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Abstract
Biogeochemical reactions associated with stream nitrogen cycling, such as nitrification and denitrification, can be strongly controlled by water and solute residence times in the hyporheic zone (HZ). We used a whole-stream steady state
15N-Iabeled nitrate and conservative tracer addition to investigate the spatial and temporal physiochemical conditions controlling the denitrification dynamics in the HZ of an upland agricultural stream. The findings demonstrate that the HZ is an active nitrogen sink in this system and that the distinction between net nitrification and denitrification in the HZ is a function of residence time and exhibits threshold behavior. Consequently, incorporation of HZ exchange and water residence time characterizations will improve mechanistic predictions of nitrogen cycling in streams.
Citation
Zarnetske, Jay P.; Haggerty, Roy; Wondzell, Steven M.; Baker, Michelle A. 2011. Dynamics of nitrate production and removal as a function of residence time in the hyporheic zone. Journal of Geophysical Research. 116: G01025. 1-12.