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Nitrogen - total as N

SPRI Emission Reporting Threshold
50,000 Kg/yr Pollutant Emissions to Land
50,000 Kg/yr Pollutant Emissions to Water
50,000 Kg/yr Pollutant Emissions to Waste Water
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Nitrogen gas naturally makes up about 80% of the air we breathe. "Total nitrogen" refers to any chemical compounds containing nitrogen - of which there is a wide range of both inorganic and organic (carbon-containing) compounds.
What is it used for?
The major use of compounds containing nitrogen is as fertilisers, both natural (manure) and man-made.
Where does it come from?
Major releases of nitrogen-containing compounds occur from combustion processes in power stations and from vehicles. They are also released into soils and water bodies as a result of fertiliser / manure application. Some are released into water bodies from industrial effluent. Oxides of nitrogen are formed naturally during thunderstorms and from forest fires.
How might it affect the environment?
An excess of nitrogen-containing substances in the environment causes damage through eutrophication and acidification. Eutrophication occurs when increased levels of nitrogen lead to excessive growth of algae in water bodies. The resulting "algal bloom" chokes other aquatic life (plants, fish and other organisms), starving them of oxygen and other nutrients and blocking sunlight. Acidification of soils results from excessive uptake of acidic nitrogen-rich compounds by plants and directly from the atmosphere. Emissions of soluble nitrogen compounds from man's activities can travel up to thousands of kilometres from the source and may therefore cause eutrophication and acidification in remote regions.
How might exposure to it affect human health?
Exposure to an excess of nitrogen-rich compounds is unlikely to harm human health directly. Indirectly however, risks are posed by algal toxins produced in eutrophic waters and by increased exposure to potentially damaging forms of toxic metals in acidified waters.
What steps are being taken to limit the potential impacts?
A range of legislation covers control of emissions of nitrogen-rich compounds to the environment. Relevant directives from Europe (which the UK, including Scotland, must implement) include integrated pollution prevention and control (96/61/EC); combating of air pollution from industrial plants (84/360/EEC); ambient air quality management and assessment (1999/30/EC); protection of groundwater against pollution (80/68/EEC); and control of nitrates from agricultural sources (91/676/EEC). The main international legislation controlling release of nitrogen-rich compounds is the OSPAR convention which was devised to protect the marine environment of the north-east Atlantic.