ABSTRACT
Nitrogen fixation by natural abiogenic processes is dominated by the conversion of molecular nitrogen to nitric oxide (NO) by lightning. Because of the possibility that lightning might be an important source of atmospheric NO, the magnitude of the lightning fixation rate became a critical issue in atmospheric chemistry. Implicit in the flash-extrapolation approach is the assumption that the global rate of NO production by all lightning flashes can be characterized by the production of NO from a so-called average or representative flash multiplied by the number of flashes occurring globally. Because the natural abundance of fixed nitrogen — many orders of magnitude less than molecular nitrogen — is often at a level sufficientiy low to be the limiting factor in plant growth, its rate of production often plays a key role in controlling the rate of growth of ecological systems.
