Rivers and lakes play an essential role in the global carbon cycle, not just in the transport of organic and inorganic particles to the oceans. Recently, it has been discovered that they also contribute greatly to the emission of CO2 into the atmosphere, assuming a prominent role as a greenhouse gas. This work aims to study the seasonality of the CO2 concentration in the Atmospheric Limit Layer (CLA) over the artificial lake of Curuá-Una, during the period from June 2015 to June 2016. The study was carried out at the hydroelectric power plant of Curuá-una, located 70 km southwest of the city of Santarém, in the state of Pará. The data were obtained using a micrometeorological buoy contained by a system of covariance of turbulent vortices, where the concentration of CO2, temperature, wind speed were obtained, as well as variables that describe the turbulent flow of the atmosphere. The results show that the average monthly concentration of maximum CO2 was 405 ppm in June 2015, while the lowest average concentration was observed in December of the same year. An interesting result found in this study was the relationship between the CO2 concentration and the intensity of vertical atmospheric turbulence (σw).