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Agricultural ammonia emissions as a source of UK secondary aerosol and the effect of emission abatement measures - AC0103

Particulate matter contained in particles smaller than 10 um aerodynamic diameter (PM10) has long been associated with human health impacts, such as promotion of asthma, cardiovascular problems, increased hospital admission and reduction of life expectancy. Only a fraction of PM10 is composed of primary particles (e.g. re-suspened dust, friction generated particles and soot from combustion processes), while much of it is formed from condensing gases in the atmosphere (secondary particles). Secondary particles include a wide range of organic compounds and inorganic compounds, such as ammonium sulphate (AS) and ammonium nitrate (AN). The ammonium salts typically contribute 15 to 25 % to the urban PM10 and even more in the rural environment. The formation of these compounds in the atmosphere relies on the presence of the precursor gases, from which they are formed: ammonia and nitric acid for AN and ammonia and sulphur dioxide for AS.
Once formed, AS remains stable in the aerosol phase, while AN can re-evaporate as the associated gas-phase concentrations drop. Nitric acid and sulphur dioxide are produced from combustion sources (vehicles & industrial), whereas ammonia is primarily emitted from livestock wastes of agricultural activity.

This project investigates the importance of agricultural ammonia emissions for concentrations of particulate matter in the UK. For this purpose, the project will review the exisiting data on concentrations of PM10, AS and AN in the UK and compile a test database of available measurements which will be used to test and optimise the performance of numerical atmospheric transport models in later stages of the project.

Through a set of process studies, the project will improve our understanding of how the agricultural (ammonia rich) and urban (nitric acid rich) air masses mix and interact to form aerosol. These measurements will be made in the laboratory, at individual farms and along a transect across an intensive agricultural region (East Anglia). The results will be used to develop improved descriptions of the process for implementation in an atmospheric transport and chemistry model.

The model will then be used to quantify the effect of agricultural ammonia emissions on the aerosol burden in the UK and in particular in UK cities. In numerical scenario calculations, the emission data used in the model runs will be modified to investigate the impact of reduced emissions of ammonia, nitrogen oxides and sulphur dioxide on aerosol emissions. Here, the model will assess the impact different levels of implementation of emission reduction measures in the UK agriculture would have on UK aerosol concentrations.
Time-Scale and Cost
From: 2006

To: 2010

Cost: £225,916
Contractor / Funded Organisations
Centre for Ecology and Hydrology
Fields of Study
Agriculture and Climate Change