Whitall, D. R. University of North Carolina at Chapel Hill,
Peierls, B. L. University of North Carolina at Chapel Hill,
Showers, W. J. North Carolina State University,
Paerl, H. W. University of North Carolina at Chapel Hill,

 
QUANTIFICATION OF INORGANIC AND ORGANIC NITROGEN SPECIES IN ATMOSPHERIC DEPOSITION IN THE NEUSE RIVER WATERSHED, NORTH CAROLINA, USA: SOURCES, FLUXES AND SPATIOTEMPORAL VARIABILITY
 
Atmospheric deposition of nitrogen (AD-N), through both wet and dry deposition of NOy, NH3/NH4+, and organics, may contribute >30% of the total N to the Neuse River watershed. Excessive N loading to N-sensitive waters such as the Neuse has been shown to promote changes in microbial and algal community composition and function (harmful algal blooms), hypoxia/anoxia, and fish kills. In an ongoing study, we quantified the weekly wet and dry deposition of inorganic and organic N at four sites on a northwest-southeast transect in the watershed from 1996 to present. Deposition varied by up to 4 orders of magnitude, with the mean AD-N flux estimated at 610 mg/m2/yr (13,000 tonnes/yr) DIN (wet+dry). Data from an earlier study (1994-1996) showed that the DON flux in the coastal region was 36.2 mg N/m2/yr. Conservative estimates of watershed N retention reveal that this contributes up to 35% of the total N reaching the waterways of the basin. Preliminary stable nitrogen isotope measurements indicate the isotopic signal for AD-NH4+ is between +1 and -10 per mil; this suggests that a mixture of mobile and agricultural emissions are the dominant sources of the NH4+ in the AD-N in the watershed.
 
Day: Wednesday, Feb. 3
Time: 10:45 - 11:00am
Location: Sweeney Center
 
Code: CS59WE1045S