Emissions of nitrous oxide (N sub(2)O) from wetland ecosystems are globally significant and have recently received increased attention. However, relatively few direct studies of these emissions in response to water depth-related changes in sediment ecosystems have been conducted, despite the likely role they play as hotspots of N sub(2)O production. We investigated depth-related differential responses of the dissolved inorganic nitrogen distribution in Phragmites australis (Cav.) Trin. ex Steud. rhizosphere versus non-rhizosphere sediments to determine if they accelerated N sub(2)O emissions and the release of inorganic nitrogen. Changes in static water depth and P. australis growth both had the potential to disrupt the distribution of porewater dissolved NH sub(4) super(+), NO sub(3) super(-), and NO sub(2) super(-) in profiles, and NO sub(3) super(-) had strong surface aggregation tendency and decreased significantly with depth. Conversely, the highest NO sub(2) super(-) contents were observed in deep water and the lowest in shallow water in the P. australis rhizosphere. When compared with NO sub(3) super(-), NH sub(4) super(+), and NO sub(2) super(-), fluxes from the rhizosphere were more sensitive to the effects of water depth, and both fluxes increased significantly at a depth of more than 1 m. Similarly, N sub(2)O emissions were obviously accelerated with increasing depth, although those from the rhizosphere were more readily controlled by P. australis. Pearson's correlation analysis showed that water depth was significantly related to N sub(2)O emission and NO sub(2) super(-) fluxes, and N sub(2)O emissions were also strongly dependent on NO sub(2) super(-) fluxes (r=0.491, p<0.05). The results presented herein provide new insights into inorganic nitrogen biogeochemical cycles in freshwater sediment ecosystems.