Natural and anthropogenic sources and fate of atmospheric ethylene

Abstract

This study attempted to estimate the amount of ethylene emitted into the atmosphere from natural and anthropogenic sources and to determine the fate of atmospheric ethylene. The total emission from the global surface was estimated to be 18–45 × 10 6 t y −1, of which 74% was released from natural sources and 26% from the anthropogenic sources. Releases from the terrestial and aquatic ecosystems comprised 89 and 11% of the natural emissions, respectively. Biomass burning in terrestial ecosystems to clear land for agriculture was the largest anthropogenic source (77%); the combustion of various fossil fuels amounts to only a small fraction (21%) of anthropogenic emissions. The relative amounts of ethylene destroyed by reactions with OH radical and O 3 in the troposphere were estimated to be 89 and 8%, respectively. The remaining 3% of the atmospheric ethylene was transported into the stratosphere. The atmospheric lifetime of ethylene was estimated to be between 2 and 4 days. We discuss the possibility that degradation by bacteria in the soil is a sink of atmospheric ethylene. The physiological effects of elevated ethylene concentrations on plants because of large-scale destruction of the terrestial ecosystem by forest fires is also discussed.