The spatial distribution of ammonia emitted from seabirds and its contribution to atmospheric nitrogen deposition in the UK

Simple bioenergetics models were used to derive annual nitrogen excretion rates of each seabird species occurring at colonies in the UK. These were combined with population distribution data and an estimated fraction of nitrogen volatilized to estimate the spatial distribution of NH₃ emissions from seabird colonies at a 1 km resolution. The effect of these emissions on atmospheric NH₃ concentrations and nitrogen deposition in the UK was assessed using the FRAME atmospheric chemistry and transport model. The total emission of NH₃ from the UK seabird colonies is estimated at 2.7 kt yr^–1. Emissions from seabirds are largely concentrated in remote parts of Britain, where agricultural and other anthropogenic emissions are minimal. Although seabirds account for less than 1% of total UK NH₃ emissions (370 kt yr^–1), their occurrence in remote areas and frequently large colony sizes results in seabirds providing a major fraction of the atmospheric nitrogen deposition for many remote ecosystems.