Caracterização físico-química das águas subterrâneas captadas em poços tubulares nos municípios do Cariri Ocidental Paraibano e do Agreste Pernambucano.

Abstract

Water, an essential natural resource for human life, is a fundamental right. Beyond its vital role, it plays a central part as both an environmental resource and an indispensable input for various economic activities. In urban peripheral areas and rural zones lacking public water supply networks, groundwater often constitutes the main, or even the only, available water source. In the crystalline semi-arid region of Northeast Brazil, despite the low yields and high salinity of the wells, this water remains of great relevance. In this context, the aim of this study was to characterize the water quality of tubular wells located in the regions of Cariri Ocidental in Paraíba and Agreste in Pernambuco, based on physicochemical parameters. Four wells located in the rural zone of Brejo da Madre de Deus - PE, five wells in the Frei Damião neighborhood in Sumé - PB, and the only well that supplies the population of the Sucuru district - PB were selected. The analyses conducted included measurements of pH, total dissolved solids (TDS), electrical conductivity (EC), chlorides, sodium, potassium, and total hardness, with the purpose of evaluating the spatial-temporal variation, verifying the water's potability according to the standards established by Ministry of Health Ordinances No. 2,914/2011 and No. 888/2021, and by CONAMA Resolution No. 375/2005, and comparing the raw water quality with the desalinated water made available to the Sucuru community. The results showed that the wells in Brejo da Madre de Deus - PE had higher salinity levels compared to the other points evaluated, including those in Sumé and the Sucuru district, characterizing it as more brackish water. However, it was identified that one of the points in Sumé presented concentrations of EC, TDS, chlorides, and total hardness similar to the wells in Brejo da Madre de Deus. Regarding compliance with potability standards, it was found that only one well in Sumé showed a tendency to approach the maximum permissible value, but it was still classified as non-compliant due to the high concentrations of TDS and the significant EC value. Concerning the comparison between raw water and water treated by membrane desalination, a significant efficiency was observed, with approximately 90% of the minerals being reduced, resulting in treated water that fully complies with the normative requirements of the Ministry of Health and CONAMA.