Correlação entre Escherichia coli e variáveis limnológicas em amostras de água da Lagoa da Parangaba

Abstract

The present work aimed at evaluating the possible relationship between the Escherichia coli counts and the concentrations of free CO 2 , dissolved oxygen, reactive phosphorus, total ammonia, nitrite and pH in water samples of the Lagoa da Parangaba (Fortaleza, Ceará). Eight campaigns were carried out every fifteen days to collect sub-superficial water samples in three sampling spots. Regression analyses were performed upon the variable with the greatest linear Pearson coefficients looking for the curve that best fitted to the observed data. The correlation between the water free CO 2 and E. coli was best represented by the equation y = 17.74 -1.16*10 -3 x + 6.76*10 -8 x² (R² = 0.75; P = 0.06), where x is the E. coli count (MPN 100 mL -1 ) and y is the water carbon dioxide concentration (mg L -1 ). It was concluded that the rich organic matter inflows of the Lagoa da Parangaba, mainly of fecal origin, have increased not only the sanitary risk to the population that use this water source, but also affected the life of the animal populations that live in it. It was also observed that the Lagoa da Parangaba's waters are highly contaminated by E. coli. Besides, they are acidic and suffer eventual episodes of hypoxia.