Modelling the aeolian transport of ammonia emitted from poultry farms and its deposition to a coastal waterbody

In response to the absence of monitoring data, the Air Pollution Model (TAPM), a 3D prognostic model that predicts both meteorology and air pollution concentrations, was used to investigate the transport of ammonia across part of the Sunshine Coast region (South East Queensland, Australia), following its emission to the atmosphere from 41 poultry farms (egg and broiler) in the district, which cumulatively house approximately 9.8 million fowl. The study estimated the total amount of ammonia that is deposited directly into the Pumicestone Passage waterbody (63 km2) and onto the surrounding catchment (1184 km2), through both wet and dry deposition processes over a twelve-month period. The results indicate that wet deposition is the dominant deposition process into the waterbody (89%) and catchment area (94%). Most of the ammonia deposition is predicted to occur within a relatively short distance from the farms, due to higher concentrations at these locations. In the base case simulation, the estimated 1823 tonnes of annual ammonia emissions were predicted to result in the direct deposition of approximately 2.3 tonnes of ammonia into the Pumicestone Passage waterbody and approximately 53.5 tonnes onto the Pumicestone Passage catchment land surface, where there was potential for its subsequent run-off into the waterbody. This annual loading into the waterbody is not insignificant and is likely to contribute to the formation of algal blooms. The fate of the remaining 91% of the ammonia estimated to be emitted from the farms was not accounted for in the deposition totals. This ammonia most likely remains suspended in the atmosphere and is transported outside of the simulation study area.