Twelve years of nitrogen deposition gap? An EMEP4UK model analysis

Massimo Vieno1, Mark Sutton2, Mathew Heal3, Anthony Dore4, Rachel Beck5, David Fowler6, Rognvald Smith7 and Stefan Reis8

An analysis of 12 years of annual nitrogen and sulphur deposition over the UK was carried out comparing atmospheric chemistry transport model (ACTM) results with an observation-derived calculation (CBED). The two deposition estimates agree well for oxidised sulphur, whereas total oxidised nitrogen deposition was underestimated by the ACTM. Possible causes of this discrepancy are the uncertainties of emissions estimates and the simplification in the ACTM aerosols formation. The CBED deposition estimates are less sensitive to uncertainties in the emissions inventory dataset as the UK deposition values are derived from observed deposition and surface concentrations. However, CBED wet deposition may be over-estimated due to dry deposition to the surface of bulk collectors. The UK deposition estimates show a general decline over the 2000-2012 period investigated; for oxidised sulphur ~86 (ACTM) and ~97 (CBED) Gg S yr-1, for oxidised nitrogen ~29 (ACTM) and ~45 (CBED) Gg N yr-1, and for reduced nitrogen ~7 (ACTM) and ~5 (CBED) Gg N yr-1.

 

1Centre for Ecology & Hydrology, mvi@ceh.ac.uk
2Centre for Ecology & Hydrology
3University of Edinburgh
4Centre for Ecology & Hydrology
5Centre for Ecology & Hydrology
6Centre for Ecology & Hydrology
7Centre for Ecology & Hydrology
8Centre for Ecology & Hydrology