Separation of river network–scale nitrogen removal among the main channel and two transient storage compartments
Article first published online: 30 AUG 2011
Copyright 2011 by the American Geophysical Union.
Water Resources Research
Volume 47, Issue 10, October 2011
How to Cite
2011), Separation of river network–scale nitrogen removal among the main channel and two transient storage compartments, Water Resour. Res., 47, W00J10, doi:10.1029/2010WR009896., , , , , , and (
- Issue published online: 30 AUG 2011
- Article first published online: 30 AUG 2011
- Manuscript Accepted: 15 JUN 2011
- Manuscript Revised: 9 JUN 2011
- Manuscript Received: 17 AUG 2010
- river network;
- transient storage
 Transient storage (TS) zones are important areas of dissolved inorganic nitrogen (DIN) processing in rivers. We assessed sensitivities regarding the relative impact that the main channel (MC), surface TS (STS), and hyporheic TS (HTS) have on network denitrification using a model applied to the Ipswich River in Massachusetts, United States. STS and HTS connectivity and size were parameterized using the results of in situ solute tracer studies in first- through fifth-order reaches. DIN removal was simulated in all compartments for every river grid cell using reactivity derived from Lotic Intersite Nitrogen Experiment (LINX2) studies, hydraulic characteristics, and simulated discharge. Model results suggest that although MC-to-STS connectivity is greater than MC-to-HTS connectivity at the reach scale, at basin scales, there is a high probability of water entering the HTS at some point along its flow path through the river network. Assuming our best empirical estimates of hydraulic parameters and reactivity, the MC, HTS, and STS removed approximately 38%, 21%, and 14% of total DIN inputs during a typical base flow period, respectively. There is considerable uncertainty in many of the parameters, particularly the estimates of reaction rates in the different compartments. Using sensitivity analyses, we found that the size of TS is more important for DIN removal processes than its connectivity with the MC when reactivity is low to moderate, whereas TS connectivity is more important when reaction rates are rapid. Our work suggests a network perspective is needed to understand how connectivity, residence times, and reactivity interact to influence DIN processing in hierarchical river systems.