Quality of water from the Barreiras Aquifer in some domains of Belém/Pará

Abstract

The behavior of the nitrate and ammonium, besides other commonly used chemistry parameters as indicators of the contamination by domestic effluent, were monitored during 2.5 years in the waters of the Barreiras Aquifer. The obtained results for pH, electric conductivity, sodium, calcium and chloride have indicated that the wells, when individually analyzed, show a relatively homogeneous behavior. However, when compared to each other, it was possible to distinguish wells with values always more elevated against those with less high values. Wells analyzed for nitrate and ammonium, allowed a classification into four behavior patterns. The established patterns express a larger or smaller distance with respect to the contamination active sources, which are decisive factors for the well’s hydrogeochemistry characterization in an urban area. Near to the septic tank (pattern 3), the reducer ambient is maintained thanks to the degradation of the organic matter. In intermediary position, the observed presence of ammonium and nitrate in high concentrations is attributed to the contact of the contaminant with waters richer in oxygen (pattern 2). When nitrate predominates (pattern 1 and 4) with respect to ammonium, it is believed that the wells are more distant of the contamination source.