A caracterização da qualidade da água da sanga ubiritama no córrego gavião: uma análise a partir dos parâmetros físico-químicos e microbiológicos com ênfase no monitoramento do fósforo e da DBO

Abstract

Land use and land cover determine the water quality of the tributaries within a drainage basin. The growth of productive activities produces deleterious effects on the quality of water resources. The objective of this research was to characterize the water quality of the Ubiritama Stream, located in the Gavião Creek, a tributary designated as a critical area in terms of water resource use by the Instituto Água e Terra (IAT). To this end, water quality was analyzed based on physicochemical and microbiological parameters, with emphasis on monitoring phosphorus (P) input and Biochemical Oxygen Demand (BOD). Sampling was carried out at three points (NP3, IP2, and FP1), located in reaches under the influence of different productive activities, such as agriculture, livestock farming, and fish farming. The results showed that the variables nitrate, Total Nitrogen (TN), Total Coliforms (TC), Total Phosphorus (TP), and Biochemical Oxygen Demand (BOD) were above the maximum permitted values (MPV) established by CONAMA Resolution No. 357/2005. In the monitoring of phosphorus input, the presence of this nutrient was observed at all sampling points, with higher concentrations in areas directly influenced by adjacent productive activities, especially agriculture and fish farming. However, high concentrations were also recorded in samples corresponding to the headwaters, whose contributing area is associated exclusively with agricultural activity. The study identified fish farming as the activity that most degrades the aquatic environment, followed by agriculture. Finally, phosphorus control measures should be implemented, such as the use of sedimentation tanks in fish farms and agricultural areas, the construction of small earth bunds and/or contour lines, proper soil management, control of fertilizer amounts applied to the soil, and the preservation of riparian vegetation.