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Ammonia monitoring in the UK - AQ0619

Ammonia is an air pollutant, mainly emitted from livestock farming, that can contribute to acidification, nitrogen enrichment and aerosol formation. In recognition of these impacts, the UK has agreed to curb ammonia emissions from 2010, under the UNECE Gothenburg Protocol and the EC National Emission Ceilings Directive. Ammonia is also one of the pollutants addressed under the EC Integrated Pollution, Prevention and Control Directive, requiring installations to use best available techniques to minimize environmental damage.

The Department for Environment, Food and Rural Affairs (Defra) runs a substantial programme of research on ammonia, including monitoring, atmospheric modelling and assessment of environmental impacts . The UK Ammonia Monitoring Network has been operated on behalf of the Department for Environment, Food and Rural Affairs since 1996. The network now contains over 80 sites monitoring concentrations of ammonia and ammonium aerosol, using a mixture of passive samplers and denuders. The Centre for Ecology and Hydrology have operated the network to date, and further information on the network, monitoring sites and data can be found on:


One of the key issues with ammonia is that the distribution is highly spatially variable in the rural environment. This is a result of it being an agricultural pollutant emitted from near ground level farm sources, of its large deposition velocity to semi-natural land and a relatively fast conversion rate to ammonium aerosol. Quantifying the spatial distribution of ammonia in the UK is essential to quantifying the problem and informing policy.

The aim of the network is to provide:

• Spatial patterns for defining the concentration field (to be mapped on 5km x 5km grid) which can be used in other Defra research contracts (where it is input to deposition models to provide total nitrogen deposition, for comparison with critical load for nutrient nitrogen and acidity).
• Spatial patterns for testing regional variations in the performance of atmospheric transport models.
• Seasonal patterns for different regional areas to help understand ammonia exchange processes and the effects on the UK ammonia budget.
• Improved estimates contributing to the UK ammonia budget, minimizing uncertainties associated with dry deposition totals.
• A baseline for the examination of responses to agricultural changes and potential ammonia emission controls in source and sink areas.
• An assessment of the influence of sub-grid variability on measurement bias in the network.


1. Operate and maintain a network measuring ammonia concentrations across the UK. Broad continuity with the current network (details of website given above) must be maintained, but tenderers should consider whether the current distribution of sites needs modification to achieve the aims outlined above more effectively and propose costed options together with a justification for proposed changes.

2. Consider the case for monitoring concentrations with local networks within a 5km grid square to assess sub-grid variability.

3. Monitor concentrations of ammonium aerosol at a subset of sites to help validate existing atmospheric models, in particular with respect to transboundary fluxes.

4. Analysis of measurement results on an annual basis to provide UK concentration fields at 5km x 5km resolution. Comparison of these results with predictions from modelling studies under other Defra contracts (e.g. Fine Resolution AMmonia Exchange model [Prof. David Fowler, CEH Edinburgh]).

5. Ensure all monitoring data, maps and results of above analyses are available on the internet, together with additional details on the sites and monitoring methodology.

6. Ensure production of representative data of high quality, using appropriate Quality Assurance/Quality Control procedures.
Project Documents
• Final Report : NAMN Final Report   (4715k)
Time-Scale and Cost
From: 2003

To: 2008

Cost: £578,265
Contractor / Funded Organisations
Centre for Ecology and Hydrology
Air Pollution              
Environmental Protection              
Fields of Study
Air Quality