The ozone layer is the part of our planet’s atmosphere that protects it from cosmic rays.It was formed only a few hundred million years ago. Scientists hypothesized that iodine could have been the reason for the delay in its formation.
Ozone layer
Scientists from Yale University conducted a study and identified possible reasons why the ozone layer did not form immediately after the Earth’s atmosphere was enriched with oxygen. Its findings are published in the journal Proceedings of the National Academy of Sciences.
The ozone layer is the region in the upper layers of the Earth’s atmosphere where there is an increased amount of a gas made up of three oxygen molecules. It retains much of the ultraviolet radiation and thus protects all life on Earth from dangerous radiation.
Ozone is a rather interesting compound. On the one hand, it is quite unstable and can decay from a variety of factors, from the presence of a long line of chemical compounds to overly energetic radiation particles. And it’s easy enough to form. All you need is oxygen and ultraviolet light.
What happened to oxygen in the past
The first living organisms that produce oxygen (cyanobacteria) appeared on our planet 2.7 billion years ago. It would seem that the atmosphere should have immediately begun to be enriched with oxygen, and thus ozone should soon be.
However, the first land plants appeared only 480 million years ago. Multicellular organisms emerged several hundred million years before that. But this is no longer very important, as no presence of single-celled living beings was also found on the surface. Only in the ocean, where the ultraviolet radiation was not life threatening.
Everything looks like there has been oxygen for almost 2 billion years and the ozone kept going somewhere. And now scientists have put forward a hypothesis as to what was happening to it.
Iodine in the ocean
In a new study, scientists have been able, as they assure, to explain what has prevented the ozone layer from forming for so long. They have scrutinized layers of rock that once formed on the ocean floor and bear traces of its chemical composition.
They were the ones that clued researchers in that iodine could be the culprit. This chemical element reacts quite easily with a wide variety of substances. In particular, it is well known that its compounds can actively deplete ozone.
Actually, iodine salts in the water of the Earth’s oceans are still abundant today. However, between 2 and 500 million years ago, these compounds were much more abundant. Iodine was released into the atmosphere from them and destroyed the ozone. And then the content of these substances decreased and the protective shell of our planet was able to form.
According to phys.org
