Variabilidade sazonal e espacial da qualidade de água em dois lagos amazônicos: Água Preta e Bolonha, Belém, Pará, Brasil

Abstract

Located in the Utinga State Park (PEUt), the Bolonha and Água Preta lakes are the main bodies of water that supply the Metropolitan Region of Belém (RMB) with drinking water through the Companhia de Saneamento do Pará (COSANPA), which is responsible for 75% of the supply to this population. Studying and understanding the hydrochemistry of these lakes is of fundamental importance, as environmental conditions and ecosystem services are directly related to the quality of the water in the lakes. The sources of input, such as pumping from the Guamá River, in natura effluent discharges and continental runoff from rainfall, require an enhanced sampling effort throughout the system. Therefore, the aim of this study was to analyze the water quality of the Bolonha and Água Preta lakes in order to identify sources of contamination and their effects on the ecosystem and public health. In order to understand and identify the physical-chemical processes and their interactions with anthropogenic activities, hydrodynamics and climate, monthly measurements were taken over 12 months at 20 points in Água Preta Lake and 4 points in Bolonha Lake. Samples were taken at 2 depths (surface and bottom) to obtain water temperature, pH, electrical conductivity, dissolved oxygen (DO), turbidity and total dissolved solids (TDS) using a HORIBA multi-parameter probe. Aliquots were separated for laboratory determination of the following parameters: ammonium, nitrite, nitrate, phosphate, nitrogen and total phosphorus, biochemical oxygen demand, thermotolerant coliforms, chlorophyll-a and total alkalinity. The measured data was statistically analyzed between points and seasonal stations, and the Trophic State Index (TSI) and Water Quality Index (WQI) were calculated.