Ammonia emissions and dry deposition from broiler barns in the Fraser Valley of British Columbia

Ammonia emissions from commercial broiler operations have been noted as one of the potential contributors to the nitrate contamination of the Abbotsford-Sumas aquifer in southwestern British Columbia (BC). The localized dry deposition of this emitted ammonia was of special interest and had not been measured in any comparable climate. Three barns, on two farms, located on the aquifer were assessed from July 2011 to June 2012. Ventilation, emission, and deposition samples were taken weekly throughout the seasons to accurately characterize the impact on the local environment. Ventilation was measured using a Fan Assessment Numeration System and timers that recorded individual fan activity. Acid impinger traps were used to measure the ammonia emitted by the sidewall fans. A methodology for measuring dry deposition by exposing air-dried soil was modified to use small Petri dishes and a 24-hr exposure time. The modified dry deposition method was found to be robust and effective for the requirements of this study. Dishes of soil were placed 2.1 and 3.6 m in front of and between each fan, as well as around the barns and farm properties. Ventilation rates for the barns were significantly and positively correlated with bird age and exterior temperature. Ammonia emissions were correlated with bird age and the emission factors for the three barns ranged from 0.19-0.37 g NH₃ bird-¹ day-¹ with annual ammonia emissions for each barn reaching 600 to 815 kg NH₃. Dry deposition levels on the two farms exceeded 50 kg NH₃ annually although this accounted for less than 10% of the ammonia emitted. The deposition levels were highest near the barns and were concentrated directly under the sidewall fan hoods. These levels of ammonia show significant potential to cause nitrate to leach into the groundwater and further contaminate the aquifer but future work and upscaling of data collection are needed.Land and Food Systems, Faculty ofGraduat