Assessment of cation exchange as conditioning processes of water chemistry in freshwater lenses

TANJAL, CAROLINA; BORZI, GUIDO; SANTUCCI, LUCÍA; CAROL, ELEONORA; RICHIANO, SEBASTIÁN

WATER ENVIRONMENT RESEARCH

WATER ENVIRONMENT FEDERATION

Año: 2023

1061-4303

Freshwater lenses are groundwater sources of limited dimensions that can be usually found in a variety of climates worldwide. These aquifers’ quality is important for socioeconomic development, being cation exchange one of the most important geochemical processes that can change the water geochemistry. This study aims to assess the cation exchange processes which determine the chemistry of freshwater lenses in a multilayer aquifer type, considering the center-east of the Pampean Region (Argentina) as a case study. Water samples were taken from the freshwater lenses at different depths to analyze major ions in the laboratory. In addition, geological profiles were made along with the extraction of sediment samples for XRD and laboratory tests to analyze the cation exchange capacity. The results show that water stored in the lenses has a vertical facies variation from Ca-HCO3 to Na-HCO3. According to the laboratory results, the change of water facies mainly occurs in the clayey sediments which divide the carbonate bioclastic material above and the loessic sediment below, being cation exchange the most important process.