title: Uncertainties in current estimates of emissions of ammonia in the United Kingdom.
abstract: Estimates of the emissions of ammonia have previously concentrated on animal husbandry sources from agricultural systems. Animal husbandry sources still constitute the major fraction of emissions of ammonia, but we have also considered the potential magnitude of other 'minor' sources, which may include coal combustion, waste incineration, road vehicles, sewage treatment plants, fertiliser manufacture and application, vegetation senescence and crop emissions, domestic pets, and human sources. Where possible, a provisional estimate of UK emissions from each of these sources is given. It is concluded that the potential magnitude of emissions from these 'minor' sources may make a significant contribution to the total emissions of ammonia to the atmosphere. On the basis of the available data, and the application of a range of emission factors to the UK situation, an additional annual emission potential lying in the range of approximately 80-140 ktonne year(-1) over and above that from animal husbandry has been calculated. The uncertainties in the emission estimates and instances in which a better resolution of sources is required are discussed. The emission factors used for animals in various inventories are reviewed and applied to the main UK agricultural animal populations. By using this approach, estimates of emissions from these sources range between 113 and 647 ktonne year(-1), which illustrates the uncertainties involved. It is suggested that our knowledge of the sources of ammonia, and their distribution, is far from complete.
authors.affiliation: AEA Technology, National Environmental Technology Centre, E5, Culham, Abingdon, Oxfordshire, UK, OX14 3DB.
authors.forename: D S
authors.initials: DS
authors.lastname: Lee
authors.forename: G J
authors.initials: GJ
authors.lastname: Dollard