Quantification of the German nitrogen cycle

Markus Geupel1, Jakob Frommer2

1 German Environment Agency, Wörlitzer Platz 1, Dessau, Germany, 06846, www.umweltbundesamt.de, [email protected]

2 Stadt Würzburg, Fachbereich Umwelt- und Klimaschutz, Karmelitenstr. 20, 97070 Würzburg, [email protected]

Abstract

Nitrogen and its compounds behave very differently in the environment. While atmospheric nitrogen is practically inert, the oxidised and reduced compounds are reactive. Human activity has led to massive changes to the natural nitrogen cycle over the past century and a drastic increase has been seen in the amounts of reactive nitrogen in the environment. Also in Germany the excessive release of reactive nitrogen compounds into the environment leads to a series of problems which must be urgently addressed. These include the loss of aquatic and terrestrial biodiversity, the impairment of air quality, the increased release of greenhouse gases, and constraints on the use of groundwater as drinking water. To improve knowledge on reasons for this situation we reviewed literature and databases to quantify the German nitrogen cycle. In Germany, some 4.2 million tonnes of reactive nitrogen enter into the nitrogen cycle annually, corresponding to some 50 kg per person. While considerable reductions have been achieved in oxidised nitrogen emissions from fossil fuel burning and also from wastewater management, reductions in the agricultural sector have been much less successful. The failure to meet targets is due in part to the fact that a comprehensive solution to the problems posed by nitrogen is hardly possible by implementing separate technical measures in individual areas. Therefore, it is necessary to adopt an integrated approach to the various problems in all relevant policy areas.