Global N2O emissions from our planet: Which fluxes are affected by man, and can we reduce these?
Søren Christensen, Kathrin Rousk
Abstract
In some places, N 2 O emissions have doubled during the last 2-3 decades. Therefore, it is crucial to identify N 2 O emission hotspots from terrestrial and aquatic systems. Large variation in N 2 O emissions occur in managed as well as in natural areas. Natural unmanaged tropical and subtropical wet forests are important N 2 O sources globally. Emission hotspots, often coupled to human activities, vary across climate zones, whereas N 2 O emissions are most often a few kg N ha −1 year −1 from arable soils, drained organic soils in the boreal and temperate zones often release 20–30 kg N ha −1 year −1 . Similar high N 2 O emissions occur from some tropical crops like tea, palm oil and bamboo. This strong link between increased N 2 O emissions and human activities highlight the potential to mitigate large emissions. In contrast, water where oxic and anoxic conditions meet are N 2 O emission hotspots as well, but not possible to reduce.