Groundwater characterization of aquifer layers using multiple isotopes approach in the Pampa Plain

GIACOBONE, DANIELA; BLARASIN, MÓNICA; MATTEODA, EDEL; LUTRI, VERÓNICA; PRAMPARO, SANTIAGO; CABRERA, ADRIANA; SCHROETER, GERMAN; PASCUINI, MIGUEL; BECHER QUINODOZ, FÁTIMA

Viena

Simposio; International Symposium on Isotope Hydrology; 2023

International Atomic Energy Agency (IAEA)

Stable and radioactive isotopes (δ18O, δ2H, 3H, 13C, and 14C) were used to characterize groundwater age and recharge areas in two sedimentary aquifer layers in the Pampa Plain (Argentina). The data show clear differences between the unconfined aquifer (UA) and the semi-confined aquifer (CAS B). In the UA the stable isotopes are more enriched and linked to the local rainfall recharge. It has high 14C pmC (percent modern carbon) and Tritium values, i.e., recent water (Holocene). The CAS B aquifer showed a recharge zone in Las Peñas Mountains and piedmont. It was interpreted that CAS B is supplied through deeper groundwater flow lines, whose recharge occurred between 20,000 and 30,000 BP, i.e., Pleistocene waters. The use of these old waters must be regulated for sustainable management.