, Volume 87, Issue 3, pp 311–323 | Cite as

Nitrogen attenuation in the Connecticut River, northeastern USA; a comparison of mass balance and N2 production modeling approaches

  • Thor E. Smith
  • Andrew E. Laursen
  • Jeffrey R. Deacon
Synthesis and Emerging Ideas


Two methods were used to measure in-stream nitrogen loss in the Connecticut River during studies conducted in April and August 2005. A mass balance on nitrogen inputs and output for two study reaches (55 and 66 km), at spring high flow and at summer low flow, was computed on the basis of total nitrogen concentrations and measured river discharges in the Connecticut River and its tributaries. In a 10.3 km subreach of the northern 66 km reach, concentrations of dissolved N2 were also measured during summer low flow and compared to modeled N2 concentrations (based on temperature and atmospheric gas exchange rates) to determine the measured “excess” N2 that indicates denitrification. Mass balance results showed no in-stream nitrogen loss in either reach during April 2005, and no nitrogen loss in the southern 55 km study reach during August 2005. In the northern 66 km reach during August 2005, however, nitrogen output was 18% less than the total nitrogen inputs to the reach. N2 sampling results gave an estimated rate of N2 production that would remove 3.3% of the nitrogen load in the river over the 10.3 km northern sub-reach. The nitrogen losses measured in the northern reach in August 2005 may represent an approximate upper limit for nitrogen attenuation in the Connecticut River because denitrification processes are most active during warm summer temperatures and because the study was performed during the annual low-flow period when total nitrogen loads are small.


Nitrogen Denitrification Mass balance Connecticut River 



We would like to thank the New England Interstate Water Pollution Control Commission (NEIWPCC) and the U.S. Environmental Protection Agency (EPA) for their assistance in funding and developing this study. Appreciation is also extended to Richard G. Kiah, Jon C. Denner, and Ann T. Chalmers of the USGS for their valuable field assistance. We thank J.K. Bohlke and James B. Shanley of the USGS for providing helpful reviews of this paper.


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Thor E. Smith
    • 1
  • Andrew E. Laursen
    • 2
  • Jeffrey R. Deacon
    • 1
  1. 1.U.S. Geological SurveyPembrokeUSA
  2. 2.Department of Chemistry and BiologyRyerson UniversityTorontoCanada

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