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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 

Lead Supervisor: Rachael Rhodes, Earth Sciences

Co-Supervisors: Liz Thomas, British Antarctic Survey & Chiara Giorio, Chemistry

Importance of the area of research concerned: 
Carbon monoxide (CO) plays a critical role global atmospheric chemistry. It reacts quickly with hydroxyl radicals (OH), removing them from the troposphere. In turn, this reaction impacts levels of atmospheric methane (CH4) because oxidation by OH is its primary sink. As carbon monoxide levels increase due to anthropogenic activity, the capacity of the atmosphere to remove accumulating methane could reduce causing the atmospheric methane burden to further increase. CO is also an important precursor to the formation of tropospheric ozone through the reaction with OH. There is little information about how the oxidative capacity of the atmosphere varied in the past in response to human-induced and natural climate changes and this causes significant uncertainty in future predictions. Bubbles trapped in ice cores provide samples of ancient air, offering the potential to fill this gap. OH cannot be measured but CO can, although few measurements have been conducted (1). A new measurement technique using laser spectrometry offers the best possibility of reconstructing the history of this critical trace gas.
Project summary : 
The primary objective of this project is to produce a history of atmospheric CO variability through the Holocene. Due to the relatively low levels of chemical impurities, ice cores from Antarctica are likely the best targets for this work and will be the focus of the first phase of this project. Obtaining CO records from several Antarctic cores will ensure a robust signal is extracted. However, due to the short atmospheric lifetime of CO, an Antarctic-based CO history will miss CO variability resulting from regional biomass burning and human activity in the Northern Hemisphere. The second phase will therefore focus on improving our ability to obtain CO records from other regions by determining the processes responsible for anomalously high CO concentrations. Your findings will inform future drilling and measurement efforts to recover atmospheric CO histories.
What will the student do?: 
You will start by developing a portable system to produce high resolution measurements of CO concentrations in ice core gas. This will use a recently-introduced method that continuously measures CO by laser spectroscopy as the gas is released from a narrow stick of ice core as it is melted (2). This system will then be used to measure ice cores from Antarctica and other latitudes either at the British Antarctic Survey (BAS) in Cambridge or in other laboratories by participating in measurement campaigns where soluble and insoluble chemistry is measured simultaneously on same ice stick as the gas. Additionally, although this project is not dependent on the collection of new ice cores, we will endeavour to include you in future ice core drilling fieldwork. In the second phase of the project, the CO records obtained will be used to target ice core samples for organics analysis. The samples will be pre-concentrated and analysed at the Department of Chemistry, following a proven method developed by the project team (3). You will also design and carry out tests to investigate the chemical and/or biological processes potentially involved in CO production within the ice.
References: 
1. Wang, Z., Chappellaz, J., Park, K., Mak, J.E., 2010. Large variations in Southern Hemisphere biomass burning during the last 650 years. Science 330, 1663–6. https://doi.org/10.1126/science.1197257
2. Faïn, X., Chappellaz, J., Rhodes, R.H., Stowasser, C., Blunier, T., McConnell, J.R., Brook, E.J., Preunkert, S., Legrand, M., Debois, T., Romanini, D., 2014. High resolution measurements of carbon monoxide along a late Holocene Greenland ice core: evidence for in situ production. Clim. Past 10, 987–1000. https://doi.org/10.5194/cp-10-987-2014
3. King, A.C.F., Giorio, C., Wolff, E., Thomas, E., Karroca, O., Roverso, M., Schwikowski, M., Tapparo, A., Gambaro, A., Kalberer, M., 2019. A new method for the determination of primary and secondary terrestrial and marine biomarkers in ice cores using liquid chromatography high-resolution mass spectrometry. Talanta 194, 233–242. https://doi.org/10.1016/j.talanta.2018.10.042
Applying
You can find out about applying for this project on the Department of Earth Sciences page.