Influence of land use and sanitation issues on water quality of an urban aquifer

Abstract

In this study, we sought to determine whether there was a relationship between sanitary aspects and land use on nitrate contamination in an urban aquifer of Fortaleza city in the state of Ceará, Brazil. For this, we analyzed land use (constructed area, exposed soil, green area and lagoons) using orbital images with a special resolution of 5 m, as well as sanitary aspects (access to sewage service and use of septic tanks and rudimentary cesspits for domiciles). To study groundwater quality, we collected 30 samples to assess the physicalchemical parameters, including nitrate, nitrite and ammoniacal nitrogen. Sectors with little constructed area produce low concentrations of nitrogenic compounds. Most occupied areas had a significant influence on nitrite concentration, likely due to infiltration from runoff and the low natural recharge from atmospheric precipitation. Areas where >75% of the domiciles were linked to sewage service suffered little nitrate contamination in rainy periods, while areas where <50% of the domiciles were linked to sewage service contribute to a high level of nitrate contamination in wet periods. The study showed that land occupation and sanitation characteristics are important variables in relation to contamination in urban aquifers. Public urban land use polices that promotes the highly effective collection of sewage services and sanitation are critical for preventing urban aquifer contamination.