NERC GW4+ DTP PhD Studentship: Development and application of a novel 15N-stable isotope probing (SIP) method for the determination of atmospheric N2 fixation in soils

University of Bristol - Faculty of Science - School of Chemistry

The project:

The major source of N-fertiliser for agriculture is the Haber-Bosch process, which chemically fixes atmospheric N2 into ammonium, ammonium nitrate and urea. The process is highly energy demanding and the over-application of industrial fertilisers results in undesirable greenhouse gas emissions and NO3-contamination of drinking water. Natural biological N-fixation via diazatrophic soil microbes constitutes a vital means of N-fertilisation in the absence of industrial fertilisers. However, a better understanding of the quantitative importance of the microbial N2 fixation capacity of soils is essential to manage agricultural N-fertilisation.

This PhD will develop a new approach for determining the importance of N2-fixation in soils globally based on 15N2 incubations and gas chromatography-combustion-isotope mass spectrometry (GC-C-IRMS) of 15N-amino acids, biosynthesised during laboratory and field incubations. The approach has been found to be highly effective revealing how different nitrogenous amendments are processed differently by the soil microbial biomass (Charteris et al., 2016). The method is readily adaptable as a novel method to assay N2-fiaxtion, with greater sensitivity and specificity compared to existing methods. Once validated, the approach will provide hitherto unobtainable quantitative information on N2 capture and flow in agricultural and semi-natural soils.

Depending on the interests of the student, the effects of different global change variables could also be investigated including warming, elevated atmospheric CO2 concentrations, or the effects of soil degradation in agricultural systems, with the potential for fieldwork in China.

Reference

Charteris, A.F., Knowles, T.D.J., Michaelides, K., Evershed, R.P. 2016. 'Compound-specific amino acid 15N stable isotope probing of nitrogen assimilation by the soil microbial biomass.' Rapid Commun. Mass Spectrom. 30, 1846–1856.

How to apply:

Please make an online application for this project at http://www.bris.ac.uk/pg-howtoapply. Please select NERC Great Western Four Plus Doctoral Training Partnership PhD on the Programme Choice page and enter details of the studentship when prompted in the Funding and Research Details sections of the form.

Candidate requirements: a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK. Applicants with a minimum Upper Second Class degree and significant relevant non-academic experience are encouraged to apply.

Funding: The majority of the studentships are available for applicants who are ordinarily resident in the UK and are classed as UK/EU for tuition fee purposes. A few fully funded studentships across the DTP are available for EU/EEA applicants not ordinarily resident in the UK (please note that this may be subject to change pending post EU referendum discussions). Applicants who are classed as International for tuition fee purposes are not eligible for funding.

Contacts: Prof. Richard Evershed, r.p.evershed@bristol.ac.uk. Contact number: 0117 9287671.

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Type / Role:

PhD

Location(s):

South West England