Ammonium availability in the Late Archaean nitrogen cycle
"The bioavailability of essential nutrients such as nitrogen and phosphorus has fluctuated with the chemical evolution of Earth surface environments over geological timescales. However, significant uncertainty remains over the evolution of Earth’s early nitrogen cycle, particularly how and when it responded to the evolution of oxygenic photosynthesis. [...]"
Source: Nature Geoscience
Authors: J. Yang et al.