Global air emission inventories for anthropogenic sources of NOx, NH3 and N2O in 1990

Global emission inventories with 1° × 1° resolution were compiled for nitrogen oxides (NO + NO2, together denoted as NOx), ammonia (NH3) and nitrous oxide (N2O) emissions. For NOx the estimated global anthropogenic emission for 1990 is about 31 million ton N year−1. The major anthropogenic sources identified include fossil fuel combustion (70%, of which the major sources are road transport and power plants) and biomass burning (20%). Natural sources contribute about 19 million ton N year−1, mainly lightning and soil processes. For NH3 the estimated global emission for 1990 is about 54 million ton N year−1. The major sources identified include excreta from domestic animals and wild animals, use of synethetic N fertilisers, oceans and biomass burning. About half of the global emission comes from Asia, and about 70% is related to food production. For N2O the major sources considered include fertilised arable land, animal excreta, soils under natural vegetation, oceans, and biomass burning. The global source of N2O is about 15 million ton N2O-N year−1 of which about 30% is related to food production. All three inventories are available on a sectoral basis on a 1° × 1° grid for input to global atmospheric models and on a regional/country basis for policy analysis.