Qualidade da água superficial da Região da Baía do Guajará, Belém-Pa

Abstract

The handling operations of polluting products such as domestic and industrial waste, ores or petroleum derivatives, during the phases of exploration, transport or commercialization are always surrounded by environmental, social and economic risks. The present work concerns the determination of physical (color, turbidity, transparency, temperature); physical-chemical (pH, conductivity); chemical (sulfate, chloride, dissolved oxygen, alkalinity, oils and grease, Cd, Co, Cr, Cu, Ni, Pb, Zn, Na and K) and biological (fecal and total coliforms) parameters of the water, contributing to evaluate qualitatively and quantitatively the system studied. The samples were collected in February 2003 during the rainy season, under ebb tide conditions. Ten sampling points were established, distributed between Guajará Bay, Guamá River and Mosqueiro Island. The methods used were based on CETESB (1978) and Standard Methods (1998) standards. The color, turbidity and pH were above the standard. The electrical conductivity was in the range of 31.2 and 80.9 mS/cm. Chloride and sulfate were within the acceptable range for human consumption. The dissolved oxygen content indicated satisfactory aeration indices. Alkalinity presented its highest concentration, corresponding to its lowest pH. For the trace elements, only Pb and Cu were above the standards. The analysis of fecal coliforms showed values above the potability standard, which can cause health risks to the riverside dwellers. In points 04 (Canal do Una), 05 (Tapanã) and 10 (Mosqueiro) levels of oils and grease were found, indicating the presence of probable disturbances caused by vessels, oil spills and others. The parameters (pH, color, turbidity, oils and grease and fecal coliforms) were above the normal allowed concentrations, according to the CONAMA Resolution 020/86.