Origin of Earth’s nitrogen-rich atmosphere lies in plate tectonics, says study

Ars Technica : One reason life developed on Earth may be the planet’s abundance of nitrogen, an essential ingredient for the formation of amino and nucleic acids. About four-fifths of Earth’s atmosphere is composed of nitrogen. Until recently, however, exactly where the nitrogen came from was unknown. Now Sami Mikhail and Dimitri Sverjensky of the Carnegie Institution of Washington propose that Earth’s plate tectonics are responsible. Nitrogen is easily incorporated into silicate minerals, not only on Earth but also on other planets, such as Earth’s nearest neighbors, Venus and Mars. Unlike those neighbors, however, Earth is geologically active, and the combination of plate subduction and volcanic eruptions results in the release of copious amounts of volatile chemicals, including nitrogen, into the atmosphere. According to the researchers’ findings, nitrogen started accumulating in Earth’s atmosphere some 3 billion years ago, which agrees with other estimates for how long Earth’s plate tectonic system has been active.