Twelve years of nitrogen deposition gap? An EMEP4UK model analysis

Massimo Vieno1, Mark Sutton1, Mathew Heal2, Anthony Dore1, Rachel Beck1, David Fowler1, Rognvald Smith1, and Stefan Reis1

1 Natural Environment Research Council, Centre for Ecology & Hydrology, Penicuik, UK,

2 School of Chemistry, University of Edinburgh, Edinburgh, UK,


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.