Introduction Nitrogen oxides (NOx = NO NO2) play a central role in the atmospheric chemistry controlling the removal of emitted gases and the production of secondary pollutants. Understanding NOx emissions both now and into the future is therefore essential if we are to tackle environmental challenges such as air pollution, climate and acid deposition. Recent studies have suggested that heavily fertilised agricultural soils could now be a major source of NOx, but current emissions inventories appear to vastly underestimate these emissions. As part of a recently funded project bringing together experts in biogeochemistry and atmospheric chemistry, this position will use the most comprehensive dataset to-date on the drivers of soil NOx production to develop a process-based model parameterisation of these emissions. Role The biogeochemical dependence of soil NOx emissions means they vary nonlinearly with region-specific agricultural management, soil conditions, and meteorology. These relationships are not currently well represented in models due in part to a lack of data capable of constraining the representation of complex soil nitrification and denitrification processes. This project aims to use existing and new data in combination with novel measurement techniques and extensive experiments to advance our process-based understanding of these complex processes. The successful applicant will use existing models of soil biogeochemical processes to identify critical model failures and work with the project team to guide ongoing extensive laboratory and field experiments to isolate the effects of environmental factors on both NOx production and NOx isotopic fractionation to provide the data required to improve model representations. Existing data from a BBSRC-funded project investigating the biogeochemical controls on reactive nitrogen emissions from agricultural soils, across a range of wheat varieties and nitrogen amendment treatments, will be explored for initial model parameterisation. The model failures identified will then direct targeted experiments at the Warwick Crop Centre to provide data capable of improving model representations. This iterative process of testing model improvements against specifically designed experiments will enable the development of a soil NOx emission parameterisation that meets the needs of global emission inventories and environmental policy. The post will be located in the Wolfson Atmospheric Chemistry Laboratories at the University of York. York is one of the UK's leading Chemistry departments and renowned internationally for research. We have been recognised consistently for our family-friendly policies and are proud of our Athena SWAN Gold Award: https://www.york.ac.uk/chemistry/ed/ We strive to provide a working environment which allows all staff and students to contribute fully, flourish, and excel. We aim to ensure that there is a supportive and egalitarian culture across all staff groups and levels. We promote good practice and a strong culture of equality in higher education. Further information can be found within this brief and on our website: www.york.ac.uk/chemistry/ Skills, Experience & Qualifications needed The successful applicant will have experience of working with atmospheric chemistry models and have advanced computer programming skills. The post is available for up to 2.5 years, from 1 September 2026. For informal enquiries: please contact Pete Edwards on pete.edwards@york.ac.uk The University strives to be diverse and inclusive – a place where we can ALL be ourselves. We particularly encourage applications from people who identify as Black, Asian or from a Minority Ethnic background, who are underrepresented at the University. We offer family friendly, flexible working arrangements, with forums and inclusive facilities to support our staff. EqualityatYork As a Disability Confident employer, we will ensure that a fair and proportionate number of disabled applicants that meet the minimum (essential) criteria for each position will be offered an interview. Read more about the University of York’s commitments under the Disability Confident scheme .