Hidden greenhouse gas emissions from urban waterways


  • Supervisors: Dr Joshua Dean, University of Liverpool
    Dr Sarah Clement, University of Liverpool
    Prof Andy Plater, University of Liverpool

  • External Supervisors:

  • Contact:

    Dr Joshua Dean (University of Liverpool) joshua.dean@liverpool.ac.uk

  • CASE Partner:

Application deadline: 10 January 2020

Introduction:

Methane (CH4) and carbon dioxide (CO2) are the two most important greenhouse gases driving global climate change. Waterways, such as rivers and canals, are large emitters of greenhouse gases, releasing the equivalent of 20% of anthropogenic CO2 and 35% of anthropogenic methane CH4 to the atmosphere (1, 2). These estimates come with large uncertainties, however, as they are mainly based on indirect measurements, with few studies directly measuring waterway emissions. Further, there is limited information available about the source of these emissions and to what degree they are influenced by anthropogenic activity.

Urban waterways have the potential to emit CO2 and CH4 from a wide variety of natural and anthropogenic sources. Studying the dynamics of these emission could reveal opportunities to reduce emissions at the city scale. London and Birmingham, for example, account for 18% of the UK’s carbon emissions (3), and have substantial canal and river networks – Birmingham alone has over 100 miles of canals, more than Venice.

All major cities rely to some degree on waterways for consumption, sanitation, trade, climate regulation and public well-being. However, we have virtually no data on the role waterways play in urban greenhouse gas emissions. Preliminary estimates suggest CH4 and CO2 emissions from Amsterdam’s canals could be equivalent to the emissions of 8% (36,000) of its households. By 2030, more than 60% of the global population (or more than 5 billion people) will live in cities. It is therefore crucial to understand how population growth will affect GHG emissions from urban waterways.

Project Summary:

This project seeks to address three key questions:

i) What is the importance of waterways to total urban greenhouse gas emissions?

ii) What are the main emission sources from urban waterways?

iii) How will increasing urbanisation affect waterway emissions?

The candidate will combine analyses of radiocarbon (14C) and stable isotopes (δ13C and δ2H) of CO2 and CH4 with comprehensive spatial and temporal studies of urban waterway emissions. Comprehensive isotopic data are currently missing, limiting our ability to determine aquatic emission sources in general. 14C is a novel and unique tracer for understanding methane cycling (particularly fugitive methane) (4), and its fate in urban waterways – is it released to the atmosphere or is it oxidised? This project will be the first to measure the 14C signature of methane in urban waterways.

The candidate will work within an interdisciplinary team, including collaborators at Radboud University in the Netherlands, providing the opportunity to match emission and source data with microbial community dynamics. This will allow comprehensive understanding of the environmental factors governing greenhouse gas production, oxidation and emission. This has future applications in mitigating leaking natural gas (CH4) from fracking, for example.

Training and initial fieldwork will take place in Liverpool, but there will be opportunities to travel to Woods Hole Oceanographic Institution in the USA, Radboud University in the Netherlands, and the NERC Radiocarbon Facility in East Kilbride. Primary fieldwork will be in Liverpool, Manchester and Birmingham, and there will be opportunities to work in London, Amsterdam and Venice.

References:

1) Raymond, P et al. (2013). Global carbon dioxide emissions from inland waters. Nature 503, 355-359.

(2) Dean, JF et al. (2018). Methane feedbacks to the global climate systems in a warmer world. Reviews of Geophysics 56, 207-250.

(3) Moran, D et al. (2018). Carbon footprints of 13 000 cities. Environ. Res. Lett. 13, 064041.

(4) Dean, JF et al. (2017). Ancient dissolved methane in inland waters revealed by a new collection method at low field concentration for radiocarbon (14C) analysis. Water Res. 115, 236-244.

(5) Mitchell, M et al. (2017). Biodiversity on the brink: Evaluating a transdisciplinary research collaboration. J. Nat. Conserv. 40, 1-11.

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