Hydrochemical implications of electrical conductivity and chloride ion on the quality of groundwater from region semi-arid of Ceará

Abstract

Ion concentration in groundwater of semiarid regions such as the Brazilian Northeast can reach very high values, restricting and/or thwarting its domestic use or in irrigation. The rural population of Crateús, a municipality located in the semiarid region of Ceará, besides problems related to shortage of water supply, also suffers with the poor quality from these resources, when they are available. The purpose of this study, conducted during twelve months, was to analyze the behavior of the Electrical Conductivity (EC) and the concentration of chloride ion (Cl-) in waters of ten wells located in the municipality of Crateús (two in urban area and eight in rural area), evaluating their influence on water quality. The conductivity values were measured in the field with aid of a conductivimeter and contents of chloride ion were obtained in laboratory using the Mohr method. The results showed that the water of the wells from rural communities of Assis, Cabaças, Curral Velho, Ibiapaba and Santa Clara, and San Jose neighborhood, can be classified with adequate quality to human consumption and can be used to irrigate several cultures. The waters of the wells located in the rural communities of the Cajás do Jorge, Lagoa das Pedras and Poti, and in the Planalto neighborhood, and can not be exploited for human consumption; also its use in agriculture has severe restrictions.