Peierls, B. L. Univ. of North Carolina at Chapel Hill, Institute of Marine Sciences, peierls@email.unc.edu
Paerl, H. W. Univ. of North Carolina at Chapel Hill, Institute of Marine Sciences, Hans_Paerl@unc.edu

 
ATMOSPHERIC DEPOSITION OF NITROGEN TO COASTAL WATERS: BIOGEOCHEMICAL AND ECOLOGICAL IMPACTS
 
During the past century, atmospheric deposition of nitrogen (AD-N) has increased by 5 to 10 fold and now accounts for 10 to over 40% of external, or "new" N loading to N-limited coastal waters. The increase of inorganic N has predictable consequences in marine systems; N loading has been linked to eutrophication, including harmful algal bloom expansion. The additional impact of organic N components and altered chemical composition of AD-N was investigated in N-sensitive, estuarine and coastal North Carolina waters. Atmospheric organic N (AON) can provide an additional nutrient source depending on its bioavailability. Enrichment of coastal water with isolated rainwater DON produced increased phytoplankton biomass and productivity that ranged from 20-60% of the response to inorganic N alone, suggesting that as much as one-half of the AON pool is available to primary producers on short (hours to days) time scales. Recent intensification of animal operations in the U.S. Mid-Atlantic coastal plain has been linked to increasing amounts of NH4+ and possibly AON deposition. The response of phytoplankton community structure and function may differ with different proportions of new N components. Future air/watershed nutrient budgets should include all atmospheric N species and consider relative fluxes to fully gauge ecological effects.
 
Day: Wednesday, Feb. 3
Time: 09:30 - 09:45am
Location: Sweeney Center
 
Code: SS50WE0930S