Monday, November 5, 2007 - 3:10 PM
43-6

The Problem of Atmospheric N Deposition in the Chesapeake Bay.

Robin Dennis, Air Resources/NOAA, Atmospheric Sciences Modeling Division, MD E243-04, NOAA Air Resources Laboratory, Research Triangle Park, NC 27711

The talk will discuss current and future projections of nitrogen (N) deposition to the Chesapeake Bay watershed and coastal systems.  The relative importance and separate behavior of oxidized- and reduced-nitrogen deposition will be summarized.  The increasing importance of ammonia emissions to the N deposition to coastal areas will be noted because NOx emissions are expected to be significantly reduced to meet ozone and PM2.5 health standards.  The sensitivity of ammonia deposition to reductions in sulfur dioxide emissions expected from the Clean Air Interstate Rule (CAIR) will also be noted.  Dry deposition budgets for local, high ammonia emission areas will be characterized indicating the prevalence of long range transport of ammonia, in contradiction of assumptions that ammonia is all locally deposited.  Final thoughts will address the importance of bi-directional exchange influencing ammonia (deposition) air-surface exchange.