Nitrogen loss through anaerobic ammonium oxidation coupled to Iron reduction from ecosystem habitats in the Taihu estuary region.

Anaerobic ammonium oxidation coupled to iron reduction, termed Feammox, is a new microbial process linked the nitrogen cycles. However, the nitrogen losses through Feammox from different ecosystem habitats remain unclear. In this study, isotope tracing technology and molecular microbial analysis were used to investigate the Feammox and its contribution to the nitrogen loss in the farmland and riparian soils, and river sediments. The potential Feammox rates were detected, which varied from 0.07 to 0.15mgNkgd among the three ecosystem habitats. Feammox rates were significantly higher in the farmlands or riparian soils than in the river sediments. Feammox, denitrification and anaerobic ammonium oxidation (anammox) were estimated to account for approximately 3.5-4.2%, 92.6-93.1% and 2.8-3.9% of the total nitrogen losses respectively, while a significant correlation was observed between the Feammox rates and the denitrification rates (r=0.72, P<0.05). In addition, a nitrogen loss at 8.3-17.8kgNhayr was linked with Feammox in the examined soils. This study demonstrated that Feammox could be a potential pathway of nitrogen loss from ecosystem habitats.