Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Hidroquímica de águas superficiais e subterrâneas em Carnaúba do Dantas/RN e aspectos associados ao uso humano e na irrigação

Hydrochemistry of surface and groundwater in Carnaúba do Dantas/RN and aspects associated with human use and irrigation

Auteur : Carvalho, Alan Kellnon Nóbrega de

Université de soutenance : Universidade Federal do Rio Grande do Norte (UFRN)

Grade : Mestrado em Desenvolvimento e Meio Ambiente 2021

Résumé partiel
Surface and groundwater resources are an important source of water in the Brazilian semiarid region, where irregular rainfall and water-rock interaction produce saline water, which is generally seen in Carnaúba dos Dantas/RN. The water-rock interaction and climatological conditions impose hydrochemical characteristics on surface and groundwater, which can eventually cause problems for agricultural production, such as soil degradation by processes such as salinization and sodification. Anthropogenic contributions can also lead to the possibility of exposing the population that consumes these waters to health risks. To close hydrochemical data gaps in the municipality, 4 samples of surface water and 7 groundwater were collected at the beginning of the rainy season in February 2020. The pH, electrical conductivity, temperature and total dissolved solids were measured in situ. The results of the chemical analyzes were interpreted from the construction of hydrochemical diagrams, Spearman correlation matrix and mathematical equations. To perform the hydrochemical evaluation, analytical tools such as the Revelle Index, Piper and Stiff diagrams, Gibbs and mixing diagrams were applied, in addition to the calculation of the chlor-alkaline index. In order to investigate possible limitations to the use of water analyzed in irrigation, indices suitable for this purpose were used, such as magnesium ratio, sodium percentage, Kelley ratio, permeability index, potential salinity and sodium adsorption ratio. The risk assessment included the calculation of risk ratios for exposure to nitrogenous compounds and heavy metals present in the samples. The surface samples showed the lowest amounts of total dissolved solids, while the underground samples showed the highest ionic concentrations, including concentrations of nitrogen compounds and heavy metals

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