The role of fixed nitrogen in atmospheric photochemistry

Abstract

Among the N compounds released to the atmosphere, NH 3 and the oxides N 2 O, NO and NO 2 are most important. Various microbial and human activities constitute the main sources of these compounds. NH 3 strongly influences precipitation chemistry, but its role in atmospheric photochemistry is probably not very im portant. The oxides of N, however, must be regarded as key compounds. N 2 O seems to be inert in the troposphere, but its oxidation is the main source of NO in the stratosphere. The more reactive NO and NO 2 act as catalysts in various photochemical reaction chains which affect the residence times of many carbon, sulphur and halogen compounds in the atmosphere through the role that they play in the ozone balance of the atmosphere. The atmospheric abundance of N 2 O , NO, NO 2 and a variety of halogen compounds is increasingly influenced by man. As one of the consequences one may expect changes in the abundance of atmospheric ozone, perhaps leading to increased intensity of ultraviolet radiation at ground level or climatic changes.