Formas de carbono nas águas superficiais dos lagos Bolonha e Água preta (Belém - PA - Brasil).

Abstract

The study evaluated the concentrations of dissolved inorganic carbon in lakes Bolonha - LB and Água Preta - LAP, relating to abiotic variables, also analyzed the quality of water in the Water Supply System in the Metropolitan Region of Belém. Water sampling in lakes Bolonha and Água Preta were carried out in the period from October 2018 to March 2019 at 4 points, at these points there were 6 consecutive campaigns, including the dry period (October and November), transition period (December and January) and rainy period (February and March). In the surface water samples, data on abiotic variables were obtained: pH, Electrical Conductivity - EC, Temperature, Dissolved Oxygen - DO, Total Alkalinity - TA, Turbidity, Biochemical Oxygen Demand - BOD and Salinity. According to the values of the superficial partial pressure of carbon dioxide - pCO2 and high concentrations of dissolved carbon dioxide - CO2aq in lakes LB and LAP, we can indicate that these systems are sources of CO2 for the atmosphere along the annual cycle. Biological processes associated with the carbonate system indicate that respiratory processes prevail over productive processes (Respiration > Production) making the system heterotrophic. The high organic load included in these systems may be associated with the accumulation of organic matter at the bottom of lakes. It was observed that the most significant concentrations of organic matter in these carbon systems are of natural and anthropogenic origin. This study allowed to characterize the parameters associated with the carbonatic system of two tropical lakes in the Amazon region. The values obtained for CO2aq, DO and pCO2 showed that these systems present high levels of pollution associated with natural processes (sedimentation/circulation in the water column) and anthropogenic ones (contributions of organic matter).