Discovering the History of Atmospheric Oxygen

Abstract

In the summer of 1771 Joseph Priestley put a sprig of mint into a quantity of air and found that the ' goodness ' of the air had been improved. He had discovered photosynthesis. Antoine Lavoisier identifi ed the gas that Priestley had made, and named it oxygen. The heroic decade of the 1770s closed with the demonstration by Jean Senebier and Jean Ingenhousz ' that light is required for the generation of oxygen by plant photosynthesis. In the 1840s Jean - Jacques Ebelmen documented much of the geochemical cycle of oxygen. However, writings about the geologic history of oxygen remained highly speculative until 1927, when AM Macgregor linked the history of atmospheric oxygen to the geologic rock record. He concluded that atmospheric oxygen was either absent or present at very low levels during the Archaean. This proposition has been confi rmed by a large number and variety of observations. It is now generally, though not universally, accepted that signifi cant quantities of oxygen fi rst appeared in the atmosphere ca. 2.4 Ga, and that oxygen levels have risen somewhat irregularly since then. The progressive oxygenation of the atmosphere is due to the evolution of green - plant photosynthesis, and probably also to gradual changes in the composition of volcanic and hydrothermal inputs to the atmosphere. ©2011 Blackwell Publishing Ltd. © 2011 Blackwell Publishing Ltd. All rights reserved.