UK Acidifying and Eutrophying Atmospheric Pollutants

Managing the UK's Rural Air Quality Monitoring Networks

Defra project number AQ0647

The UK Eutrophying and Acidifying atmospheric Pollutants (UKEAP) network measures air pollutants at rural sites across the UK. For more information about the UKEAP project please email the Project Coodinator.

Precipitation network (Precip-Net)
Fortnightly inorganic anion & cation concentrations in precipitation at 39 sites, operational since 1985.

National Ammonia Monitoring Network (NAMN)
Monthly gas phase ammonia concentrations in air at 85 sites, operational since 1996.
Particulate phase ammonium at a subset of sites since 1999.

Acid Gas and Aerosol Network (AGANet)
Monthly gas phase SO_2, HNO₃, HCl; major particulate phase inorganic anions and cations at 30 sites, operational since 1999.

NO₂Net
Four-weekly NO₂ concentrations at 24 sites, operational since 1994.

EMEP Supersites
Harwell Supersite, Oxfordshire: rural, mixed land use site (Ricardo Energy & Envrionment)
Auchencorth Moss Supersite, Scotland: upland deep peat site (CEH)

The objective of the five components UKEAP 2012-16 is to have a coherent strategy for understanding the composition of the background and rural UK atmosphere available for science and policy use. UKEAP 2012-2016 removes the historic disconnect between low frequency and high frequency measurements allowing linkages to be made between the datasets and hence a higher level of information is derived from them both. An over-arching objective is to provide on-going high and low frequency chemical monitoring and campaign mode measurements of the rural and semi-rural background atmosphere to inform the scientific understanding of the non-urban contributions to PM levels, at urban, UK and international scales. The UKEAP project data is publically available and archived on UKAir and reported to EMEP annually.

Defra’s aims for the network are to primarily to monitor the concentrations of eutrophying and acidifying species in air and precipitation in rural areas of the United Kingdom with sufficient spatial and temporal resolution to allow:

the evaluation of policy measures to reduce concentration and deposition
risks to ecosystems and exceedences of critical loads to be assessed
estimates of secondary aerosol for PMx

Currently other Defra funded projects use the pollutant concentration datasets to calculate and map pollutant exposure and pollutant budgets. This activity downstream of the UKEAP project is a key element in estimating risks to ecosystems and evaluating the impact of policy measures in reducing such risks. The measurements also help support many of the other measurements made within Defra and other Agency-supported monitoring in the UK, for example at Environmental Change Network (ECN) sites and heavy metal monitoring sites.

The objective of the EMEP Supersites is to give high quality highly speciated information on the composition of air at two sites, in order to fulfil the UK’s commitment within the UNECE and to aid research including theory and modelling of atmospheric chemistry, physics and deposition processes.

AGANet (CEH)	NAMN (CEH)

The UK Acid Gases and Aerosols Monitoring Network has been in operation since September 1999, providing monthly measurement data of acid gases and aerosols. An extension of the DELTA system at the NAMN sites is used to additionally sample gaseous HNO₃, SO₂, HCl and particulate NO₃^-, SO₄^2-, Cl^-, Na⁺, Ca²⁺, Mg²⁺. The new expanded to include measurements of gaseous SO² and particulate SO₄^2-	Established in 1996, the objectives of the network are to quantify temporal and spatial changes in air concentrations and deposition in NH3 and NH4+ (included since 1999) on a long term basis. The monitoring provides a baseline in the reduced nitrogen species (NH₃ + NH₄⁺), which is necessary for examining responses to changes in the agricultural sector and to verify compliance with targets set by international agreements.
PrecipNet (Ricardo Energy & Environment)	NO2-Net (Ricardo Energy & Environment)

There are 39 sites in PrecipNet at which the chemical composition of precipitation (i.e. rainwater) is measured. Six of the sites, Lochnagar, Llyn Llagi, Scoat Tarn, Loch Chon/Tinker, River Etherow, Beaghs Burn and Crai Reservoir (Head of the Valleys) were specifically located within sensitive ecosystems. The network allows estimates of wet deposition of sulphur and nitrogen chemicals.	The nitrogen dioxide measurements are made at 24 of the 38 PrecipNet composition sites. Diffusion tubes are used to measure nitrogen dioxide. The tubes are mounted on the upright of the rain collector stand and exposed for four or five week periods throughout each year. Triplicate nitrogen dioxide diffusion tube measurements are compared with automatic AURN instruments at three sites (Yarner Wood, Harwell and Eskdalemuir).