Predicting atmospheric ammonia dispersion and potential ecological effects using monitored emission rates from an intensive laying hen facility in Ireland

Agriculture is responsible for 98% of atmospheric ammonia (NH3) in Ireland, which pigs and poultry produce 7%; with laying hens specifically contributing 0.6%. Though a small proportion the national NH3 total emissions, ecological impacts on sensitive sites attributed to hen farms can be substantial. emission monitoring was conducted Spring (February March) Summer (July August) 2016 account seasonal variation. The average ventilation rate 0.25 g bird−1 day−1 931 cm3 s−1 bird−1. This lower than previously used factor Irish inventory 0.5 day−1, but broadly similar factors reported United Kingdom (UK) European Union (EU). Dispersion modelling using monitored data indicated potentially acute effects within 84 m, critical level exceedance 312 m 0.3 kg N ha−1 year−1 deposition 2.9–5.2 km. sensitivity model tested SCAIL-Agriculture rates showed P-values one tailed below 0.01 all models, indicating that when normalised maximum extents modelled by AERMOD were significantly different. analysis having more influence rate. Both parameters combined had greatest increase dispersion extent, 55.8% greater use rates. A occur 5.1–7.7 km Indicating recommended would have been sufficiently precautionary assess negative Natura 2000 site under Habitats Directive (92/43/EEC). In relation Appropriate Assessment (AA) screening, any contribution from source set distance may an appropriate full AA trigger.