Key unknowns in estimating atmospheric emissions from UK land management

Abstract

Robust emission inventories of atmospheric pollutants are critical to understanding and predicting impacts, identifying key sources and mitigation opportunities. The objective of this study was to review the extent to which UK land management is accounted for as a source of emission of ammonia (NH 3 ), nitrous oxide (N 2 O), nitrogen oxides (NO x ), organic nitrogen (N org ), methane (CH 4 ), non-methane volatile organic compounds (NMVOC), particulate matter (PM) and heavy metals (HM), in comparison with the current state of scientific knowledge; to ascertain whether there is evidence for significant gaps or that key emission sources have been overlooked. The processes leading to emissions of NH 3 , N 2 O and CH 4 are largely understood and all major sources are thought to be captured in the current inventory. Quantification of uncertainties in the estimates for some of these sources is still required, as is an assessment of the potential improvement in accuracy of estimates through the development of country-specific emission factors for N 2 O and CH 4 in particular. There is limited knowledge about sources and processes leading to emissions of N org and the role that these may play in local and global nitrogen budgets. Land management is known to be a source of NO x , NMVOC and PM emissions, and potentially also HM emissions. Improved quantification is required to assess the importance of land management as a source of these pollutants in comparison with other sectors and, if appropriate, to determine the potential for mitigation. ► Major emission sources of NH 3 , N 2 O and CH 4 from land management are accounted. ► The importance of land management for NO x , NMVOC and PM emissions is less certain. ► Emissions of organic nitrogen and their role in the atmosphere is poorly understood. ► Better quantification of the uncertainty in pollutant emission estimates is needed.