Reactive Nitrogen in Germany

Reactive nitrogen in Germany Causes and effects – measures and recommendations Summary ▸ Nitrogen and its compounds behave very differently in the environment. While atmospheric nitrogen is practically inert, the oxidised compounds (e.g. nitrogen oxide or nitrous oxide) and reduced compounds (e.g. ammonia) are reactive. Depending on the nature of the compound and the concentration, they can either be life-supporting nutrients or harmful pollutants. Therefore, these compounds are also referred to as reactive nitrogen in the environmental discussion. ▸ 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. However, the levels vary considerably worldwide, e.g. in tropical Africa, nutrient-poor soils rep- resent a serious problem which leads to agricultural yields remaining well below the potential levels. ▸ In Germany, some 4.2 million tonnes of reactive nitrogen enter into the nitrogen cycle annually, corresponding to some 50 kg per person. About 6 kg per person per year is consumed in food. The re- mainder is contained in products, or finds it way unused into the environment. ▸ 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 con- straints on the use of groundwater as drinking water. ▸ In Germany, considerable reductions have been achieved in nitrogen emissions from the man- ufacturing sector, the energy industry, traffic and transport, and also from wastewater management. ▸ However, reductions have been much less successful in the agricultural sector, which meanwhile accounts for more than 60 per cent of Germany’s nitrogen emissions. ▸ In order to stimulate a significant improvement for the environment, the levels set in the German government’s sustainability strategy for the nitrogen surplus should be revised. UBA recommends setting a target for the nitrogen surplus of 50 kg per hectare per year by 2040. ▸ The Fertiliser Ordinance (DüV) is a key instrument for the reduction of nitrogen losses from farming into the environment. It is currently being reformulated in order to meet ecological require- ments. By means of additional measures in the agricultural sector, further reductions are possible. ▸ An important contribution to achieve a balance in the nitrogen cycle can be made by changes in consumer behaviour, e.g. by reducing consumption of animal protein, or by avoiding the waste of food. 2 Contents 1. Reactive nitrogen – too much of a good thing? 4 2. Negative impacts of the intensified nitrogen cycle 7 2.1 Threats to biological diversity 7 2.2 Threats to air quality 8 2.3 Threats to water quality 9 2.4 Climate change 10 2.5 Effects on materials 12 2.6 Economic effects 13 3. Needs for action and policy strategies 14 4. Germany’s nitrogen cycle 19 4.1 Budgeting nitrogen flows in Germany (2005 – 2010) 19 4.2 Comparing the German cycle with European and global levels 22 4.3 Emissions of reactive nitrogen 22 4.4 Changes over time of key emissions 23 5. Measures and recommendations for action 26 5.1 Agricultural policies 26 5.2 Clean air policies 33 5.3 Surface waters 33 5.4 Energy sector and small combustion units 34 5.5 Industry 35 5.6 Transport 35 5.7 Municipal water management 36 5.8 The influence of consumers 36 6. The global dimension 39 7. Conclusions and outlook 40 Annex 1: Amounts of nitrogen, reference periods and data source for the nitrogen flows in Chapter 4 42 Annex 2: New target values for the nitrogen surplus 44 References 46 3 1. Reactive nitrogen – too much of a good thing? Nitrogen (N) can take various forms. Mostly it occurs in In addition to the desirable effect of increasing agricul- its molecular form as a relatively inactive gas in the at- tural production, the intensified nitrogen cycle today mosphere. However, it also occurs as reactive nitrogen leads to many negative environmental impacts (Galloway in various compounds. Paradoxically, these reactive ni- et al., 2003). According to Rockström et al. (2009), the trogen compounds can be both essential nutrients and global boundaries of ecosystems have been exceeded harmful pollutants (Box 1). by anthropogenous impacts on these cycles (Fig. 1b). International scientists therefore recommend a marked Over the past century, human activities have more than reduction in the conversion of atmospheric nitrogen into doubled the amounts of inactive atmospheric nitrogen reactive nitrogen (Rockström et al., 2009, Fowler et al., being converted every year into reactive nitrogen (Fig. 2013). Discussions are ongoing to establish a target value 1a), and in Europe the amount has quadrupled. This was which would ensure nutrition and at the same time re- either intentional, e.g. in order to produce artificial fer- main within environmental boundaries. Recent contri- tilisers and thus ensure the food production for the grow- butions state that the global conversion of atmospheric ing world population, or was an unintended by-product nitrogen to reactive nitrogen should be limited to about from the combustion of fuels. half the current level (De Vries et al., 2013). In its final Figure 1a Global trends in the production of reactive nitrogen by human activities (as fertiliser, biological fixation or in the form of nitrogen oxides from combustion processes) 7000 200 180 6000 160 5000 140 120 4000 100 3000 80 World population (millions) 2000 60 Nitrogen release (terragram, Tg) 40 1000 20 0 0 1900 1920 1940 1960 1980 2000 World population NOx-emissions (Tg N) Chemical fertiliser (Tg N) Total anthropogenic Nr (Tg N) Biological N fixation in farming (Tg N) after Galloway et al., 2003 4 report, the Commission of Enquiry of the German Parlia- the final reports on the international assessment of the ment on “Growth, Welfare, Quality of Life” names a sus- nitrogen cycle at European and global levels (Sutton et tainable, less-intensive nitrogen cycle as an essential ob- al., 2011, Sutton et al., 2013). jective (Deutscher Bundestag, 2013). In the following chapters, the nitrogen cycle in Germany is analysed. On the basis of the results, options are out- lined for reducing the negative effects. A comprehensive overview of the nitrogen flows in Ger- many, their effects, and possible reduction measures is provided in the report of the German Federal Environ- ment Agency (UBA) “Integrated Strategy for the reduction of nitrogen emissions” (UBA, 2009a and b), on which this publication is based. Further important sources are Figure 1b Planetary boundaries in nine sectors For loss of biodiversity, climate change, and the nitrogen cycle (which also impacts on the other sectors) the authors find that the boundaries have been exceeded beyond the level of uncertainty (Azote Images/Stockholm Resilience Centre) limate change n C tio lu d) Oc ol fie ea p ti n al n ac c ua id i q i m t fi e e ca h y C t ti o o n n ( ) o d S g z c e o t i n i r i f r i n a e d t e t o h a n d s o a p l e p u s l p h o q o l e t e s m r e t t o i i c y r o A t e n o a n ( ( f s N b l c o s i i y o w o t l c r g o l b y e e t g o o i e u s c r n h n e d e v i a m d r i y P o c i c h a B y l o ) c s l e p h e f o r s e u r s o h d w n u a a l t s e n i r e u G g s e n a l h C o b a l Rockström et al. (2009) 5 Box 1 Reactive nitrogen and the nitrogen cascade Reactive nitrogen includes the following compounds: - - Oxidised inorganic nitrogen compounds: Nitrates (NO3 ), nitrites (NO2 ) and nitrous oxide (N2O) + Reduced inorganic nitrogen compounds: Ammonia (NH3) and ammonium (NH4 ) Organic compounds containing nitrogen (Norg): Mainly in proteins (amino acids) in organisms and their remains. Once nitrogen is in a reactive form, it can lead to effects in a variety of further chemical forms (NOx,NHy, Norg) in various places and with differing environmental impacts (air, soil, water, vegetation, fauna including humans). This is called the nitrogen cascade (Galloway et al., 2003). Human Atmosphere activities Effects on and of Effects of Stratospheric effects Energy production ozone concentrations particulate matter NOx NH3 NHx N2O Greenhouse effects NOx NOy Food produciton NOx N2O Effects on agro- Effetcs on ecosystems terrestrial NH ecosystems x Crops Animal Plants NOy N2O (terrestrial) N Soils NO Soils oganic 3 Terrestrial ecosystems Human (food, fibres) NO3 Effects on Effects on surface coastal water water N2O (aquatic) Effects on oceans Aquatic ecosystems Indicates Effects on denitrification groundwater potential after Galloway et al., 2003 6 2. Negative impacts of the intensified nitrogen cycle The intensified nitrogen cycle leads to negative impacts Figure 2 in various sectors of the environment (UBA, 2011). This Exceeding critical loads for eutrophication chapter gives a short overview of these threats and im- by nitrogen depositions in rural ecosystems pacts. (More detailed information about the individual for 2009 aspects is provided in the the corresponding references) According to current knowledge no long-term negative effects are In addition, an outlook is provided, showing the situation expected for terrestrial biodiversity below these values that is expected to develop by 2020 or 2030 if no further measures are introduced.

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