Assessment of Atmospheric Nitrogen Deposition Response to EGU Pollution Controls for the Escambia Bay, Florida Watershed

Justin Walters
Southern Company, 600 N. 18th St., 14N-8195, Birmingham, AL 35203

Krish Vijayaraghavan
Atmospheric & Environmental Research, Inc., 2682 Bishop Dr., Ste 120, San Ramon, CA 94583

Jay L. Haney
ICF International, 101 Lucas Valley Road, Suite 260, San Rafael, CA 94903

Rochelle Balmori
Atmospheric & Environmental Research, Inc., 2682 Bishop Dr., Ste 120, San Ramon, CA 94583

Shu-Yun Chen
Atmospheric & Environmental Research, Inc., 2682 Bishop Dr., Ste 120, San Ramon, CA 94583

Sharon G. Douglas, Tom C. Myers
ICF International, 101 Lucas Valley Road, Suite 260, San Rafael, CA 94903

John J. Jansen
Southern Company, 600 N. 18th St., 14N-8195, Birmingham, AL 35203

Eladio M. Knipping
Electric Power Research Institute, 3420 Hillview Ave., Palo Alto, CA 94304

Christian Seigneur
Atmospheric & Environmental Research, Inc., 2682 Bishop Dr., Ste 120, San Ramon, CA 94583

A series of simulations using four air quality models were performed in order to assess atmospheric nitrogen deposition over Escambia Bay and its watershed in the western portion of the Florida panhandle and southern Alabama. This analysis is part of a larger study that used these data to drive two watershed models to estimate the impact of NOx and SO2 controls at a local coal-fired power plant on nitrogen loads to the bay. Model performance evaluations were conducted on the CMAQ-based models using observations from NADP, CASTNET, IMPROVE and SEARCH monitoring stations.

Three of the air quality models are 3-D Eulerian chemistry transport models derived from CMAQ version 4.5.1:
1. CMAQ-VISTAS: includes secondary organic aerosol modifications made for VISTAS RPO modeling;
2. CMAQ-MADRID: implements the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID), including sectional particle size distribution, heterogeneous nitrate formation and sea-salt nitrate interactions; and

3. CMAQ-MADRID-APT: employs the advanced plume treatment (APT) module for the simulation of the plumes from 40 large coal-fired power plants in the southeastern United States including the plant under consideration.

The fourth air quality model is the California Puff Model (CALPUFF), a Lagrangian puff dispersion model with simpler parameterizations for chemistry and deposition processes.

Model simulations utilized previously developed meteorology and emission inputs for the base year of 2002. The Eulerian models were applied over a domain in the Southeast centered on Alabama and Georgia. CALPUFF was applied to a single power plant near Escambia Bay. The meteorology in all four models was driven by the same MM5 fields developed by the VISTAS RPO. Emissions and initial/boundary conditions were obtained from Georgia EPD, VISTAS, ICF and Southern Company, and are consistent for the three Eulerian models except for small differences in power plant emissions and wildfire emissions.

The presentation will present the results of the model performance evaluation and summarize the results from the four models in terms of total and speciated nitrogen deposition.