Methane is a globally significant greenhouse gas with 28 times the warming potential of carbon dioxide gas. It has increased in concentration (2.6 fold) since pre-industrial times and thus has a significant role in earths warming (1). Anthropogenic emissions from fossil fuels, agriculture and wetlands are important sources methane while chemical reactions in the atmosphere are the predominant sink. Due to its high warming potential and a short atmospheric lifetime of 9 years, reduction of methane is an effective option to mitigate climate change. However, we still do not know if the recent increases in concentration are due to greater emissions or attenuation of sink processes.
Conventionally, methane is measured using land, air and satellite based spectroscopy and spectrometry systems. This geographically tracks elevated concentrations which in turn can be used to quantify and refine carbon emissions budgeting and Earth system models that describe the methane cycle and project future scenarios of change (1). However more specific source and temporal information is required. Radiocarbon (14C) is a naturally occurring radioactive isotope of carbon which is commonly used for dating archaeological dating of artefacts. However, it can also be used as a tracer in carbon cycle studies, including methane cycling. At present, radiocarbon analysis of methane is costly and protracted, which limits its widespread use.
Innovative, state-of-the-art technology for 14C measurement has been invented at the host institution, SUERC. This, Positive Ion Mass Spectrometry (PIMS) system (2) has been discovered by the supervisory team at SUERC to be the first mass spectrometer capable of DIRECTLY measuring 14 in methane (14CH4). This circumvents much of the laborious sample preparation that is typically required. Further development of PIMS technology for 14CH4 analysis will result in faster and cheaper analysis at reduced cost. The successful student will be embedded in the 14CH4 PIMS team and be involved in machine development with the supervisory team. The student will be able to use the optimised PIMS technology to produce some of the first 14CH4 PIMS datasets from field sites which will provide insight methane cycling and allow for detailed estimates of bottom up releases of methane from various sources.
SUERC is the only research organisation worldwide with a PIMS instrument and will lead this field, for the UK and its scientific community, enhancing international standing and collaborative reach. This project is critical for all scientists (and stakeholders) who need to understand better the global CH4 cycle to address how to live a sustainable future. Additionally, it is green field project that is anticipated to high impact publications.
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Figure 1. Left to right. A raised peat bog; The GENeco biomethane plant; The SUERC PIMS system
Training will be split into development of the PIMS technique and application to globally relevant science challenges. PIMS development will take place in a tiered fashion, first analyzing pure methane taken from biomethane gas-to-grid plants. Secondly, methane rich samples from anaerobic digesters will be used for development of mixed gas analysis and lastly, PIMS specific chemical preconcentration techniques will be developed for analysis of atmospheric samples with low concentrations of methane. The final goal is to have the best technique for comprehensive compositional and isotopic analysis of atmospheric methane.
Concurrently at each level, application to globally relevant science projects will occur focusing on future energy pathways and degraded landscape restoration. Future energy pathways include developing renewable and unconventional hydrocarbon resources. Quantification of biomethane through the production process from waste to grid as well tracking fugitive emissions from leaks to the atmosphere. Unconventional hydrocarbons (fracking) also will benefit from rapid response identification of fugitive leaks. Disrupted landscape restoration applications will focus on using radiocarbon to determine the extent rehabilitation of mine sites and peat bogs. Using UK site discharges will form a step towards engaging larger global sites including abandoned coal mines and restoration of degraded tropical peat swamps drained for palm oil production.
Literature review and laboratory training. Collection and analysis of pure methane samples from biomethane plants for PIMS radiocarbon development and validation.
Extension of PIMS analysis to mixed gas analysis from anaerobic digestors and a local raised peat bog site. Attend and present at an international conference.
Design/development of PIMS specific preconcentration techniques of atmospheric level gas analysis.
Completion of analysis and thesis write up.
Comprehensive training will be provided at SUERC (UoG) and the Lyell Center (HW) for the geochemical characterization of gases. Techniques involved: (i) sampling and preparation of gas for analysis; (ii) analysis of greenhouse gas composition by chromatography; (iii) stable isotope analysis for 13C: (iv) 14C analysis by PIMS and AMS. Training and development with the only PIMS systems worldwide will take place at SUERC and NEC in the USA. The supervisory team are experts with more than 30 years of experience in the field and are supported by a skilled team of technicians. The scholar will be enrolled at the University of Glasgow as part of the training program and will have regular meetings at Heriot Watt. Interaction with stakeholders in the biomethane and land restoration industries associated with the methane PIMS project.
References & further reading
(1) Saunois et al (2019) The Global Methane Budget 2000-2017. DOI: 10.5194/essd-2019-128.
Applications: to apply for this PhD please use the url: https://www.gla.ac.uk/study/applyonline/?CAREER=PGR&PLAN_CODES=CF18-7316