The text written up, after the CNRS press release, in english: http://www.cnrs.fr/en/new-tool-predict-volcanic-eruptions Earth’s atmosphere is made up of 78% nitrogen and 21% oxygen, a mixture that is unique in the Solar System 1 . The oxygen was produced by some of the first living organisms. But where did the nitrogen come from? Did it escape from Earth’s mantle through volcanic activity? To try to answer these questions, Jabrane Labidi, a CNRS researcher at the Institut de Physique du Globe de Paris (CNRS/IPGP/IGN) 2 and his colleagues collected samples of gas from several volcanic sites on our planet. Their study, published on 16 March 2020 in the journal Nature, shows that nitrogen from magma formed within the mantle does not have the same isotopic 3 composition as atmospheric nitrogen, implying that the latter does not come from degassing of the mantle. However, the team were able to use these measurements to identify, in geysers, fumaroles and other phenomena involving v