Citation:

Burke Jr., R A. AND J. Molinero. NITRATE AND NITROUS OXIDE CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT. Chapter 3.4, Russo, R.C. (ed.), NATO/CCMS Pilot Study: Modeling Nutrient Loads and Response in River and Estuary Systems. NATO - CCMS, Brussels, Belgium, , 79-89, (2005).

Impact/Purpose:

Improve the scientific understanding of the processes controlling nutrient distributions in surface waters. Produce a suite of enhanced models for characterizing nutrient distributions in surface waters by incorporating improved process understanding in existing models (e.g., WASP), by developing new models (e.g., WHAM, reactive transport), and improving linkages between model components.

Description:

We are measuring dissolved nitrate and nitrous oxide concentrations and related parameters in 17 headwater streams in the South Fork Broad River, Georgia watershed on a monthly basis. The selected small streams drain watersheds dominated by forest, pasture, residential, or mixed land uses. Mean stream nitrate concentrations are lowest in forested watersheds (0.09 to 0.20 mg N L(-1)) and somewhat higher in streams draining agricultural (0.39 to 0.99 mg N L(-1)) and mixed (0.39 to 1.08 mg N L(-1)) land-use watersheds. One of the residential watersheds showed an appreciably higher mean stream nitrate concentration (1.79 mg N L(-1)) than any of the other watersheds but nitrate levels in the other residential watersheds were similar to those in watersheds with other land uses. Nitrous oxide concentrations vary widely from about 10 nM (approximate atmospheric equilibrium concentration) to greater than 80 nM among the streams. Overall, the streams draining watersheds dominated by residential and agricultural land use have significantly higher dissolved nitrous oxide concentrations than those draining forested watersheds. Our results suggest that small streams could be a significant conduit of nitrous oxide from the terrestrial environment to the atmosphere in some watersheds.

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