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Veröffentlichung Comparison of methods for the estimation of total inorganic nitrogen deposition to forests in Germany(2020) Ahrends, Bernd; Schmitz, Andreas; Geupel, Markus; Prescher, Anne-KatrinA reliable quantification of total inorganic nitrogen (TIN) deposition to forests is required for the evaluation of ecological effects of TIN inputs to forests and to monitor the success of clean-air policy. As direct measurements are scarce, different modeling approaches have been developed to estimate TIN deposition to forests. Three common methods are the (i) "canopy budget model," (ii) "inferential method," and (iii) "emission based estimates" using a chemical transport model. Previous studies have reported considerable and site-specific differences between these methods, complicating the interpretation of results. We use data from more than 100 German intensive forest monitoring sites over a period of 16 years for a cross-comparison of these approaches. Non-linear mixed-effect models were applied to evaluate how factors like meteorology, terrain and stand characteristics affect discrepancies between the model approaches. Taking into account the uncertainties in deposition estimates, there is a good agreement between the canopy budget and the inferential method when using semi-empirical correction factors for deposition velocity. Wet deposition estimates of the emission based approach were in good agreement with wet-only corrected bulk open field deposition measurements used by the other two approaches. High precipitation amounts partly explained remaining differences in wet deposition. Larger discrepancies were observed when dry deposition estimates are compared between the emissions based approach and the other two approaches, which appear to be related to a combination of meteorological conditions and tree species effects. © 2020 Ahrends, Schmitz, Prescher, Wehberg, Geupel, Andreae and MeesenburgVeröffentlichung National nitrogen budget for Germany(2021) Häußermann, Uwe; Bach, Martin; Fuchs, Stephan; Geupel, MarkusEmissions of reactive nitrogen (Nr) give rise to a wide range of environmental problems. Nitrogen budgets for various systems and on different scales are an established tool to quantify the sources and fate of Nr. The national nitrogen budget (NNB) for Germany calculates the nitrogen flows for eight 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 transboundary N-flows. In Germany, in total 6,275 kt Nr a-1 has been introduced into the nitrogen cycle annually (mean 2010 to 2014), of which 43% stem from ammonia synthesis. Domestic extraction and import of nitrogenous fossil fuels (lignite, coal, crude oil) releases another 2,335 kt Nr a-1. Import of food, feed and materials contributes 745 kt Nr a-1, while biological N fixation converts 308 kt Nr a-1 into organically bound nitrogen. In terms of Nr sinks, the combustion and denoxing of fuels and the refining of crude oil converts 2,594 kt Nr a-1 to N2. In waters, soils, and wastewater treatment plants, denitrification leads to the release of 1,107 kt Nr a-1 as N2. Via the atmosphere and hydrosphere, Germany exports 755 kt Nr a-1 to neighbouring countries and into coastal waters. On balance, Germany releases 1,627 kt Nr a-1 annually to the environment. However, the NNB as a whole and the individual pool balances involve substantial uncertainties, which have to be considered when interpreting the results. ©2021 The Author(s)