Ammonia pollution damaging more than 60% of UK land

Over 60 per cent of the United Kingdom land area currently receives ammonia concentrations above the critical level set to protect lichens and bryophytes (1 μg m-3), according to a report commissioned by the UK government. Just over 3% of the UK land area receives ammonia concentrations above the critical level set to protect higher plants (3 μg m-3) in 2013–2015. The higher ammonia levels are concentrated around a few hotspots in Northern Ireland and England. In Northern Ireland as much as 17.2% of the land area is affected by the higher concentrations.

The report also covers exceedance of critical loads for nitrogen and acid, which occur when significant harmful effects are reached for a specific habitat.

Critical loads of nutrient nitrogen (nutrient-N) were exceeded in 62% of nitrogen-sensitive habitats in the UK in 2014–2016. That is a reduction from 75% in 1995–1997. The area with the largest reduction was seen in Scotland, where the area of exceedance went from 59% to 41% between the two periods. In England there has been very little change, from 98% to 96%. Almost all of the area of unmanaged beech woodland shows exceedance of nutrient-N critical loads.

However, the magnitude of exceedance nearly halved from 22.7 kg N per ha per year in 1995–97 to 12.1kg N per ha per year in 2014–16.

The area of acid-sensitive habitats in the UK that exceeded acidity-critical loads fell by more than one third, from 73% in 1995–97 to 43% in 2014–16, due mainly to decreases in sulphur deposition. The greatest change was seen in Scotland and the least in Northern Ireland.

Trends Report 2018: Trends in critical load and  critical level exceedances in the UK Link: http://www.cldm.ceh.ac.uk/content/trends-report-2018-trend