Deposition and concentration of nitrogen and sulphur for protected sites in the UK, 2018-2020

The Air Pollution Information System (APIS), through the 'Site Relevant Critical Loads' tool and APIS new mapping interface, provides critical loads for acidity and nitrogen and critical levels for ammonia, sulphur dioxide and nitrogen oxides for designated features within every SAC, SPA or A/SSSI in the UK. In addition, deposition and concentration data for nitrogen, sulphur pollutants and non-marine base cations are provided at each site to give an estimate of critical load/level exceedance.

The data provided is based on pollutant deposition gridded maps for nitrogen and acid deposition and concentration maps of ammonia, nitrogen oxides, sulphur and non-marine base cations, which are overlayed to a GIS shape file of site boundaries in the UK (e.g. SAC, SPA, SSSI). These gridded maps were then clipped to provide the pollutant values for each grid square including the area of the clipped grid. The resulting data was then queried to generate site statistics in the form of a minimum, maximum and area weighted average values for each of the pollutants.

For nitrogen and acid deposition values, base cations deposition and ammonia concentrations, 3 year average pollutant maps were used at a resolution of 1 x 1 km from the CBED model for the years 2018-2020. For nitrogen dioxide and sulphur dioxide concentrations the 1 x 1 km PCM model was used based on the 3 year average (2018-2020). Deposition values are generated for specific habitat types (forest and semi-natural) to be used in critical load exceedance calculations.

The full methodology is available in the contextual metadata available with this dataset.

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), the Scottish Environment Protection Agency (SEPA), and Scottish Natural Heritage (SNH).

THIS DATASET HAS BEEN WITHDRAWN

A mapping error occurred in the ammonia data of CBED 2018-2020. This also translates to an error in total nitrogen deposition.

The origin of the error is an R software update problem using the library 'proj4' to project to British National Grid which did not project correctly. Further QC checks have been put in place to help prevent this type of error occurring again. As an update, CBED and APIS - 2019-2021 will be published soon.

If you need access to the archived version, please contact the EIDC