Scientists at Cambridge and Oxford Universities have discovered that volcanic eruptions deliver ozone-damaging gases and
create holes in the ozone layer.
Even relatively small volcanic eruptions can produce enough harmful gases to create ozone "mini-holes" in the stratosphere. Till now, researchers were more concerned about the climatic effects of the tiny particles of volcanic sulphuric acid created from the sulfur dioxide gas emitted during volcanic blasts.
Analyzing data from a 2000 minor eruption of the Hekla volcano (photo), Iceland, the team uncovered that volcanic gases lead to the formation of nitric acid particles. Nitric acid activates volcanic chlorine gases, and these gases are powerful ozone consumers. Dr. Genevieve Millard at the Department of Earth Sciences, University of Cambridge said: 'We have shown for the first time that volcanic eruptions which penetrate the stratosphere can lead to the formation of the type of clouds that promote reactions with volcanic chlorine gases - gases that destroy stratospheric ozone and lead to the formation of "mini-ozone holes"'.
The ozone mini-holes, due to the small volcanic eruption at Hekla, persisted for about two weeks, but - after that - the ozone layer recovered to normal levels. This observation is the first time when people have seen the complete disappearance of a local ozone cover, following a volcanic eruption. "Now we want to find out what might happen to the ozone layer after a much larger eruption', said Dr David Pyle, University of Oxford, project coordinator, 'for example is there significant loss of ozone, and increased ultra-violet radiation, at low latitudes following large explosive eruptions? We want to understand this, so that we can have a better picture both of what might have happened in the past, and of what may happen in the future."
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