Nitrous oxide emissions from tropical hydroelectric reservoirs

Abstract

We report original data on nitrous oxide (N2O) fluxes from two tropical reservoirs, their rivers below the dam, and from natural aquatic ecosystems and rainforest soils in French Guiana and Panama. We also review published N2O fluxes from other tropical reservoirs and natural environments. We show that: (1) N2O emissions from tropical reservoirs occur mainly at the reservoir surface, fluxes downstream of dams being minor; (2) Because preflooding natural N2O fluxes are significant, the net N2O emissions from reservoirs are less than ∼50-70% of gross N2O emissions; (3) the contribution of N 2O to the global warming potential of emissions from reservoirs could be significant for gross emissions, but less than 10% for net emissions, disregarding N2O degassing emissions. Copyright 2008 by the American Geophysical Union.