Water quality of Guamá river in the surroundings of an insular environmental protection area in Belém - Pará, Brazil

The current research has as objective analyze the water quality of Guamá river in the surroundings of Combu island, insular area of Belém - Pará, through the following parameters: thermotolerant coliforms, E. coli and chlorophyll a. Six samples were collected in low tide, in rainy periods and in strategic points of the river, near tourism areas. After the collection were submitted to quantitative test technique with enzymatic substrate to the result of more probable number (MPN) to thermotolerant coliforms and E. coli. To chlorophyll a, the samples were submitted to the method of extraction and reading in the visible spectrophotometer. The results showed values above of the legal limits of 1,000 MPN/100 ml determined by CONAMA 357/2005 for thermotolerant coliforms and E. coli, with mean of 7,001 MPN/100 for the first and 2,330 MPN/100 ml for the second. About the chlorophyll a, although the values do not pass the legal limit of CONAMA 357/2005 of 30 µg/L in all collection points, with mean of 4,73 µg/L, the index of trophic state - ITS result in indication of river eutrophication. It can be highlighted the deficiency in basic sanitation services in Combu island, which interferes both in the quality of Guamá river, with high concentration of coliforms indicatives of fecal contamination, and in the health of local population, which demands the use of water for survival , but that has the potential risk of waterborne diseases in the most vulnerable communities.