Emissions of greenhouse gases in terrestrial areas pre-existing to hydroelectric plant reservoirs in the Amazon: The case of Belo Monte hydroelectric plant

Hydroelectric generation is important in many countries. In Brazil, it accounts for over 70% of this generation. Despite a renewable energy source, there is great concern about potential emissions of greenhouse gases produced by the hydropower reservoirs. Pre-existing reservoirs creation, the greenhouse gas measurements should considered to calculating the net contribution of each project. Net greenhouse gas (GHG) emissions from hydropower reservoirs has been defined as the differences between balances of GHG emissions and removals during post- and pre-impoundment regimes of mass transport and storage in the affected area Due to the expansion of this type of energy to Brazil׳s Amazon region, this study was developed to evaluate emissions of pre-existing terrestrial areas of the future Belo Monte located in the Amazon region. Four campaigns were carried out over a period of one year, fifteen areas sampled in each campaign, scattered in areas with vegetation of forest and grassland. The carbon dioxide fluxes (CO2), methane (CH4) and nitrous oxide (N2O) of soils were measured. The median values of CH4 emissions were 9.97±3.55mg CH4 m−2d−1 and 11.34±1.62mg CH4 m−2d−1 for pasture and forest, respectively. For CO2 in the pasture was 10448.41±3036.48mg CO2 m−2d−1 and 8004.50±1314.98mg CO2 m−2d−1 for forest. The median fluxes for N2O were near zero, and 0.78±0.56mg N2O m−2d−1 for pasture and 0.67±0.29mg N2O m−2d−1 for forest. The study showed that the terrestrial areas previous reservoir creation act as potential emitter of greenhouse gases.