaux par les minéraux dominants ,en utilisant le modèle thermodynamique Phreeqci, révèle la susceptibilité des minéraux carbonatés à la précipitation, et les minéraux évaporitiques et fluorurés à la dissolution. The present work deals with the presence and the hydrochemical origin of fluoride in Terminal Complex aquifer of Ouargla. The results show the presence of fluoride in studied water. The concentrations vary between 0,9 and 1,42 mgl-1. The calculation of water saturation index in relation to the preponderant minerals, using the thermodynamic model phreeqci reveals a sensitivity of carbonate minerals towards precipitation, and dissolution of evaporitic minerals and fluorides clays as well

Assessment and Mapping of Groundwater Quality for Irrigation and Drinking in a Semi-Arid Area in Algeria

Groundwater is the main resource used to meet the people’s drinking water and irrigation needs of the Ain Oussera plain, because of the lack of surface-water resources. This paper intended to evaluate the suitability of groundwater for agriculture and drinking in the Ain Oussera plains. The data of the study were gathered and analyzed from twenty (20) groundwater samples collected to assess the plain groundwater quality, using the Water Quality Index (WQI) and GIS, carried out on physico-chemical parameters, including potential of hydrogen (pH), total dissolved solids (TDS) electrical conductivity (EC), potassium (K+), sodium (Na+), magnesium (Mg2+), and calcium (Ca2+) and major anions (Cl, HCO3, NO3, SO4), as well as, the water suitability test for agricultural purposes, using the sodium adsorption ratio. These parameters were inserted into the GIS platform to create a spatial distribution map for each parameter using the inverse interpolation technique (IDW). The results indicated that the concentrations are within the Algerian permissible limits. The water quality index (WQI), which evaluates the suitability of water for consumption, varies from 31 to 173 with an average value of 81. 70% of the samples from the Ain Oussera plain fall within the excellent and good quality categories. Its water is suitable for consumption (WQI < 100), while 30% is in the poor water category. From the calculation of SAR values, it was found that 90% of the groundwater samples are considered excellent and suitable for irrigation. According to the classification of the United States Salinity Laboratory USSL, the Ain Oussera water quality is classified as poor for irrigation purposes

REE and Y distribution and speciation in fossil water: The northwestern African Continental Intercalaire aquifer, Algerian Sahara

The Continental Intercalaire aquifer is a part of the Northwestern Sahara Aquifer System which, extending through Algeria, Tunisia and Libya with over one million km2, is one of the largest fossil aquifers in the world, with an age of about 775,000 years, water resource estimated at ~31000×109 m3 and negligible recharge rate at 1×109 m3/year. The fossil water of the Algerian Sahara, part of the Continental Intercalaire aquifer, was examined, for the first time, for its REE+Y composition, speciation, and geochemical significance in order to constrain the processes affecting the REE+Y distribution and fractionation pattern in a peculiar aquatic system. The fossil water of the Algerian Sahara has total mineralization in the 1170 and 2309 mg/l range and the prevailing hydrochemical facies is Na-Cl-SO4. The recorded REE+Y concentrations increase downstream, along with the dissolved silica content and temperature, as a function of water flow. The water samples are in equilibrium with 2:1 and 1:1 clay minerals with the exception of few upstream samples, characterized by alkaline pH values, that are in equilibrium with Na- and K-feldspars. The REE+Y speciation is mainly controlled by carbonate species. The Ln(CO3)+ species increase and the Ln(CO3)2 - species decrease downstream as the carbonate rocks of the aquifer dissolve and the PCO2 equilibrating pressure increases. The LnSO4 + species are mostly LaSO4 + downstream the aquifer and, more in general, LaSO4 + largely prevails up to pH between 6.9 and 7.2. The low negative cerium anomalies affecting most of the samples might be explained by the CeO2 precipitation following Ce3+ transformation to Ce4+. Ce oxidation is probably promoted by Mn-minerals by oxidative scavenging, whereas positive Ce anomaly could be due to the preferential desorption of Ce3+ over Ce4+. Finally, the pronounced negative samarium anomaly observed in some samples may reflect depletion of organic matter and Sm adsorption onto clay minerals

Geothermometry and geochemistry of groundwater in the Continental Intercalaire aquifer, southeastern Algeria: Insights from cations, silica and SO4–H2O isotope geothermometers

Characterization of geochemistry and geothermometry of the groundwater from the Continental Intercalaire (CI) aquifer, one of the largest aquifers in the world, stretching over one million km(2) surface area shared between Algeria, Tunisia and Libya, was conducted in southeastern Algeria nearby the border with Tunisia. Thirty-two water samples were collected from boreholes to analyze the physicochemical parameters and stable isotopes (delta O-18((H2O)), delta O-18((SO4)), delta S-34 ((SO4))) and determine the origin of water mineralization of the CI aquifer. Water temperature was assessed using several geothermometers, such as cations, silica and SO4-H2O stable isotopes. The CI aquifer displayed a discharge temperature varying from 45 to 65.1 degrees C due to water circulation at deeper depths ranging from 1000 to 2200 m. The Results show that CI water contains high total dissolved solids (TDS) and neutral to slightly alkaline pH. The most frequent water types were Na-Cl-SO4 and Ca-SO4 indicating the geological formation nature of CI aquifer which is mainly composed of evaporites. The application of Na-K and Na-K-Ca geothermometers yielded unreliable temperatures. However, Na-Li geothermometer resulted in relatively plausible temperatures ranging from 74.69 to 147.83 degrees C. Quartz and CaSO4-H2O isotope geothermometer are the most suitable methods for temperature estimation, due to their attainment of equilibrium resulting in temperatures ranging from 62 to 93 degrees C, and validation by the multiple mineral equilibrium approach. The present study demonstrated a successful application of CaSO4-H2O isotope geothermometer in a low enthalpy (<100 degrees C) geothermal system. The results corroborate previous findings on the same CI aquifer at the Tunisian side and on carbonate-evaporite geothermal reservoirs. Furthermore, geothermal potential of the CI aquifer has been highlighted suggesting its use as a source of renewable energy which could be applied in heating greenhouses and/or generating electricity.24 month embargo; published online: 12 December 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Fractures and lineaments mapping and hydrodynamic impacts on surface and groundwater occurrence and quality in an arid region, Oued M’ya basin–Southern Sahara, Algeria

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