Background and Importance
Ammonia (NH3) has an ever-growing influence on air pollution in the UK and worldwide with numerous considerable deleterious impacts such as the formation of secondary particles (now the dominant contribution), nitrogen deposition and eutrophication. Despite the importance of NH3, emissions of NH3 are highly uncertain and have remained poorly quantified. This project aims to significantly improve the estimates of NH3 emissions in the UK through targeted measurements using a mobile laboratory. The need to reduce NH3 emissions in Europe as part of controlling the long-range transport of air pollution is well-established through international commitments. While emissions of other pollutants that are also controlled internationally such as NOx, SOx and PM2.5, NH3 arguably poses the greatest challenge to effectively control. Moreover, while the emissions and concentrations of most other key pollutants have decreased over the past two decades, emissions of NH3 have not and may even increase in future as the climate warms.
Underpinning these issues is the weak evidence related to NH3 sources in terms of their magnitude, spatial and temporal distributions. The lack of robust evidence in this area is a major limitation in understanding of current and future impacts of NH3 emissions in the UK and beyond; and is out of step with the current evidence available on emissions and concentrations. For example, the main UK NH3 network only provides monthly average data which is not sufficient to develop a good understanding about sources of NH3. As the health evidence related to the adverse effects of air pollution continues to strengthen, there will be more focus on controlling particulate precursors such as NH3. However, any current or future policies aiming to control NH3 emissions will need to be based on robust information on the emission source strength from numerous types of sources e.g. including agriculture and combustion sources.
Aims of the PhD
The main aims of this PhD project will be to use the Wolfson Atmospheric Chemistry Laboratories (WACL) mobile laboratory to develop and refine methods for NH3 emissions quantification and develop an improved understanding of the spatial distribution of ambient concentrations. The mobile laboratory has the potential to measure a wide range of air pollutants and greenhouse gases including NOx, NO2, CO, SO2, particulate matter (at a range of sizes) CH4 and CO2. The addition of NH3 measurements would provide a rich suite of multipollutant data and considerably enhance the ability to characterise and quantify a wide range of sources e.g. related to combustion and non-combustion emissions. The fast response measurement of multipollutant data has the potential to provide a much-improved basis for source differentiation.
The project will use a dedicated new, highly capable instrument for measuring NH3 in the atmosphere based on a Quantum Cascade Laser Absorption Spectroscopy. The short open-path instrument will be added to the mobile laboratory for making fast (up to 10 Hz) measurements of NH3. The instrument also has the capability of making atmospheric flux measurements to quantify area source emissions.
At York, considerable progress has been made in developing improved quantitative techniques for mobile measurement data; mostly focused on vehicle emissions quantification. This is an important area of research and has enormous scope for further progress. While it is challenging to develop new techniques for the analysis of mobile / spatial data, a focus on this area is likely to yield new approaches that would be of interest internationally, and which could be applied to a wide range of problems. While developments have been made to better quantify vehicle emissions using mobile measurements, much less progress has been made at identifying discrete sources both in urban and rural settings. The project will also use inverse air quality modelling using a local scale dispersion model to locate and quantify different discrete sources through plume transect measurements.
Benefits to student
The student would join one of the UK’s leading centres for atmospheric research. The PhD would offer broad training and experience covering instrument use, development of mobile measurement capabilities through fieldwork, and a strong emphasis on developing excellent analysis and interpretation skills. The PI (Prof. David Carslaw) has a joint position with Ricardo Energy & Environment, which is the UK’s largest consultancy for air quality and which leads many large national and international projects related to air pollution. These and other links, offer a wider experience for the student, which will help place new research in a wider context in terms of its impact. The results from this project would be of direct interest to organisations such as Defra and the Environment Agency who are responsible for regulating both emissions and concentrations of air pollutants in the atmosphere, giving the student experience in the importance of this research for policy-makers. It would be anticipated that the outputs from this project would provide invaluable new information to the National Atmospheric Emissions Inventory (NAEI), where the uncertainties of NH3 emissions is well-recognised, and several strong journal publications.
All Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills: https://www.york.ac.uk/chemistry/postgraduate/training/idtc/
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/.
For more information about the project, click on the supervisor's name above to email the supervisor. For more information about the application process or funding, please click on email institution
This PhD will formally start on 1 October 2023. Induction activities may start a few days earlier.
To apply, submit an online PhD in Chemistry application: https://panorama-dtp.ac.uk/how-to-apply/
You should hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject. Please check the entry requirements for your country: https://www.york.ac.uk/study/international/your-country/
The NERC Panorama DTP are hosting ‘Demystifying the PhD application process’ webinars on the 9th and 12th December – sign up now!