Groundwater geochemistry and quality in the municipality of Serra do Ramalho, Bahia, Brazil

ABSTRACT

This study aimed to characterize groundwater geochemistry and quality in the municipality of Serra do Ramalho, west Bahia, with emphasis on nitrate (N-NO₃ ^-) concentrations. Water was sampled from 26 tubular wells during 2010 and 2011 (rainy season) and 2012 (dry season). Physicochemical parameters were measured and groundwater was sampled in each sampling station for laboratory analyses of the main anions (titrimetry and spectrophotometry) and cations (ICP OES) and fluoride (SPANDS). The pH ranged from 6.60 to 8.70, with the following decreasing order of major elements: rCa²⁺ > rNa⁺ > rMg²⁺ > rK⁺ and rCO₃ ^2- - rHCO₃ ^- > rCl^- > rSO₄ ^2- > rNO3^- > rF^-. Calcic bicarbonated hydrochemical facies (49%), calcic chlorinated facies (21%) and calcic mixed facies (15%) were the most representative in the study area. Fluoride and nitrate concentrations were above potability limit in 25 and 12% of the wells, respectively. Groundwater pollution is a challenge to the management of water resources, sanitation, land use and public health, and should be better understood, monitored and remedied.

Keywords:
groundwater; nitrate; basic sanitation