Rivers emit ~2-3 Pg of carbon as the greenhouse gas carbon dioxide (CO2) to the atmosphere each year. This is equivalent to 20% of annual anthropogenic CO2 emissions and an important component of the global carbon cycle. Methane (CH4) emissions from rivers, a greenhouse gas 34 times stronger than CO2 over a 100-year timeframe, are estimated to be ~27 Tg of CH4 each year, equivalent to 8% of anthropogenic CH4 emissions. Rivers, acting as conduits for terrestrial greenhouse gases, can thus influence ongoing climate change. Landscape disturbance, either through human activity or climate change, can enhance river carbon emissions adding substantially to an already overloaded atmospheric carbon pool. Characterising the magnitude and source of river carbon emissions across globally representative ecosystems is therefore urgently needed for us to understand and predict current and future climate change.
Carbon emissions from rivers are primarily derived from the landscapes they drain. But carbon sources within these landscapes can vary greatly depending on the ecosystem. Sources can include decaying plant and soil carbon, soil carbon that has accumulated over millennia such as in Arctic, temperate and tropical peatlands, and even ancient geological carbon derived from erosion and weathering. This PhD studentship will explore the importance of terrestrial and geological carbon cycling to river carbon emissions.
The project will seek to address three core objectives:
1) How do the magnitude and source of river carbon emissions vary across ecosystems?
2) Does the input of aged carbon to rivers, whether from landscape disturbance or natural landscape carbon cycling, result in its rapid emission to the atmosphere?
3) How do we use the isotopic composition of river carbon emissions as an indicator of a disturbed carbon cycle?
To address these objectives, the project will explore the role of erosion in supplying carbon to rivers and the subsequent emission of this carbon to the atmosphere. Erosion rates will be determined across a range of catchments using brand new luminescence techniques developed at the University of Liverpool. River CO2 and CH4 emissions will be measured directly using a state-of-the-art greenhouse gas analyser (Los Gatos Inc.), and the sources of these emissions will be determined using radio- and stable carbon isotopes. These techniques will initially be applied to catchments in the UK, with the potential to carry out investigations in New Zealand, Australia, Europe and the Arctic.
The outcome of this project will help to understand how river biogeochemical signals reflect carbon cycling in their catchments. This information can be used to inform management strategies for short- and long-term carbon storage in landscapes, such as soil and geologic carbon sequestration. For example, how efficient are soil carbon storage or enhanced weathering as negative emission technologies – technologies designed to remove carbon from the atmosphere in order to meet the Paris climate targets?
This studentship will form an integral part of an international research network funded by a NERC Global Partnership Seedcorn grant “CONFLUENCE – Disentangling the role of rivers as greenhouse gas conduits”, and will be supported by additional funding and training from the UKRI National Environmental Isotope Facility. The candidate will also gain comprehensive training in greenhouse gas measurements, hydrology, statistical modelling in R, and luminescence approaches.
This PhD topic is one of eight eligible for funding support through the recruitment of two Graduate Teaching Assistants within Geography & Planning and Earth Sciences at 0.5 FTE over a five-year period. The expectation is that no less than 50% of your time will be made available for the pursuit of your PhD or MPhil studies. In addition to your application for the PhD (detailed here), you are also required to apply for the 0.5 FTE University Teacher Salary: (£29,177 - £33,797 pa – at 0.5FTE pro rata) ensure that, in the funding section of the PGR application form, you mark your application ‘GTA SoES Post’.
For enquiries please contact Dr Joshua Dean on: [Email Address Removed]
To apply please visit: https://www.liverpool.ac.uk/study/postgraduate-research/how-to-apply/
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