Hydrochemical and isotopic characterization of fissural aquifers from Itabuna/BA region

Abstract

Crystalline aquifers represent important water reserves around the world and are characterized by the complexities that govern the water movement and storage in its geological discontinuities. Similar complexity is observed in the mechanisms acting on the rock/water interaction. The understanding of the physical and geochemical processes in these aquifers is crucial for their management. This work presents a preliminary hydrochemical characterization of the groundwater stored in the fractured aquifer of the Itabuna/BA region, identifying of the prevailing hydrochemical types. The chemical analyzes indicate a high variability of the groundwater composition, which may be related to the occurrence of several distinct processes, including the interaction with the seawater and different degrees of interaction with the rocks that host the water in their geological discontinuities. The groundwater samples were clustered in two distinct groups: the first group is represented by the sodium chlorate water type, with lower values of electrical conductivity, associated with the samples collected in shallower sub-surface portions; the second group is represented by hydrochemical types of sodium, calcium or calcium-magnesium bicarbonate, most likely associated with waters with high degree of interaction with the aquifer rocks, from preterit recharge. The results of isotopic analysis of underground and meteoric water suggest the existence of a slight excess of deuterium, due to local climatological conditions.

Keywords

• Aquífero fissural. Interação rocha/fluido. Caracterização isotópica.