Atmospheric Emission of Reactive Nitrogen during Biofuel Ethanol Production

This paper evaluates emissions to the atmosphere of biologically available nitrogen compounds in a region characterized by intensive sugar cane biofuel ethanol production. Large emissions of NH3 and NO x , as well as particulate nitrate and ammonium, occur at the harvest when the crop is burned, with the amount of nitrogen released equivalent to ∼35% of annual fertilizer-N application. Nitrogen oxides concentrations show a positive association with fire frequency, indicating that biomass burning is a major emission source, with mean concentrations of NO x doubling in the dry season relative to the wet season. During the dry season biomass burning is a source of NH3, with other sources (wastes, soil, biogenic) predominant during the wet season. Estimated NO2-N, NH3-N, NO3 −-N and NH4 +-N emission fluxes from sugar cane burning in a planted area of ca. 2.2 × 106 ha are 11.0, 1.1, 0.2, and 1.2 Gg N yr−1, respectively.