Isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica |
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Authors: | Ricardo Sánchez-Murillo Germain Esquivel-Hernández Oscar Sáenz-Rosales Gilberto Piedra-Marín Alicia Fonseca-Sánchez Helga Madrigal-Solís |
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Institution: | 1. Chemistry Department, Stable Isotope Research Group, National University of Costa Rica, Heredia, Costa Rica;2. Chemistry Department, National University of Costa Rica, Heredia, Costa Rica;3. Environmental Hydrology Laboratory, Biological Sciences Department, National University of Costa Rica, Heredia, Costa Rica |
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Abstract: | The linkage between precipitation and recharge is still poorly understood in the Central America region. This study focuses on stable isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica. During the dry season, rainfall samples corresponded to enriched events with high deuterium excess. By mid-May, the Intertropical Convergence Zone poses over Costa Rica resulting in a depletion of 18O/16O and 2H/H ratios. A parsimonious four-variable regression model (r2?=?0.52) was able to predict daily δ18O in precipitation. Air mass back trajectories indicated a combination of Caribbean Sea and Pacific Ocean sources, which is clearly depicted in groundwater isoscape. Aquifers relying on Pacific-originated recharge exhibited a more depleted pattern, whereas recharge areas relying on Caribbean parental moisture showed an enrichment trend. These results can be used to enhance modelling efforts in Central America where scarcity of long-term data limits water resources management plans. |
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Keywords: | air mass back trajectories Costa Rica deuterium excess groundwater management hydrogen-2 isotope hydrology oxygen-18 precipitation |
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