Nitrogen in the Earth’s outer core

Bajgain, S. K., Mookherjee, M., Dasgupta, R., Ghosh, D. & Karki, B. B.

Using first principles molecular dynamic simulations, we explore the effects of nitrogen (N) on the density and sound velocity of liquid iron and evaluate its potential as a light element in the Earth’s outer core. Our results suggest that Fe‐N melt cannot simultaneously explain the density and seismic velocity of the Earth’s outer core. Although ~2.0 wt.% N can explain the bulk sound velocity of the outer core, such N content only lowers the density of liquid Fe by ~3%. Matching both the velocity and density by the other light elements limits the N in the core to ≪2.0 wt.%. Our finding suggests that nitrogen is a minor to trace element in the Earth’s core and is consistent with the geochemical mass balance with terrestrial abundance of N and alloy‐silicate partitioning data, which suggest that there cannot be significant N in the core.

Bajgain, S. K., Mookherjee, M., Dasgupta, R., Ghosh, D. & Karki, B. B. (2019). Nitrogen in the Earth’s outer core. Geophysical Research Letters 46, 89-98. doi:10.1029/2018GL080555