DOI: 10.5285/c4c2c5ae-d926-4ee0-b069-6479ecab2787
title: Source Attribution - deposition of nitrogen and sulphur to UK protected sites

description: This dataset contains source attribution data for nitrogen and sulphur deposition across the UK. The FRAME (Fine Resolution Atmospheric Multi-Pollutant Exchange) atmospheric dispersion model, using emission data from 2012 was used to provide 90 source footprints of nitrogen and sulphur deposition across the UK on a 5 x 5 km grid. A minimum, maximum and gridded average deposition value has been provided for the following protected sites throughout the UK:
 (i)	Special Areas of Conservation (SAC)
(ii)	Special Protection Areas (SPA)
(iii)	Sites of Special Scientific Interest (SSSI). 

The pollutants are further split into both wet and dry deposition, as well as local and long-range sources.

Habitat-specific data are provided for (i) forest, (i) moorland (short semi-natural vegetation), and (iii) grid average (average of arable, grassland, urban, forest and moorland land cover types) forest everywhere.

The work in generating and compiling this dataset has been funded by the UK pollution and conservation agencies: Natural Resource Wales (NRW), the Environment Agency, Northern Ireland Environment Agency, Natural England, the Joint Nature Conservation Committee (JNCC), Scotland and Northern Ireland Forum for Environmental Research (SNIFFER), the Scottish Environment Protection Agency (SEPA), and Scottish Natural Heritage (SNH).

description: The Air Pollution Information System (APIS), through the 'Site Relevant Critical Loads' tool, provides critical loads and critical levels for designated features within every SAC, SPA or A/SSSI in the UK. Deposition and concentration data for nitrogen and sulphur pollutants are provided at each site to give an estimate of critical load/level exceedance. In addition, pollutant deposition for nitrogen and acidity have been modelled for the emission year 2012 to provide source apportioned statistics at each site. 

The FRAME (Fine Resolution Multi-pollutant Exchange) model was used to assess the long-term annual mean deposition of reduced and oxidised nitrogen and sulphur over the United Kingdom. Emissions of Sulphur and Nitrogen for input into the model were split into 160 different sub-sectoral emission categories. This included 22 individual point sources and background 'area' emissions of SO2, NOx and NH3 split into 11 SNAP sectors (Selected Nomenclature for Air Pollution, European Environment Agency, 2013), international shipping and European import emissions.

For each 5 km grid square across the domain, pollutant compounds for SOx, NOy and NHx deposition were calculated for all footprints. In addition the output deposition data was split into more detailed chemical species to provide an approximation of how much of each 'source attribution type (e.g. livestock, fertiliser, shipping, etc.) is a short or long range input. 

Deposition data was output to three different ecosystem types - forest, moorland (representing short semi-natural vegetation) and a grid average (an average of arable, grassland, urban, forest and moorland). The resulting datasets were calibrated to CBED - Concentration Based Estimated Deposition for the three-year period 2011-2013.

The FRAME output consists of 90 footprint files which were merged with a gridded UK protected site shapefile to create to a dataset which only contained data for all SAC, SPA and SSSI sites in the UK. The minimum, maximum and grid average deposition value for each pollutant, and each footprint at each site was then calculated.

The full methodology is available in the contextual metadata which can be found attached to this record.

The work of APIS is jointly funded between the Centre for Ecology & Hydrology and the UK pollution and conservation agencies including Natural Resources Wales (NRW), the Environment Agency, Northern Ireland Environment Agency, Natural England, the Joint Nature Conservation Committee (JNCC), Scotland and Northern Ireland Forum for Environmental Research (SNIFFER), the Scottish Environment Protection Agency (SEPA), and Scottish Natural Heritage (SNH).