Diagnosis of the water quality in the Papicu/Maceió hydrological system at Fortaleza, Ceará State, Brazil

Abstract

The present study is meant as a diagnosis of the water quality in the hydrological system comprised of Papicu Lagoon/Maceió Creek and its mouth located at Mucuripe Beach. That is supposed to be an important element for the ecological balance in this area, in addition to representing a zone for leisure and landscape harmony. Its intense urbanization has contributed for the increase of domestic effluents flow by means of stormwater, with a consequent impact on water quality and biochemical balance of those bodies. In all, seven stations were surveyed along a transect which stretched from Papicu Lagoon to the Maceió’s Creek mouth whose water physicochemical and bacteriological parameters were submitted to estimation, namely temperature, salinity, pH, conductivity, dissolved oxygen, nitrite, nitrate, ammonium, total phosphorus, biochemical oxygen demand (OBD5 ), total and thermotolerant coliforms, and Escherichia coli concentration. The results were as follows: the pH values ranged from 6.54 to 7.64; the values of dissolved oxygen varied from 0.85 mg.L-1 to 6.22 mg.L-1, with the most critical value (0.85 mg.L-1) having been registered at Papicu Lagoon. In accordance with the CONAMA Resolution 357/2005, stations 1 and 4 were shown to have oxygen values (5 mg.L-1) below the legal limit for this parameter, the reverse being true of nitrite, nitrate and OBD5 that were above their respective legal-limit values. The indices of total and thermotolerant coliformes, and Escherichia coli indicate high fecal-related pollution. As the main outcome of this research work, the contamination sources were identified and mitigating measures were proposed so as to minimize the negative impacts that were shown to be at work in the study area