Atmospheric ammonia assessments on six designated sites in Northern Ireland. Year 1: June 2020 – May 2021

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. •The monitoring strategy at each designated site aims to capture the high spatial variability of NH3 and any associated atmospheric concentration gradients away from sources, where the highest concentrations (and local sources) may be and where the largest ecosystem impacts are likely to occur. •The sites are also part of the cross-border INTERREG Va funded Collaborative Action for the Natura Network (CANN) project (2017-2021), managed by the Special EU Programmes Body. •The measurement data will provide supporting evidence to develop site-specific mitigation strategies, if necessary and appropriate. •It is hypothesised that boundaries of a designated site that are closest to, and downwind of sources (e.g. intensive livestock units) will be exposed to the highest NH3 concentrations and therefore most at risk from adverse effects on sensitive vegetation. •This report presents monthly NH3 measurements from the first year of monitoring, between June 2020 and May 2021.