Ammonia futures – the changing face of atmospheric nitrogen emissions

Introduction

Air pollution is the greatest environmental threat to human health, and impacts biodiversity, and ecosystem services. Emissions of ammonia have been fairly static in recent decades, unlike many other priority air pollutants which have reduced substantially. Ammonia contributes to the formation of airborne particulate matter, which is associated with human health impacts, and is deposited to the surface causing harm to ecosystems.

With stretching Net Zero targets requiring decarbonisation of all sectors of the economy, there is potential for a large-scale change in where, and in what form, nitrogen is emitted. Some examples of potential areas of change which could affect ammonia emissions include:

- Increasing use of anaerobic digestion for methane production and low carbon electricity;

- Ammonia as a fuel and as a hydrogen carrier;

- Phase out of internal combustion engine cars and vans;

- Fertilisation supporting increased use of energy crops, trees and vegetation cover;

- Requirement for more food production from less land;

- Decentralisation of heat and power generation;

- Use of selective catalytic reduction for more applications burning low carbon fuels;

- Changes to farming practice including moves to new systems such as vertical farming; and

- Agricultural system responses to changing climate.

Climate change via changes to temperature and rainfall will also impact how much ammonia is emitted, how it partitions between the gas and aerosol phase and therefore where its impacts are generated.

The project

This project will explore the breadth of changes being suggested as plausible actions over the next period. Using systems-based approaches, expert elicitation, and literature meta-analysis, we will look at how these changes might manifest and therefore what potential ‘ammonia futures’ they could represent. We will carry out systems mapping and analysis to establish what the pathways are that affect key outcomes, including ammonia emissions, as well as where there is the potential for technical or policy influence. We will identify areas of specific interest from these processes and carry out atmospheric modelling to evaluate how changes in activity and location of emissions could lead to different atmospheric chemical compositions to those seen today, and what that might mean for air quality and deposition to ecosystems. This will support decision-makers when considering the breadth of change that will be occurring and to identify opportunities for beneficial change or emerging issues of concern.

During this project the student would be expected to be involved in designing and facilitating workshops and engaging with stakeholders. This work will be carried out in partnership with the Department for the Environment, Food and Rural Affairs (Defra) and with support from their Air Quality Expert Group. Collaboration and knowledge exchange with other PhD students on the same programme will be encouraged.

The student will be based in the Wolfson Atmospheric Chemistry Laboratories (WACL), in the Department of Chemistry at the University of York. WACL is the largest atmospheric chemistry facility in the UK, providing access to state-of-the-art facilities and a wide range of interdisciplinary expertise. The student will benefit from research training and events tailored for atmospheric chemistry students, including training courses provided by the National Centre for Atmospheric Science.

Close links with Defra will give the student experience of working at the science-policy interface, engaging with policy makers to produce research with real-world impact. There will also be an opportunity to undertake work-shadowing or a placement in Defra.

You will follow our core cohort-based training programme to support the development of scientific, transferable and employability skills, as well as training on specific techniques and equipment. Training includes employability and professionalism, graduate teaching assistant training and guidance on writing papers. https://www.york.ac.uk/chemistry/postgraduate/training/idtc/idtctraining/  

There will be opportunities for networking and sharing your work both within and beyond the University. Funding is provided to enable you to attend conferences and external training. The department also runs a varied and comprehensive seminar programme.

Equality and Diversity

The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/

As part of our commitment to Equality and Diversity, and Widening Participation, we are working with the YCEDE project (https://ycede.ac.uk/) to improve the number of under-represented groups participating in doctoral study.  

Entry requirements 

You should hold or expect to achieve the equivalent of at least a UK upper second class degree in subject such as atmospheric science, chemistry, physical sciences, natural science, environmental science, geography . 

For more information about the project, click on the supervisor's name above to email them. 

For more information about the application process or funding, please click on email institution.

Guidance for applicants: https://www.york.ac.uk/chemistry/study/postgraduate-research/phd-mphil/

Submit an online PhD in Chemistry application: https://www.york.ac.uk/study/postgraduate/courses/apply?course=DRPCHESCHE3

Applications may close early if a suitable applicant is found.

The start date of the PhD will be 15 September 2025