Hydrogeochemical Processes and Groundwater Evolution of the Crystalline Aquifer of Amargosa Sheet, SD.24-VD-II, South-Central of Bahia

• Main Author: Silva, Josimar André da
• Publication Date: 2021
• Other Authors: Barbosa, Natanael da Silva, Santos, Cristovaldo Bispo dos
• Format: Article
• Language: por
• Source: Águas Subterrâneas (São Paulo. Online)
• Download full: https://aguassubterraneas.abas.org/asubterraneas/article/view/30023
• topic: Hydrochemical facies; Hydrogeochemical processes; Crystalline aquifer.; Fácies hidroquímicas; Processos hidrogeoquímicos; Aquífero cristalino.

Hydrogeochemical investigations were carried out in order to identify the processes that affect the chemistry of groundwater in the south-central region of Bahia that comprises the Amargosa sheet. Forty-nine hydrochemical analysis of representative wells in the area were used and their results interpreted according to the chemistry of the major ions, using conventional and bivariate graphs. There is a wide range of hydrochemical facies, with mixed cationic species (Ca-Na + K) and Cl- and HCO3- predominating as the dominant anionic facies. In general, HCO3- facies occur in regions of sub-humid climate and active flow while the Cl- facies occurs in semi-arid conditions and slow flowlines. The mechanisms of water-rock interaction and evaporation are the main hydrogeochemical processes that control the chemistry of groundwater, with an emphasis on the weathering of silicates (plagioclases, pyroxenes and biotite); chlorine-alkaline imbalance, common in HCO3 facies and cation exchange reaction, representative of Cl facies. Therefore, this work contributes to fill gaps and present contextual information about the processes that control the geochemical signature of the crystalline aquifer and possible variations in the quality of groundwater, in order to raise the knowledge of a complex system and establish the basis for a more rational exploration of anisotropic aquifers.