Greenhouse gases emissions from the Three Gorges Reservoir (TGR), China
Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) are important greenhouse gases (GHGs) emitted from ecosystems. Recently, the amount and rates of GHG emissions from the Three Gorges Reservoir (TGR) have triggered broad concern in academic circles and among the public. In this study, the CH4, CO2 and N2O emissions from TGR water surfaces and drawdown areas along the mainstream of the Yangtze River were monitored from November 2009 to June 2011 with floating and static chambers and gas chromatography. The spatial and temporal pattern of the emissions was examined, and the influence of the environmental factors was further analyzed.
Based on the observation data from our study and other researches on branches of the TGR, the total global warming potential(GWP) of the GHGs emission from the TGR was estimated to be 0.63 - 1.308 TgC-eqv·yr-1, which was only 2.6% - 5.4% of that of the GHG emission from thermo power plants when the same amount of electric power (84.7 billion kWh) was generated. Therefore, the TGR hydropower plant provides a mitigation benefit of 22.73 - 23.41 TgC-eqv·yr-1. The GWP of N2O emission was as much as 45% - 70% of that of CH4 emission from the water surface, while in the drawdown area the GWP of N2O emission was even higher than CH4, indicating that N2O might also be an important GHG emitted from reservoirs.