Process and mechanism of nitrogen loss in the ocean oxygen minimum zone.

There is a big imbalance between the input and output of oceanic nitrogen in global ocean nitrogen cycles, because a part of the fixed nitrogen is reduced to N or NO and then lost from the ocean. Oxygen minimum zone (OMZ) is the most important area for nitrogen loss, which could lose fixed nitrogen up to 40 to 450 Tg·a through the denitrification and anammox. A summary of the two main roles of nitrogen loss in the different OMZ sea areas reveals that heterotrophic denitrification dominates in eastern tropical Pacific, Arabian Sea, and marine sediments.