The relative implications of ozone formation both in the stratosphere and the troposphere

Abstract

SynopsisAlthough ozone (O3) occurs in both the troposphere and the stratosphere, mechanisms of O3 formation and removal in both regions of the atmosphere are very different. Moreover, the presence of O3 in the two layers has very different implications for the biosphere, especially vegetation. This introductory paper gives an overall appreciation of the two pools of O3 and their relative influences upon plant life. In the troposphere, natural and unburnt hydrocarbons (HCs) not only participate in the formation of atmospheric O3 but are also involved in the formation of free radicals from O3 which go on to injure plant tissues. In the stratosphere, O3 absorbs significant amounts of ultraviolet radiation (285-315 nm, UV-B) from sunlight which would otherwise harm biological systems. Depletion of stratospheric O3 by chlorofluorocarbons (CFCs) has prompted urgent studies to assess the consequences of enhanced UV-B radiation on vegetation. Preliminary assessments of possible changes to UK crops are described in this paper.