The speciation of nitrogen in silicate phases

One of the ultimate goals in science is to illuminate the processes responsible for the development of habitable conditions on Earth, and this project will provide fundamental constraints on the storage, cycling, and release of nitrogen to Earth’s surface environment. Achieving this ambitious goal requires an understanding of the physical-chemical controls on the development of habitability on the planet’s surface, sub-surface, and marine environments. In this regard, the chemical nature of nitrogen is paramount. The addition of nitrogen to a planet’s surface is the result of both surficial and subsurface processes, including weathering and meteoritic influx, but are primarily added through though volcanism. Therefore, how nitrogen is stored within rock-forming minerals is information essential to understanding how their chemical activity varies though time, and their provenance in Earth’s formative years, as life got started.
We have conducted experiments at 2 GPa and 1450 oC using the CMAS system to examine the speciation of nitrogen in silicate melts as a function of oxygen fugacity, which is currently believed to be the main factor that drives it. The speciation of nitrogen in melts is thought to be crucial for its incorporation in minerals. According to literature, the other main factors that control nitrogen speciation in melts are temperature, pressure and melt composition, which might also have an important influence on nitrogen solubility in silicate melts. The speciation of nitrogen is being and will be studied by the use of solid-state nuclear magnetic resonance (NMR) spectroscopy. This technique has been chosen for its unparalleled precision and accuracy in determining an element’s bonding environment.
We will present the effects of oxygen fugacity and other factors on nitrogen speciation and discuss the possibility of creating a predictive model for nitrogen solubility and speciation in silicate melts. We will also address the application of these results to the study of nitrogen’s incorporation mechanism in common rock-forming minerals.