Análise da demanda bentônica de oxigênio dissolvido em rio urbano: estudo de caso do rio uberabinha, bacia hidrográfica do rio araguari, triângulo mineiro

Abstract

This work aimed to analyze the benthic Oxygen demand of the bottom sediments of urban rivers in a tropical climate. For that, a case study was developed in the Uberabinha River, an important watercourse that cuts through the city of Uberlândia/MG, Brazil. The analysis methodology of this research was based on the literature recommendations for the application of the respirometric technique for measuring and modeling the DBOS. In this sense, five anaerobic reactors were built and fed with bottom sediment and water samples from the Uberabinha River, all collected at a fixed georeferenced point of the watercourse and at different times, with the aim of characterizing the BOD in the period flood and drought. The sediment was characterized according to its granulometry according to ABNT NBR 7181/2018. The concentrations of Dissolved Oxygen (DO) in the reactors were measured, at regular intervals of time, using a measuring probe in accordance with the norms of ABNT NBR 11958/2015. These data were organized in the form of an electronic spreadsheet through which it was possible to determine the DO decay rates in the water and in the bottom sediment. The obtained results demonstrated that the sediments are predominantly sandy. In addition, it was noticed that the highest decay rates tend to occur in the cycle of the first 10 hours of analysis, a time interval with the highest intensity of oxidation reactions of organic matter. Finally, it was noticed that the DBOS tends to be higher in the flood periods when compared to the dry periods.