Caracterização físico – química e microbiológica da bacia hidrográfica do rio puraquequara

Abstract

The Puraquequara region is known for being less urbanized compared to the central area of Manaus, however, it has been facing urban growth and development, which can impact local water resources in various ways: deforestation and soil sealing; urban pollution; inadequate sanitary sewage disposal and alterations to the aquatic ecosystem. To assess the water quality of the Puraquequara River Basin, we used the parameters suggested by the Amazonas State Water Resources Plan - PERH/AM, which are: chlorides, thermotolerant coliforms, electrical conductivity, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), phosphate, total phosphorus, nitrate, nitrite, ammoniacal nitrogen, organic nitrogen, total nitrogen, dissolved oxygen (% and mg/L), pH, total dissolved solids, total solids, air temperature, water temperature and turbidity. In addition, the Water Quality Index (IQA) was used and metals were determined using an ICP-OES for evaluation. Water samples were collected over a 10-month period at 7 points across the basin, and the results of each parameter were compared using the river levels, with a dry month (October/2022) and a full month (June/2023). The results of each parameter were compared to the maximum permitted value (VMP) established by CONAMA Resolution nº 357/2005. Thus, it was observed that the dissolved oxygen, BOD and nitrite parameters were outside the established limit, in addition to the pH parameter, but in comparison with the Resolution it does not reflect the reality of the region. The parameters total nitrogen, organic nitrogen, temperature, total solids, conductivity, phosphate and COD have no limit set by the Resolution. The other parameters comply with the legislation. Based on the IQA classifications, the results for the month of lowest river level in relation to the collections (October/2022), points 1 and 2 were ACCEPTABLE, point 3 GOOD, points 4, 5 and 6 ACCEPTABLE, and point 7 GOOD. In turn, for the month with the highest river level in relation to the collections (June/2023), point 1 was classified as ACCEPTABLE, and points 2, 3, 4, 5, 6 and 7 as GOOD. It was found that each parameter behaves differently during changes in the river level. Of the 60 metals analyzed, only 10 were consistently detected: aluminum, boron, beryllium, calcium, iron, potassium, magnesium, sodium, silicon and titanium. The data found provided information that anthropogenic actions are increasing.