P03 - Deoxygenation and de- nitrification 

Convenor: Wajih Naqvik
Co-Convenors: Bo Thamdrup 

Ongoing data indicates to a steady decline in the oxygen content of subsurface waters including the oxygen minimum zones. Furthermore, there is an increase in the number and intensity of the coastal hypoxic zones. These changes, arising from human activities - mostly global warming and fertilizer loading to the ocean, are expected to greatly affect marine biogeochemistry and ecosystems. The nitrogen cycle that dominates the biogeochemistry of the oxygen-deficient zones is expected to be severely impacted by deoxygenation, with enhanced conversion of reactive nitrogen to molecular nitrogen through denitrification and anaerobic ammonium oxidation, and to nitrous oxide through nitrification and denitrification. This, in turn, may affect biological productivity and provide feedback to climate change. The impact of deoxygenation on the nitrogen cycle and its links with cycles of other elements, especially iron and sulphur, is a topic of widespread interest and global significance.

This session will bring together observational oceanographers and modellers to evaluate the ongoing trends in deoxygenation and its impact on the nitrogen cycle focusing on the processes involved and prediction of future changes.