Annex 1: Nitrogen Pollution: Sources and Impact
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Box 2: Human Activities and Nitrogen Pollution |
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Agriculture–Fertiliser |
Manufactured fertiliser containing urea, ammonium and nitrate, used to replace naturally occurring nitrogen in soil, increases agricultural production , 1 but over-use can run off and leach from crops and grasslands into water systems causing pollution . 2 Impact: The build-up of nutrients can lead to growth in some plants and algae leading to habitat changes and potential reduction in oxygen levels (i.e. eutrophication) . 3 In estuaries this can affect invertebrates, smother saltmarsh vegetation and interfere with waders and waterfowls’ ability to feed. Excess nitrate in groundwater can also impact upon ecosystems which depend on such sources but also upon freshwaters, such as lakes, wetlands and headwater streams . 4 It can also affect drinking water quality and lead to methaemoglobinaemia (‘blue baby syndrome’), which was a particular risk to babies before the 1950s . 5 To avoid this a nitrate standard was set - 50 milligrams of nitrates per litre , 6 and a nitrite standard of 0.5 milligrams per litre . 7 |
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Agriculture–Animal Waste |
Animal waste, particularly manure and slurry but also organic fertiliser, can lead to ammonia and nitrous oxide emissions and nitrate and phosphorous leaching into water systems , 8 if it is not managed correctly . 9 Impact: As with fertiliser, manure leaching can cause eutrophication and affect ecosystems and drinking water . 10 If it leads to ammonia emissions this can contribute to acidification and atmospheric particulate pollution, while nitrous oxide is a potent greenhouse gas , 11 and pollutant. Ammonia emissions can also have a deleterious impact on fauna and fungi . 12 |
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Soil Quality Impact |
Depending on its use, the quality and composition of soil can affect both water and air quality by allowing various nutrients including nitrogen, to run off into water and wider ecosystems . 13 Impact: can lead to eutrophication and impact on various ecosystems . 14 |
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Sewage (Urban Waste Water) |
Sewage is a mixture of domestic waste water from kitchens, bathrooms and toilets, the waste water from industries discharging to sewers and rainwater run-off from roads and other impermeable surfaces such as roofs, pavements and roads draining to sewers . 15 This can cause a problem if it finds its way into water systems, for example, through discharges or flooding. Impact: Untreated waste water can lead to chronic ecosystem damage due to oxygen depletion of receiving waters from the biodegradation of organic matter . 16 They also pose potential health risks from water-borne pathogens from discharges to waters used for recreational activities, such as swimming and canoeing . 17 |
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Air Pollution |
Air pollution is caused by the emission of pollutants, either directly or through chemical reactions in the atmosphere. Sources include power stations, transport, household heating, agriculture and industrial processes. Key pollutants include nitrogen oxides (NOx), ammonia (NH3); and particulate matter (PM10 and PM2.5) and they can mix with other pollutants, such as ozone and sulphur dioxide. Nitrogen oxides are the generic name for a range of gases, including nitrous oxide, nitrogen dioxide, nitric oxide and nitrous oxide. Road transport is the main source of nitrogen oxides (particularly nitrogen dioxide and nitric oxide), followed by the electricity supply industry and other industrial and commercial sectors. The main sources of agricultural nitrogen oxide emissions are soils and animal waste. The over use of nitrate fertiliser is mainly responsible for nitrous oxide, a greenhouse gas. The main source of ammonia pollution is agriculture (82% in 2016), mainly through fertiliser use and livestock farming. Impact: Air pollution is “caused by the emission of pollutants, which either directly or through chemical reactions in the atmosphere lead to negative impacts on human health and ecosystems” . 18 Nitrogen oxides (NOx), especially nitrogen dioxide and nitric oxide, along with particulate matter (PM), and ozone (O3) cause tens of thousands of early deaths, costing billions of pounds in health impacts each year . 19 They can also have a negative impact on wildlife, such as a significant reduction in biodiversity . 20 This is because when any of the nitrogen oxides dissolve in water and decompose, they form nitric or nitrous acids which can lead to acidity and eutrophication . 21 One of the nitrogen oxides - nitrous oxide, is also powerful greenhouse gas and is measured by the Committee on Climate Change . 22 The two main sources of agricultural nitrous oxide emissions are agricultural soils (77% in 2016) and waste and manure (20% in 2016) particularly through the use of inorganic fertiliser and urine and dung deposited on grassland . 23 |
1 The ability to use large amounts of manufactured nitrogen-containing fertiliser was enabled by the Haber-Bosch process, which allowed the creation of anhydrous ammonia and offered an alternative to techniques such as crop rotation (see BASF, A new century in agriculture – the Haber-Bosch process), while other processes have allowed the mass production of urea and nitrate (see European Fertiliser Manufacturers’ Association, Production of urea and urea ammonium nitrate, (2000)).
2 See Parliamentary Office for Science and Technology, Diffuse Pollution of Water by Agriculture, POST Note 478, (2014), pp 1–2; Food and Agricultural Organisation (FAO), Control of water pollution from agriculture - FAO irrigation and drainage paper, (1996), Chapter 3; Wessex Water (NO30007); Professor Penny Johnes (NO30024); Brighton ChaMP for Water (NO30027); Wildlife and Countryside Link (NO30032); Friends of the Earth Northern Ireland (NO30034); RSPB (NO30037).
3 For eutrophication, its causes and consequences for ecosystems see: Chislock, M. F et al, Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems. Nature Education Knowledge, (2013), vol. 4, no. 4, p 10; European Environment Agency, Eutrophication, (accessed 21 May 2018): National Ocean Service, What is eutrophication?, (accessed 21 May 2018).
4 Defra Written Evidence (NO30049); Plymouth Marine Laboratory NO30004.
5 For the symptoms of methemoglobinemia see: Lorna Fewtrell, Drinking-Water Nitrate, Methemoglobinemia, and Global Burden of Disease: A Discussion, Environmental Health Perspectives, vol. 112, no 4, (2014), pp 1371–1374; Sally Bradberry, Complications of poisoning: Methemoglobinemia, Medicine, vol. 40, Issue 2, (February 2012), pp 59–60. See also Dr Paul Kay, University of Leeds NO30006.
6 See WHO, Nitrate and nitrite in drinking-water Background document for development of WHO Guidelines for Drinking-water Quality, (2011), p 16.
7 These levels are set in the EU Drinking Water Directive (98/83/EC), p 330/50.
8 See: National Farmers Union, Diffuse Water Pollution Guidance, (accessed 5 June 2018); Parliamentary Office for Science and Technology, Diffuse Pollution of Water by Agriculture, POST Note 478, (2014), p 2; Sue Everett (NO30003). Wessex Water (NO30007); Professor Penny Johnes (NO30024); Brighton ChaMP for Water (NO30027); ADAS (NO30029); Centre for Ecology and Hydrology (NO30033); Friends of the Earth Northern Ireland (NO30034).
9 See: National Association of Agricultural Contractors, Best Practice in Slurry and Manure Application, (2008).
10 See: National Association of Agricultural Contractors, Best Practice in Slurry and Manure Application, (2008).
11 Eurostat, Agriculture and Environment: Pollution Risks, (December 2017), p 7. Natural England estimated in 2009 that agriculture contributed to 90% of ammonia emissions in the UK, of which the majority is from livestock farming (Natural England, Environmental impacts of land management, NERR 30, (2009), p 52), whilst in 2017 the National Audit Office estimated that this figure was 81% (NAO, Air Quality, (December 2017), p 6).
12 See: Plantlife, We need to talk about Nitrogen: The impact of atmospheric nitrogen deposition on the UK’s wild flora and fungi, (June 2018).
13 Environmental Audit Committee, Soil Health, (HC 180; June 2016), p. 5, p 17, p 22, and p 30,
14 We recommended that the Government should “produce and consult on proposals to increase the ambition, scope and effectiveness of cross compliance to mitigate the impact of agriculture on soil health and incentivise provision of wider ecosystems services such as water quality and flood protection”.
15 See: European Commission Environment Directorate, Glossary of terms related to Urban Waste Water, (accessed 10 June 2018); Defra, Waste water treatment in the United Kingdom – 2012: Implementation of the European Union Urban Waste Water Treatment Directive – 91/271/EEC, (2012), p 3.
16 For eutrophication, its causes and consequences for ecosystems see: Chislock, M. F et al, Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems. Nature Education Knowledge, (2013), vol. 4, no. 4, p 10; European Environment Agency, Eutrophication, (accessed 21 May 2018): National Ocean Service, What is eutrophication?, (accessed 21 May 2018).
17 See: Defra, Waste water treatment in the United Kingdom – 2012: Implementation of the European Union Urban Waste Water Treatment Directive – 91/271/EEC, (2012), p 3.
18 Defra, Emissions of Air Pollutants in the U1K 1970 to 2016, (February 2018), p 3.
19 See also NAO, Air Quality, (December 2017); Lancet, Commission on Pollution and Health, (October 2017); Royal College of Physicians and Royal College of Paediatrics and Child Health, Every Breath We take: The Lifelong Impact of Air Pollution, (2016); p 6 and Defra, Effects of air pollution, (accessed 10 June 2018). See also European Environment Agency, Air Quality in Europe - 2017, (October 2017), Chapter 10, pp 55–60..More recent research has suggested that air pollution can also cause brain damage and impact on intelligence - see: Xiaobo Zhang, Time to act: air pollution is damaging our brains as well as our lungs, Daily Telegraph, (October 2018) and Xin Zhang, Xi Chen, and Xiaobo Zhang, The impact of exposure to air pollution on cognitive performance, Proceedings of the National Academies of Sciences of the United States of America, (August 2018), vol 115, no 37, pp 9193–9197.
20 See also: Defra, Emissions of Air Pollutants in the UK: 1970–2016, (February 2018), p 4 and Plantlife, We need to talk about Nitrogen: The impact of atmospheric nitrogen deposition on the UK’s wild flora and fungi, (June 2018). See also European Environment Agency, Air Quality in Europe - 2017, (October 2017), Chapter 11, pp 61–65.
21 See: European Commission, In-Depth Report: Nitrogen Pollution and the European Environment Implications for Air Quality Policy, (2013), pp 5–9.
22 See: The Conversation, Nitrogen pollution: the forgotten element of climate change, (December 2016).
23 Committee on Climate Change, Reducing UK Emissions: 2018 Progress Report to Parliament, (June 2018), p 184 -188.
Published: 22 November 2018