Carla Maria Salgado Vidal Silva,Maria Marlúcia Freitas Santiago,João Manoel Filho,Horst Frischkorn, Universidade Federal do Ceará, Física, carla@fisica.ufc.br
ABSTRACT
In areas of water shortage and subject to periods of drought, aquifer recharge is an important parameter for the administration of the existent water resources. Environmental isotopes oxygen-18 and deuterium were analyzed in groundwater samples from the Sedimentary Apodi Basin, stored in the Açu sandstones, confined, and in the Jandaíra limestones, unconfined. The area is located in the northeast of the State of Ceará and the northwest of the State of Rio Grande do Norte, in the Apodi Plateau. Waters were collected from deep wells and springs. The relationships 18O vs. D and electric conductivity vs. 18O distinguish clearly the waters of the two aquifer systems Jandaíra and Açu and they evidence that the springs produce waters from the Jandaíra aquifer. The isotope data also show that the waters of the Jandaíra aquifer are of recent recharge and are, therefore, renewable. The Açu waters are paleo-waters and, therefore, should be considered a strategic resource with restricted use.
Keywords: Oxygen-18, Deuterium, Apodi Plateau, Semi-arid Northeast