Peierls, B. L. Univ. of North Carolina at Chapel Hill, Institute of Marine Sciences,
Paerl, H. W. Univ. of North Carolina at Chapel Hill, Institute of Marine Sciences,

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