Acid Deposition

The Acid Deposition Monitoring network (ADMN) was established in 1986 to monitor the composition of precipitation and hence to provide information on deposition of acidifying compounds in the United Kingdom. Its main emphasis has always been the assessment of potential impacts on UK ecosystems. Other measurements are also made within the programme - sulphur dioxide, nitrogen dioxide, particulate sulphate - to provide a more complete understanding of precipitation chemistry in the United Kingdom.

Parameters Measured

Monitoring Sites and Data

Acidity in precipitation
Acidity wet deposited
Ammonium as N aerosol (coarse)
Ammonium as N aerosol (fine)
Ammonium as N in precipitation
Ammonium as N wet deposited
Bicarbonate wet deposited
Calcium in precipitation
Calcium wet deposited
Chloride aerosol
Chloride aerosol (coarse)
Chloride aerosol (fine)
Chloride in precipitation
Chloride wet deposited
Conductivity
Magnesium in precipitation
Magnesium wet deposited
Nitrate as N aerosol (coarse)
Nitrate as N aerosol (fine)
Nitrate as N in precipitation
Nitrate as N wet deposited
Nitric acid gas as N
Nitrogen dioxide
Nitrogen dioxide as N
Non-marine sulphate as S in precipitation
Non-marine sulphate as S wet deposited
Particulate ammonium
Particulate nitrate
pH in precipitation
Phosphate as P in precipitation
Phosphate as P wet deposited
Potassium in precipitation
Potassium wet deposited
Rainfall
Sodium aerosol
Sodium aerosol (coarse)
Sodium aerosol (fine)
Sodium in precipitation
Sodium wet deposited
Strong acid in precipitation
Strong acid wet deposited
Sulphate as S aerosol
Sulphate as S aerosol (coarse)
Sulphate as S aerosol (fine)
Sulphate as S in precipitation
Sulphate as S wet deposited
Sulphur dioxide as S
Sum of ammonia and ammonium
Sum of nitric acid and nitrate

Current Sites: 82
Total Sites: 130
Data Availability: 01/01/1973 to 13/04/2010

This network has evolved substantially over time. It was originally based on two sub-programmes - a 'primary' network providing high quality and high frequency data, which could be used to identify trends over time and a 'secondary' network providing information on the spatial distribution of acid deposition in the UK. Originally, there were 9 primary and 59 secondary sampling sites. Subsequent changes made to the programme, including different measurement techniques, altered sampling frequencies and reductions to the number of monitoring sites, have made this distinction less clear cut.

In 1999, seven new sites were established to monitor rainwater composition in ecologically-sensitive areas. The UK Nitric Acid Monitoring Network was also introduced to the acid deposition contract in 1999; this provides monthly data on acid gases and particulates. Further changes in 2006 saw the exposure of triplicate nitrogen dioxide diffusion tubes at three sites and the installation of a wet-only daily precipitation collector at one site. In addition, sulphur dioxide measurements undertaken by the ADMN and Rural SO₂ Monitoring Network (part of the Acid Deposition Processes contract) were terminated at the end of 2005, being replaced by measurements made as part of the expanded nitric acid monitoring network.

In 2007, the network covered the following measurements and sites:

The Acid Deposition Monitoring Network - site numbers and measured parameters

Precipitation Composition	Rainwater sampling using a bulk collector on a fortnightly basis at 38 sites Rainwater sampling using a bulk collector on a daily basis at 1 of the above sites Additional wet-only measurements on a daily basis at 1 site
Particulate Sulphate, Nitrogen Dioxide	Sampled on a daily basis at 5 sites Diffusion tube measurements on a monthly basis at 24 sites. Of these sites, 3 operate triplicate tubes
Nitric Acid, other acid gases and aerosol	Denuder (DELTA) measurements on a monthly basis at 30 sites

Acid Deposition

The Acid Deposition Monitoring Network - site numbers and measured parameters

Non-automatic monitoring stations for acid deposition, nitric acid and ammonia during 2007