Unravelling groundwater and surface water sources in the Esteros del Iberá Wetland Area: An isotopic approach
In the Esteros del Iberá Wetland Area (EIWA, NE Argentina), the southern sector of the transboundary Guarani Aquifer System (SAG) is overlain by the Ramsar listed Iberá Wetlands and several rivers, that combined extend across 37,930 km2 and represent one of the largest freshwater systems on the Sout...
| Authors: | , , , , , , , , , |
|---|---|
| Format: | article |
| Status: | Versión aceptada para publicación |
| Publication Date: | 2022 |
| Country: | España |
| Institution: | Universidad Politécnica de Cartagena(UPCT) |
| Repository: | Repositorio Digital UPCT |
| OAI Identifier: | oai:repositorio.upct.es:10317/13361 |
| Online Access: | http://hdl.handle.net/10317/13361 https://www.sciencedirect.com/science/article/pii/S0048969722045739?via%3Dihub |
| Access Level: | Embargoed access |
| Keyword: | Guaraní Aquifer System Iberá wetlands water sources 222-Rn δ18O and δ2H EMMA Explotación de Minas 2503 Geoquímica 2506 Geología 2506.05 Hidrogeología |
| Summary: | In the Esteros del Iberá Wetland Area (EIWA, NE Argentina), the southern sector of the transboundary Guarani Aquifer System (SAG) is overlain by the Ramsar listed Iberá Wetlands and several rivers, that combined extend across 37,930 km2 and represent one of the largest freshwater systems on the South American continent. Previous hydrogeological studies encompassing the entire SAG proposed preferential discharge of groundwater of various origins and ages to the EIWA. In this study, a multi-tracer study using major ionic species, δ18O, δ2Hand222Rn was conducted in lagoons, rivers, wells, and boreholes in the EIWA to confirm if discharge from the transboundary SAG is contributing to the sur-face water system. End-member Mixing Analysis (EMMA) determined the existence of four main end-members: groundwater from the SAG, more saline groundwater from the deeper Pre-SAG, and two poorly mineralised end-members from shallow, Post-SAG. EMMA calculations clearly illustrated complex binary and ternary mixing patterns involving the four end-members and highlighted the role of geological structures, specifically regional steep faults, in controlling the mixing patterns. 222Rn activities allowed in-situ identification of preferential deep groundwater dis-charge into both surface waters and shallow groundwaters. These findings provide strong evidence for the widespread existence of upward flows along major faults in this sector of the SAG, inducing complex mixing flow patterns and explaining the presence of old groundwater in shallow aquifers. Mapping the sources of water and the hydrological interactions are relevant for improving water balance estimates and develop management policies towards the preservation of these wetlands. |
|---|