Estudio multiisotópico ( δ 2 H, δ 18 O, δ 13 C-TDIC, δ 18 O-TDIC, 87 Sr/ 86 Sr) e hidroquímico en acuíferos someros fracturados kársticos y detríticos en la región pampeana, Argentina

BERNAVA GUSTAVO VICENTE; GLOK GALLI MELISA; DANIEL MARTINEZ; QUIROZ LONDOÑO; IÑAQUI VIDALLILLO PEREZ; A SILVA BUSSO; SILVIA P BARREDO

ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2020

1025-6016

ABSTRACTFluxes between fractured-karstified and detritic aquifers are commonly poorly understood in many environments. These two types of aquifers are in contact in the southeastern Pampean region in the Argentine Buenos Aires province, and the aim of this work is to analyze their relationship contributing to improve the hydrological model. A joint application of hydrochemical and multi-isotope (δ2H, δ18O, δ13C-TDIC, δ18O-TDIC, 87Sr/86Sr) tools was used. TDIC, δ2H, δ18O and δ13C-TDIC allowed differentiating two main end members. Water in the Pampeano aquifer (PA) which is transferred from the fractured-karstic aquifer (F-KA) is characterised by high TDIC around 500–700 mg/L, isotopically depleted in 18O (about −5.5 ‰) and high δ13C-TDIC (around −10.0 ‰). The other end member is direct recharge water infiltrated into the PA with TDIC ranging from 400 to 500 mg/L, slightly enriched in 18O (δ18O = −4.8 ‰), and δ13C-TDIC in the range of soil CO2 as a result of reactions with calcrete concretions (from −20.0 to −9.0 ‰). Dolomite dissolution is the main process controlling the chemistry of the low-mineralized (Mg–Ca-HCO3) waters, whereas high-mineralized (Na-HCO3) waters are strongly influenced by ion-exchange reactions with adsorbed Ca2+ and Mg2+ and by evaporation.KEYWORDS: Argentine Pampean regioncarbon-13fractured-karstic aquifershydrogen-2isotope hydrologyoxygen-18Pampeano aquifer87Sr/86SrTDICPrevious articleView issue table of contentsNext articleAcknowledgmentsThis article is also a contribution to the Research Group of the ‘Junta de Andalucía’ (Hydrogeology Group, RNM-308). Authors are also thankful to Tec. G.V. Bernava and Prof. V. Colasurdo, who performed the chemical analyses. We recognise to anonymous reviewers, who largely contributed to the improvement of the manuscript.