The nitrogen cycle: perturbations due to man and their impact on atmospheric N2O and O3

Abstract Features of the global cycle of fixed nitrogen are reviewed with an emphasis on perturbations due to man. It is argued that agricultural practices and combustion may lead to an increase in the concentration of atmospheric N2O with consequent effects on 03. The level of 03 may drop by about 20 % over the next 100 years if world population and the demand for food should continue to grow at anything like rates which prevailed in the recent past. Uncertainties in the model are highlighted and note is taken of areas where there is need for additional data.