Atmospheric Emission of Reactive Nitrogen during Biofuel Ethanol Production

摘要

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 NH_3 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 NH_3, with other sources (wastes, soil, biogenic) predominant during the wet season. Estimated NO_2-N, NH_3-N, NO_3~--N and NH_4~+-N emission fluxes from sugar cane burning in a planted area of ca. 2.2 × 10~6 ha are 11.0, 1.1, 0.2, and 1.2 Gg N yr~(-1), respectively.