Indicadores ambientais do complexo hídrico Papicu/Maceió, Fortaleza - Ceará

Abstract

The present master’s thesis identifies and analyzes the e nvironmental conditions of the Papicu/Maceió draining water system as anatte mpt to evaluate their present situation and to put forward alternative measure to lower the environmental negative impacts dedected in that region. This case study actually started with a cartographic survey and field observations which later carried on with the determination of water and sediment quality by estimating physical and chemical parameters by means of samples collected during the dry and rainy seasons. Sediments analyzedas to its grain size, through the sifting technique, went into a textural classification as median to fine sand. Physical-chemical parameters of the water in relation to turbidity, color and smell varied according to the dry and rainy seasons. Turbidity values ranged from 3,5 uT to 39,0 uT during the rainy season and 2,0 uT to 6,5 uT during the dry season, the color presented indices upwards of 25,0 uH and the smell showed sulphyde and vegetable characteristics. The values of biochemical demand for oxygen varied in the ranges of 14,0 – 53,0 mg.L -1 and 4,8 – 37,2 mg.L -1, respectively during the rainy and dry seasons, therefore well above the 5,0 mg.L-1 -limit setup by CONAMA’s Act no 20/86. This is an indication that the studied water system has been receiving domestically-produced effluents. The dissolved oxygen content ranged from 2,6 mg.L -1 to 4,0 mg.L-1, but the Papicu lakelet was shown to be totally devoid of that element. Since that, according to the above-mentioned Act the oxygen content in any samples must be higher than 2,0 mg.L-1, only on the water body Papicu lakelet this parameter was found to be below that standard limit. Other water physical and chemical parameters, such as pH, alcalinity and hardness showed values which are compatible with the environmental features of the study area. Nitrite, nitrate and ammonia contents are not, in general within the standard limits of CONAMA’s Act no 20/86. Amendatory and mitigating guidelines are proposed aiming at ruling out evident negative impacts and at preserving environment’s quality of Papicu/Maceió draining water system.