Caracterização físico-química das águas subterrâneas na Bacia Potiguar

Abstract

Waters from the most important aquifers of Rio Grande do Norte State, the limestone of the Jandaíra Formation and the Sandstone Açu Formation, were sampled during two campains, one after the wet season and the other at the end of the dry one. During each one nearly 100 samples were collected, aiming at a homogeneous coverage of the area. Analyses were made for the major elements (Ca2+, Mg2+, Na+, K+, Cl-, SO4 2-, CO3 2- e HCO3 -), the N-compounds (NH4 +, NO2 -, NO3 -), total iron, for electric conductivity (CE) and pH. Adequacy for irrigation is illustred through USSLS SAR vs. CE diagrams; potalility is analysed estatistically based on Resolution No 396 (2008). Salinity of the two aquifers exhibit distinct features. The Jandaira covers a large range of CE up to 10,000 μS/cm, with waters of HCO3 -/ Ca2+ and HCO3 -/ mixed types mainly. The Açu aquifer shows CE were uniform, around 550 μS/cm, and waters of the HCO3 -/ Na+ and HCO3 -/ mixed types. A large scale influence of human action on physical-chemical parameters was not detected.