Citation:

Poor, N., R. Pribble, AND D. Schwede. Application of Watershed Deposition Tool to Estimate from CMAQ Simulations of the Atmospheric Deposition of Nitrogen to Tampa Bay and Its Watershed. JOURNAL OF AIR & WASTE MANAGEMENT ASSOCIATION CONTROL TECHNOLOGY. Air & Waste Management Association, Pittsburgh, PA, 63(1):100-114, (2013).

Impact/Purpose:

The National Exposure Research Laboratory′s (NERL′s)Atmospheric Modeling Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.

Description:

The USEPA has developed Watershed Deposition Tool (WDT) to calculate from the Community Multiscale Air Quality (CMAQ) model output the nitrogen, sulfur, and mercury deposition rates to watersheds and their sub-basins. The CMAQ model simulates from first principles the transport, transformation, and removal of atmospheric pollutants. We applied WDT to estimate the atmospheric deposition of reactive nitrogen (N) to Tampa Bay and its watershed. For 2002 and within the boundaries of Tampa Bay’s watershed, modeled atmospheric deposition rates averaged 13.3 kg N ha-1 yr^-1 and ranged from 6.24 kg N ha^-1 yr^-1 at the bay’s boundary with Gulf of Mexico to 21.4 kg N ha^-1 yr^-1 near Tampa’s urban core, based on a 12-km x 12-km grid cell size. CMAQ-predicted loading rates were 1,080 metric tons-N yr^-1 to Tampa Bay and 8,280 metric tons-N yr^-1 to the land portion of its watershed. If we assume a watershed-to-bay transfer rate of 18 % for indirect loading, our estimates of the 2002 direct and indirect loading rates to Tampa Bay were 1,080 metric tons-N and 1,490 metric tons-N, respectively, for an atmospheric loading of 2,570 metric tons-N or 71 % of the total N loading to Tampa Bay. To evaluate the potential impact of USEPA’s Clean Air Interstate Rule (CAIR, replaced with Cross-State Air Pollution Rule), Tier 2 Vehicle and Gasoline Sulfur Rule, Heavy Duty Highway Rule, and Non-Road Diesel Rule, we compared CMAQ outputs between 2020 and 2002 simulations, with only the emissions inventories changed. CMAQ-projected change in atmospheric loading rates between these emissions inventories was 857 metric tons-N to Tampa Bay, or about 24 % of the 2002 total N loading to Tampa Bay from all sources.

URLs/Downloads:

SCHWEDE - FINAL FINAL.PDF  (PDF, NA pp,  5807.73  KB,  about PDF)

Journal of the Air and Waste Management Association  

Record Details:

Record Type:DOCUMENT( JOURNAL/ PEER REVIEWED JOURNAL)

Product Published Date:01/24/2013

Record Last Revised:07/02/2013

OMB Category:Other

Record ID: 250573

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