Salas-Navarro Jessica, Sánchez-Murillo Ricardo, Esquivel-Hernández Germain, Corrales-Salazar José Leonardo
a Stable Isotope Research Group, Chemistry School , Universidad Nacional , Heredia , Costa Rica.
Isotopes Environ Health Stud. 2019 Mar;55(1):25-40. doi: 10.1080/10256016.2018.1546701. Epub 2018 Nov 20.
This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δO and δH in rainfall resulted in a highly significant meteoric water line: δH = 7.93·δO + 10.37 (r = 0.97). Rainfall isotopic composition exhibited a strong amount-dependent seasonality. The isotopic variation (δO) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23 ± 0.03 (Sacramento) and 1.42 ± 0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.
