Reactive nitrogen flows in {Germany} 2010 - 2014 ({DESTINO} {Report} 2)

Publication Type:

Journal Article


p.152 (Submitted)


Emissions of reactive nitrogen give rise to a wide range of environmental problems. In order to develop reduction measures it is necessary to quantify sources, sinks and flows of Nr, and as part of the Convention on Long-Range Transboundary Air Pollution (CLTRAP) it was agreed in the Gothenburg Protocol to construct national nitrogen budgets. The “Guidance document on national nitrogen budgets” of the Economic Commission for Europe forms the starting point for this task. The Nr flows are determined for the following pools: “Atmosphere”, “Energy and Fuels”, “Material and products in industry”, “Humans and settlements”, “Agriculture”, “Forest and semi-natural vegetation”, “Waste”, and “Hydrosphere”, as well as for the “Trans-boundary N-flows” (imports and exports). The N-flows are taken directly from statistical reports, publications, etc., or are calculated as the product of the quantity of transported or converted substance and the mean nitrogen contents. Some 150 N-flows are described, and the uncertainty of the results is graded in four levels from “very low” to “high”. In Germany, approximately 6275 kt Nr is introduced into the nitrogen cycle every year (mean value from 2010 to 2014), of 43 % is by ammonia synthesis. Domestic extraction of nitrogenous fossil fuels (lignite, coal, crude oil) and imports contribute 2335 kt N a-1. Natural nitrogen fixation converts 308 kt N a-1 into organically bound nitrogen. Conversely, processes involving the combustion of fossil fuels and regenerative fuels and the refining of crude oil to mineral oil products result in 2711 kt N a-1 being transformed to N2. In waters, soils, and wastewater treatment plants, denitrification leads to the release of 1107 kt N a-1 as molecular nitrogen. Via the atmosphere and hydrosphere, Germany exports 745 kt N a-1 to neighbouring countries and the coastal waters. The changes in N-stock in soils have to date only been determined for forest soils, where they are 293 kt N a-1. On balance, reactive nitrogen totalling 1627 kt N is released in Germany every year, with negative impacts on the ecosystems and their functions. The national nitrogen budget involves considerable uncertainties, and this should be taken into consideration when interpreting the results.