Cryptic Sulfur and Oxygen Cycling Potentially Reduces N2O-DrivenGreenhouse Warming: Underlying Revision Need of the Nitrogen Cycle

Increasing global deoxygenation has widely formedoxygen-limited biotopes, altering the metabolic pathways ofnumerous microbes and causing a large greenhouse effect ofnitrous oxide (N2O). Although there are many sources of N2O,denitrification is the sole sink that removes N2O from thebiosphere, and the low-level oxygen in waters has been classicallythought to be the key factor regulating N2O emissions fromincomplete denitrification. However, through microcosm incuba-tions with sandy sediment, we demonstrate here for thefirst timethat the stress from oxygenated environments does not suppress,but rather boosts the complete denitrification process when thesulfur cycle is actively ongoing. This study highlights the potentialof reducing N2O-driven greenhouse warming andfills a gap in pre-cognitions on the nitrogen cycle, which may impact our current understanding of greenhouse gas sinks. Combining moleculartechniques and kinetic verification, we reveal that dominant inhibitions in oxygen-limited environments can interestingly undergotriple detoxification by cryptic sulfur and oxygen cycling, which may extensively occur in nature but have been long neglected byresearchers. Furthermore, reviewing the present data and observations from natural and artificial ecosystems leads to the necessaryrevision needs of the global nitrogen cycle

Automated summary

Increasing global deoxygenation has led to oxygen-limited biotopes and intensified nitrous oxide greenhouse effect. Previous understanding considered low oxygen as the key factor affecting N2O emissions from incomplete denitrification, but this study demonstrates for the first time that sulfur cycling can enhance complete denitrification even in oxygenated environments. This research highlights the potential to reduce N2O-driven greenhouse warming and fills a gap in our knowledge of the nitrogen cycle.