Reactive and Non-reactive Species of Nitrogen in Atmospheric Emission Inventories – A Review

Nitrogen in different forms is naturally available in abundance in the atmosphere. Excess nitrogen, however, has gradually become the one cause for the most pressing environmental problems we currently face in various regions of the world, since the Haber-Bosch process has made the industrial scale production of nitrogen fertilisers possible. Interactions between the drivers, namely emissions of ammonia, nitrogen oxides and nitrous oxide and pressures such as air pollution, acidification and eutrophication of soils and freshwater ecosystems, ecosystem damages and biodiversity impacts, leaching of nitrates into groundwater and global warming are very complex (see Galloway et al., 2003). Furthermore, trade-offs between effects and the control of emission sources lead to a need to balance the management of nitrogen at all stages of the nitrogen cycle. This paper aims to review, how emissions of different nitrogen species, oxidise and reduced, reactive and non-reactive, are currently treated in emission inventories. While the paper and presentation here will focus on a European perspective and discuss some aspects of emissions in China, it forms part of a journal paper currently in preparation which will investigate how the situation of N species in inventories is addressed in Europe, the United States of America, and The People’s Republic of China. Focusing on anthropogenic sources, the aim of the work presented here is to discuss the current state-ofthe-art of quantifying the emissions of NH3, NOx and N2O and to assess, if current inventories provide a solid data basis for atmospheric dispersion models. In addition to that, aspects such as the potential synergies and trade-offs of attempts to manage different substances with often contradicting objectives and results are taken into account. For the purpose of this conference, the paper will focus on Europe and China, and specifically investigate aspects of agreement between different inventories, temporal and spatial resolution, and observed trends in emissions in the past and anticipated future developments.