Swedish National Nitrogen Budget - Atmosphere

In this report, pool 7 ‘Atmosphere’ (AT) of the Swedish National Nitrogen Budget (NNB) is presented.

The atmospheric pool of NNB is one of the 8 major pools defined by the Task Force of Reactive Nitrogen (TFRN) which together represent a total national nitrogen budget capturing all major flows of all forms of reactive nitrogen (Nr) within a country and across the country borders.

The methodology to calculate NNB has been provided by the Expert Panel on Nitrogen Budgets (EPNB) in the Annexes to the ECE/EB.AIR/119 – “Guidance document on national nitrogen budgets".

The major flows of Nr to and from the tropospheric air masses above Sweden, including the Swedish national coastal waters, were calculated for the year 2015. Except for the small amount of Nr generated by lightnings, the atmospheric Nr pool is dominated by four main flows: the import and export of Nr by transboundary transport; by Swedish emissions of Nr; and by atmospheric deposition. 

The principal source of the emission data has been the official Swedish reporting to the Centre on Emission Inventories and Projections (CEIP) under the Air convention (The Convention on Long-range Transboundary Air Pollution, CLRTAP).

For the reactive nitrogen deposition in Sweden the official national operational estimates by the MATCH Sweden system were used.

The results show that in 2015 Sweden was a net importer of air pollution in the form of Nr, i.e. the import of Nr from the emission sources outside the country (139 kt N) was larger than the export (96.1 kt N).

The Swedish emissions of Nr in 2015 were in total 117 kt N. The largest emissions come from two sectors: Agriculture (43.4 kt N) and Energy & Fuels (40.6 kt N). The deposition of Nr to Swedish ecosystems in 2015 was 160 kt N, of which 87% originated from emission sources abroad.

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