Atmospheric ammonia assessments on six designated sites in Northern Ireland. Report 2: June 2020 – May 2022

Prepared between the UK Centre for Ecology & Hydrology (UKCEH) and the Department of Agriculture, Environment and Rural Affairs (DAERA) Northern Ireland Environment Agency (NIEA). Atmospheric ammonia (NH3) gas concentrations were monitored on six designated sites of international and national importance (Special Areas of Conservation, SAC and Areas of Special Scientific Interest (ASSI)) across Northern Ireland, to assess threats from atmospheric nitrogen inputs. A total of 37 NH3 monitoring points were established, with between 4 and 9 monitoring points on each of the six designated sites, depending on the size and complexity of each site. Monitoring was carried out at monthly intervals, with continuous time-integrated measurements made with passive UKCEH ALPHA® samplers. This report presents monthly NH3 measurements from two complete years of monitoring, between June 2020 and May 2022. Monthly measurements were aggregated to estimate annual average concentrations for the assessment of critical levels exceedance (annual thresholds). The monthly monitoring periods also enabled the construction of seasonal profiles across the sites, which is helpful for identifying peak emission periods as well as likely source types (for example, slurry spreading activities during spring