Estimated Sources of Nitrogen Oxides (Tg N per year)

Natural

  • Soils
    		•

    5-20(1)

  • Lightning
    		•

    2-20(2)

  • Transport from Stratosphere
    		•

    ~1

    Anthropogenic

  • Fossil Fuel Combustion
    		•

    24(3)

  • Biomass Burning
    		•

    2.5-13(4)

  • Tropospheric Aircraft
    		•

    0.6


    (1) Dignon et al., 1991;
    (2) Atherton et al., 1991;
    (3) Hameed and Dignon, 1992;
    (4) Dignon and Penner, 1991