Contribution of Industrial Atmospheric Ammonia Emissions to Nitrogen Loading in the Tampa Bay Estuary, Tampa, FL, USA

We used the CALMET/CALPUFF modeling system to simulate for May 2002 the emission, dispersion, and transport of ammonia (NH3) released from the fertilizer industry in west central Florida, based on SIC codes and annual emission rates reported in the 2001 USEPA toxic release inventory. For May 2002 at the Gandy Bridge monitoring site, which is adjacent to Tampa Bay, the modeled and measured 12-hour average ammonia plus ammonium (NHy) concentrations were 0.5 µg m-3 and 2.5 µg m-3, respectively. We estimated that the direct dry deposition of atmospheric NH3 from the fertilizer industry was 0.06 kg-N ha-1 mo-1 (6 metric tons), compared with 0.34 kg-N ha-1 mo-1 (35 metric tons) from all sources. This loading rate represented ~10 % of the total direct deposition (wet + dry) of nitrogen to Tampa Bay