Marvic Ortueta Milan, Zahily Herrero Fernández, José Araújo Dos Santos Júnior, Romilton Dos Santos Amaral, Lino Angel Valcárcel Rojas, Artur Paiva Coutinho, Taiwo Saheed Yinusa, Robert Fernandes de Melo, Josineide Marques do Nascimento Santos, Mariana Brayner Cavalcanti Freire Bezerra, Leorlen Yunier Rojas Mazaira, Yelina Gonzáles Pérez, Yasmin Marques Dos Santos
This study presents a regional survey of treated and untreated water sources in the Seridó Ocidental region of Paraíba, Brazil. A single-sampling campaign was conducted to evaluate chemical, microbiological, and radiological parameters against national standards. High concentrations of sodium (up to 5000 mg L-1), chloride (up to 1579 mg L-1), calcium (up to 105 mg L-1), and magnesium (up to 124 mg L-1) were observed, exceeding recommended limits and affecting taste and hardness. Turbidity in untreated water reached up to 105 NTU, about 20 times the permissible limit. Nitrate levels reached 34 mg N-NO3- L-1 (26% non-compliance), and lead concentrations up to 0.026 mg L-1 were found, both exceeding regulatory limits. Activity concentrations of 226Ra (up to 1.28 Bq L-1) and 228Ra (up to 1.20 Bq L-1) in some untreated sources also exceeded standards, associated with local geochemical conditions such as uranium- and thorium-rich minerals and high salinity. Calculated annual effective doses for children aged 1 to 10 years exceeded the WHO reference value of 0.1 mSv in several cases, indicating a need for further assessment and management. These results highlight the need for continuous monitoring and targeted interventions to ensure safe water in vulnerable semi-arid regions.