Project highlights

  • New research to unravel the sources of N2O from terrestrial systems.
  • A blend of laboratory and field experience, accessing skills ranging from novel analytical chemistry to molecular techniques.
  • Access to state-of-the-art instrumentation and opportunities for wider collaboration in UKRI-funded research projects.


Atmospheric nitrous oxide (N2O) concentrations have increased by an alarming 20% since pre-industrial times (Myhre et al. 2013) and future increases are anticipated. With nearly 300 times the global warming potential of CO2 over an atmospheric lifetime of approximately a century, N2O represents an important greenhouse gas and certainly the most important greenhouse gas in agricultural systems. Microorganisms are the primary source of N2O, which release the gas as a by-product of nitrogen metabolism in soils, sediments, and water bodies. Global estimates indicate that fertilized agriculture as well as lands that are not currently cultivated contributes 24-56% of total annual N2O emissions. Moreover, N2O is the dominant ozone-depleting substance in the stratosphere that is not controlled by the Montreal Protocol (Ravishankara et al. 2009). It is important, therefore, to understand the processes that generate N2O if viable management strategies are to be developed that reduce fluxes to the atmosphere. While its importance to atmospheric chemistry is well understood, the spatial and temporal variation in N2O fluxes at regional scales remain poorly constrained. This has led to significant uncertainties in the climate models used to estimate emissions, assess mitigation strategies, and predict feedbacks of global change (Butterbach-Bahl et al. 2013). As a result, policymakers lack accurate information regarding how to control N2O emissions effectively.

To help better constrain sources of N2O, this studentship will employ isotope-based methodology that allows the separation of specific soil microbial processes (nitrification vs. denitrification) responsible for N2O production in natural and managed ecosystems. The unique approach relies on the fact that N2O produced by nitrification has a significantly different intramolecular arrangement of N and O isotopes compared to N2O derived from denitrification (Hyodo et al. 2018). Thus, N2O derived from each source has a unique isotopic “fingerprint”. This approach has been validated in a small number of laboratories worldwide and has yielded novel insights regarding the processes responsible for N2O production. The PhD student will continue the development of this method using a newly acquired isotope-ratio mass spectrometry system capable of measuring N2O isotopomers. This project will measure N2O isotopomers in agronomic and natural systems and couple these measurements to molecular characterisation of N2O-producing microbes.


University of Warwick


  • Climate and Environmental Sustainability
  • Organisms and Ecosystems


Project investigator

Ryan Mushinski, University of Warwick ([email protected])


Gary Bending, University of Warwick ([email protected])


How to apply


Aim 1. Develop methodology for quantifying N2O isotopomers on an Elementar isoprime precisION isotope ratio mass spectrometer coupled to an Elementar iso flow GHG peripheral. Here we will develop and validate working standards and subsequent methods.

Aim 2. Determine N2O bulk and isotopomer composition from natural and agronomic soils at a farm in central England. In conjunction with a BBSRC-funded project, we will collect in-situ headspace gas samples from soil and analyse isotopic N2O composition. A manuscript will be prepared to report the findings from this aim.

Aim 3. Couple microbial composition and activity to N2O isotopomers. Here we will culture N2O-producing microbes from soil taken in Aim 2 and analyse their individual N2O isotopomer signal. A manuscript will be prepared to report the findings from this aim.

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

Training during this fellowship includes a wide range of molecular techniques and analyses (traditional culturing, DNA extraction from soil, PCR, sequencing, and bioinformatics) as well as analytical chemistry (isotope ratio mass spectrometry, building sampling mesocosms). Field-based sampling and measurements from natural ecosystems will also be emphasized with additional training opportunities through possible collaboration with industry partners.

Further details

Please add project/institutional contact details including a link to the application website if applicable

Environmental Processes Lab Website:

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Possible timeline

Year 1

Develop methodology for quantifying N2O isotopomers.


Year 2

Determine N2O bulk and isotopomer composition from natural and agronomic soils.

Year 3

Couple microbial composition and activity to N2O isotopomers.

Further reading

  • Butterbach-Bahl K, Baggs EM, Dannenmann M, Kiese R, Zechmeister-Boltenstern S. (2013). Nitrous oxide emissions from soils: how well do we understand the processes and their controls? Phil. Trans. R. Soc. B3682013012220130122.
  • Hyodo A, Malghani S, Zhou Y, Mushinski RM, Toyoda S, Yoshida N, Boutton TW, West JB. (2019). Biochar amendment suppresses N2O emissions but has no impact on 15N site preference in an anaerobic soil. Rapid Comm. Mass Spec. 33: 165-175.
  • Myhre G, et al. (2013). Radiative forcing of the direct aerosol effect from AeroCom Phase II simulations. Atmos. Chem. Phys. 13: 1853-1877.
  • Ravishankara AR, Daniel JS, Portmann RW. (2009). Nitrous oxide (N2O): the dominant ozone-depleting substance emitted in the 21st century. Science 326: 123-125.


The School of Life Science at the University of Warwick has SOP’s in place to allow research to continue in light of respiratory infection outbreak. This includes reducing the capacity of people in laboratory spaces, placing protective barriers between workstations, and working from home when possible. The laboratory portion of this work will proceed as normal, within the scope of the SOP’s. All meetings associated with this project will be in line with current guidelines. The field component will proceed within the confines of a subsequent SOP – to be developed between the PI in accordance with all University- and government-mandated requirements.