Deposition of nitrogen compounds

Nitrogen compounds are primarily emitted into the atmosphere through the combustion of fossil fuels, e.g. in transport, and in agriculture. Combustion processes mainly produce oxidised nitrogen compounds, namely nitrogen monoxide and nitrogen dioxide. Reduced nitrogen occurs in the air mainly in the form of ammonia, with the main sources being livestock farming and the application of fertilisers. In the air, some of the emitted nitrogen undergoes chemical transformation and is therefore often an important precursor to the formation of secondary particulate matter.