Carbon dioxide emissions from Tucurui reservoir (Amazon biome): New findings based on three-dimensional ecological model simulations

We used a three-dimensional model to assess the dynamics of diffusive carbon dioxide flux (FCO2) from a hydroelectric reservoir located at Amazon rainforest. Our results showed that for the studied periods (2013 summer/wet and winter/dry seasons) the surface averaged FCO2 presented similar behaviors, with regular emissions peaks. The mean daily surface averaged FCO2 showed no significant difference between the seasons (p>0.01), with values around −1338mgCm−2day−1 (summer/wet) and −1395mgCm−2day−1 (winter/dry). At diel scale, the FCO2 was large during the night and morning and low during the afternoon in both seasons. Regarding its spatial distribution, the FCO2 showed to be more heterogeneous during the summer/wet than during the winter/dry season. The highest FCO2 were observed at transition zone (−300mgCm−2h−1) during summer and at littoral zone (−55mgCm−2h−1) during the winter. The total CO2 emitted by the reservoir along 2013year was estimated to be 1.1TgCyear−1. By extrapolating our results we found that the total carbon emitted by all Amazonian reservoirs can be around 7TgCyear−1, which is 22% lower than the previous published estimate. This significant difference should not be neglected in the carbon inventories since the carbon emission is a key factor when comparing the environmental impacts of different sources of electricity generation and can influences decision makers in the selection of the more appropriate source of electricity and, in case of hydroelectricity, the geographical position of the reservoirs.