Von Korff, B.H., M.F. Piehler, and S.H. Ensign. 2014. Wetlands 34(6):1047–1060.
Denitrification in tidal freshwater river channels and their adjoining freshwater wetlands greatly affects nitrogen export from river networks, yet the relative importance of these two habitats to nitrogen export has not been examined. Knowledge of how these habitats contribute to denitrification of the river nitrogen load is critical for improving models of nitrogen transport. Denitrification rates were measured in sediments from the channel, bank, and floodplain at upstream and downstream sites of two forested tidal freshwater zones (TFZs) in North Carolina, the New River and Newport River, using membrane inlet mass spectrometry to measure N2 production. Denitrification rates did not usually differ statistically between the channel, bank, and floodplain, although denitrification was highest on the floodplain at the upstream site in the Newport River. When these rates were extrapolated across the entire area of the TFZ, the channel contributed more to the N2 flux than the riparian zone. These results indicate that denitrification rates are comparable between the channel and riparian zone in forested TFZs, and that the importance of the channel versus the riparian zone depends on channel and floodplain morphology.