Credit: Dennis Harries

Earth's nitrogen may have originated in the icy reaches of the primordial Solar System.

A team led by Dennis Harries of the University of Jena in Germany discovered and analysed a chromium nitride mineral inside two meteorites (pictured). The researchers say that the mineral could have formed from ammonia in ices that swirled around the newborn Sun. Shock waves from distant collisions between fragments in this protoplanetary disk heated up the ammonia, releasing it to react with metals such as chromium. The team also found that the isotopic signature of the nitrogen in the mineral is similar to that of Earth's atmospheric nitrogen.

Much of the early Solar System's nitrogen could have been released in this way, with some ending up in Earth's early atmosphere, the authors suggest.

Nature Geosci. http://dx.doi.org/10.1038/ngeo2339 (2015)