CO₂ concentration and flux in hydroelectric reservoir of Balbina (AM)

ABSTRACT

The reservoir Balbina (59º 28’ 50W, 1º 53’ 25’’ S), located near the city of Manaus, Amazonas, in Central Amazônia, Brazil, is the second largest hydroelectric reservoir in an area located in the Amazon Basin. In this reservoir, CO₂ measurements were performed at high frequency (10 Hz), CO₂ flux with gas analyzer infrared (IRGA) coupled to a floating chamber and meteorological variables with a buoy instrumented to 2 m from the lake surface. The average CO₂ concentration was 392 and 426 ppm for the day and night, respectively, and the daily average emission rate was 40.427±24.040 µmol^-1.m^-2.d^-1. The accumulation of CO₂ in the lake overnight, beyond respiration, shows to be affected by low wind speeds, waterside convection, physical processes involving high concentrations of CO₂ for the surface and the presence of land breeze. The fluxes show no statistically significant difference with the meteorological variables and were considerably lower than a previous study for the same lake. However, the values are in agreement with other studies in Amazonian tropical lakes and other reservoirs.

Keywords:
meteorological variables; CO₂; breeze