Glaciers and ice sheets: (Bio)mechanochemical nutrient bioreactors for the oceans

Biogeochemical Cycles

IAP2-20-141

Overview

Subglacial water outflowing from under glaciers and ice sheets can be an important source of otherwise limiting nutrients such as phosphorous, silicon and iron for supporting productivity and CO2 drawdown in marine ecosystems (Death et al., 2014 Biogeosciences, 11, 2635-2643). To date, the fluxes and controls on nutrient production and export from ice sheets are poorly constrained. This project will investigate how “mechanochemical” reactions (the physical breaking of mineral bonds during rock crushing and subsequent free radical reactions; Telling et al., 2015, Nature Geoscience 8, 851-855) can help support subglacial microbial activity and promote nutrient cycling beneath glaciers and ice sheets. To date, studies have focused on the production of hydrogen from rock crushing, however an equal molar ratio of oxidants should also be formed during the splitting of water. This project will investigate how this additional oxidant supply can alter the energy and nutrients available to subglacial microbial ecosystems and alter the fluxes and bioavailability of nutrients exported to the oceans. Samples will be available from a range of a range of subglacial environments, including recently sampled Antarctic subglacial lakes and samples from the Greenland Ice Sheet. The PhD student will gain skills in state-of-the-art low temperature/high pressure experimentation, analytical geochemistry techniques, next generating sequencing, and geochemical modelling.

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Image Captions

Sampling subglacial debris (the dark bands) under Engabreen glacier (photo credit: Jon Telling).

Methodology

This project will:
i. Use geochemical thermodynamic modelling to model the effect mechanochemical reactions on subglacial biogeochemistry.
ii. Conduct laboratory experiments (both abiotic and with microbial inoculae) on subglacial material using dedicated newly installed low temperature/high pressure apparatus. Changes in solutes and dissolved gases will be analyzed via ion chromatography, UV-vis spectrometry and gas chromatography/mass spectrometry. Changes in microbial community will be assessed through comparisons of community composition, and changes in functional potential will be assessed through quantitative PCR (qPCR) of genes responsible for metabolic processes.
iii. Statistical analysis/synthesis. Relevant statistical methods (e.g. ANOVA, regression analysis, PCA analysis) will be used to assess the significance of results. Results will be synthesized with existing literature on subglacial biogeochemistry.

Project Timeline

Year 1

Literature review, training in geochemical and microbiological analytical techniques and thermodynamic modelling, pilot low temperature experiments at both ambient and elevated pressure, presentation at a UK conference

Year 2

Core experimentation assessing role of mechanochemistry on key subglacial biogeochemical reactions and community composition, linked to thermodynamic modelling. Further training in molecular biology techniques. Preparation of first manuscript, and presentation at a conference.

Year 3

Final experiments, data analysis, writing up thesis, preparation of second manuscript.

Year 3.5

Completion of thesis, preparation of further manuscripts.

Training
& Skills

Newcastle University has a faculty run postgraduate research development programme (http://www.ncl.ac.uk/sage/learningandteaching/postgraduateresearch/postgraduateresearcherdevelopmentprogramme/#creditrequirement that follows the Vitae Researcher Development Framework (http://www.vitae.ac.uk/). Each PhD student has a tailor made Personal Development Plan, with the expectation of them taking 60 credits in the first year and 40 credits in the second year covering both specific skills required for the project (e.g. analytical methodology, statistical analysis) and transferable skills.

The candidate will also gain expertise in the use of specialised low temperature/high pressure experimental apparatus, geochemical analyses, molecular biology and bioinformatics, biogeochemical interpretation, and core research skills such as experimental design, data analysis and scientific writing.

References & further reading

Death et al., 2014 Antarctic ice sheet fertilises the Southern Ocean. Biogeosciences 11, 2635-2643
Telling et al. 2015, Rock comminution as a source of hydrogen for subglacial ecosystems. Nature Geoscience 8, 851-855

Further Information

Please contact Dr Jon Telling for further information on this project (jon.telling@newcastle.ac.uk)

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